The Space Shuttle Discovery is set to launch on Saturday afternoon about 2 PM PDT. It will be delivering the Japanese Kibo laboratory to the International Space Station, the largest of the space station modules to be taken to orbit. It is 37 feet long and 14 feet in diameter. It cost Japan about 1 billion dollars to build. Already, the International Space Station has the living space of a four bedroom house; on the exterior, it is about as long as a football field. This will simply add to the enormity of the space structure, which is by far the largest object human beings have ever built in space.
Meanwhile, the Phoenix is working perfectly on Mars, sending back images and flexing its 8 foot robot arm preparing to start digging into the permafrost in search of evidence of life. Visit the official JPL website for the Phoenix.
How do they keep the ISS orbit from decaying?
According to Wikipedia, the ISS is maintained at an orbit from a minimum altitude limit of 173 miles to a maximum limit of 286 miles. The normal maximum limit is 264 miles to allow Soyuz rendezvous missions. Because ISS is constantly falling due to minute atmospheric drag and gravity gradient effects, it needs to be boosted to a higher altitude several times each year. A graph of altitude over time shows that it drifts down almost one and a half miles per month. The boosting can be performed by two boosters on the Zvezda module, a docked Space Shuttle, a Progress resupply vessel or by ESA’s ATV and takes approximately two orbits (three hours) in which it is boosted several miles higher. While it is being built the altitude is relatively low so that it is easier to fly the Space Shuttle with its big payloads to the space station.
Sounds like they gotta fly fuel up there with almost every launch.