The ExoMars Trace Gas Orbiter, along with an Entry, Descent and Landing Demonstrator Module (EDM), form the first mission in the European-led ExoMars program. The Orbiter and EDM are scheduled to arrive at Mars in 2016. This image shows the Orbiter and the EDM in cruise configuration.

WASHINGTON — NASA is starting the planning process for its scaled-back robotic Mars exploration program immediately and will use 2012 funds previously slotted for work on outer planets missions to shore up the effort.

NASA will spend about $30 million in 2012 on its retooled Mars exploration program, a cross-agency effort known in budget documents as Mars Next Generation.

In total, NASA plans to spend approximately $700 million on the mission. It is tentatively penciled in for launch in either 2018 or 2020. Mars Next Generation was conceived to fill the void NASA's planetary science program created after big cuts in the White House's 2013 budget request forced NASA's exit from the joint ExoMars sample cache-and-return campaign with the European Space Agency and Russia. Those missions remain slated for 2016 and 2018.

"NASA is committed to develop an integrated strategy to ensure that the next steps for the robotic Mars exploration program will support science, as well as longer-term human exploration and technology goals," NASA Administrator Charles Bolden wrote in a Feb. 13 letter to lawmakers on Capitol Hill. [7 Biggest Mysteries of Mars]

Bolden's letter accompanied NASA's 2012 operating plan, a copy of which was obtained by Space News.

Of the $30 million NASA is spending on Mars Next Generation planning this year, $20 million will come from money the agency expects to have left after paying to close out its ExoMars work and fund ongoing missions. The other $10 million is being taken from the Planetary Science Division's outer planets program, which is being downsized as NASA tables plans for a large-scale mission to a planetary destination beyond Mars.

Another $24 million was diverted from outer planets for "foundational technology work on critical sensor development in support of the revised future Mars mission as well as other future planetary missions, as recommended by the recent decadal survey," according to the operating plan.

The first ExoMars mission, the European-built Trace Gas Orbiter, would have launched in 2016 followed in 2018 by a sample-caching rover. NASA's planned ExoMars contributions included science instruments, landing technology and launch services.

NASA began signaling a pullout last year and made it official when the White House released it 2013 budget request earlier this month. NASA's overall budget would drop less than one percent, to $17.71 billion, but planetary science would see a 21 percent reduction, with Mars exploration hit even harder. After taking a 40 percent hit in 2013, the Mars budget would continue its steep decline, bottoming out in 2015 at $188 billion — about one-third its current level.

NASA has to date spent about $45 million on four instruments for the 2016 ExoMars mission. That work will cease once all the instruments reach preliminary design review, Jim Green, NASA's planetary science director, said. Closeout costs for the 2016 instrument programs will not be known until later, Bolden said in his letter to lawmakers.

Despite withdrawing from the joint Mars program with Europe, Bolden said, NASA seeks international collaboration on the replacement mission.

"NASA will also actively seek the collaboration of our international partners," the NASA chief wrote.

After leaving Europe hanging, one planetary scientist doubted that Bolden's invitation to join Mars Next Generation would be well received overseas.

"The concern is credibility with NASA and the U.S. government, really, in the eyes of the world in terms of whether they would dare to collaborate with us," said David Des Marais, a geochemist based at NASA's Ames Research Center in Mountain View, Calif.

Des Marais, chairman of NASA's Mars Exploration Program Analysis Group, spoke at a Feb. 23 meeting of the NASA Advisory Committee Planetary Science subcommittee. Members convened via teleconference. Des Marais' group was to meet Feb. 26 in Washington to begin discussing more detailed concepts for Mars Next Generation.

Des Marais is not alone in his concern about NASA's reputation on the international scene.

"The international disarray in planetary science reflects deeper policy problems that are made worse by a difficult budget environment," said Scott Pace, director of the Space Policy Institute at the George Washington University here. "I continue to find it odd that NASA is not considered an important science agency, worthy of similar support. The administration proposed increases for the National Science Foundation, the National Institute of Standards and Technology, and the Office of Science in the Department of Energy but not NASA."

Meanwhile, with the funding changes described in the operating plan, NASA will now be spending only $9 million on outer planets programs in 2012. Those funds will all go toward studies for missions to the planetary science community's highest-priority outer-solar-system destinations: Jupiter's icy moon Europa, the gas giant Uranus and faraway Neptune. A concept study for a mission to Enceladus, one of Saturn's moons, is planned for 2013.

"The new plan has pushed what we thought we were going to do so far down that it's basically squeezed the life out of that flight program," said Washington University Professor William McKinnon, chairman of NASA's Outer Planets Assessment Group. "We can't fly under these circumstances any flagships."

Results of studies on three Europa mission concepts will be completed in time to be presented late March at the next meeting of the Outer Planets Assessment Group, to be held in St. Louis.

This article was provided by Space News, dedicated to covering all aspects of the space industry.