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[January 4, 1970] Word for the Day: ARPANET

January 4, 2025 Vicki Lucas Leave a comment

by Victoria Lucas

OK, kiddies, the word for today is ARPANET. Well, yes, good point, it’s not a word, is it? It’s an acronym jammed into an abbreviation. But a juicy one.

I found out what it means because Mel (my husband) and I have these friends in Orinda, California (a town east of Berkeley, nice place). Sharon is more of a stand-up comedian than a housewife, who uses her housewifery–-and sometimes herself–-as the butt of her jokes. Dick Karpinski is a fuzzy bear of a man who is the first computer programmer I ever met. We don’t get to their place too often, since it’s off our beaten track between SF/Berkeley and Fortuna that we usually run on the weekends and holidays (or when neither of us has an active temp job in the Eureka area).

Richard Karpinski works for the University of California at San Francisco, supporting users of the IBM 360 and other tasks

At a recent visit, Dick was quite excited, and Sharon was complaining about her “three years of back ironing.” I don’t have much to say about the ironing, but once Dick had explained to me the reason for his excitement I admitted to some buoyancy myself. I wonder how you will feel about it.

With its initial transmission in October last year, ARPANET (Advanced Research Projects Agency Network) is the first large-scale, general-purpose computer network to link different kinds of computers together without a direct connection. Not only that, but different kinds of networks are coming online following this one. But who cares, right? I mean who of us has ever even seen a computer?

The IBM 360 with operator

FAR OUT!

Up to now you could only connect the same kind of computers, and then only by special-purpose cables and outlets in the same building, unless you could connect your computer to a "modem” (modulator-de-modulator) that converts digital (computer talk) to analog (telephone signaling) and back again when connected to your telephone line. The same protocols and hardware can connect a computer to “terminals,” boxes that can interact with a computer but do not have the smarts to actually process data. Multiple people could use the same computer at the same time (the miracle of "time sharing" that Ida Moya talked about a few years back, but again, only at the same site or by telephone. No matter what, connections were direct: point to point and dedicated. If you wanted to interact with another computer, you had to go to another terminal hooked up, directly or via modem, to the new machine.

An electronic translator of one type of signal to another, the modem

But what if you wanted to access multiple other computers from a single terminal? What if you wanted your computer to talk to another, farflung computer of a different make (ie connect an IBM to a CDC?) Here’s where Dick had to bring out his yellow pad and start writing and drawing.

Dick draws a box on his pad. “One computer, right?”* he says. “And here’s another” as he draws another box to make #2. Now you could connect a single terminal to any number of computers using a newly developed "protocol" for connection. (A protocol, drawn as lines from that word toward the boxes, is a set of rules or instructions about how to do something, and it’s above a program, which is more of a detailed list of steps to use when doing something.) Rather than using specific hardware, the protocol allows computers to "speak" a common language, over phone-lines lines… regardless of computer make or location!

As Dick, the “Nitpicker Extraordinaire,” might have written at the top of his pad (I’m a little fuzzy about how the conversation progressed), the first set of computers involved in the evolution of this network would have belonged to the US Department of Defense as part of its Advanced Research Projects Agency (ARPA), an almost direct result of the success of Sputnik. When NASA (National Aeronautics and Space Agency) was formed in 1958, most of ARPA’s projects and funding were moved to that group. That left ARPA with high-risk or far-out projects, such as computer networking. I can't tell you which computers are involved, nor the details of the protocol (even if I understood them) because they're classified. The main reason for the ARPA network is to test the survivability of communications in the event of a nuclear war. Because if one big computer is destroyed, someone could just use their terminal to contact a different one to complete a process.

Talk to any computer anywhere, without a telephone

An ARPANET processor

While this exciting technology is limited to the ARPA for the moment, technology tends to spread to civilians eventually. Just think about it! The ARPA network and others like it will make it possible to distribute programs and data widely without printing it out and mailing it. As long as a computer can talk back, you can get and send data from and to it. Even more amazing, the initial transmission speeds showed that messages were being sent to a place 350 miles away 500 times faster than local data was traveling before. It was so fast that the initial speed caused a system crash, followed by a rebuild to handle the velocity, all during the very first transmission. It's not faster than light, but it's a darn sight better than having a computer operator working on far-out national research projects for ARPA fall asleep on his or her keyboard waiting for an answer.

What miracles could you work with a fast, smart, terminal that could connect to any computer in the world? Now that’s exciting!

*To Dick’s other friends. Yes, I know Dick, but I don’t remember any specific conversation like this. Any mistakes or misrepresentations are my responsibility.

[New to the Journey? Read this for a brief introduction!]

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Science / Space Race

[December 14, 1969] West Germany Joins the Space Race: The Azur Mission

December 14, 2024 Cora Buhlert Leave a comment

by Cora Buhlert

One Large Step

Last month, in the early hours of November 8 to be precise, West Germany joined the ranks of spacefaring nations and became the eighth country to put a satellite in orbit with the launch of Azur, also known as German Research Satellite GSR A, to return radiation data from its vantage hundreds of kilometers above the Earth.

A Scout-B rocket lifts off at Vandenberg — The Scout-B rocket carrying Azur lifts off at Vandenberg Air Force Base in California.

Cheers erupted at the newly established German Space Operations Center in Oberpfaffenhofen, Bavaria, when footage of Azur taking off into orbit aboard a NASA Scout-B rocket from Vandenberg Air Force Base in California was broadcast on the great viewscreen in the control center. The fact that the launch had been delayed due to a malfunction and fuel leak during a test countdown was forgotten. And even more cheers erupted, when a ground station in Johannesburg, South Africa, made the first contact with Azur.

Control Center Viewscreen — The great viewscreen at the German Space Operations Center in Oberpfaffenhofen, Bavaria.

Technicians working at consoles at the German Space Operations Center in Oberpfaffenhofen — Technicians at work at the German Space Operations Center in Oberpfaffenhofen

A Massive Project

Azur weighs 71 kilograms and carries the hefty price tag of eighty million Deutschmarks, which includes the establishment of the German Space Operations Center in Oberpfaffenhofen. The satellite is the result of years of development and cooperation between various companies and agencies. On the administrative side, the West German Ministry of Science, the Deutsche Forschungs- und Versuchsanstalt für Luft- und Raumfahrt (German research and testing agency for air and space travel) and the Gesellschaft für Weltraumforschung (Society for space research) and were all involved, as was NASA who supplied the Scout-B rocket that carried Azur into orbit. The experiments and payload were developed by the Max-Planck-Institut für Aeronomie (Max Planck Institute for aeronomics) and the actual satellite was built by a consortium of West German aerospace companies including Messerschmitt-Bölkow-Blohm GmbH and ERNO Raumfahrttechnik GmbH.

Azur satellite in the EMI test chamber — Azur inside an EMI test chamber

The latter is of particular interest to me, because ERNO Raumfahrttechnik GmbH is based in my hometown of Bremen, a city with a long and illustrious history of aeronautics engineering. That is, the ERNO headquarters are in Bremen, but actual production facilities, where parts of Azur were manufactured, are located in an industrial park in Stuhrbaum, only some four kilometers from where I live. As a matter of fact, I have often driven past the drab ERNO production halls, which – very likely intentionally – give little indication from the outside of the cutting edge technology being developed and manufactured within.

Technicians in yellow labcoats surround the Azur satellite — Azur being assembled.

The Future is Bright… and Blue

Putting a satellite into orbit is a triumph in itself, but Azur also has a research mission beyond purely proving that West Germany can do it. Out of hundreds of suggestions, the Max-Planck-Institut für Aeronomie in the small town of Katlenburg-Lindau selected seven experiments, which are supposed to research cosmic radiation, solar particles and their interaction with the magnetosphere, the Van Allen belt and the aurora borealis. That's also the reason why Azur's orbit crosses the polar regions at an inclination of 103 degrees at a height of between 368 and 1445 kilometres.

Azur satellite on the integration stand — Azur on the integration stand.

One issue was that the satellite designs suggested by NASA proved to be unsuitable for Azur, since its mission would take it across the polar regions, where the external solar panels with a fixed setting would not be able to supply sufficient power to the satellite. So German engineers came up with the solution to cover the entire exterior of the satellite with more than five thousand solar cells. The shimmering blue colour of these solar cells also gave the satellite its name: Azur.

Azur satellite being fitted to a Scout-B rocket. — Azur is being fitted to the Scout-B rocket that will carry it into orbit at Vandenberg Air Force Base in California. The distinctive blue colour that gave the satellite its name is clearly visible.

Setbacks and Mysteries

The excitement about the successful launch of Azur was somewhat dampened when it turned out that the settings of many of the scientific instruments aboard had been changed and needed to be reset. The team at the control center in Oberpfaffenhofen reset the all the instruments to their correct parameters, only to find them changed again after every circumnavigation.

There were suspicions that a hostile power, most likely the Soviets, had somehow managed to gain access to Azur and were messing with the settings. The solution to the mystery, however, was far from a James Bond movie, even though espionage did turn out to be at fault, albeit unwittingly. For the control center team noticed that the setting changes always happened whenever Azur was above the US west coast and Alaska, areas where there are a lot of radar stations spying on the USSR. Azur picked up the signals broadcast by those radar stations and misinterpreted them as commands. Requiring a command to be repeated two or even three times before an order is executed would have prevented this issue. However, NASA specialists had assured the West German Azur developers that this wasn't necessary.

Another setback occurred last week, when the onboard magnetic data storage tape recorder failed, so that the data collected by Azur can only be broadcast in real time now. Luckily, a network of German and foreign ground stations means that eighty percent of the data can be received anyway, so the failure of the onboard recorder is only a minor inconvenience.

Azur ground station in Northern Finland — One of the Azur ground stations in Northern Finland beyond the Arctic Circle.

Space Research in East and West Germany

Azur is projected to collect and broadcast data for at least one year. And though Azur was West Germany's first step into space, it won't be the last, for the next West German satellite, DIAL-WIKA is expected to launch in only four months, this time via a French Diamant-B rocket in cooperation with the Centre national d’études spatiales.

Meanwhile, on the other side of the iron curtain, East Germany is a partner in the Soviet Interkosmos program and supplied several of the instruments aboard the Interkosmos-1 research satellite which was launched in October.

The Soviet Interkosmos-1 satellite, which includes instruments manufactured in East Germany.

Interkosmos-1 fully extended — Interkosmos-1 with its solar panels fully extended.

"Space is the final frontier", as the opening narration of a popular American TV-show that has yet to air in Germany puts it. Both East and West Germany have taken their first tentative steps across that final frontier. As we enter the new decade, more steps will follow and maybe we will even see a German astronaut (or cosmonaut) in space one day.

Christmas Lights on Lange Straße in Delmenhorst in December 1969 — As Azur races past far overhead, the Lange Straße in the North West German town of Delmenhost is all decked out for the final Christmas of the decade.

Christmas Lights in the Lange Straße in Delmenhorst — Another look at the Christmas lights in the Lange Straße in Delmenhorst.

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Science / Space Race

[December 6, 1969] Here comes the Sun (and Moon) — Orbiting Solar Observatory, Apollo, ESRO, and Explorer 41!

December 6, 2024 Gideon Marcus Leave a comment

[New to the Journey? Read this for a brief introduction!]

by Gideon Marcus

With the Apollo missions taking so much of our attention (there were four flights this year), it is understandable that unmanned missions and science have gotten short shrift. I'm going to try to address this oversight now.

Far out!

Do you remember Pioneer 6 (launched Dec. 16, 1965) and Pioneer 7 (launched Aug. 17, 1966)? They are deep space probes designed to observe the Sun from widely different vantage points. In fact, we've been a bit remiss: since '66, two more identical Pioneers have gone up: Pioneer 8 (December 13, 1967) and Pioneer 9 (November 8, 1968). A fifth and final Pioneer was launched August 27, 1969, but its carrier rocket exploded. The loss of that one is pretty bad; whereas the others are all spread out fairly equidistantly around the Sun, more or less as far away from it as the Earth, Pioneer "E" was going to be put in an orbit that kept it close to Earth, where it would be used to give as much as a two-week warning of dangerous flare activity.

Nevertheless, NASA is blazing along with four satellites. Indeed, thanks to the longevity and spread-out positions of Pioneers 6 and 7, they were able to perform an unique experiment. On Nov. 6, the two satellites were 175 million miles apart on a common line with the Sun, and scientists observed the difference in behavior of solar wind particles due to their passage through space in opposite directions. In a similar vein, on Dec. 2, when the spacecraft reached points on a common spiral line leading out from the Sun (the star rotates, so it flings out particles in a spiral rather than linear fashion), scientists measured different kinds of solar particles coming from the same events on the Sun.

We'll have to wait for the journals to publish any papers, but this is the kind of large-scale, long-term science made possible by the Pioneer probes!

Another cool example of Pioneer science

Far in!

While the Pioneers study the Sun far from Earth, there are a host of spacecraft monitoring our home star from Earth orbit. For instance, we haven't talked about the Orbiting Solar Observatories (OSOs) for a while, but there have been six so far. They were the first heavy satellite series to be launched by NASA, providing nearly continuous coverage of the Sun since 1962, in wavelengths we can't observe from Earth because they are blocked by the Earth's atmosphere: ultraviolet, X-Ray, and gamma ray.

Why was the Sun such an early focus? Three major reasons: 1) understanding the dangers posed by flares and their relation to the high energy particles trapped by Earth's magnetic field is critical to ensuring astronaut safety, 2) surveying the Sun and comparing changes on the solar surface with fluctuations of space weather near Earth tell us both about the interactions of the two as well as the nature of both, and 3) the Sun is the closest star at hand, and what we learn about the Sun as a star can be applied to the millions of other stars we can observe.

The revelations OSO have given us are not easily conveyed. It's not like Explorer 1, which discovered the Van Allen Belts—a hitherto unexpected phenomenon—or the TIROS weather satellite, which discovered storms we hadn't even known about. Rather, they give us a huge body of data with which we can refine our understanding of how the Sun works, and also so that we can better predict space weather. What's called "basic research."

OSO 1 operated continuously from March-May 1962, and intermittently on to August 1963, returning data on 75 solar flares—most importantly, what events preceded, succeeded, and coincided with them in many different wavelengths, a fingerprint of an eruption, so to speak.

(ground-taken picture of the Sun flaring)

OSO 2 expanded its coverage to the corona, that bright bit of the Sun you can only see during a lunar eclipse. Its launch was delayed until February 3, 1965 because the original OSO B was damaged in a launch explosion, April 14, 1964, that killed three technicians! Though OSO 2 returned data for nine months, I can't find a single article on the Sun that stemmed from it. There's one on about 20 other stars observed by the satellite, though, and the difficulties of seeing through the Sun's glare to them.

OSO 3, the one that launched March 8, 1967, and not the one that failed to orbit in August 1965, was more successful. It returned interesting solar data, for instance finding solar X-ray sources that weren't flares, determining that the chromosophere (visible surface) didn't necessarily heat up before a flare, and monitoring the change in the solar spectrum over the course of its 28-day rotation.

And the onboard gamma ray experiments told us a lot about the universe. For instance, the torrent of gamma rays streaming in from the universe is highly confined to the galactic plane, and particularly toward the Milky Way's core, which means it must be galactic in origin. OSO 3 also observed X-ray bursts from a star (maybe stars) that isn't the Sun: Scorpius X-1, later determined to be a neutron star, and Lupus XR-1 (which may or may not be the same source—the literature is unclear). The satellite stopped working just last month.

OSO 4 went up October 18, 1967, and was the first OSO to carry an international experiment—a University of Paris device that measures the Sun in the ultraviolet frequency that best shows solar activity ("Lyman-alpha"). Indeed, it was the first OSO to scan the Sun in ultraviolet at all. Also really cool is that its X-ray resolution is such that it could watch flares in X-ray wavelengths as sharply as we could see it on the ground in the visual spectrum, so scientists could make one to one comparisons.

You'll note the use of past tense—the satellite is still in orbit, but its tape storage failed in May 1968, and last month, OSO 4 was ordered into standby mode.

That brings us to the OSOs we haven't covered yet. OSO 5 went up on January 22, 1969, and has the ability to scan the Sun in the X-ray range more quickly and thoroughly. OSO 6 went up August 9. I don't have too much to say about them because it's too early for papers. NASA reports both did their jobs fine, and they're still operating. Like OSO 3 did, they not only study the Sun but also galactic X-ray sources…so stay tuned.

Small satellites are doing their part, too. For instance, Explorer 41, the latest in the Interplanetary Monitoring Platform series, launched June 21 into a high orbit that goes almost halfway to the Moon. The Sun this satellite examined has been unusually quiet, an expected trait of the "solar maximum"—the time in the Sun's 11-year cycle of highest output. On the other hand, low-energy galactic cosmic rays rates fluctuated more than usual, and interplanetary conditions appeared to be more disturbed. The satellite is still operating.

Finally, and only tangentially related to the Sun, there are the missions of Aurorae and Boreas, launched October 3, 1968 and October 10, 1969, respectively under the auspices of the European Space Research Organization (ESRO). They report on the brightness of Earth's aurorae, the composition and temperature of the ionosphere, and the charged particle environment in orbit. The first satellite is still working just fine, but Boreas went into a lower than expected orbit, and it reentered on November 23rd. Still, the mission was deemed successful.

Rocks to dig

Veering back into the manned space program, there was some exciting coverage during the Apollo 12 flight that I didn't have a chance to relate. As Conrad, Bean, and Gordon finish their three weeks in quarantine (joined on Dec. 2 by 11 scientists and technicians who had accidentally been exposed to lunar samples), this is a good time to talk about what we've learned from Moon rocks brought back by the Apollo 11 astronauts.

Walter Cronkite had, as a guest on his programming, Dr. John O' Keefe—a geologist at NASA's Goddard Space Center. The visibly excited O'Keefe stated that the most extraordinary aspect of the Moon rocks is that they are deficient in nickel and cobalt as compared to the Sun, that latter body presumably being representative of the nebula that originally coalesced and formed our solar system.

Why is that significant? Well, the Earth's crust is similarly lacking in nickel and cobalt (and other "precious metals" that dissolve easily in iron, collectively called "siderophiles"). We know Earth has a dense iron core because nothing else would account for the planet's mass with respect to its volume, and also, it explains why the planet has a magnetic field. While our planet was first cooling, it makes sense that the siderophiles melted and mostly sank to the center of the planet.

The Moon has no core—we know this because its density (volume divided by mass) is too low, and it has no appreciable magnetic field. That the Moon's surface rocks correlate to Earth's surface rocks, and because its density appears to be constant from crust to center, that suggests that the Moon was somehow formed from Earth's crust. It is, in fact, a piece of our planet's outer surface that somehow spun off into orbit and formed its own little, low-density world.

What causes this is still unknown. Perhaps the Earth was spinning so fast when it was formed that its middle flew off. Or maybe a rogue planet smashed into the Earth. What we do know is that the composition of the Moon rocks puts paid the hypothesis that the Moon formed separately from and at the same time as Earth, since we'd then expect its crust's composition to either be more like that of the Sun, or for our moon to have a dense core.

We also know that whatever created the Moon happened quite early in Earth's history. The lunar rocks have been dated as 4.6 billion years old. That's very close to the estimated age of the Earth. What I found particularly exciting is that the Moon rocks must be the very oldest rocks we've ever encountered, except maybe for meteorites. That's because erosion and vulcanism are constantly erasing the Earth's surface, and the oldest rocks I know of down here are somewhere around 3 billion years old.

As we continue to explore the cosmos, we shall find more data points with which to create an holistic view of the universe, something that would be impossible were we to stay Earthbound. I am happy that I live in the Space Age, when our scientific knowledge is expanding exponentially. Who knows what new discoveries 1970 will bring!

[New to the Journey? Read this for a brief introduction!]

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Science / Space Race

[August 8, 1969] Two by Four (Mariners 6 and 7 go to Mars)

August 8, 2024 Gideon Marcus Leave a comment

by Gideon Marcus

Into the Wild Black Yonder

Ten years ago, when we started our planetary series of articles, none of other worlds in our solar system had been explored. Since then, five intrepid spacecraft have toured two planets. Mariner 2 and Mariner 5 probed Venus, returning the revelation that the shrouded world is a seething cauldron. Mariner 4 returned the first pictures of the Red Planet, shocking humanity with images of Moonlike craters and reports of a vanishingly thin atmosphere, dashing forever the vivid, science fictional conception of Mars as an inhabitable world.

Now, twin Mariners 6 and 7 have flown by Mars, dramatically increasing what we know about the fourth planet. While we'll never get back that fantasy so elegantly woven by Edgar Rice Burroughs and Leigh Brackett, the new Mars is also not a blasted husk either.

Distant views of Mars, as seen by Mariner 7 as it approached the planet

The Next Generation

Despite the blow to morale given by Mariner 4, Mars still seemed like the most hospitable place for life to have arisen apart from Earth. After all, are there not microorganisms living in the harsh environments of Antarctica and at the bottom of the sea? Even though the Martian atmosphere is just 1% as thick as that of Earth, this is still plenty dense compared to, say, the Moon. Moreover, Earth's atmosphere is just 1% that of Venus. Who's to say when an atmosphere is "thick enough"?

So, just a few months after Mariner 4 flew past Mars, Mariners 6 and 7 were authorized. At first glance, they look a lot like their predecessor, but the differences are profound—both internally and externally.

From top to bottom: Mariners 2, 4, 5, and 6/7 (note the family resemblance of the last three—Mariner 5 was actually a modified Mariner 3/4 backup!)

First, the insides: the new Mariners are the first spacecraft made only to examine their target planet. All of the prior Mariners had experiments for monitoring the interplanetary environment—solar wind, magnetic fields, that sort of thing. Mariners 6 and 7 carry two TV cameras (one narrow, one wide-angle), an infrared radiometer (to measure the temperature of Mars), and ultraviolet and infrared spectrometers (to determine the chemical makeup of the Martian atmosphere and surface). That's it.

As for the outsides, since 1965, when Mariner 4 passed by the Red Planet, there has been a revolution in communications technology. Not only do the new Mariners carry more powerful transmitters and antennas, but with the construction of the new 210 foot antenna at Goldstone, supplementing the old 85 footers, data can be transferred between the spacecraft and Earth at a rate more than 2000 times the 8.33 bits per second speed of Mariner 4. It also helps that Mars is closer to Earth this time around, and that the rocket carrying Mariners 6 and 7 is the beefy new Atlas Centaur, which can loft more weight than the old Atlas Agena so the onboard electronics can be heftier and thus more capable.

The 210' "Mars Dish" at Goldstone, California

What this means for us on the ground is that instead of sending back just 22 images of Mars, the new Mariners could transmit hundreds of pictures, all while returning real-time spectrographic and radiometer data. All of this aided by the installation of the first computer equipped on an interstellar probe, capable of remembering 128 "words" some 22 characters in length. And that computer can be reprogrammed on the fly from Earth!

On their Way

Jet Propulsion Laboratory, the same folks who built the other Mariners, assembled four spacecraft for the mission. The first was a stay-at-home test model, the second a source of spare parts. The other two were redundant probes—an understandable precaution given the loss of Mariners 1 and 3. However, the twin ships weren't entirely redundant; Mariner 6 was targeted to fly over the Martian North Pole while #7 was aimed over the South Pole.

Problems with the spacecraft began before liftoff. Mariner 6's Atlas rocket, which maintains its structure through internal fuel pressure, sprung a leak and began to deflate like a balloon. It had to be replaced with Mariner 7's rocket, and a new one ordered from Convair. This did not delay the launch, however (which had to go at a set time to reach Mars with a minimum of fuel use), and Mariner 6 blasted off on February 24th. Mariner 7 took off on March 27, but because of its course, was set to reach Mars just five days after its sister.

The launch of Mariner 7

Both rockets performed beautifully, requiring only minor mid-course corrections early in the flight to ensure they zoomed close by the fourth planet. There were some minor technical problems: The radio on Mariner 6, used to determine range from Earth, kept locking on its own signal rather than Earth's, making it useless. It fixed itself later in the flight, however.

Similarly, the star tracker designed to keep Mariner positioned properly lost sight of Canopus. After weeks of engineers scrambling to find an alternative guiding star (they even tried the Large Magellanic Cloud, but the galaxy was too diffuse to be useful), that system fixed itself, too. Finally, the onboard solar sensors that told how much sunlight was hitting Mariner 6's power panels, began reading too low. Was the Sun going out? No. The sensors had just drifted out of calibration.

Mariner 7's only issue was a radio receiver that dropped to about 20% of its sensitivity, apparently due to cold. Ground controllers switched it to high power, which warmed the thing up and fixed it.

Thus, its vexing teething pains dealt with, NASA now had, for the first time, two fully operating probes with which to explore Mars.

The Great Galactic Ghoul

On July 29, even as Mariner 6 was finishing the transmission of 33 low-resolution approach images, Mariner 7 suddenly began spinning wildly, all of its scientific data telemetry channels scrambled. Had an asteroid hit the spacecraft? Had there been an instrument explosion or some kind of short circuit? Was there some kind of Great Galactic Ghoul guarding the Red Planet? No answer was quickly forthcoming.

Collage of Mariner 6 images as it approached Mars

Nevertheless, engineers raced to salvage the mission—with Mariner 7 arriving shortly after its sister, and from a more favorable angle, the JPL science team wanted the spacecraft's experiments all in working order.

Cautiously, computer engineers went over every bit of code and methodically tested all of Mariner 7's instruments. They were in working order, but because of the accident, uncalibrated and useless. How to get real data points to use to base the radiometer and spectrometer data against?

Engineers at the Mariner control center at JPL

As it turned out, the two TV cameras on board were in good order and unaffected. By pointing them at Martian targets and using the data they returned, it was possible to calibrate the other experiments. And so, just in the nick of time, Mariner 7 was ready, come close encounter time, to do some real science.

Exploring Barsoom

So what did the two probes find as they whizzed past Mars, almost grazing it from a scant few thousand miles away?

Well, at first they seemed to confirm Mariner 4's findings. There were all the craters in stark detail. There was no evidence that there had ever been widespread water—absent was the erosion one would expect from oceans or even rivers.

A lunar landscape, courtesy of Mariner 7

On the other hand, if Mars wasn't Earth's twin, neither was it sister to the Moon. As each Mariner went behind the planet, beaming radio signals through the Martian atmosphere, it was confirmed that surface pressure was around 7 millibar—a refinement rather than a revelation. But they did determine that carbon dioxide makes up a greater percentage of the air than even on Venus. Nitrogen was completely absent, which was a surprise. So was ozone, which means that the surface is fairly baked by ultraviolet—again, a strike against life on the planet.

The Red Planet is not quite geologically moribund, however. The vast Hellas region, smooth of craters, and a region of convoluted terrain akin to the American Badlands, suggests some kind of volcanic activity in comparatively recent times.

Unlike the Moon, clouds scud across the Martian sky, mostly composed of dry ice. While it may not rain on the planet, it does frost, and maybe even snow ice and carbon dioxide. The climate changes with the seasons, with polar (dry?) ice caps spreading and receding. The tropical highs soar to a balmy 60 degrees, but the polar lows plunge to 240 degrees below zero.

A view of the Martian North Pole, snapped by Mariner 6—note the ice cap

Thus, Mars is an inhospitable place…but it if it lacks biological life, it is nevertheless an interesting living, breathing planet in its own right.

What's next?

Mariners 6 and 7 are still functioning, and their onboard systems should work until at least 1971. Not only might they return pictures of any asteroids or comets that drift by, they will also constitute an experiment in and of themselves. As they drift through the solar system, terrestrial scientists will measure variations in the timing of their telemetry signals and use them to prove General Relativity—something that requires great distances to detect subtle theoretical variations.

As for successors, a Martian orbiter is already in the works for the 1971 alignment, and in 1973, a probe will use the gravity of Venus to enable a probe to fly by and then visit, for the first time, Mercury, the closest planet to the Sun.

And also in 1973, the Viking orbiter/lander combo, successor to the overlarge Voyager project, will give Mars a real look.

The 1971 Mars Orbiter

If the 1960s were the dawn of interplanetary science, the 1970s will see its maturity. I find this as momentous an achievement as footprints on the Moon.

I can't wait to rewrite all of the articles in our solar system series!

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Science / Space Race

[July 20, 1965] No War of the Worlds After All? (Mariner IV reaches Mars)

July 20, 2020 Kaye Dee 5 Comments

by Kaye Dee

Just a few days ago, on July 15, NASA’s Mariner IV space probe made history by being the first spacecraft to successfully reach the planet Mars, capturing images of its surface. These are the first close-up views of another planet in our solar system and the initial pictures suggest that, despite what science fiction would have us believe, Earth won’t have to fear an invasion from Mars any time soon!

The first close-up image ever taken of Mars, showing the limb of the planet and a haze-like feature that might be clouds. The smallest features in this image are roughly 3 miles across, but there's no sign of Martian canals!

The Canals of Mars

Mars has been an object of intense scientific and popular fascination since the last century, when telescope observations first suggested that the planet was potentially Earthlike, since it showed polar caps and surface changes that appeared to represent seasonal variations due to the growth and die-back of vegetation. Then, in 1877, the Italian astronomer Schiaparelli observed what he called “canali” on Mars. He apparently meant grooves or channels on the Martian surface, but his work was translated into English as “canals” and some astronomers took this literally to mean that he had observed structures that were the work of intelligent beings.

A section of one of Percival Lowell’s maps of Mars, published in his 1895 book Mars. The complete map depicted 184 named canals marked on it using numbers.

By the end of the 19th Century, the idea that there is intelligent life on Mars had taken hold, thanks particularly to the writings of American astronomer Percival Lowell (the same Percival Lowell who is also associated with the discovery of the Planet Pluto!) He believed in a Martian civilisation that had constructed vast networks of canals to bring water from the planet’s poles and wrote several books and innumerable newspaper articles detailing his observations of canal systems on the Red Planet. Science fiction stories like H.G. Well’s War of the Worlds, first published in 1897, and Edgar Rice Burroughs' "Barsoom" series further encouraged popular belief that there was intelligent life on Mars and generated something of a ‘Mars mania’ that has grown across the 20th Century.

Cover of the August 1927 issue of Amazing depicting the iconic Martian machines from Wells' War of the Worlds. This powerful story has been re-interpreted on radio and film and has had a tremendous influence in shaping popular perceptions of life on Mars.

The Mars Race

Most scientists have accepted for a decade or more now that modern telescope observations indicate that it is unlikely that higher forms of life will be found on Mars after all. Yet the fascination with Mars has been so strong that it’s not surprising the planet became an early target for space exploration, after the Moon. The Soviet Union started the race to Mars in October 1960, with “Marsnik” 1 and 2. We don’t know much about these probes, but it seems they both failed even to reach orbit. The USSR’s Mars 1 flew past Mars in June 1963, but it had stopped sending back data in March. Sputnik 22 and Sputnik 24, both launched around the same time as Mars 1, are also believed to be elements of a failed Mars mission. Zond 2, launched just 2 days after Mariner IV, is also assumed to be an attempted Mars mission, though it, too, ceased transmitting en route. Clearly, getting to Mars is hard. Mariner IV was meant to be a twin mission with Mariner III, but that mission also failed at launch.

Even though Mars 1 ceased transmitting long before it reached Mars, the USSR still celebrated it as an achievement on its 1964 Cosmonauts Day stamp.

Mariner IV was launched on an Atlas Agena rocket from Cape Canaveral at 12:22 GMT on November 28, last year. It has an octagonal magnesium frame, 50 inches across the diagonal and 18 inches high, which houses the electronic equipment, propulsion system and attitude control gas supplies and regulators. Four solar panels, containing a total of 28,224 solar cells, are attached to the top of the frame. They are able to generate 310 watts of power at the distance of Mars from the Sun. Mariner also has two antennae for transmitting data back to Earth: An elliptical high-gain parabolic antenna and an omnidirectional low-gain antenna, mounted on a seven-foot, four-inch-tall mast next to the high-gain antenna.

Mariner IV is an incredibly sophisticated space probe for its size, packed with scientific instruments, plus its television camera system. Its design is a radical departure from the conical design used for the Ranger Moon probes and NASA's successful Mariner II mission to Venus.

Deep Space Laboratory

For its relatively small size, Mariner IV is a spacegoing scientific laboratory, designed to measure the conditions in deep space between Mars and the Earth and in the vicinity of Mars itself. Its scientific instruments include a helium magnetometer to measure the characteristics of the interplanetary and planetary magnetic fields; an ionization chamber/Geiger counter, to measure the charged-particle intensity and distribution in interplanetary space and in the vicinity of Mars; a cosmic ray telescope, to measure the direction and energy spectrum of protons and alpha particles; a solar plasma probe, to measure the very low energy charged particle flux from the Sun, and a cosmic dust detector, to measure the momentum, distribution, density, and direction of cosmic dust. Although the Geiger counter failed in February and the plasma probe's performance is degraded, the other instruments are all working well.

Mariner IV's 'endless loop' magnetic tape recorder. Its 330ft of tape has a storage capacity of 5.24 million bits – right at the cutting-edge of recording technology!

Probably the most important instrument on Mariner IV, and certainly the one of the most interest to the public, is its television camera, designed to obtain close-up images of the Martian surface. The camera is mounted on a scan platform at the bottom centre of the spacecraft and consists of 4 parts: a Cassegrain telescope with a 1.05° by 1.05° field of view; a shutter and red/green filter assembly with 0.08s and 0.20s exposure times; a slow scan vidicon tube which translates the optical image into an electrical video signal, and the electronic systems required to convert the analogue signal into a digital signal for transmission. During the fly-by of Mars, all the television images and the data gathered by the scientific instruments were stored on an ‘endless loop’ four-track magnetic tape recorder for later transmission back to Earth.

First Pictures from Another World

On July 15 Mariner 4 passed within 6117 miles of Mars, spending just 25 minutes doing visual observations of the planet’s surface. During that brief time, its television camera captured 21 full pictures and part of a 22nd, the first ever close-up images of the surface of another planet. Each photo covers an area of about 77 square miles. It takes about 10 hours to transmit each image back to Earth and each picture is being transmitted twice to ensure that all the data is correctly received.

The second Mariner IV image released by NASA shows the border of Elysium Planitia and Amazonis Planitia. Taken from around 9,940 miles, the picture is about 310 miles across and 560 miles from top to bottom because the surface is curving away. North is up and the sun is illuminating the area from the southeast.

Only three of the Mariner Mars images have so far been released, but already they have disappointed scientists and the public alike by putting an end to any hope of finding intelligent life on the Red Planet. What they have so far revealed is a world that looks more like the Moon than the Earth, with no signs of water, vegetation or animal life. When this is coupled with the findings of the scientific instruments, which show that Mars has an atmosphere of carbon dioxide with only a very low atmospheric pressure (only a fraction of that found on Earth, which was quite a surprise to scientists), a daytime temperature of -148 degrees F and no magnetic field (meaning that the surface of the planet is bombarded by the solar wind and cosmic radiation), it means that the prospects for any kind of life on Mars are very small indeed. However, Mariner’s images only cover just 1% of the Martian surface, so perhaps we should not entirely give up hope that future missions will find Mars more exciting and scientifically interesting than it seems right now. After all, the pictures have not yet revealed the cause of the apparent seasonal changes observed from Earth….

The third image we have seen so far shows the Orcus Patera region in western Amazonis Planitia. It was taken with the sun only 13 degrees from vertical, so the topography is hard to make out, although some raised areas can be seen at upper left. The image is 202 miles across and 319 miles from top to bottom. The resolution is about 1.9 miles and north is up.

Australia Plays Its Part

Australia has played a crucial role in the Mariner IV mission, with its first images being received at the Tidbinbilla tracking station outside Canberra. NASA’s second Deep Space Network station in Australia, Tidbinbilla became operational in December 1964 so that it could support the Mars mission. As the signal from Mars is very weak, the station asked the civil aviation authorities to divert any aircraft that might interfere with the reception of the signals from Mariner at the time of the fly-by. This resulted in an amusing incident: at the critical time, just when Mariner 4 had gone behind Mars, the direct phone from Canberra Airport rang and the station was asked if it was experiencing interference from a UFO! It now seems that the offending object was a weather balloon and not a Martian saucer come to check on what the Earthmen are up to.

Nestled in a secluded valley, for protection from radio interference from nearby Canberra, NASA's Tidbinbilla Deep Space Network Station received the first images of Mars from Mariner IV. Australia is host to a growing number of NASA tracking stations covering all its space tracking networks.

A Role for a Radio Telescope

Australia’s Parkes radio telescope, the largest fully steerable radio telescope in the world, also played a role in receiving Mariner IV’s Mars images. NASA is basing the design of its new 210 ft antennae for the Deep Space Network on that of the Parkes telescope. As a demonstration of its tracking capabilities, Parkes has also tracked Mariner IV and received some of its images from Mars. Its greater antenna size, and therefore better reception capabilities, mean that its images will be more detailed than those received by the 85 ft dishes at Tidnbinbilla and other NASA stations and they will enhance the overall quality of Mariner IV’s Mars pictures when the Parkes and Tidbinbilla images are combined. I hope that NASA will release the rest of the Mariner images soon: even if they have dashed almost a century of Martian fantasies, they are revealing a planet that is very different from what we have expected and I wonder what further surprises might be in store for us as we explore more of Mars and the rest of the Solar System….

The world-leading radio telescope developed by the Commonwealth Scientific and Industrial Research Organisation, Australia's national civil scientific research body. Located near Parkes, New South Wales, this astronomical instrument is also proving its value as a space tracking facility and I'm sure that NASA will call on it again in the future for further tracking support

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Science / Space Race

[February 20, 1965] Twice as nice (Ranger 8)

February 20, 2020 Gideon Marcus 1 Comment

by Gideon Marcus

Last time, I talked about how America's space program has reached a level of reliability that you can…well…rely on! Three days ago, at 1:05 PM EST, February 17, 1965, the eighth in the Ranger moon probe series took off successfully from Cape Kennedy.

Really, a Ranger has three launches. First, the Atlas-Agena launched Rancher from the surface to a "parking orbit" 115 miles above the Earth. Fourteen minutes after that, the Agena upper stage fired again for 90 seconds, changing Ranger's orbit such that its trajectory would intersect with the Moon. Finally, the next day, Ranger executed a mid-course burn, firing its onboard engines for 59 seconds. Now, instead of missing the Moon by 1,136 miles, it was set to hit Mare Tranquilitas at 4:57 AM EST, February 20.

That target, one of the darker areas of the Moon known as a "sea", was not easily decided upon. Since Ranger 7 had impacted the Sea of Clouds, some scientists wanted Ranger 8 to hit a different kind of lunar terrain, perhaps the highlands further north. Others were keen on exactly duplicating Ranger 7's mission so as to have two sets of data they could compare. Ultimately, however, program manager George Mueller chose a target that would be support the Apollo mission — a flat area close to the equator.

Ranger 7 had started started its footage just ten minutes before impact. Ranger 8, on the other hand, started shooting 23 minutes before the crash so that its first images would match the resolution that could be gotten from the best Earth-based cameras. The moment of truth was a tense one — Ranger 6 had died right at the moment it turned on its TV cameras.

But Ranger 8 performed beautifully, taking a broader swath of photos than its predecessor and revealing an unprecedented wealth of information on the lunar surface before it kamikazed into the Sea of Tranquility at just under 6,000 mph. Before its demise, it had returned 7,000 photos of the lunar surface.

At first blush, it doesn't look like we've learned much new. The pictures Ranger 8 returned might well be swapped with those from Ranger 7 and none would be wiser. On the other hand, it is nice to know that the Seas of the Moon are consistent.

What we still don't know is how safe the Moon is to land on. Drs. Urey, Kuiper, and Whitaker all believe the lunar soil will hold a spacecraft, the latter two saying that the Ranger data say the Moon's dirt is something like crunchy snow in texture. But it won't be until the soft-landing Surveyors start going to the Moon next year that we'll have real answers.

Originally, there were going to be up to seventeen Rangers. However, the lack of success of earlier missions, and the fact that new spacecraft in the form of Lunar Orbiter and Surveyor will be online shortly, has reduced the remaining Ranger missions to just one.

As a result, it is likely that Ranger 9 will be given a more purely scientific mission, perhaps to some place no Apollo crew will visit. Either way, given America's current track record, and that of Ranger, specifically, we can all hope it will be a crashing success!

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Science / Space Race

[February 18, 1965] OSO Exciting! (February 1965 Space Roundup)

February 18, 2020 Gideon Marcus 1 Comment

by Gideon Marcus

Remember the early days of the Space Race, when launches came about once a month, and there was plenty of time to ruminate over the significance of each one?

Those days are long past, my friends. Like every other aspect of this crazy modern world we live in, the pace of space missions is only accelerating. Just look at this grab bag of space headlines, any one of which might have been front page news just a few years ago:

Staring at the Sun

Three years ago, NASA launched the first of its "Observatory Class" satellites, the 200 kg Orbiting Solar Observatory (OSO). Its mission was unprecedented: to get the first long-term observations of the Sun in all of the frequencies of the electro-magnetic spectrum, not just the narrow windows visible from the Earth's surface.

For two years, OSO gazed at the Sun with its thirteen instruments, dutifully reporting its findings to the ground. The observatory revolutionized our understanding of our neighborhood star, particularly in finding the correlation between solar flares and the little microflares that precede them.

OSO 1 went silent last May. Like nature, NASA abhors a vacuum — at least one without satellites floating through it! So on February 3, 1965, OSO 2 sailed into orbit to pick up where its predecessor had left off.

The new observatory only has eight instruments, but given that the weight of the craft is similar to that of OSO 1, I have to believe the new load-out is intentional. Moreover, OSO 2 has some neat developments. Its Ultraviolet spectrometer, Solar x-ray and UV telescope, and White-light coronagraph are all mounted on the "sail" of the spacecraft, and they can scan the disk of the sun from end to end, like a TV camera. That should allow for more precision in the measurements.

Also, OSO 2 has a digital telemetry system rather than the analog FM system of OSO 1. Digital systems are far less prone to error, and more information can be sent over any given length of time. The new system can dump 3 million bits of data in just 5.5 minutes.

Finally, OSO 2 is smarter — it can accept some 70 commands from the ground instead of just 8. Just what NASA scientists do with those commands, I don't know. Maybe OSO brews great coffee.

The most important thing about OSO 2 is the timing of its launch. Every 11 years, the Sun completes an output cycle, warbling from active to inactive status. 1965 is the Solar minimum, and this year marks a concerted international effort to watch the Sun from many different vantage points to take advantage of the opportunity.

You can bet OSO 2 will have some interesting data for us come 1966!

Requiem for a Vanguard

Hands over hearts, folks. On February 12, NASA announced that Vanguard 1 had gone silent, and the agency was finally turning off its 108 Mhz ground transceivers, set up during the International Geophysical Year. The grapefruit-sized satellite, launched March 17, 1958, was the fourth satellite to be orbited. It had been designed as a minimum space probe and, had its rocket worked in December 1957, would have been America's first satellite rather than its second. Nevertheless, rugged little Vanguard 1 beat all of its successors for lifespan. Sputniks and Explorers came and went. Vanguards 2 and 3 shut off long ago. Yet the grapefruit that the Naval Research Laboratory made kept going beep-beep, helping scientists on the ground measure the shape of the Earth from the wiggle and decay of Vanguard's orbit.

The satellite's cry had slowly become weaker as its solar cell-charged batteries failed. Finally, some time last year, Vanguard could be heard no more, though NASA kept listening for several more months. It's not all sad news, however: Vanguard 1 will remain in orbit for hundreds of years more, and it can still be optically tracked. That means it still has a long, useful life ahead of it, even now that it is mute.

Whole World in its Eyes

Here's a little TIROS tidbit. Remember TIROS 9? The first weather satellite launched into a polar orbit so it can see the whole Earth once a day as the planet rotates underneath?

We now have the very first picture of the world's weather. It won't be the last:

The joys of being regular

There was a time when space was a hit-and-miss affair. Seemed every time I opened the paper, there was news of yet another rocket blowing up. These days, we can practically take success for granted. Ranger 7 broke a six mission losing streak, the first two Gemini launches went swimmingly, TIROS has gone nine for nine.

Similarly, the Saturn 1 rocket, the biggest booster ever made, has had an impeccable launch record. The lift-off on February 16 kept the streak going; the eight engine monstrosity delivered what I believe is the biggest satellite ever to be put into orbit.

Called Pegasus, it is an enormous cylinder with giant panels affixed to either side. The panels occupy some 2300 square feet, and their job is to measure the density of micrometeoroids in orbit over the course of a many-year lifespan.

It sounds pretty mundane when you reduce the mission to its bare essentials. Pegasus is like a big fly-catcher, spending its orbit running into space rocks. But it's not the experiment that's so exciting, but the idea that we can now loft giant structures with a single launch. Imagine that Pegasus was actually a space station module, and that it's wings were solar panels. Now imagine assembling a few of them together using a maneuverable spacecraft, perhaps a Gemini derivative…

Yes, America is just on the edge of being in the space construction business.

Scenes to Come

Yesterday (February 17, 1965), the eighth Ranger blasted off from Cape Kennedy, destination: Moon. If we've truly reached an era of reliability, we can expect the craft to hit its target on the morning of the 20th. Stay tuned — you'll read about it here first!

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Science / Space Race

[November 23, 1964] Let’s Go Exploring! (NASA’s latest Explorer satellites)

November 23, 2019 Kaye Dee 2 Comments

by Kaye Dee

I’ve written before about how much I love satellite spotting and this month has given me three new ‘man-made moons’ to watch out for, with the latest additions to NASA’s Explorer scientific satellite program. Each of the new Explorer satellites is very different and their research tasks are all of real interest to me, as I’m concentrating on space physics for my Masters degree. But before I talk about them, I’m excited to share the most recent news from Woomera.

A Textbook Test Flight

On October 20, the second test flight of the Blue Streak stage for ELDO’s Europa launch vehicle took place. After the problems that occurred towards the end of the first test flight, which led to the rocket’s flight falling short of its intended landing area (see June entry), this latest launch was a complete success, demonstrating that the fuel sloshing issue has been solved. The engines fired for the 149.1 seconds, fractionally over their anticipated performance, and the Blue Streak impacted almost 1,000 miles down range. Everyone at the WRE is really pleased (and relieved) with this textbook test flight, as it means that the Europa development program can now keep moving forward. Can’t wait for the next test flight!

Blue Streak F-2 prepares to blast off at Woomera’s Launch Area 6.

But what has really captured my attention this month are the new missions in NASA’s Explorer program (which I last covered on September 6 and October 16). This series of scientific satellites continues to study the near space environment around the Earth and the nature of the Sun, as well as contributing to astronomy and space physics.

Taking a Hit for Science

Explorer 23 was launched on 6 November, using a Scout rocket fired from NASA’s Wallops Island facility in Virginia, from which many satellites in the Explorer series have been launched. Also called S-55C, Explorer 23 is the third in a series of micrometeoroid research satellites. Explorer 13 (launched in August 1961) was the first in the series. It was also known as S-55A, following the failure of its predecessor, the original S-55 satellite (the S standing for Science). Explorer 16 (S-55B) was launched in December 1962. The purpose of the S-55 series is to gather data on the micrometeoroid environment in Earth orbit, so that an accurate estimate of the probability of spacecraft being struck and penetrated by micrometeoroids (very tiny pieces of rocks and dust from space) can be determined.

Explorer 13 was the first micrometeoroid research satellite to take a hit for science.

Each of the S-55 spacecraft is about 24 inches in diameter and 92 inches long, built around the burned out fourth stage of the Scout launch vehicle, which forms part of the orbiting satellite. Explorer 23 carries stainless steel pressurized-cell penetration detectors and impact detectors, to acquire data on the size, number, distribution, and momentum of dust particles in the near-earth environment. Its cadmium sulphide cell detectors were, unfortunately, damaged on lift-off and will not be providing any data. Explorer 23 is also designed to provide data on the effects of the space environment on the operation of capacitor penetration detectors and solar-cell power supplies.

(left) An illustration of Explorer 23 in orbit, showing its modified design compared to its predecessors. (right) Part of the backup Explorer 23 satellite.

Two Satellites for the Price of One Launch

November 21 saw the Explorer 24 and 25 satellites launched together on a Scout vehicle fired from Vandenberg Air Force base in California, which will put the satellites in a near-polar orbit. These two Explorers have been launched as part of the research program for the International Quiet Sun Years (IQSY). Just as the International Geophysical Year took place in 1957-58, during a period when solar activity was at its height, the IQSY is focusing on the Sun in the least active phase of the solar cycle, across 1964-65. This makes it possible to compare the data from Explorer 24 and 25 with earlier observations made from orbit when the Sun was more active. Having the satellites in dual orbits also makes it possible to compare the atmospheric density data gathered by Explorer 24 directly with the radiation data from Explorer 25.

A stamp from East Germany highlighting satellite-based research into the Van Allen radiation belts and other aspects of the near-space environment during the International Quiet Sun Years.

Explorer 24: A Balloon in Orbit

Although the two satellites work in conjunction with one another, they couldn’t be more different! Explorer 24 is a 12-foot diameter balloon made of alternating layers of aluminium foil and plastic film. It’s covered all over with 2-inch white dots that provide thermal control. Deflated and packaged in a small container, the balloon was packed on top of the Explorer 25 satellite for their joint launch and then inflated in orbit. A timer activated valves that inflated the balloon using compressed nitrogen. This process took about 30 minutes, after which the satellite was pushed away from the carrier rocket by a spring.

Explorer 24 hitched a ride to orbit on top of Explorer 25, before being inflated in space.

Explorer 24 is identical to the previously launched balloon satellites Explorer 9 (launched in February 1961) and 19 (launched in December 1963). Explorer 19 was also known as AD-A (for Air Density) and Explorer 24 is also designated as AD-B. All three of the balloon satellites have been designed to provide data on atmospheric density near the perigee (lowest point) of their orbit, through a series of sequential observations as they move across the sky.

Like its predecessors, Explorer 24 will be tracked both visually and by radio, as it carries a 136-MHz tracking beacon. Explorer 19’s tracking beacon failed while it was in orbit, and so it could only be tracked visually by the Smithsonian Astrophysical Observatory’s network of Baker-Nunn telescope cameras. There is one of these stations at Woomera and my former computing colleagues at the WRE’s Satellite Centre in Salisbury, South Australia, assisted with converting its observations into the orbital calculations that the scientific researchers needed.

Explorer 25: Studying the Ionosphere

Explorer 25’s primary mission is to investigate the Ionosphere, make measurements of the influx of energetic particles into the Earth’s atmosphere, studying atmospheric heating, as well as the Earth’s magnetic field. It will be magnetically stabilised in orbit through the use of a magnet and a magnetic damping rod and carries a magnetometer to measure its alignment with the Earth’s magnetic field. One of its particularly interesting tasks will be to study and compare the artificial radiation belt created by the Starfish Prime high-altitude nuclear explosion and the natural Van Allen radiation belts.

Explorer 25 is also known as Injun 4 and Ionosphere Explorer B (IE-B). It is the latest satellites in the Injun series, which have been developed at the University of Iowa under Professor James Van Allen, after whom the Van Allen radiation belts are named. Van Allen himself gave these satellites the name Injun after the character Injun Joe in Mark Twain’s Adventures of Tom Sawyer. The first three Injun satellites were only qualified success and were not actually part of the Explorer program. However, as IE-B, Injun 4/ Explorer 25 extends the research being carried by Explorer 20, that I wrote about in September.

James Van Allen (centre) with a replica of the Explorer 1 satellite, for which he provided the scientific instruments that contributed to the discovery of the Van Allen radiation belts. With him are William Pickering (left), the Director of the NASA’s Jet Propulsion Laboratory and (right) Wernher von Braun, whose team developed the Juno rocket that launched Explorer 1.

Explorer 25 is roughly spherical and almost 24 inches in diameter. It has 50 flat surfaces: 30 of them are carrying solar cells that are used to recharge the batteries that power the satellite. The satellite is also equipped with a tape recorder and analogue-to-digital converters, so that it can send digital data directly to a ground station at the University of Iowa.

Science Streaks Across the Sky

It is simply marvelous how rapidly we are expanding our knowledge of the universe above. Just seven years ago, there hadn't been a single Explorer; now there are twenty five! I’m looking forward to spotting all these science gatherers in the evening sky over the coming weeks — and eventually telling you what they find up there!

[Join us at Portal 55, Galactic Journey's real-time lounge! Talk about your favorite SFF, chat with the Traveler and co., relax, sit a spell…]

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Science / Space Race

[Oct. 16, 1964] Three in One (The next leg of the Space Race)

October 16, 2019 Gideon Marcus 2 Comments

by Gideon Marcus

A whole new ballgame

It's not often that news of the next stage in the Space Race is eclipsed by an even bigger story. Yet that's exactly what happened this tumultuous week, a handful of days so crazy that we halted publication ("STOP THE PRESSES!") to keep up with events.

It all started with "Kosmos 47", launched just after midnight (San Diego time) on October 6. While the Soviets were typically close-lipped about its purpose, from its orbital path, it was suspected that the 24 hour flight was actually an uncrewed test of a new type of Soviet spacecraft.

Sure enough, just six days later, Voskhod ("Sunrise") #1 took off. On board were three cosmonauts: Commander Vladimir Mikahilovich Komarov, civilian scientist Konstantin Petrovich Feoktistov, and civilian physician Boris Borisovich Yegorov.

This is huge news — both the American Mercury and Soviet Vostok space programs ended more than a year ago. Those spacecraft only fit one person. Since then, the United States has been hard at work on both its three-person Apollo lunar craft and its intermediate two-seat Gemini ship. Although Gemini has already flown once, the first crewed flight won't happen until early next year.

And here are the Soviets, already throwing up a three person spaceship! Could they be closer to a Moon mission than we thought?

On their eighth orbit, Voskhod's cosmonauts passed over the United States and radioed, "From aboard the spaceship, Voskhod, we convey our best wishes to the industrious American people. We wish the people of the United States peace and happiness."

Interestingly, a second radio exchange was heard afterwards, during orbit sixteen: the three cosmonauts requested permission to extend the mission beyond 24 hours. The request was denied, and the flight ended just one day after it had begun.

Why is this strange? Well, one of the stated goals of the mission was "Extended medio-biological investigations in conditions of a long flight." And while 24 hours is a long flight by American standards (that of Gordo Cooper in Faith 7 was about a day and a half), the Soviets have been flying day-long and longer missions since Gherman Titov's flight in 1961. Did something go wrong with the spaceship?

It turns out the problem was on the ground. Even as the three cosmonauts were making history in space, the Presidium was holding a vote of no confidence, citing Khruschev's age and health as reasons for his dismissal. Leonid Brezhnev was elevated to Secretary of the Communist Party and Andrei Kosygin was named Premier. When the space travelers landed, they were whisked to Moscow where they must have been quite surprised to meet the new leadership!

Still, regardless of who is wearing the crown behind the Iron Curtain, there is no question that Voskhod was a tremendous accomplishment. The question now is: What will they follow it up with?

Beep Beep, says America

Though perhaps not as impressive to some, the United States maintains the lead in automated space science. Just this month, we launched the two latest Explorer satellites, 21 and 22. And while those numbers seem a lot lower than what the Soviet "Kosmos" series has gotten up to, we have to remember that Kosmos conceals a wide variety of satellites, most of which have never resulted in a scientific paper. They have probably snapped a great many photos of Midwest missile bases, though.

In contrast, the Explorer program is just one of many devoted to returning scientific data from the heavens. Explorer 21, launched on October 4 (seven years after Sputnik) is the second of its type. Also known as Interplanetary Monitoring Platform (IMP) B, its job is the same as that of Explorer 18, launched in last year — to measure the magnetic fields, cosmic rays, solar wind, and charged particles far from the Earth. This helps us understand the physics of the solar system, and it lets us map the electromagnetic "terrain" of the space between Earth and the Moon. The IMPs are blazing a trail for Apollo, making sure it's safe for people out there.

Unfortunately, the third stage on IMP-B's Thor Delta launch booster fizzled, and instead of soaring 160,000 miles from the Earth, Explorer 21 barely gets to 60,000. This is within the hellish Van Allen radiation belts, so even though Explorer 21's nine instruments are performing perfectly, the data being returned tells nothing about the universe beyond Earth's magnetic system.

However, Explorer 22, launched October 10, is doing just fine. It's the last of NASA's first phase of ionospheric explorers, measuring the electron density in the upper atmosphere. Before your eyes glaze, that just means it sees how electrically charged the air is in the layer that reflects radio waves. Such experiments help us better understand how the Sun affects our broadcasts — and allows us to make plans for unusual space weather events.

The satellite, also known as Beacon Satellite B ("A" failed to orbit on March 29) is also the first of NASA's geodetic satellites, measuring the shape of the Earth with tremendous precision. What's neat about Explorer 22 is that the spacecraft is actually quite unsophisticated, just three radio beacons and a laser reflector. More noteworthy are the 80 tracking stations run by 50 scientific groups in 32 countries. These provide a worldwide web, collecting navigational data on an unprecedented scale.

And since it's a civilian probe, we'll probably even share the information with the Communists. You tell me who's winning the Space Race…

[Join us at Portal 55, Galactic Journey's real-time lounge! Talk about your favorite SFF, chat with the Traveler and co., relax, sit a spell…]

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Science / Space Race

[May 30, 1964] Every journey begins… (Apollo's first flight!)

May 30, 2019 Gideon Marcus Leave a comment

by Gideon Marcus

One Step

Humanity took its first halting steps toward the Moon with the (mostly) successful launch of the first Apollo spacecraft into orbit on May 28, 1964. Blasting off from Cape Kennedy's Pad 37B, the sixth Saturn I, biggest rocket in existence, carried a boilerplate, non-functional spacecraft.

The mission marked firsts in several ways. Whereas the previous five Saturns had been topped with Jupiter-C nosecones, SA-6 was the first to prove the actual Apollo structure. Less auspiciously, the flight also marked the first malfunction of the Saturn rocket: 122 seconds into its mission, 24 seconds before planned cut-off, engine #8 prematurely shut down.

But out of the jaws of failure came ultimate success. The other engines continued to fire an additional two seconds, the four inboards shutting down shutting off 142 seconds into flight, the remaining three outboards going dark at Launch + 148. Despite these compensations, AS-101 (the name for the spacecraft) was still flying "low and slow"; the second stage then ignited and compensated for the balky first stage, ultimately delivering the Apollo spacecraft almost perfectly into its planned orbit.

That's Wernher von Braun in the middle; next to him, with the glasses, is George Mueller, who used to run the Pioneer lunar project at STL

Thus, the failure of engine #8 actually proved a blessing in disguise — we now know that the Saturn guidance system works quite nicely. Moreover, given the excellent track record of the first stage's H-1 engines, I suspect the causes of the shutdown will be determined and remedied in short order.

AS-101 will be in orbit about one more day before it plunges into the atmosphere. Like the first Gemini mission (last month), the spacecraft will not be recovered.

SA-7/AS-102 will be a largely identical mission that will test the escape tower, the little rocket that will rescue Apollo astronauts in the event of a launch failure. It is due to go up at the end of August. Crewed spaceflights should happen as early as 1966!

No News is…

In other news, there isn't much news. Since our last update, the Soviets launched Kosmoses 29 and 30 (April 25 and May 18), both of which landed just a week after launch, which suggests they were really spy satellites a la our Discoverer program. Meanwhile, the United States Air Force lofted two birds of its own, a small one on April 27, and a big one on May 19. I'd bet the first one was some a traditional film-return spy satellite (the kind that snaps photos in space and then sends the shots down to Earth for development in a little capsule). As for the second, either it carries multiple canisters, or it's some kind of advanced system — maybe a real-time TV eye in orbit?

By the way, on April 21, I understand an Air Force rocket went boom, and the satellite it was carrying, a navigational Transit was on board. That'd be no big deal…except this Transit was powered by the radioactive decay of plutonium-238. I haven't heard much reporting on the subject, but I sure hope the flyboys are more careful next time!

The Soviets did launch Polyot-2 on April 12. This is a special satellite that is able to change orbits. That could mean that it's a precursor to the next Communist space vehicle (that's the thought advanced in Martin Caidin's recent novel, Marooned) or it could be a spacecraft designed to intercept missiles or other vehicles in space. We won't know for a while, if ever.

Coming Attractions

As we head into the summer, it looks like things will remain pretty calm, unless the Russians pull another surprise out of their hats. The only big event on the horizon is the launch of Ranger 7 in July. After ten straight failures on the way to the Moon, I can't imagine the betting is particularly good for this flight.

But hope springs eternal… See you then!

[Come join us at Portal 55, Galactic Journey's real-time lounge! Talk about your favorite SFF, chat with the Traveler and co., relax, sit a spell…]

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55 years ago: Science Fact and Fiction