WASHINGTON — A member of the team setting science objectives for NASA’s Mars 2020 rover mission warned colleagues that major upgrades are almost certainly out of the question for the planned copy of the $2.5 billion Curiosity rover the U.S. space agency will send to the red planet on what scientists insist must be a sample-caching mission.

“You’ve got to understand the major cost saving is heritage,” Ken Farley, a professor of geochemistry at the California Institute of Technology and a member of the Mars 2020 Science Definition Team, told members of the National Research Council Space Studies Board’s Committee on Astrobiology and Planetary Science here Sept. 4. “We’ve just done the mission concept review [at the Jet Propulsion Laboratory, which will manage Mars 2020], and they’re afraid about breaking heritage. This is a real concern.” 

“Breaking heritage,” in this case, means altering the design of the Curiosity rover. NASA has decreed that the Mars 2020 rover, whatever its mission, be built from Curiosity’s spare parts for about $1.5 billion — some $1 billion less than Curiosity ended up costing after missing its original 2009 launch window by two years. 

Some alterations will be necessary, members of the Space Studies Board committee acknowledged. For example, committee co-chairman and Arizona State University professor Philip Christensen pointed out, no one has ever built a sample-collection mechanism that will have to store what it collects for as long as the Mars 2020 rover will. NASA has no clear plan or timetable for retrieving those samples and returning them to Earth. 

Curiosity’s instrument payload cost NASA’s contractors $187 million to build, former NASA Mars czar Scott Hubbard told committee members. The Mars 2020 Science Definition Team, in its report, drew up two sample instrument payloads for the next-generation rover. These, including the novel sample-caching-and-storage unit, would cost around $100 million, according to the report.

At least one member of the committee was quick to speak out against changes other than those explicitly necessary to turn the Curiosity design into a sample-caching machine. 

“We’ve got to be really thoughtful here,” Laurie Leshin, dean of the School of Science at Rensselaer Polytechnic Institute in Troy, N.Y., said at the Sept. 4 meeting. 

Leshin, former deputy associate administrator for NASA’s Exploration Systems Mission Directorate here, said she literally shuddered at the very mention of upgrading Curiosity’s entry, descent and landing systems, even though an upgrade would give the Mars 2020 rover a better chance of finding scientifically compelling samples. 

An entry, descent and landing upgrade could cost anywhere from $30 million to $200 million, depending on the sophistication of the system chosen, Science Definition Team member John Grant, a geologist at the National Air and Space Museum here, told the committee.

“If you add in these capabilities, [landing sites] that would not be accessible to the [Curiosity] system as flown become accessible,” Grant said.

Mars scientists and engineers will get a chance to discuss landing options in more detail in spring 2014, Grant said, when NASA hopes to hold a workshop about possible landing locations for the Mars 2020 rover.

Meanwhile, well before the landing site workshop, NASA plans to solicit ideas for Mars 2020 science investigations. Michael Meyer, lead Mars scientist at NASA headquarters here, said the solicitation would arrive in late September or perhaps early October. He declined to be more specific.

In an Aug. 12 notice posted online, NASA said the Mars 2020 solicitation would not be released before Sept. 16. NASA’s Goddard Space Flight Center in Greenbelt, Md., wasted no time wading into the competition. The center on Sept. 3 issued its own procurement notice seeking ideas for a pump that could be used as part of a mass spectrometer for the Mars 2020 rover. Responses are due to Goddard Sept. 17.

Dan Leone is the NASA reporter for SpaceNews, where he also covers other civilian-run U.S. government space programs and a growing number of entrepreneurial space companies. He joined SpaceNews in 2011.Dan earned a bachelor's degree in public communications...