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Headshot of Emily Lakdawalla

An unheralded anniversary

Posted by Emily Lakdawalla

28-08-2012 11:57 CDT

Topics: pretty pictures, history, Venus missions before 2000, spacecraft

Yesterday, August 27th, 2012, was, in a sense, the 50th anniversary of interplanetary travel. Fifty years ago yesterday, Mariner 2 launched toward Venus, and became the first object to leave Earth and travel to another world. By means of robot avatars, humans have been interplanetary travelers for half a century. For me, this anniversary is a big deal, insofar as round-number anniversaries mean anything, but I've hardly seen a mention of it except for a few Tweets.

Mariner 2


Mariner 2

There were places where I could have noted this date and planned ahead for it, but, for whatever reason, I didn't notice. There are lots of anniversaries being noted and celebrated these days, the most celebrated one this year being the 50th anniversary in February of John Glenn's circling the Earth in Friendship 7.

Mariner 2 was not a sexy mission, so it's not surprising it's relatively obscure. It didn't carry a camera. Its science experiments were, by modern standards, pretty rudimentary, but there was an impressive number of them. It had a cosmic ray detector and a cosmic dust detector. It had a solar plasma spectrometer, a microwave radiometer, and an infrared radiometer. But by visiting Venus, it learned a number of basic facts about the planet about which we'd been ignorant until the encounter. According to the National Space Science Data Center:

Scientific discoveries made by Mariner 2 included a slow retrograde rotation rate for Venus, hot surface temperatures and high surface pressures, a predominantly carbon dioxide atmosphere, continuous cloud cover with a top altitude of about 60 km, and no detectable magnetic field. It was also shown that in interplanetary space the solar wind streams continuously and the cosmic dust density is much lower than the near-Earth region. Improved estimates of Venus' mass and the value of the astronomical unit were made.

All of the facts in that paragraph are pretty much all the basic facts that you'll learn about Venus in anything other than a college-level textbook. For me -- someone who's never known a time when there weren't interplanetary spacecraft -- I am struck by how ignorant we were about our nearest neighbors in the universe, before we began visiting them with robots, fifty years ago yesterday.

Before Mariner 2, everything in the universe was an astronomical object. After Mariner 2, we had turned one of those points of shimmering light into a world -- a world with atmosphere, climate, and weather, like ours. Yet it was also a world whose most basic physical properties -- like how fast it rotates -- were utterly alien to our own. When Mariner 2 visited Venus, not only did we learn about our neighbor planet, but the possibilities of things we could imagine finding at other planets became both more specific and more varied.

We still have not managed to send humans to any of these worlds beyond the Moon.  The death of Neil Armstrong last weekend is poignant, because although he didn't talk about it very much, Armstrong clearly hated the idea that he and his fellow Apollo astronauts would be not just the first but also the last astronauts to visit the Moon. As much of a fan as I am of robotic exploration, I am not going to argue that robotic exploration replaces or competes with the desire that many of you share with Armstrong, to see humanity become a spacefaring species.

But robots can -- and do, every day, these days -- go to places that no human now living could ever hope to go. Into the acid-washed inferno of Venus' hellish atmosphere. Flying among the glittering icy moons and rings of Saturn. And they've been doing that for fifty years, serving as our eyes, ears, and organs of other senses that humans don't even have.

There weren't many images of Mariner 2 available online, so I tried calling JPL media and got connected to an archivist who was able to supply me with a couple from their collection. (Very quickly, too!) Here's one of Mariner 2 during final pre-launch preparations, to give a sense of scale. Although it's considerably taller than the two men in the photo, there's not a lot to it; take off the solar panels and the skeletal science instrument mast and it's a petite little thing, a bus only a meter across and a third of a meter thick.

Mariner 2 being prepared for launch


Mariner 2 being prepared for launch
The Mariner 2 spacecraft is shown in an assembly facility at the Atlantic Missile Range (AMR), Cape Canaveral, Florida. The spacecraft was designed and built by JPL, then shipped to AMR, where the antenna and solar panels were assembled prior to testing and launch in August 1962.

But here's the best photo I came across in my searching: A replica of Mariner 2 and Venus in the Pasadena Tournament of Roses Parade, January 1, 1963. The Grand Marshal of the parade was JPL's director, William Pickering. A lot has changed in fifty years, but Pasadena still decks out cars in fantastical floral sculptures every New Year. I hope someone puts a flower-bedecked Curiosity rover on their float this year!

Mariner 2 gets the Rose Parade treatment


Mariner 2 gets the Rose Parade treatment
On New Years Day 1963, a model of JPL's Mariner 2 spacecraft above a floral "Venus" moved down Colorado Boulevard in the annual Tournament of Roses Parade. JPL Director William Pickering, Grand Marshal of the parade, rode just ahead of the float, which was built and funded by JPL volunteers.
See other posts from August 2012


Or read more blog entries about: pretty pictures, history, Venus missions before 2000, spacecraft


Wil: 08/28/2012 01:16 CDT

Thank you Emily. I enjoyed your article very much. You really have a talent for writing! I had forgotten about the Venus float in 1963. I first attended the Tournament of Roses Parade in 1962. I do love these old photos. Although I am a great supporter of the manned space program, my heart belongs to the robot missions. They seem more democratic to me. I enjoy and appreciate the science as well as the access to data... especially the photos.

Mikael: 08/28/2012 02:28 CDT

My thoughts go to this lonely probe. It is strange to think that these machines still exist, drifting around the solar system and sometimes beyond it. Does anybody know where Mariner 2 is - right now? I presume that we cannot track it actively, but is it possible to calculate with any certainty? - Thanks and keep up the good work! -Mikael

Ursus: 08/28/2012 03:13 CDT

Especially since we missed yesterday's anniversary, I'd like to nominate December 14th—the day Mariner 2 succeeded in its mission and made us interplanetary explorers.

David: 08/28/2012 06:02 CDT

What about Venera 1? It may have been nonfunctional by the time it got there, but it became the first man-made object to reach another planet in May 1961.

John: 08/28/2012 08:26 CDT

looks like Mariner-2 is in orbit around the Sun

Leonidas: 08/29/2012 03:02 CDT

Emily, that was an excellent article and a huge pleasure to read, as always! Two quick points though: 1) Historically, the first ever probe to leave Earth's orbit and travel to another planet, was the Soviet Venera 1, launched February 12th 1961 towards Venus. Eventhough by the time it reached the planet contact was lost, technically it was the first ever interplanetary probe. The Soviets pulled off quite a few firsts back in the day! (As is the case with Mars 3, which was the first ever to soft land on Mars succesfully, on December 1971 and lasted for just 20 seconds!). That doesn't mean Mariner 2 wasn't a tremendous achievement and it deserves all the celebration it can get! 2) I really LOVE robotic probes! But in the end, that's what they are: probes! Precursors to human missions. If human space exploration had continued uninterrupted after Apollo 11, right now we would be celebrating the 38th anniversary of the first human fly-by of Venus with the Apollo Applications Program! And the Mars landing on August 5th of this year, would probably have involved a typical change of personnel on our manned outpost on Mars. The saddest part is that it's not that we couldn't achieve all these. It's that we just didn't want to.

gellis: 08/29/2012 03:36 CDT

Nice article from Emily as always. Leonidas is spot on with his comments, too. I’d like to add two points: Within the foreseeable limits of our technology (before it may become “magic” according to A.C. Clarke) there will always be a lot of places that probes will be able to go but not humans. Like the Venus surface or the radiation struck parts of space around Jupiter. Humans could do well on the Moon, Mars certainly, and maybe some Asteroids and last not least Titan or simply “space” as envisioned by Gerard O'Neill. Secondly, I am too a fan of robotic probes and the recent extremely successful Mars Landers and Rovers. We should nevertheless admit that, for example, all the travelling and probing that Opportunity and Spirit did within the last 8 years sums up to about one or two days sorties of a crewed Mars expedition using their feet and a MRV (Mars Roving Vehicle). I know this is comparing apples and oranges because amongst other things the time factor (observing seasonal changes etc.) also counts. But still.

Zorbonian: 08/29/2012 03:02 CDT

Good points, gellis, Leonidas and others. You make good points in favor of manned exploration: Earth HQ can send a message to the crew to do "X" number of things, and they will be able to do them without interruption and having to give and get feedback (to proceed to the next step) so frequently. And I believe that actually setting up a living environment in one or more of those Mars tunnel systems will expand our technological abilities, understanding and knowledge of how to live in these extreme environments exponentially. You are right, Leonidas - we just didn't want to. Thanks for getting the great photos, Emily.

David Frankis: 08/29/2012 03:51 CDT

This story was covered at Centauri Dreams and at Dr. Schenk's 3D House of Satellites, so not completely ignored.

John Rumm: 08/29/2012 04:57 CDT

Looking back now with the benefit of 50 years' hindsight, it's both remarkable and somewhat amusing to realize that no one really knew for sure what Mariner 2's instruments would reveal about the cloud-shrouded planet. Although there had been some hints that the Venusian surface temperatures might be much higher than Earth's, many people still held out hope that beneath those clouds might be oceans and lush forests teeming with life. That Venus, so close to Earth in diameter, turned out to be a hothouse came as a rude and perplexing surprise, just as, three years later, many people were startled when the first blurry images of Mars from Mariner 4 revealed large craters. Perhaps it is mere coincidence, but the rise of the environmental movement in the late 1960s almost surely was triggered, at least in part, by discoveries such as these and by distant images of our our world seen from space, which served to underscore just how precious and fragile our terrestrial abode really is.

Leonidas: 08/29/2012 07:23 CDT

gellis, you are right, there are places in space we couldn't probably live and visit with current technology. A good analogy can be drawn here on Earth too. There are places on Earth, like the bottom of the oceans where in some places the pressure is the same with Venus's surface. We don't inhabit those regions, and we only explore them with unmanned submersibles. And places along hydrothermal vents. (Yet, what fabulous discoveries we have made about these places!) But that doesn't stop human civilisation from occupying any other place on the map it can, including remote and deep-freezing Antarctica. And, what a fantabulous achievement, a foothold on Moon,Mars and beyond would have been!

Lou: 08/30/2012 08:04 CDT

Beautiful essay, especially "Before Mariner 2, everything in the universe was an astronomical object. After Mariner 2, we had turned one of those points of shimmering light into a world -- a world with atmosphere, climate, and weather, like ours." Indeed. The worlds out there changed everything about understanding our own.

Bill McKinnon: 08/31/2012 08:46 CDT

Just as a technical note, the NSSDC overstated some things. CO2 was first detected spectroscopically in the Venus atmosphere back the 1930s and it was the Soviet entry probes that established that CO2 was in fact the overwhelmingly dominant gas. The rotation rate of Venus was determined, as with Mercury, by ground-based radar. What Mariner 2 is justifiably famous for is establishing that the anomalous microwave brightness of Venus was due to its atmosphere, which meant that the surface of Venus was really, really hot!

bware: 09/05/2012 02:06 CDT

Just reminder -- NASA came to my school in 1965 recruiting for APOLLO Astronaut/Pilots. The then NASA speaker stated that project was to have been terminated after the 40th flight ending around 1989. Two duplicate control rooms (MSC - now JSC) would each control one mission, both flown at the same time). After that NASA hoped private mining operations and colonization would take hold. Before the lecture/recruitment the NASA speaker had one survey question. Who would like to be an Astronaut/Pilot? Several hands went up. After the lecture which explained the job the questions was asked again. Only my hand went up. Prior to what he said I was already familiar with the risks and they were acceptable then and still acceptable after the lecture.

Zorbonian: 09/05/2012 02:48 CDT

That's pretty cool, bware! Back in 1965 it looks like NASA was on track to have the REAL space station by 2001, with mining and whatnot happening on the moon! Blasted politicians!!

Zorbonian: 09/07/2012 03:10 CDT

I guess it's not just the politicians -- the public seemed to lose interest as well.

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