WASHINGTON — A blue-ribbon panel chartered to help NASA reboot its robotic Mars Exploration Program outlined several approaches Sept. 25 for returning samples from the red planet to Earth but did not endorse any one plan.

NASA called for the reboot in February after withdrawing from the European Space Agency’s ExoMars sample-collection campaign, citing budget constraints. Former NASA Mars czar Orlando Figueroa was selected to lead the Mars Program Planning Group, which was assigned to come up with options for a $700 million to $800 million mission that could be launched as soon as 2018. Figueroa and his team started their work in March and publicly released their preliminary report Sept. 25.

The preliminary report includes concepts and cost estimates for four rovers and four orbiters that could be sent to Mars between 2018 and 2024. Favorable Mars launch opportunities occur only about every two years.

John Grunsfeld, NASA’s associate administrator for science, said during a media teleconference following the report’s release that the agency will announce its plans for the so-called Mars Next Decade effort in February with the release of the White House’s 2014 budget request. Grunsfeld said that NASA is free to consider spacecraft and mission architectures other than those outlined in the Figueroa group’s report.

It is not yet clear when Mars Next Decade would launch. But Grunsfeld said that if NASA decides to take advantage of the 2018 launch opportunity, work would have to get going within the next four to six months and the chosen mission would be subject to “an $800 million cost bogey.”

With that budget constraint, NASA would be limited to an orbiter, Figueroa said.

“That drives you toward either launching an orbiter first or delaying until 2020 and then beginning with a rover,” said Figueroa, affirming a statement he made in May when his group was still in its fact-finding phase. To send a rover to the martian surface, “you’re now talking $1 billion to $1.5 billion or so,” he said. “So with that, that means that you have to delay things and accumulate the money you need to implement that.”

Rover concepts included in the Sept. 25 report ranged from designs based on NASA’s twin Mars Exploration Rovers, launched in 2003, to variations of the Curiosity rover at the heart of NASA’s car-sized flagship Mars Science Laboratory mission. Curiosity touched down on the martian surface Aug. 6 to begin a two-year mission to determine whether Mars could ever have supported life.

Of the orbiter concepts discussed in the report, one whose cost and scope cleaves closely to the criteria NASA laid out in February is a combination telecommunications and science spacecraft that would be based on previously flown NASA designs and launched aboard a Space Exploration Technologies Corp. Falcon 9 rocket. This orbiter would cost about $700 million to build and launch and combine elements of NASA’s 2005 Mars Reconnaissance Orbiter and the 2013 Mars Atmosphere and Volatile Evolution spacecraft, according to the Sept. 25 report.

A barebones telecommunications-relay orbiter with no science payload, which Figueroa said was the absolute minimum for the Mars Next Decade mission, would cost about $200 million to build.

One sample-return proposal in the report calls for using the Space Launch System (SLS) heavy-lift rocket NASA is developing for future crewed missions beyond Earth orbit to send a lander and combined data-relay and sample-return orbiter to Mars in a single launch.

Figueroa’s report said such a mission, launched by the 70-metric-ton variant of SLS and dependent upon a yet-undeveloped Mars Ascent Vehicle, would not be possible until after 2024, seven years after SLS’s planned maiden flight.

Meanwhile, it will take until mid- to late-October for the group to release its full report, including lengthy appendices, that will “really allow us to dig in to the technical details of some of the elements” proposed in the preliminary report, Grunsfeld said.

Although Mars Next Decade was conceived as a stand-in for ExoMars, planetary science advocates, citing the priorities established in their latest 10-year decadal survey science roadmap, made the case for keeping sample return at the heart of Mars Next Decade. If NASA could not afford a Mars Next Decade mission that contributed to sample return, the agency should instead spend its money on a mission to some other solar system destination, Steven Squyres, the head the of the NASA Advisory Council, said in February.

Grunsfeld and Figueroa both said Sept. 25 that the easiest way to design a Mars Next Decade mission that benefits three different NASA mission directorates — science, human spaceflight and space technology — was to center the mission on sample return.

“Sample return represents the best opportunities to find synergies, technologically, between the programs,” Grunsfeld said.

Likewise, Figueroa said “sample opportunity stands out as a prime opportunity to connect those objectives.”

At least one former NASA official was pleased that sample return figured so prominently in the Figueroa group’s report.

“As a long time Martian I am delighted to see that sample return architectures were identified as the most promising way to move forward,” said Scott Hubbard, NASA’s first Mars czar and the former director of NASA’s Ames Research Center.

Dan Leone is a SpaceNews staff writer, covering NASA, NOAA and a growing number of entrepreneurial space companies. He earned a bachelor’s degree in public communications from the American University in Washington.