BOULDER, Colorado - NASA faces thorny technological problems and money woes in furthering its Mars exploration agenda over the years to come, SPACE.com has learned.

The MEPAG findings were the product of a meeting held September 10-11 at the Jet Propulsion Laboratory (JPL) in Pasadena, California. Some 150 members of the Mars science community attended the meeting and participated in a range of topics.

MEPAG has four goal subgroups, studying Mars issues related to life, climate, geology, as well as preparation for human explorers.

In a Sept. 24 letter report from MEPAG to James Garvin, NASA Lead Scientist for Mars Exploration at space agency headquarters in Washington, D.C., questions, findings and discussion points stemming from the meeting are highlighted.

That document, obtained by SPACE.com, was authored by the MEPAG Executive Committee, under the chairmanship of Bruce Jakosky, a space scientist here at the University of Colorado, Boulder.

A key issue noted in the MEPAG report is the status of the 2009 Mars Science Laboratory (MSL). This would be a large, probably nuclear-powered robotic rover built for pinpoint landing and wheeling itself and a battery of instruments across Mars.

The price tag for MSL through development is already busting a cost cap, the MEPAG report observes, without specifying cost figures. Furthermore, this big bill does not fully include funds needed for planetary protection issues, meaning thorough sterilization of MSL to kill off any hitchhiking Earth microbes.

There is risk, the MEPAG report explains, "that the project will require either delays or descopes in order to come in within budget." Either one would cripple the MSL effort and the Mars exploration program, MEPAG adds.

Descoping MSL equates to lessening the rover's science-gathering skills -- so much so that the value of the mission could be called to question.

MEPAG participants also raised concerns about a nuclear-powered MSL having an uncontrolled impact on Mars at a zone rife with water ice.

If a crash occurs, MSL's nuclear energy sources may allow long-term subsurface heating that could melt Martian ice. That might permit Earthly microbes carried along on the spacecraft to grow. This scenario has not been examined in sufficient detail to be understood thoroughly, the MEPAG letter report notes.

Furthermore, plopping down MSL in an area thought absent of water ice is suspect. Ruling out water ice at a given site via remote-sensing techniques before landing is not possible, the MEPAG report stresses.

"MEPAG would be very concerned if these uncertainties forced MSL to shift into an 'avoid the water' strategy," the report says.

In regards to keeping Mars free of Earth microbes, MEPAG raises a concern.

"Even a spacecraft that is fully and thoroughly sterilized," the report points out, "may contain a large number of now-deceased microbes and other contamination by organic molecules that could jeopardize the scientific integrity of measurements that would search for indigenous organic components."

MEPAG thinks a "rapid-response" Science Steering Group is warranted to ponder this particular matter in connection with the Mars Science Laboratory.

Like numbers of Mars study groups, MEPAG also supports the return to Earth of Mars samples -- rock, soil, and atmosphere -- "at the earliest feasible opportunity."

Doing so would be of "tremendous value for making fundamental advances in our understanding of the history of Mars and its potential to have had life or to have it at present," the report notes.

But within the Mars community, there has also been an ongoing debate about how best to collect Mars specimens for return to Earth.

Gathering up a suite of carefully picked samples from diverse locations is one favored approach. The other is to snag more limited samples within reach of a robotic arm on a lander, now identified as the Groundbreaking Mars Sample Return mission.

"As much as I would like any sample mission, or series of sample return missions, not getting it doesn't mean the program dies," MEPAG chair, Bruce Jakosky, told SPACE.com. The money to back a robotic Mars return sample effort does not appear to be available at present, he said.

Jakosky said that a cutting-edge Astrobiology Field Laboratory (AFL) is under discussion. It would do on-the-spot science, tightly focused on the question about whether Mars has been or is an abode for life. A study group will look into the AFL in more detail, he said, fleshing out technology and cost issues.

"But right now, the AFL looks like a first-rate mission," Jakosky said. He added, however, that he would trade AFL in a second for Mars-to-Earth sample returns.

"You can do things back in the lab on Earth that you just can't do on the surface of Mars," Jakosky said. "So I would trade AFL for a sample return in a second, hands down."

In the recent MEPAG deliberations, concerns were raised that the Mars exploration program may have become too limited in scientific scope. Increasingly, their report observes, portions of the Mars science community are "feeling disenfranchised by the current program."

Science gaps exist in the Mars exploration endeavor, the MEPAG report says. There was no consensus on what action to take, however.

Another MEPAG discussion point was the potential value of a science-payload attached to a Mars Telecommunications Orbiter now scripted for the 2009 time frame.

Jakosky said in an interview that while MEPAG has identified issues for NASA, the Mars exploration agenda of today -- some elements literally en route to the red planet -- is striking. "It's an incredibly vigorous, active, vibrant program. And anybody that says otherwise isn't adding up the numbers," he said.

"The problem is that we are asking very broad questions," Jakosky said. "No one mission is going to address them fully. That means that even with all these missions this decade, we are not, almost explicitly, not going to get an answer to the one question we want to know about -- whether there's life."

Jakosky said that as NASA sketches out the next decade of Mars investigations, the signature theme for red planet researchers could likely migrate from "follow the water" to "follow the life."

In response to the MEPAG letter, NASA's Garvin said that the space agency is listening, reacting, and doing its best within the programmatic constraints to keep the Mars Exploration Program (MEP) balanced. At the same time, NASA recognizes "that certain science topics are more challenging and offer greater breakthrough potential than others," Garvin told SPACE.com.

As to specific points detailed in the MEPAG letter, Garvin said that, in the case of the Mars Science Laboratory, NASA is taking very seriously the issues of cost growth and contamination in order to preserve flexibility in landing the craft at a desired locale on Mars.

Similarly, Mars sample return to Earth is embraced within NASA's next decade planning, on the basis of its scientific importance. Within the current Mars Technology Program at NASA, Garvin said, low-level investments are being made to support certain aspects of robotic return of samples from Mars.

There is the possibility, Garvin noted, of fitting an 11-pound (5-kilogram) science payload to the Mars Telecommunications Orbiter (MTO). This project is still in the concept stage, however, with a major review of that spacecraft set for spring 2004. "The possibility of real science from the MTO -- albeit constrained by mass and dollars -- remains open," he added.

Garvin hopes competitions in NASA's Mars Scout program, starting in 2011, "will help diminish any sense of disenfranchisement that the community may exhibit."

He added: "It is my view that MEPAG has delivered exactly what we need to continue to adapt to the changing dynamic of the science of the planet Mars."

Garvin said that NASA is in the midst an unprecedented period of intensified Mars exploration.

There is the possibility of the agency doubling its experience by 2004, Garvin concluded, given the upcoming Mars rover surface science missions, as well as using new orbital assets to understand the planet far better than even now.