WASHINGTON -- NASA has refined its strategy for future robotic exploration of Mars, advocating for a regular cadence of smaller missions to answer key questions in advance of human missions.
NASA released Dec. 11 its "Expanding the Horizons of Mars Science" plan, which outlines a strategy for the next 20 years that calls for flying low-cost missions at every launch opportunity while taking more advantage of commercial and international partnerships.
NASA released a draft version of that plan in March 2023 and the final version is "not dramatically different," Eric Ianson, director of the Mars Exploration Program at NASA Headquarters, said at a side meeting during the annual American Geophysical Union conference to discuss the plan. "Previously, we had presented a 25-or-so-page PowerPoint package and now we're rolling out a 154-page written document."
The plan focuses on a "science-driven robotic Mars program" separate from Mars Sample Return, which is going through a separate agency review on ways to reduce its cost and schedule expected to wrap up before the end of the year. It also does not include any future human missions to the planet.
What the document does offer is a strategy of future robotic missions that can tackle key science questions about Mars, including any evidence of past or present life, while also laying the scientific groundwork for future crewed missions.
The strategy has three "co-equal" science themes, said Becky McCauley Rench, program scientist in NASA's planetary science division and co-lead of the study. One, called "exploring the potential for Martian life," is focused on looking for any evidence of life on Mars. "Did life ever arise on Mars, and if so, does it exist today?" she said. "If life never developed, why not?"
A second theme, "supporting the human exploration of Mars," is looking at the "synergistic observations" that could be made with robotic missions ahead of the first crewed missions, including key knowledge gaps to fill. "How can we prepare to maximize that precious human time on the surface and the resources in connection with the export community here on Earth?" she said.
The third theme, called "revealing Mars as a dynamic planetary system," includes other science topics, with an emphasis on comparative planetology. "We want to learn as much about Mars as we know about Earth," she said.
To perform the science in those three themes, the plan advocates a regular series of mission, focusing on smaller spacecraft. "This program is looking at changing the paradigm of how we think about Mars missions," Ianson said. "Every opportunity there is when a launch window opens up, can we send something up?"
"We want to do that with lower-cost missions that are science driven and has the capability of providing flexible, rapid response to discoveries," said McCauley Rench, "not necessarily taking 10 years between thinking about a mission and actually seeing it launch."
Those smaller missions, with projected costs of $100 million to $300 million each, would focus on specific scientific questions with a single instrument or small suite of instruments. NASA proposes to augment them with less frequent but larger missions with more complex instruments. An example would by the Mars Life Explorer lander concept included in the planetary science decadal survey.
The plan also includes flying payloads as "missions of opportunity" on missions by other space agencies or even commercial missions. Also included is revitalizing what Ianson called "critical and aging infrastructure" at Mars such as communications relays and the high-resolution imagery currently provided by the nearly 20-year-old Mars Reconnaissance Orbiter.
Infrastructure is one area where commercial partnerships may contribute to the plan. NASA awarded studies in May to nine companies to examine the feasibility of commercial systems to deliver payloads to Mars and to provide communications and imagery services.
Ianson said the studies were promising. "There really is some merit here and we think there is something that merited further studies and further work," he said, such as how to structure any public-private partnerships to carry out such missions.
One issue with commercial Mars missions, he said, will be the business case for companies performing such missions. A simple fee-for-service model, where NASA pays only for the services once provided, "is probably not a totally workable solution," he said, based on the outcomes of the studies. "There probably needs to be some level of investment through a public-private partnership on the NASA side up front."
The agency is taking initial steps to implement the strategy. NASA's 2025 budget proposal included $40 million to invest in Mars robotic exploration technologies. NASA is allocating $30 million of that to internal efforts, picking 25 projects out of 90 proposals received from agency centers. The remaining $10 million may be offered to industry and academia for "innovative robotic mobility technologies," Ianson said.
The plan itself does not include any specific mission plans or budget requirements, and Ianson emphasized its flexibility. "Obviously, we would love to do everything in the plan. However, that's not realistic under challenging budget circumstances and competing priorities," he said. "I look at this plan less as a roadmap but more as a menu of options to choose from, based on the availability of budget and the most pressing needs to support Mars science."