Space shuttle programme

Space shuttle programme: the way ahead

At least 12 more flights are planned for the space station’s construction

Key lessons learnt from the Atlantis mission

Pull tests on Endeavour’s thermal blankets performed

The successful return of seven astronauts aboard NASA’s shuttle Atlantis kicks off a challenging construction year for the International Space Station (ISS).

Atlantis returned Saturday with veteran shuttle flyer Rick Sturckow at the helm to complete NASA’s STS-117 mission to deliver new trusses, solar arrays and one crew member to the ISS.

Accomplishments of the STS-117 mission included delivery of a truss segment (a structure to support solar arrays). The S3/S4 truss segment that Atlantis carried is 45 feet long, about the length of a school bus.
Wingspan

The station’s truss will eventually contain 11 segments and will span more than 300 feet. The solar arrays to be deployed will have a wingspan of almost 240 feet. These arrays will provide about a quarter of the station’s power when the space station is completed.

The shuttle’s 14-day spaceflight readied the ISS for new additions to be undertaken later this year and early 2008. These include a new connecting module and the European Space Agency’s Columbus laboratory, as well as the first pieces of Japan’s three-segment Kibo module in early 2008.

NASA plans to launch the space shuttle Endeavour’s STS-118 mission on August 9 to deliver a small spacer piece to the station’s starboard truss.

The shuttle Discovery follows on October 20 to haul the Harmony connecting node to the ISS, with Atlantis again on tap to deliver Columbus in December. Each of those spaceflights, plus vital spacewalks and other assembly tasks by ISS crews in between them, must occur in order to continue the station’s construction.

“I think there’s even bigger challenges in front of us as we continue assembly through the rest of this year,” said Bill Gerstenmaier, NASA’s associate administrator for space operations, on www.space.com.NASA plans at least 12 more shuttle flights through September 2010 to complete the space station’s construction.

Two additional shuttle flights to ship cargo, spare parts and equipment to the ISS, may also take place. One additional flight to service the Hubble Space Telescope in September 2008 is also on tap.
Thermal blanket

Gerstenmaier said NASA and its international partners have taken key lessons from Atlantis’ STS-117 mission. A thermal blanket peeled back from its left aft engine pod mount during Atlantis’ June 8 launch.

STS-117 spacewalker Danny Olivas secured the torn blanket with medical staples and pins. While an initial inspection found a slight gap between the blanket and surrounding heat tiles after landing, the anchor pins were still in place, NASA said.

To prevent such tears in future, engineers have already performed a series of pull tests on blankets aboard Endeavour to ensure they are secure.

Gerstenmaier said that a major crash of vital Russian control and navigation systems during the STS-117 mission has also paid off with lessons of the limits of current and future station hardware. Engineers and ISS cosmonauts traced the crash to the failure of surge-protector like circuits within the computers, and then bypassed the fault using jumper cables.

But it will likely take months to determine exactly what caused the circuits to fail in the first place.

During that time, ISS engineers will take a close look at similar computer systems aboard the Columbus laboratory and Europe’s unmanned station cargo ship, the Automated Transfer Vehicle, Gerstenmaier said.
Challenger disaster

The shuttle programme has come a long way since the Challenger disaster in 1986 when the shuttle exploded into a fireball soon after launch, killing all seven astronauts on board.

More than 100 shuttle missions have taken place since the Challenger disaster, all of them successful except one — the Columbia shuttle which exploded during re-entry in 2003, killing all astronauts aboard including Indian American Kalpana Chawla.