Part 4 of 5: If I could be an astronaut...
Regular Coffeehouse patrons know that I love astronomy. I also have an interest in space medicine. I'm also way too old (37) and way too out of shape to become an astronaut. So if I could be an astronaut… I wouldn't be an astronaut; I'd be a flight surgeon for NASA on the first manned mission to Mars. The flight surgeon is the doctor who's in charge of maintenance of the most complicated, most reliable, least expendable, and least well understood system in manned space flight – the astronauts. He reviews the medical records of the flight crew, examines them before the mission, and sits in mission control during the mission watching the biotelemetry -- the vital data about the health of the crew. The crew doesn't really like the flight surgeon. They've trained all their lives to take great risks for the sake of completing a mission that will take them farther than any human has ever gone; it's my job to ground them if I think that risk is too high. They see me as a hurdle to get over or around so they can do their job; I see them as highly dedicated brilliant well-trained daredevils that have to be stopped from killing themselves.

The greatest challenges of the first manned mission to Mars will not be technical. Witness the extraordinary accomplishments of NASAs two semi-autonomous rovers that have been exploring Mars now for over a year. We understand well what it takes to get there, what awaits us, and how to work there. The greatest challenges will be medical, and they will be substantial. No human has ever been farther than the moon, a trip of a few weeks; a mission to Mars would last several months one way. That's longer than anyone has ever been out of Earth's magnetic field, which protects us from high-energy ionizing solar radiation. No one really knows if that radiation will have long-term adverse consequences. The astronauts know they may all get lymphoma in ten years. Do you think that will dissuade any of them?

Zero gravity for that long is also a big problem. The crew will have to do daily exercises to slow the steady loss of bone and muscle tissue in zero G, and even with a rigorous program they will arrive at Mars much weaker than they left Earth. Mars has only about a third of the gravity of Earth, so they won't need to have their full strength to do their work on the planet surface. But when they return to Earth, back in normal gravity, they will be weak as kittens, and will need prolonged physical therapy to rebuild their lost muscle mass. They'll all know that. That won't dissuade any of them either.

One of the most difficult issues will be psychological. The crew will have to endure isolation that is as difficult and as prolonged as any humans ever have. Psychologists are studying submarine crews and South Pole science station crews to try to predict the psychological challenges that a crew to Mars will face. The crew will spend every waking moment with each other and without direct contact with any other human. That's a lot of togetherness, and it's easy to imagine how small interpersonal friction could simmer for months into homicidal frustration. Even on the moon, astronauts were only 1.2 light seconds from Earth, meaning that a message took only 1.2 seconds to go each way. That's a noticeable delay, but still allows normal conversations. Depending on their positions around the sun, Earth and Mars are between about 6 and about 20 light minutes apart. That means that as the crew gets farther and farther from Earth, messages will take longer and longer to go back and forth. At delays of tens of seconds, a normal conversation becomes impossible. Once the delay is several minutes, communication becomes essentially leaving voicemail (or video messages) for the other party, and waiting for an answer. That may seem like an insignificant difference, but to an astronaut who can only get voice mail from his wife for a year and never actually feels like he's talking to her, that's very isolating. The crew will in a very real way be entirely alone, and any critical help, or information, or moral support will always arrive many minutes after it is requested. And unlike submariners or South Pole explorers, even in the worst case scenario, if the mission is aborted and they return home, home is months away.

So before every irreversible step in the mission, there is a go/no-go decision – a decision whether to proceed with the next step or to abort. That decision is made by the flight controller by going around the room at ground control and polling the people in charge with every mission system. Each person decides if the system he's responsible for can proceed through the next step. The various systems have jargony names, and I have no clue what most of them refer to. The flight surgeon is usually polled last.

Flight control: OK. I need a final go/no-go on Mars orbit insertion, which is scheduled in about 46 minutes, Earth receive time. Telmu?
Telmu: Go, flight.
Flight: Guidance?
Guidance: We're a little fast, but within parameters. Guidance is go.
Flight: Fido?
Fido: Fido is go.
Flight: E comm.?
E comm.: Go.
Flight: GNC?
GNC: GNC is go.
Flight: Surgeon?

And that would be me. And I would be thinking that fortunately there had been no disasters so far. The constant nightmare of an unpredictable catastrophe, like appendicitis, hadn't materialized, thank Heavens. I'd be worried because Mission Specialist Gonzales had some vomiting about 16 hours earlier despite the anti-emetics he was taking. He's a pretty small guy and the dehydration made him tachycardic for a while, but he hasn't thrown up since then and has been drinking lots of fluids, and his urine output is back up. Everybody else looks great, although, of course, all my data is 12 minutes old now.

Doctor Bean: Go, flight.
Flight: Liberty, this is Houston. You're Go for Mars orbit insertion.

The answer would arrive a very boring 24 minutes later.

Flight Commander Smith: Houston, this is Liberty. We copy Go for Mars orbit insertion. Computer shows engine burn starting in 20 minutes. We'll talk to you next from Mars orbit. Liberty out. - served up by Doctor Bean @ 9:36 PM