Full Crew
Published on May 27, 2009 at 11:38 am.
1 Comment.
Filed under space station.
The Soyuz TMA-15 lifted off some hours ago to carry three crew members to the International Space Station. At first glance, this might not seem so unusual. After all, Soyuz spacecraft have been visiting the ISS for some time. When the Space Shuttle was not flying, the Soyuz was the only way to and from the station. After the Space Shuttle ceases operations, then the Soyuz craft will once again be the way to and from the space station. What’s different, though, about this mission is that the crew heading to the Space Station are not going to simply replace the crew already there. Instead, the new crew are staying, and so are the crew members already at the station (at least for a while). This means that the ISS is finally up to near its planned full staffing. This is the first time that so many people have been at the space station at one time other than while a shuttle was docked (and that was only temporary).
So, why is this important? Part of the goal of the ISS is to learn to work in space. The ISS is supposed to be a research facility. The crew are supposed to be doing science and engineering experiments. They are learning how materials behave in a microgravity environment. Scientific experiments require controlling variables. If gravity influences an experiment, then you may be able to learn something by changing that variable. But, you can’t change gravity on Earth. You can do a research flight on an aircraft, as I did in January, where gravity is effectively reduced for a few seconds at a time, but sometimes that is not enough. You need to have an extended period of time with low gravity. That is the beauty of a space station. You can have all the time you want with low gravity. There have been many discoveries made in microgravity. A number of important pharmaceutical products have been developed. There have been discoveries in material science, biology, etc. I don’t have time to go into all of the benefits coming from space-based science, but you can check out the NASA web site for all sorts of spin-offs.
While some experiments are autonomous (they are delivered to the space station, ignored by the crew, and retrieved by a later mission), others require continual crew involvement. The crew can only do the science part of their mission, though, when they have time. However, space is a very harsh and unforgiving environment. Space travel is filled with perils. The lives of the crew require that the space station be operating as it is supposed to. But, the space station is a very complex piece of equipment. The space station operates as an orbiting spacecraft of limited maneuverability. It requires a crew to keep it running. I remember reading a number of years ago that it took roughly most of the time of two crew members just to keep the station operational: fixing the things that need fixing, adjusting the things that need adjusting, and other routine station operations. That means that with a crew of three, there is only the equivalent of one person doing science. That was the reasoning behind trying to get the station fully staffed as soon as possible. I do not have any reason to believe that those numbers have changed significantly. The station is more nearly completed, so some of the tasks would ease up, but the station is also larger than it was then, so there will be other tasks. Soon, the station will be growing old enough that more things will need to be repaired as they break.
After the Columbia loss, the crew was cut back to two because the Russian Progress modules could not supply enough supplied for the full three person crew then on board. Consequently, far less science was done until the Space Shuttle fleet was up and running again. Well before the space station was constructed, there were plans for a crew transfer vehicle and an escape vehicle that were to be associated with the ISS. These would permit a much larger crew onboard. For safety reasons, no crew larger than that which can be safely evacuated are permitted on the space station. Since the crew escape vehicles were never constructed, Soyuz craft are used as life boats. They can hold only three crew. For a long time, only one Soyuz at a time was available, so only three crew members could be at the space station at a time. The other problem, though, was a logistics problem. Crew members eat, drink, and require oxygen. The Progress modules could only ship supplies for two crew members. The Space Shuttle, though, with its larger cargo bay, can carry far more supplies to the space station (often in the form of a temporary module attached to the space station filled with supplies). So, space shuttle flights supplemented the Progress modules. But, even so, supplies were limited. Space Shuttle flights never became as frequent as they had been billed to become back in the late 1970s and early 1980s. And, of course, the Space Shuttle fleet is about to be retired. So, what is to come of the ISS?
Fortunately, the European Automated Transfer Vehicle (ATV) is now operational, and it is far larger than the Progress modules. Its larger cargo capacity means that it can supply a space station with a much larger crew. The ATV has proven to be reliable, so now is the time to send a larger crew to the space station. With the larger crew, the real work of the station can begin. This will begin a time in history marking the largest number of people working in space on a continual basis since the dawn of the space age. It is exciting.
-Astroprof
Images courtesy NASA, NASA TV
azawakh on May 29, 2009 at 7:54 pm: 1
Usually a lot of us are not interesting in this kind of things but when i found your articul i could´n go out and i finish to read, congratulation for the way than you write and belive me i came back soon.