A new approach
- Re-using existing technology
- New methods for project management
- Reducing the time from concept to launch
- Minimising launcher costs
Mission to Mars set to revolutionise ESA's working methods
Mars Express (so called because of the streamlined development time) is pioneering faster and cheaper ways of building space science missions at ESA. If successful, the new working methods will be applied to future medium-sized, or `flexible', missions in the agency's long-term scientific programme.
With a total budget of just 150 million Euros (1996 prices), Mars Express will be built and launched (in 2003) for about half the cost of previous, similar missions. The budget includes all spacecraft development costs, launch by a Russian Soyuz-Fregat launcher, operations, testing and management costs. Savings are being made by re-using existing hardware, adopting new project management practices, shortening the time from original concept to launch, and minimising launcher costs. "What we are doing with Mars Express will affect flexible missions at the agency, which may in future be linked more closely to major missions. We are making savings, but we are not taking big risks," says Rudi Schmidt, Mars Express Project Manager.
Re-using existing technology
Mars Express is making maximum use of pre-existing technology that is either `off-the-shelf' or has already been developed for Rosetta, an interplanetary mission also due for launch in 2003. Items not in common with Rosetta constitute only about 20% of the spacecraft and include the solar arrays, the structure, the interface with the Fregat launcher, the on-board mass storage and the on-board software. The tanks, thrusters and 400 N engine have been developed for other ESA space missions: the solar array elements are off the Globalstar production line.
Items in common with Rosetta
- Command and data handling system (on-board computer)
- Transponder (transmitter and receivers in S and X band)
- Low gain antenna
- Gyroscopes and accelerometers
- Solar array drive mechanism, a motor and gearbox to rotate each array by more than one turn in each direction
- Power control unit to ensure maximum power generation by the solar array
- Power distribution unit to distribute power to all on-board consumers and avoid short circuits should one of them fail
- Remote terminal units to interface a system, such as the sun sensor or science instruments, with the on-board computer
- Interface unit to the on-board computer for attitude determination sensors
ESA is using Mars Express as a test case for future medium-sized or flexible missions that can re-use hardware which has already been developed for a major, cornerstone mission. Hardware can be re-used in this way only when two synergistic missions coincide, so ESA is also introducing a new type of mission, called SMART (Small Missions for Advanced Research and Technology), specifically to develop and test ambitious new technologies for cornerstones. New technologies will first be tested in SMART missions, then applied to cornerstones, and finally re-used in subsequent flexible missions. The aim is to provide more launch opportunities by reducing the time taken for technology development.
New methods for project management
ESA believes that the scientific community and European industry have gained sufficient experience during past scientific projects for industry to take on more responsibility for the management of interfaces, in particular with the scientific payload. Hence, MMS, Toulouse, the prime contractor for Mars Express, is taking on tasks that previously would have been done by the project team at ESTEC. These include interacting directly with the principal investigators for the scientific payload and with the launch services supplier, Starsem, to ensure that technical interfaces are compatible. As a consequence of this shift in responsibility, the Mars Express project team at ESTEC is only ten-strong compared with at least 20 for earlier comparable missions.
The use of previously developed technology means that the number of models can be reduced without substantially increasing risk. This will also shorten the schedule and limit costs.
Reducing the time from concept to launch
Selection of the scientific payload by ESA's scientific advisory bodies and mission definition by industry were performed simultaneously, instead of sequentially as in previous missions. This cut the time from concept to awarding of the design and development contract from about five years to little more than one year. The design and development phase will take under four years, compared with up to six previously.
Minimising launcher costs
The Soyuz-Fregat launcher will be provided by Starsem, which is jointly owned by Arianespace, Aerospatiale, the Russian Aviation and Space Agency and the Samara Space Centre. The launcher matches the needs of Mars Express well and is thus able to offer a good price-to-performance ratio. Although the Fregat upper stage is new, the Soyuz is well established and reliable having launched more than 1000 times over the past 30 years or so. The Fregat was qualified to launch ESA's Cluster satellites in summer 2000. Mars Express is also fully compatible with a launch on Delta II. The switch from Soyuz-Fregat to Delta II would be required should Fregat production be discontinued. In principle, Mars Express is also interface compatible with Ariane-4 and 5 and thus, it could fly on a variety of launchers.