LES INVITES DU COSMOPIF

N°179 (lundi 14 janvier 2008)

James Newman raconte

Souvenirs de la mission Discovery/STS-51

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Texte original

STS-51, September 12-22, 1993

There are a number of things they don't tell you about space flight. Sure, you hear that the atmosphere is "a thin blue line" during the days. But at night, the atmosphere glimmers with a faint glow and is three times as high. The very top of the atmosphere glows the brightest! During the day, some of the atoms and molecules in the air store light from the sun in metastable states. The photons come back out hours later. This is why clear nights in the mountains are so bright and only the cloudy nights are truly dark! I had learned about "airglow" in grad school, but to see it so clearly! And the shadows - you know how at sunrise or sunset your shadow is really long? Well, imagine looking down at the terminator, the line that separates night from day on the earth. Now some clouds stick way up above the others and they can cast shadows that stretch hundreds of miles, all the way to the terminator. Wonderful!

After our second launch attempt, we scrubbed at T-19 sec, I realized it was silly to get excited until the solid rocket boosters ignited. This came in handy during our third attempt, when we scrubbed at T-3 seconds. Getting inside of T-31 seconds is serious. The Shuttle onboard computers take over the launch count and the important stuff gets turned on. The three main engines start about 7 seconds before liftoff, just to make sure they are working that day, and we could feel the lateral vibration. Dan and I were on the flight deck, right behind Frank and Bill, the Commander and Pilot. Using our knee board mirrors, usually for looking at the switch panels behind us, we could see out through the overhead windows, down into the main engine flame trench. After the mains ignite there is a lot happening down there. But then it got very quiet, at T-3 sec, that third try.

I don't know how I'd have felt if we had launched on our first attempt. Everyone must wonder how he or she will feel that first time. But I do know that on our fourth attempt, I felt little more than relief. I was just glad not to have to get out and smile at the cameras and go back to Houston. Frank at one point called out one hundred thousand feet altitude. We go into orbit upside down and I remember looking at my mirror, down at the ocean, and seeing the clouds getting very small indeed.

Right after main engine cutoff, eight minutes and thirty-two seconds after liftoff and we were already going 17500 miles per hour, Carl and I got out of our seats and started taking pictures of the external tank falling away from us. That first view out the windows at the earth was really spectacular. We're really here, I thought. The IMAX movies do a great job capturing the view, but they don't quite get it all.

That first evening I couldn't bring myself to go to bed on time, so I got out my favorite tape, we get to bring six and a cassette player, and went up to the flight deck. Floating upside down, stretched out over the commander's and pilot's seats, I put my head up to the window and just lay there, watching the earth go by, listening to my music.

After a few days a routine develops and we all got used to helping out at the daily chores. It becomes quite natural to float around. It is more difficult in zero g to actually do anything besides float around or go from one place to another. So we learned how to restrain ourselves in place to do real work, reading, typing at the computer, or hooking up equipment. The days are so packed with scheduled activities there is hardly time to do everything planned, much less do the extra stuff, like exercise on the bike or just look out the window.

Flight day 5, our space walk, was to be a special day. Carl and I, with Bill's help, got a good start and were out the door a bit early. The water tank training is really good and we felt right at home. Most space walk tasks are easier in zero g than in the tank and it astonished me at how good the engineering on the space suits is, to make going outside so simple. The suits are bulky and the hands get a real workout, but to be able to work in a vacuum at all is amazing. Although busy, we stole the occasional glance at the earth below us, zipping by at 5 miles per second. At one point, the Capcom called to let us know we were right overhead Houston. It was nighttime below us. In a single glance I could see San Antonio, Austin, Dallas-Fort Worth, Houston, Galveston, then east to New Orleans, the Florida panhandle, and all of Florida outlined in lights. Miami is huge! Finally could see well up the East coast and we departed over the Florida Keys, the Bahamas, and then down across South America. That evening I ate my one steak dinner, stolen from flight day 8's menu, and wished I had ordered more. We were tired, but elated. It's quite possible that could be a once in a lifetime experience. It was while we were outside that I settled on the one word I could use to describe it all - unbelievable!

There is never enough time to just look out the windows. It is astonishing how much of the earth is actually covered by water. When over the Pacific, there is water forever, and maybe then a tiny little island, every once in awhile. How did the original Pacific Islanders ever find them? Most anywhere there is land; there is also evidence of people. The slash and burn agriculture in South America was quite evident. The tracts of land cleared for agriculture stand out during the day. At night the lights make it easy to see where people have settled. And every night there is incredible lightning, all over the world. And the shuttle itself glows. At night, if we turned the cabin and payload bay lights down, we could see the effects of the atomic oxygen into which we were ramming. There is not much atmosphere as high as we were, but there is definitely a little bit, and the side of the shuttle facing into "the wind" glows faintly as the shuttle reacts with the oxygen.

Because the weather at the Kennedy Space Center was not good enough for us to land on our first attempt, we had to stay up another day! After cleaning up and reconfiguring the cabin, we had only a few hours in our evening to enjoy some time off. But it was such a pleasure to get to spend some time just floating, listening to music, relaxing, and looking at the view.

Gravity is an incredibly strong force, and it was during reentry that I was particularly made aware of that. At first a gentle pull down into the seat, it built up to be quite a drag. All motion became an effort. The head movement and attitude sensors in the inner ear become quite sensitive after ten days in orbit. Slow head movements are important. Sitting in the astro van right after we got off the shuttle, I saw the most amazing thing. Bill told Carl to throw his water bottle to Dan. He did and to my utter astonishment, it went in an arc, up and then down, very rapidly, over to Dan. For the first time I had seen the path of a thrown object, I mean really seen it. We are so accustomed to gravity that normally we just don't notice. It is a parabola, that arc, certainly not the straight line we had just gotten used in space. When we got to the medical facility they were getting ready to draw some of my blood for various medical studies. As I lay back, I felt something reach up and grab me by the back and pull me down to the bed. I lay there, pinned, not really wanting to move. It was quite clear that I was again firmly attached to the earth, at least until next time!

James Newman

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