NASA is looking for ways to get rock samples back from Mars for less than the $11 billion the agency would need under its own plan, so last month, officials put out a call to industry to propose ideas.
Boeing is the first company to release details about how it would attempt a Mars Sample Return mission. Its study involves a single flight of the Space Launch System (SLS) rocket, the super heavy-lift launcher designed to send astronauts to the Moon on NASA's Artemis missions.
Jim Green, NASA's former chief scientist and longtime head of the agency's planetary science division, presented Boeing's concept Wednesday at the Humans to Mars summit, an annual event sponsored primarily by traditional space companies. Boeing is the lead contractor for the SLS core stage and upper stage and has pitched the SLS, primarily a crew launch vehicle, as a rocket for military satellites and deep space probes.
All in one
Green, now retired, said the concept he and Boeing engineers propose would reduce the risks of Mars Sample Return. With one mission, there are fewer points of potential failure, he said.
"To reduce mission complexity, this new concept is doing one launch," Green said.
This argument makes some sense, but the problem is SLS is the most expensive rocket flying today. Even if NASA and Boeing introduce cost-cutting measures, NASA's inspector general reported last year it's unlikely the cost of a single SLS launch would fall below $2 billion. The inspector general recommended NASA consider buying commercial rockets as an alternative to SLS for future Artemis missions.
NASA's Perseverance rover, operating on Mars since February 2021, is collecting soil and rock core samples and sealing them in 43 cigar-size titanium tubes. The rover has dropped the first 10 of these tubes in a depot on the Martian surface that could be retrieved by a future sample return mission. The remaining tubes will likely remain stowed on Perseverance in hopes the rover will directly hand off the samples to the spacecraft that comes to Mars to get them.
In his remarks, Green touted the benefits of launching a Mars Sample Return mission with a single rocket and a single spacecraft. NASA's baseline concept involves two launches, one with a US-built lander and a small rocket to boost the rocket samples back off the surface of Mars, and another with a European spacecraft to rendezvous with the sample carrier in orbit around Mars, then bring the specimens back to Earth.
"This concept is one launch vehicle," he said. "It's the SLS. What does it do? It's carrying a massive payload. What is the payload? It's a Mars entry and descent aeroshell. It has a propulsive descent module."
The lander would carry everything needed to get the samples back to Earth. A fetch rover onboard the lander would deploy to drive out and pick up the sample tubes collected by the Perseverance rover. Then, a robotic arm would transfer the sample tubes to a container at the top of a two-stage rocket called the Mars Ascent Vehicle (MAV) sitting on top of the lander. The MAV would have the oomph needed to boost the samples off the surface of Mars and into orbit, then fire engines to target a course back to Earth.
Boeing has no direct experience as a prime contractor for any Mars mission. SpaceX, with its giant Starship rocket designed for eventual Mars missions, and Lockheed Martin, which has built several Mars landers for NASA, are the companies with the technology and expertise that seem to be most useful for Mars Sample Return.
NASA is also collecting ideas for Mars Sample Return from its space centers across the United States. The agency also tasked the Jet Propulsion Laboratory, which was in charge of developing the original dead-on-arrival concept, to come up with a better idea. Later this year, NASA officials will reference these new proposals as they decide how to proceed with Mars Sample Return, with the goal of getting samples back from Mars in the 2030s.
Maslow’s hammer
Green said Boeing’s concept meets NASA’s goal of returning samples before 2040, when the agency’s previous multi-launch architecture would bring Martian rocks back to Earth for scientific analysis. The concept he outlined Wednesday would launch in 2034, land on Mars in early 2035, and spend a few weeks transferring samples to the capsule that will return them to Earth.
Then, the MAV would launch off of the red planet and get the samples back in the hands of scientists by the end of 2035. Due to budget limitations, the existing Mars Sample Return architecture NASA has developed with the European Space Agency would stretch out over a decade between 2030 and 2040.
Green did not offer a budget estimate for the Boeing concept, which he said still must undergo a cost analysis.
With lower-cost super heavy-lift rockets on the horizon, it seems like the Space Launch System has a finite shelf life. Using the SLS is probably the best chance NASA has to fly astronauts to the Moon in this decade, but by the 2030s, large reusable launchers like SpaceX's Starship and Blue Origin's New Glenn should be flying regularly.
SpaceX's Starship, mostly developed with private funding, is the vehicle Elon Musk says will send people to Mars. Sending Starship beyond low-Earth orbit will require the mastery of in-space refueling, something SpaceX and NASA are working on together because the agency selected Starship as the first human-rated lunar lander for the Artemis program.
Abraham Maslow's axiom—"if the only tool you have is a hammer, you tend to see every problem as a nail"—rings true with Boeing and the Space Launch System. Boeing pushed for NASA to use the SLS rocket to launch the Europa Clipper mission to explore one of Jupiter's icy moons. Ultimately, NASA decided on a launch aboard SpaceX's Falcon Heavy rocket later this year at a fraction of the cost.
Nevertheless, SLS has proven it can successfully fly. The basic version of the Space Launch System performed flawlessly on its first test flight in 2022. If NASA could really set aside an SLS rocket for the Mars Sample Return mission at a cost of $2 billion, this would probably not be the most expensive element of the concept Boeing put forward.
The concept would deliver a massive lander of nearly 25 metric tons to the surface of Mars, using an inflatable aeroshell and heat shield to protect it from the high temperatures of entry into the Martian atmosphere. The MAV itself would be 11 metric tons, big enough to have the energy to send the samples directly from Mars back to Earth, according to Green. This is much larger than the rocket NASA originally conceived for Mars Sample Return.
The concept for a larger MAV goes against the thinking NASA officials shared last month when they announced they were seeking new ideas for Mars Sample Return. Developing a lighter lander and a smaller rocket would reduce complexity, according to Doug McCuistion, former director of NASA’s Mars exploration program, who is now consulting the agency on the MSR program. This is the same argument Boeing is making for sending a larger spacecraft and MAV to Mars.
"Those are the drivers of mass and those are the drivers of cost and complexity, so it’s important to draw those down," McCuistion said.
