An artist's concept of Mars Express. Image: ESA

Space mission planners have devised several proposals to re-use the satellite design created for the European Space Agency's Mars Express spacecraft.

The reasoning behind the decision to pursue a mission that would re-use the Mars Express platform design lies purely in efficiency and cost savings. Using the same design on a future mission would cut down on planning and construction costs because the workforce would already have experience in building a similar craft, European Space Agency officials say.

If ESA decides to proceed with at least one mission, the flight would launch in 2005, just two years after Mars Express itself launches in 2003.

Requirements for the proposed mission includes a launch in 2005, no major changes to the original Mars Express platform, and a readily available payload.

The new mission would be based on the Mars Express spare spacecraft, which will be released for further use after Mars Express enters Martian orbit in late 2003.

After the original call for mission ideas was issued in March, nine proposals were received by ESA by the deadline of May 18.

Three of those nine missions were then selected in June for further review. The missions still in contention are:

• Venus Express-A mission to orbit Venus and to study the planet's atmosphere and plasma environment.
  
  
• Galactic (Cosmic) Dune-Near Earth Dust Observatory.
  
  
• Sport Express-The Cosmic Microwave Background Polarization Observatory will observe the "afterglow" of the Big Bang.

"Sport Express was endorsed for study by the relevant committees provided that some open questions related to that proposal are satisfactorily responded to by mid-July," Mars Express Project Manager Rudolf Schmidt told Spaceflight Now.

In an update last week, Schmidt said that the issue had since been cleared and that Sport Express -- along with the other two proposals still on the table -- is continuing to be studied for possible implementation.

The three projects currently under consideration will continue to be scrutinized until around October 15, at which point the results from those studies will be peer-reviewed over a month's time.

If ESA officials decide that the best candidate meets all guidelines and requirements set, then the announcement of the selected mission could come as early as December 4 of this year.

The operating parameters of the proposed mission would be similar to those of Mars Express, with possible variations depending on the craft's destination and payload. The baseline Mars Express platform features a lifetime of at least two years and a weight of around 2,500 pounds, including the payloads.

The approximate 130-pound weight of the Beagle 2 lander, which will be strapped to Mars Express during the journey to the Red Planet, is also included in the weight available for payloads on the Mars Express re-use mission. That could increase the payload mass by up to 34 percent.

A launch vehicle has not been picked for the possible mission, but the Soyuz, Delta 2, and Ariane 5 rockets are the most likely candidates. Mars Express will launch on a Soyuz, but is also compatible with the Delta 2.