Here's my experiment (the part at the lower right corner of the solar panel on the Sojourner rover) on Mars!
Two months ago, nobody seemed to know or care what I was working on-- something technical, something boring that has to do with NASA. But now, for the moment, everybody in the world seems to know about the Pathfinder mission. Neighbors stop me on the street to tell me that they saw my picture in the paper; friends I haven't heard from in 20 years e-mail to mention that they saw me briefly on television.
It was a summer where there just wasn't time. Something is always happening, new data coming down from Mars, old data that needs to be analyzed. This has been the busiest summer of my life.
This is what it was like. This is my Mars journal.
The science operations groups--we call them SOGs-- work out the schedule for the Pathfinder spacecraft; what it will do each day; where the rover is sent, which objects the camera photographs using which camera filters at what time of day. The SOG that I'm on is Atmospheric Imaging Research, or "AIR." This was originally called Atmospheric Aerosols, but the first thing that the group did after we met was to decide on a new name. After fifteen minutes, I finally came up with the acronym "AIR," and Pete Smith said, "AIR Mars! Yes!"
So I guess I'm the one responsible for the acronym this time, and now other people will be confused. But at least the AIR Mars group studies air.
The public affairs office at JPL is predicting that there will be a thousand reporters covering the Pathfinder landing. That's incredible! We need three different badges to get into the operations facility where they will be running Pathfinder: our ordinary NASA badge to get us in to JPL, the badge for the Space Flight Operations Facility, and then a separate Pathfinder Operations badge to get to the second floor.
My involvement with Mars Pathfinder actually dates back to when the mission was still called Mars Environmental Survey, and was to be a network of eight or twelve tiny landers spread across the globe of Mars. The first of these would prove the feasibility of the airbag landing concept; after that, four spacecraft to Mars every two years.
The survey mission never got approved for flight--too ambitious, too expensive--but the Pathfinder spacecraft became the first of the new "Discovery" series of spacecraft, tiny, inexpensive space probes to replace the old NASA strategy of huge, multi-functional robotic probes. "Think small, in large numbers."
As a solar-array physicist, the questions I had were: will solar arrays operate in the dusty environment of Mars? Is there enough sunlight? Will the accumulating dust degrade the performance?
We needed data.
My instrument is a little sensor named Materials Adherence Experiment, or MAE. The challenge was to build an instrument that didn't interfere with any of the rover systems and weighed almost nothing. I built the first working model myself, but I was lucky enough to have Phil Jenkins (an engineer who had started out as a student in our branch, and then became a NASA contractor)design the flight unit; he made a nitinol-based actuator that was smaller and lighter and more reliable than anything that I could make. The fact that it works so well is more of a testimony to his careful attention to engineering than to my fanciful designs.
And now it's on its way to Mars.
I am in the science operations area at JPL, watching the same television picture everybody else is watching, the same I would have watched if I were at home-- there is nothing we can do except watch. At the science working group meeting this morning, the last meeting before the landing, Matt Golumbek quoted: "At launch and at landing, science and religion coincide. You've done all you can, and now all you can do is pray."
Landing--
--now.
--Now the downlink reports a signal from the spacecraft. It worked-- the spacecraft is not dead! Everybody is clapping and cheering. In the TV showing the spacecraft control area, you can see everybody embracing. It worked!
The spacecraft is transmitting a surface semaphore. The base petal is down-- the spacecraft landed upright. Everybody is cheering.
So many things could go wrong, but it didn't break! It worked! All those months I've been holding my breath, and it worked! Pathfinder is down, and it's transmitting from the surface of Mars!
YAHOO!! We're on MARS!
Now we have hours to wait for the solar arrays to open, and the spacecraft to locate the sun and the Earth...
3PM: we have a signal from Mars. The downlink is established; the spacecraft has found the sun and used the sun's position to calculate where the Earth is and point the high-gain antenna.
Now the first images from Mars start to appear on the big monitors over the science work area-- black and white images of the airbags, at first, and suddenly the intercom in science operations stutters on, and the Beatles blast across the room, with "Twist and Shout.." Somebody up in flight control has a rock 'n roll sense of style. "Twist and shout" is exactly the feelings of the scientists; everybody is clapping and cheering. That's Mars. It's not a test! This is real! Now there's an image that shows the surface outside the airbags, and the geologists are going crazy. I scribble down what the other scientists are saying.
"Oh, look at that." "Oh, man, are we lucky." "That's incredible." "That's one big rock." "Ooh." "Look! It's hill." "Scenery!" "We got Martian Alps in the background!" "Damn!" "Oh, my goodness, look at the drift material." "Gosh." "Almost a balancing rock." "The rover guys are going to have a real time driving this. It's a real test." "The rover guys are nervous." "It's clear the other direction."
This is Mars, live from Pathfinder! I'm staring at the wall-mounted monitors, scribbling notes as fast as I can write. On every computer people are downlinking images; on all the monitors the images flash by as fast as they are downlinked.
"We need to get an image to the Vice President." "Here's a good one." "Yeah, that one." "Is that the first one? He wants the first one." "The Vice President is waiting for this-- give me a time." "Fifteen minutes." "No, ten." "The Vice President wants an image right now."
"Oh, wow-- look, there's the top of a hill. You can see some banding. It could be layering, it could be terraces, it could be differential erosion."
"Not a bad landing site," says Matt Golumbek. He is smiling; this is his triumph. "Not bad" is an understatement, and he knows it. "What's amazing is the variety-- hills to look at, rocks to look at, sand to look at. You want to go out there and explore. I don't know where we are, but it's a damn good place." Matt, chief scientist for the mission, was the one who had made the final choice of the landing site-- and had to defend it in endless review meetings from criticisms that it was too rocky, not rocky enough, too dangerous, too boring, too flat.
Everybody else is still talking at once:
"Holy smokes."
"Look at all the rocks."
"Viking could never have landed here-- too many big rocks."
"This is great! Let's do some science."
"Mars never looked so good."
"This is too cool."
"What is that? Unbelievable!"
"So many things to look at, it's hard to guess."
"Can you believe we're experiencing this?"
"No-- No."
"Can you believe this? This is incredible!"
"What a block party!"
"Can you write a caption for the mission-success pan?"
"Is that hills, or are those craters?"
"We think they're hills."
"Absolutely astonishing. We're not just good-- we're lucky."
"I love those hills in the background-- it's the sphinx."
"Not a good site," says Matt. "It's excellent."
___
While the scientists are ecstatic about the images, the engineering team, looking at the same images, sees problems. The next operation is for the Sojourner rover to roll off of the petal, but the images show that both sides of the petal are covered by loose fabric from the deflated airbags, blocking deployment of the exit ramps. The rover team has proposed a fix. They want to use the petal deployment motor to lift the rover petal up off the ground, retract the airbag, put the petal back down, and then command another series of pictures to check that the retraction has cleared the ramp.
This astounds me-- in all of the ORTs and tests, nobody even mentioned that such an operation might even be possible. But they try it, and, surprisingly, it works--- the front ramp is clear, and in the last uplink of the day, rover is commanded to drive off the ramp and onto the surface.
Midnight. The experiment operations working group meeting is after the day's data is in. The first report is from the flight engineer, Guy Beutelschies. "What did we do today? We landed on Mars."
Everybody applauds.
"The lander's been kicking butt today. It's pretty good."
And everybody applauds again.
It's one AM. I'm not tired, even though that's 3 AM Cleveland time, and I got up early. It's been a long day, but I'm still not ready for it to end.
There's a communications problem between the lander and the rover, we are told. This is why I haven't gotten any information from my MAE experiment yet; the rover is being recalcitrant in communicating with the lander. This is something to worry about, maybe, but it's still early in the mission-- lots of things to try.
The MAE is a nice experiment, for its size, which is about as big as an "Elvis" postage stamp. It features, however, a tiny piece of unsupported glass about the size of a fingernail, and I've been biting my own fingernails hoping that the airbag landing didn't break it. The communications glitch between the lander and the Sojourner rover won't make me sleep any easier!
I've been staring at the pictures. The first picture the lander took, proving that the Pathfinder landed successfully on Mars-- shows my experiment, right in the middle of one frame-- but the resolution just isn't quite good enough to tell if the tiny glass cover is OK.
One day down on Mars, and already we know where we are: the landing spot has been nailed. We are slightly above and left of the small crater-- the two mountains in the far distance are the giant buttes, the streamlined islands to the south.
Justin Maki wins the betting pool to guess the landing site.
3:30 PM, morning on Mars. Downlink. The rover is talking! The MAE worked! It didn't break! We've got an experiment on Mars! The MAE sees dust-- we see dust. [My Materials Adherence Experiment is a great experiment, but it uses a tiny piece of glass about the size of a fingernail, and I've been biting my own fingernails hoping that the bouncing landing didn't break it]
I have an experiment on Mars! This is the moment I've been working toward for the last four years. It works!
The geologists have pieced together a wall-sized mosaic of the view from the lander and taped it to the wall of the small conference room, the one we call the "fishbowl," since it has windows on all four sides. The geologists have been giving pet names to the rocks they are studying, and Matt announced that the process should be documented, so everybody knows which rock is which. So if there's a rock you think you have a good name for, you put the name on a yellow sticky-note, and stick it on the mosaic.
The big rock near the rover exit ramp didn't have a name yet. I said, say, do we have a name for the big guy yet? Mike Malin said, "Sure, go name it 'Big Guy'." So I took a closer look at it-- it looks just like a the head of a bear, so I said "Yogi Bear." --Mike shortened that to "Yogi."
"Big Guy," aka Yogi
"Wedge" was obvious, so I put a sticky on it. Another nearby one looked a little like an animal head, maybe a chimpanzee, so I named it "Chimp." I'd been doing some analysis on a mountain visible way in the distance, almost faded into the sky and I'd been thinking of it as "Misty Mountain," so I wrote that on a sticky.
Naming rocks on Mars-- what fun!
The meetings come after the day's last load of data has come down, and the sun has set on Mars. Since Pathfinder operates on Mars solar time, this comes late in the evening Pacific time-- and later each night.
Now that the rover is off the ramp, Matt says that the engineering is done, and from now on, all the press conference will be science. Up to now, the NASA Select TV coverage has hardly ever showed the science operations area-- makes us scientists feel neglected. Or it would have made us feel neglected, if we weren't too damn busy!
When Sojourner came down the ramp, the whole rover operations team was invited to the press conference. This was the first press conference I've been at. Everybody cheered and clapped. Afterwards, before the science assessment meeting, there was champagne in the conference room.
The working group's agenda starts with the report from the project chief scientist. Matt looks up, and reports: "One happy dude."
Then he goes back to looking at his data. A very brief report!
My naming Yogi has started a trend; at least a dozen other rocks now sport names of cartoon characters, from a nearby rock named "Scoobie Doo" to a white rock tagged "Casper." Yogi has been set to be the next target for the rover, and I've been watching with an odd proprietary interest as "my" rock is featured on the daily TV news.
Matt's postdoc student Nathan was named to be the Czar of rock names, to give some formality to the naming process. If he decides that the name fits, he keeps it; if not, it's gone.
My proposed "Tip of Buried Pyramid" got shortened to just "Pyramid." Oh, well, "tip of buried pyramid" was too long anyway.
I tagged a group of three angular, almost square small rocks "The Dice." Close to the lander there's another one that's very angular, I tagged it "Buried Brick," which is just what it looks like. And two more that look like animals: "Otter," and "Baby Otter."
What's it like? You get up early in the morning, go to a windowless room. The science working area. It is filled with computers, lining all the walls. The computers all have names: sisko, janeway, chakotay, vidiian. (The one I've been assigned has a more boring network tag, alas: MPF8.) The relentless fluorescent light of the science working area tends to fuzz you out, after working for twelve or fourteen hours, you have no idea whether it's sunny outside or the middle of the night.
But that doesn't matter. What's important is what's coming down from Mars. This is it. This is why we're here.
At the science working group meeting, people talking in acronyms, jargon, and sequence numbers: "We're targeting 44 to image an area that's disturbed." "Take out 5044, 5046, and run 5020." Darkstrips, nullstrips. PSG, SOG, APXS, IMP, ASI/MET. To an outsider it would be incomprehensible.
And still, at odd moments, I would suddenly smile: we're on Mars!
An odd effect of working on Pathfinder is that although we are in Pasadena, we are not living on Pacific time-- we're on Mars time. Pathfinder is a solar-powered spacecraft, and so our schedules are fixed by when the sun rises over Ares Valles, Mars.
By an odd coincidence, a day on Mars is almost the same length as an Earth day-- a mere forty minutes longer. What this forty minutes means, though, is that compared to Pacific Daylight time, the schedules of everybody in the science team are slowly slipping later and later. It's the Martian time-slip. Every three days, our day starts two hours later. Right now, for example, I can have breakfast only at restaurants that are open 24 hours a day. And, after eight hours of operations, I have supper at breakfast time, getting odd looks from the waitress as I order a dinner-sized meal at breakfast time. I'm at Denny's right now-- "Always open" looks awfully good when you're living on Mars time.
But each day, we are working later and later. Soon we will be moved back to "normal" time. That will be strange, to be on the streets the same time other people are around!
In science operations, things are calming down. Scientists are going back to their home institutions; the operations room is no longer jammed with excited geologists exclaiming over each image.
The Pathfinder and Sojourner are complicated robots; you program them, and they do what you tell them to do. After the operations working group meeting, the uplink shift has about seven hours to write the sequences to be sent to Mars to program the spacecraft for the next day's operations. The command approval meeting is the last meeting to make sure the sequences do what they are supposed to, and don't program the spacecraft do anything that would damage it. After working all night, the command approval meeting is likely to be even more filled with jargon than the working group meetings. I work the downlink shift, so I don't usually sit in on command approval meetings. When I do, the conversation seems almost opaque:
"Chris, there's no 267 in the sequence?"
"That's right."
"D you still have the redlines from the 02 and 03 sequences?"
"02 had some peculiarities. What was it you found in the 02?"
"02 has an extra receive."
"That's OK. What about the low DPT? Anybody figure out why 02 fires into a low DPT?"
--and so on.
Just east of JPL is a walking trail up the arroyo into the National Forest; the day is warm and the trail alternates between dusty heat and tree-shaded cool. It's taken this long, nearly two weeks for the slow accumulation of dust to build up enough data to analyze. I'm thinking about my data, thinking that I can analyze it enough to tell something about global sedimentation patterns on Mars, thinking this could be enough for a paper in Science.
It's been a long day, fourteen hours in science operations, and then a two-hour hike. But I can't imagine what I'd rather do. Mars Pathfinder is already yesterday's news to the newspapers, the TV, the internet pages, but to us it's barely begun, and there's no end in sight.
I've got data, real good data. Who could ask for anything more?
At the science assessment meeting, I was picked to talk about my dust deposition experiment's results at tomorrow's press conference. This will be my first formal press conference-- too bad most of the press have gone home. At the very last science meeting before the landing, Matt set out very clear rules for press conferences: informal. No neck ties, he told us. Anybody who wears a tie to a Pathfinder press conference will be booted off the science team right then and there.
Works for me-- I haven't worn a tie in over ten years.
I don't have a lot to present, really, just a graph of dust accumulation. No pretty pictures. But the data is good data, and I think I can resolve a genuine scientific controversy: where does the dust go when it leaves the atmosphere?
Everybody I meet tells me that the press conference went well, and I did a good job of making dust seem interesting. Odd-- to tell the truth, it had slipped my mind that other people might not find dust interesting.
The high point: around noon I went to the library, and a guy walked past, stopped, turned around, and said "Say, didn't I just see you on TV?" (said he liked my presentation, too).
Back in Cleveland. Work hasn't stopped because I've been out in Pasadena with Pathfinder; it's been piling up, and it may be weeks before I've got myself unburied from accumulated mail.
I came in to the house this evening, and as I was opening the door, the kid next door and his friend come up, and park their bikes next to my car. "Say, tell me if it's true. Did you really name a rock on Mars?"
"Sure," I say.
"Cool!" He turns to his friend. "See? I told you so!"
Data from my experiment is still coming down from Mars, although I am back, catching up on other experiments now. My experiment on the 2001 Mars lander will be even more elaborate, and will not only look at the rate of dust accumulation, it will have a microscope to examine individual dust particles in detail. It's only four years to launch-- time to get working!
But I'm sure it will not be the same. After 21 years, Pathfinder brought us back to the red planet, and although there will be other missions, none of them will be Pathfinder. This summer was special.
It was the summer I spent on Mars.
