The international space station has been called a "bridge to new worlds" and a "steppingstone to the moon, Mars and beyond" — but it's meant more in the sense of a technological test bed rather than a literal platform for space journeys.
When NASA heads out to the moon, sometime before the year 2020, it won't be using the space station as a way station. And Mark Uhran, the agency's assistant associate administrator for the space station, says that was never the intent.
"I was there when it was originally sold, and using it as a steppingstone to a lunar base was never a primary objective," Uhran said.
Rather, its primary purpose — at least in terms of the way NASA will use the station — is to serve as a platform for research that will be applied to those future trips to the moon, Mars and beyond, Uhran said. "NASA is a mission-driven research agency," he explained. "What that means is that our research is focused on the needs dictated by our mission."
Through all the various "twists and turns" of the space station's development, NASA hasn't compromised on the space station's core capabilities, he said.
Nevertheless, some compromises have been made. For example, when the Russians joined in the project in the 1990s, the angle of the station's planned orbit was shifted more steeply so that crew and payloads could be launched from Russia's Baikonur Cosmodrome in Kazakhstan. Because of that inclination, the station's orbit isn't in sync with that of, say, the Hubble Space Telescope — and it would be tricky to send a spaceship outward from the station to the moon, though not impossible.
That shift in the orbital setting is a decision NASA's current leadership regrets. "Had the decision been mine, we would not have built the space station we're building in the orbit we're building it in," NASA Administrator Mike Griffin told USA Today last year.
But on the plus side, it was that steeply inclined orbit that allowed the Russians to keep the station resupplied for the two and a half years when the shuttle fleet was grounded, in the wake of the 2003 Columbia tragedy. If it weren't for that accessibility, "we may have lost the vehicle, or we may have had to change the configuration and cut it back," Uhran said.
Compromises also had to be made on the space station's research capabilities: Because of tight budgets and the tight time frame for completing assembly, millions of dollars' worth of hardware have had to be left on the ground. Millions of dollars' worth of scientific experiments have had to be axed from the station's schedule as well.
"Clearly it promised too much to too many people," said Keith Cowing, a former NASA scientist who now monitors the space agency through his independent online publication NASA Watch.
Despite the criticism, even Cowing agrees with Uhran's statement that the station will be an "extraordinarily capable spacecraft" once it's finished. He worries that the station could fall victim to "a bad habit NASA has oftentimes, of pooh-poohing the previous space program." But if the push to the moon, Mars and beyond is held up for some reason over the next decade, the international space station just might become the jewel in NASA's crown, he predicted.
"Suddenly the station will become the hip place to be," Cowing said.
Here are a few of the research and technology initiatives that have been given NASA's green light for work on the station:
- Researchers are looking into how to preserve food and medicines during long-duration spaceflights. "We're concerned that some of the foods we're sending up lose their nutritional content while they're up in space for long periods of time. ... We're concerned that medicines lose their effectiveness as well," said Carl Walz, acting director of the Advanced Capabilities Division in NASA's Exploration Systems Mission Directorate. Station program scientist Don Thomas said "it's something we really don't understand. ... It isn't the zero-gravity effect, but maybe these are radiation effects."
- Engineers have developed U.S. equipment for replenishing the station's oxygen and water supply in orbit — tasks that are primarily done by Russian-based life support systems today. The newly developed life support systems and environmental monitoring equipment will serve as a much-needed backup for station operations and also "inform future technology directions" for NASA's moon missions, Walz said.
- On the health care front, NASA is trying to develop a telemedicine system called Advanced Diagnostic Ultrasound in Microgravity, or ADUM, Thomas said. Astronauts aren't able to have X-rays or MRI scans done in orbit — but with a few hours of training, they can use ultrasound devices that send their data back down to Earth for remote analysis by physicians. "We have an operator on the ground, a specialist in ultrasound, guiding the hand of the astronaut — looking over their shoulder, if you will," Thomas said. "We've got great earth-based needs for this technology."
- NASA is studying combustion and soot formation in orbit — research that could lead to better smoke detectors for spacecraft as well as earth-based applications, Thomas said. Even the exercise equipment aboard the station is the subject of research. Right now, astronauts have to exercise two hours a day to counter bone and muscle loss in orbit. Any innovations that can cut down on the amount of exercise required will free up precious time for work in orbit.
"It's a great test bed to try out some of these technologies," Thomas said.