The European Space Agency could provide ground station tracking for Russia's sample return Phobos-Grunt mission in return for a Khrunichev Space Center Proton rocket launch to limit the growing costs of ESA's Exomars rover project.

Following the adoption of an independent scientific advisory board's recommendations for more science, the costs of Exomars have grown by almost 50% from €650 million ($875 million) to €950 million with a larger rover that has a 16.5kg (36.3lb) instrument payload, double the original size.

That €950 million excludes the cost of its launch, now scheduled two years later than planned for 2013. As part of ESA's wider co-operation agreements with Russia's Federal Space Agency (FSA) the multinational agency has discussed providing tracking for the FSA's mission to the Martian satellite Phobos in return for a launch. The Phobos-Grunt orbiter could also act as a data relay for the rover. No money would be exchanged.

Because the rover is so much larger, the entry, descent and landing system (EDLS) will also have to be enhanced, although ESA insists the rover/EDLS module mass is still within the envelope of the proven landing systems used by NASA's Spirit and Opportunity rovers.

"The choice [of a larger rover] has been made to maximise the science return of the mission. As well as tracking there would be Russian scientists on the Exomars team. We need the [additional €300 million] approved by the member states by November to achieve the 2013 date," says ESA's Aurora programme manager Bruno Gardini. Last week ESA and the FSA had a meeting in Moscow that included Phobos-Grunt and Exomars co-operation discussions.

The rover already has US instruments and NASA scientists to analyse the sensors' data. Through its co-operation NASA's existing and future orbiters around Mars may also provide data relay services for Exomars. But the current rover design does allow for direct data transmission back to Earth.

Gardini added that although the tracking-for-launch swap involves no funds, ESA is to purchase flight-qualified Russian radioisotope heaters to ensure the long-term operation of the rover's batteries.

Because ESA's member states had oversubscribed to the original €650 million cost of Exomars, the agency had considered adding its own orbiter. However the orbiter is now simply a consideration, part of an ongoing mission evaluation and is unlikely to be built.

An additional €175 million would have been needed, on top of the oversubscription, to pay for the orbiter's development and the Arianespace Ariane 5 launch required for the mass of a rover orbiter system.

Source: Flight International