While politicians banter about NASA’s budget and the future of manned space flight, the space agency is prepping the critical technology its remaining four space shuttle missions will deliver to complete the International Space Station.

The space shuttles’ retirement follows almost 30 years of service and after September will leave the US without any major way of launching astronauts into space (NASA has plans to fly astronauts onboard Russian Soyuz spacecraft after 2011). NASA today told reporters that it could ramp the program back up if it were instructed to do so. NASA program manager John Shannon said it costs $200 million a month to keep the shuttle fleet flying. Shannon noted to that NASA has the external fuel tank and twin solid rocket boosters for at least one more shuttle mission beyond the four remaining flights, should it be needed in case of emergency.

10 NASA space technologies that may never see the cosmos

With that as a backdrop, production is well under way to finish out the program with some key missions. First, the next space shuttle, Discovery, currently is sitting on Launch Pad 39A at NASA's Kennedy Space Center. NASA technicians are testing out is propellant system. The shuttle uses what NASA calls hypergolic propellants which it says are the fuels and oxidizers which ignite on contact with each other and need no ignition source. The fuel is monomethyl hydrazine and the oxidizer is nitrogen tetroxide, NASA says. The shuttle uses these fuels for its Orbital Maneuvering system that handles orbital insertion, major orbital maneuvers and deorbit, NASA said.

On this mission, which is set to launch April 5, Discovery will carry a multi-purpose logistics module which is basically a big storage unit that in this case will be filled with science racks for ISS laboratories. The mission has three planned spacewalks, with work to include replacing an ammonia tank, retrieving a Japanese experiment from the station’s exterior, and switching out a gyro, NASA stated.

In May, shuttle Atlantis will use a 12 day mission to deliver an Integrated Cargo Carrier and a Russian-built Mini Research Module to the International Space Station. The Russian Mini Research Module will be attached to the bottom port of the ISS’s Zarya module. The module also will carry US cargo.

Three spacewalks are planned to stage spare components outside the station, including six spare batteries, a boom assembly for the Ku-band antenna and spares for the Canadian robotic arm extension. Other parts such as a radiator, airlock and European robotic arm for the Russian Multi-purpose Laboratory Module also expected top be on this flight, according to NASA.

In July shuttle Endeavor will return to space for a 10 day mission that will have it delivering a variety of spare parts to the ISS, including two S-band communications antennas, a high-pressure gas tank, additional spare parts for the Canadian robotic arm and micrometeoroid debris shields. Such shields are considered to be ever more important and the amount of space junk flying around or near the ISS has been increasing.

In September Discovery is set to be the final shuttle launched into space. Its nine day mission will bring the Express Logistics Carrier 4 and other spare components to the ISS. This will be the 134th and final shuttle flight and the 36th shuttle mission to the station. The logistics carriers add cargo space to the ISS.

In the end the shuttles will have helped complete the ISS at a cost to NASA from 1994 to 2010 to be $48.5 billion, according to a recent Government Accountability Office report. NASA says once the ISS is finished, the ISS crew will be able to focus its efforts on dedicated utilization of the onboard research capabilities.

NASA’s budget currently reflects plans for retirement of the ISS at the end of 2015. The Review of Human Space Flight Plans Committee has proposed extension of the ISS until 2020 in three of its five possible scenarios and Congress has directed NASA to take steps to ensure that it remains capable of remaining a viable and productive facility for the United States through at least 2020, but there has not been a commitment yet to continue operations.

If not extended, there will be only 5 years between the end of construction in 2010 and ISS retirement in 2015 to utilize the ISS research facilities. Under this deadline, the potential for long-term science and for building a robust ISS user community is limited, the GAO concluded.

Meanwhile on April 15, President Barack Obama will host a White House Conference on the Administration's new vision for America's future in space. The President and space experts will further outline the controversial course the Administration is charting for NASA.

According to a number of reports on the meeting, this one from the Houston Chronicle, Obama is expected to designate Mars as the nation's next destination in space looking to spark inspiration, assuage an anxious, space-reliant work force and cement the allegiance of Sen. Bill Nelson, D-Fla., a crucial political ally heading the Senate panel with jurisdiction over NASA and the highest ranking Democrat elected statewide in Florida.