Phoenix landing: Coping with Mars time
In the toilets at the Science Operations Center, there are bags containing vials and plastic jugs. A sign above the bags warns: “Do not throw these away!”
It is part of an experiment within an experiment. Phoenix scientists are going to sample Mars' ice; Walter Sipes is going to sample the Phoenix scientists' urine -- as a way of assessing their body clocks.
Sipes, a NASA psychologist at Johnson Space Center in Houston, Texas, usually works with astronauts on the International Space Station, helping them adjust their body clocks when they suddenly need to perform a maneuver on, say, Moscow time.
Now he'll help the Phoenix scientists adjust to Mars time. They work through the night to have fresh instructions ready to relay to Phoenix before it starts its day. As deputy project scientist Deborah Bass puts it: “We do the Martian night shift. The lander works the day shift. It has it easy in that respect.”
Since the the Martian day is longer than Earth's by almost 40 minutes, the scientists have to come in a little later each day. The effect on their bodies is as if they are continually flying west across time zones, says Sipes.
Twenty scientists were recruited for the experiment. They will be given light boxes to put by their computer workstations. At specific times of the day, they are dosed with solid blue light which helps reset body clocks by triggering the production of melatonin.
Every four hours, the scientists are expected to collect some urine. Sipes and his colleagues will look for melatonin spikes. If the spikes shift along with Mars time, he'll know that the scientists are following his strict sleep and light regimen.
A final part of the experiment is to see if the effort is worthwhile. Every day, at the beginning and end of their shifts, the test subjects will take cognitive tests. Sipes says he didn't have enough money to do a control group. But he'll still be able to look for differences in cognitive test results between diligent subjects and the slackers who avoid the body clock regimen. He'll know who is being good and who is being naughty because the subjects wear special wristwatches that are sensitive to both motion and light; Sipes can thus tell if the scientists are in the dark and motionless (and, presumably, sleeping).
Bass hopes that the team will take Mars times somewhat seriously: “In the beginning you run on adrenaline. But you need to protect people from themselves.”
Comments
Isn't the average "freewheeling" sleep cycle when people live isolated from reinforcing daylight cues supposed to be something like 25 hours a day?
Posted by: Michael McNeil | June 8, 2008 11:56 PM
We now know the endogenous circadian period is closer to 24 hours. The average circadian period reported in Science (Czeisler et al., 1999 Jun 25;284(5423):2177-81) is ~24.2 hours.
Posted by: Phoenix Fatigue Countermeasures Study | July 18, 2008 11:53 PM