STS-118: The Inside Guide
What’s going on beside the spacewalks.
A long-delayed trip for teacher-turned-astronaut Barbara Morgan, the first flight of the refurbished orbiter Endeavour in nearly five years, and continuing construction of the International Space Station are among the highlights of the STS-118 mission, due to run through August 22. Along with the spacewalks and the robotic assembly tasks, here are a few of the less publicized activities going on in space this week.
After Endeavour’s last flight, in December 2002, it went back to the hangar for a series of planned upgrades, including installation of an advanced glass cockpit. Among the nearly 200 modifications is a new system that for the first time allows the shuttle to draw electrical power from the space station’s solar arrays. That requires some conversion, since the station runs on 120 volts and the shuttle runs on 28 volts. Hardware for the Station-to-Shuttle Power Transfer System, which can siphon eight kilowatts of power from the station, is already in place on the orbiting laboratory. Endeavour has been fitted with new power cables. The shuttle docks with the station on the afternoon of August 10, and shortly afterward, the astronauts will activate the power system and begin checkouts. The payoff is that future shuttles will be able to stay docked to the station for up to 12 days instead of just eight.
As you might expect, the windows on the space station are fairly complex structures—multi-layered, and tough enough to withstand the occasional speck of debris hitting the pressurized vessel at 17,500 mph. The station’s Destiny laboratory has a 20-inch circular window in its floor, facing Earth, through which the astronauts take photographs and gaze at the passing scenery. The innermost pane of this window, called the scratch pane, has a thin coating of Lexan plastic. If an object were to hit the window hard enough to shatter the glass, the Lexan would contain the fragments and keep them from spraying into the laboratory.
The problem is, over time the scratch pane has become scratched. Astronauts press their noses and cameras against it, and one crew, thinking they were helping, tried to clean the plastic, which only made matters worse. So on the seventh day of this shuttle mission (or earlier if they can get to it), the astronauts will replace Destiny’s scratch pane with one that has a more durable coating. The job should take no more than an hour.
Last year, two shuttle crews—on STS-121 and STS-115—reported noticing something odd when they were trying to sleep in the shuttle’s mid-deck cabin. Astronauts are accustomed to having stuffy noses in orbit (weightlessness makes body fluids rise), but these crews experienced more than the usual stuffiness, along with headaches. One theory is that carbon dioxide from their exhalations had built up in the mid-deck. But instruments detected no rise in CO2, and the astronauts sleeping on the space station did not report feeling anything unusual while the shuttle was docked. During this mission, Endeavour’s crew will have extra CO2 sniffers on the mid-deck to search for “hot spots.” The sniffers will be turned on at bedtime, and turned off when the crew wakes up. One possibility is that a booster fan that was shut down on previous missions to save on power may need to stay on to keep the air circulating properly.
It’s been a long haul for 55-year-old Barbara Morgan. Before she became an astronaut, she was a NASA teacher-in-space finalist, the backup to Christa McAuliffe, who died along with the rest of Challenger’s crew shortly after their shuttle lifted off in January 1986. Morgan is no longer a teacher but a full-fledged member of the astronaut crew (she’ll run the shuttle’s robot arm for part of the station assembly work). But having waited more than 20 years for this flight, Morgan will still devote time to a few onboard educational activities, and after her return to Earth will continue taking NASA’s message to classrooms.
Endeavour is carrying 10 million basil seeds, which will later be distributed to schoolchildren for use in a NASA-sponsored challenge to design a plant growth chamber for a lunar colony. Remember the 12.5 million tomato seeds that spent six years in orbit back in the 1980s? Some 8,000 people reported back that space tomatoes were not significantly different from their Earthly counterparts. We’ll see how the basil does. And if NASA ever decides to send up a shuttle full of mozzarella cheese, the astronauts will have a nice salad.
For a full rundown on all the activities planned for the STS-118 mission, click here to download NASA’s press kit in PDF (Adobe Acrobat) format.
To read our “inside guide” to the last shuttle mission,click here.