Boeing Frontiers
June 2003
Volume 02, Issue 02
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Integrated Defense Systems


Boeing engineering studies move Space Station work forward


ISSStudies by Boeing engineers have helped NASA keep the International Space Station viable for the foreseeable future.

After the U.S. Space Shuttle Columbia accident on Feb. 1, NASA asked engineers at Boeing NASA Systems in Houston, part of Integrated Defense Systems, to look at options to maintain a safe and operable ISS.

The team, which includes a group called VIPeR, or Vehicle Integrated Performance and Resources, has taken into account the delay of the unique cargo-ferrying capabilities of the space shuttle.

As such, the team has had to rely on Russian vehicles—Soyuz and Progress—as the only means of transporting cargo to the ISS until the shuttle returns to flight or the European Space Agency's Automated Transfer Vehicle is available.

The Boeing team has focused primarily on a smaller ISS crew—two people rather than three—and the need for spare hardware. Working closely with NASA's ISS mission integration group, the Boeing team has tracked the primary consumables used by the station and its crew, and has conducted analyses to balance ISS supply and return requirements with vehicle performance and research.

The VIPeR team has focused primarily on station propellant, which keeps the ISS in the proper orbit and orientation and has been one of the most critical consumables in past studies. The team concluded that planned Progress launches will meet propellant resupply needs.

The next critical consumable is water to support the crew and system. A crew member uses about two kilograms of water a day for drinking, food and oxygen generation. The Boeing team has looked at how water can be brought up and has examined ways to reduce water needs.

A significant area of study is the number of crew members on board the ISS.

"We looked at how long we could leave three crew members up there and when we would go to two crew members," said Neil Lemmons, senior systems engineer with the Boeing VIPeR team.

"Without the space shuttle, it was quickly determined by all involved that a three-person crew could not be sustained," said Bob Korin, manager of the VIPeR team. Keeping a crew on the ISS is important, he added, because it would "give us a set of eyes, hands and creative thinking capability to respond to things that arise."

The Boeing team, backed by a strong effort from the safety community, has concluded that no significant safety issues are associated with a two-person crew.

Although there would be some limits, a two-person crew could continue to keep scientific research going and maintain support for preventive and corrective maintenance, anomaly investigation and response, and other ISS system operations needs.

Boeing and NASA engineers have studied the impact of a two-person crew on future science research.

"The focus has been on new samples and consumables for the science and research apparatus already on board the ISS that require minimal space and weight," said Rick Golden, program manager of ISS payload integration.

"Our group (Boeing and its subcontractors, Teledyne Brown Engineering and United Space Alliance) ensures that interfaces between the science experiments and the space station are compatible," Golden said.

"A lot of our focus has been working the safety aspects to fly U.S. payload hardware on Soyuz and Progress launches," Golden explained. "We are positioning a select number of payloads at the Baikonur launch site in order to be able to take advantage of any space that becomes available on upcoming Progress flights."

The Boeing ISS team has reassessed the manifests for several planned shuttle launches. "We had to support system maintenance which may have required changing out filters, valves, bags and things along those lines or other items to support system repair," Korin said.

The team has come up with a prioritized shopping list of what could be taken up without the space shuttle. This includes the amount of propellant, water, gas, and dry cargo needed to support the ISS and its crew. The ISS subsystem teams, including the logistics and maintenance team, have played a critical role in defining the shopping list of needed items.

The Environmental Control and Life Support System group has identified the selector valve and filter for the Carbon Dioxide Removal Assembly, and the Internal Thermal Control System group has identified the Pump Package Assembly as essential spares to be manifested on Russian Soyuz and Progress flights.

The Soyuz is the ISS crew escape vehicle used in case of emergency. It is certified for 200 days of life and is rotated every 180 to 190 days. Soyuz vehicles are normally taken to the ISS by a taxi crew" that brings the "old" one back. The Progress vehicle is unmanned and carries crew supplies and hardware spares to help maintain the life of the ISS. There are normally three Progress flights a year.

"The Russians have given us about a 30-kg (66-lb.) allocation for U.S. items to be launched on Soyuz 6S, so we have been working very hard with NASA to make sure all these items are certified to be launched on a Russian vehicle and the Russians properly stow them for launch," said Ray V. Gonzales, Boeing launch package manager for Russian vehicles. "We are also working to get these items to Moscow and then to Baikonur, Khazakstan, where they will be launched."


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