“We’ve never landed something like this on Mars”
All About Space catches up with Chris Carberry, cofounder of Explore Mars Inc, about plans to land humans on Mars’ moon Phobos
Why would you choose to go to Mars’ moon Phobos rather than directly to Mars?
This plan is just a concept. It is US policy right now to go to Mars and to the surface of Mars at some point in the 2030s. However, the Jet Propulsion Laboratory (JPL) came out with a plan in which they decided that it might be useful to have a manned precursor mission to Mars orbit first, and in particular go to Phobos and test out key technologies before using it as a stepping stone to Mars.
What key technologies still need testing?
When mission designers talk about the biggest problems in getting to Mars, the two items that keep cropping up are usually life-support technology to keep the astronauts alive and entry, descent and landing (EDL). In other words, keeping the astronauts breathing and making sure they don’t crash! They figure that by going to Phobos first they can reduce the risk by testing out some of the key elements, particularly the life-support systems.
What is complicated about landing craft on Mars?
To appreciate the scale of the challenge, the largest weight we have landed on Mars was the Curiosity rover back in 2012, and then Perseverance in 2020, which I believe was around one tonne. But when we send astronauts to Mars we would need to land at least 30 or 40 tonnes. We wouldn’t be able to lower them with a ‘sky crane’ like we did with the Curiosity rover, and we certainly aren’t landing people with air bags like the rovers had for bouncing into a landing. We’re going to have to find a way to land them softly with retrograde rockets, parachutes or some combination of them both.
We’ve never done anything close to landing something like
that on Mars, so that’s the real challenge. What makes it particularly difficult is the atmosphere. If you ask any Mars scientist, they will tell you that Mars doesn’t have enough atmosphere to be of any use in slowing a spacecraft down, but it’s just enough that you can’t ignore it either. It creates challenges and doesn’t slow you down much either, so it doesn’t have the benefits that the thick atmosphere of Earth has.
Going to Phobos and then Mars sounds expensive. Is it feasible?
JPL designed the Phobos precursor mission under the assumption that NASA wouldn’t get any major increases in budget – just increases for inflation. Under this assumption, the aim is to get to Mars orbit by 2033 and land on the surface of Mars by the late 2030s or early 2040s. However, at Explore Mars we advocate speeding that process up a bit, and we don’t think we have to assume it will be a flat budget with just inflationary increases.
We plan for certain increases in NASA’s budget over a period of time – and not even permanent increases, just spikes in the budget which might be able to speed it up so that we would be able to land on the surface of Mars by the mid-2030s. The spikes in the budget would be built into the process and scheduled to accelerate the building of certain pieces of hardware, like if they needed to complete a crew vehicle or a transit vehicle by a certain date, the spike would allow that to be done on schedule.
How much would it cost?
When you’re talking about plans over the next 20 years, it’s always challenging to get the cost accurate, but Explore Mars has been working with a number of other groups to try and determine the probable cost of such missions. We’ve run several ‘affording Mars’ workshops, which have resulted in the release of our ‘Humans to Mars’ report. We brought together most of the key experts with some international participation, although not a lot, as well as academia, to review whether we could go to Mars affordably.
After many discussions, we agreed that it can be done affordably. We can’t provide an exact amount, but it isn’t going to cost remotely anywhere near what many of the pundits are saying. Even recently I have heard numbers ranging from half a trillion dollars to
1.5 trillion dollars, and it shouldn’t cost anywhere near close to that. Most of those numbers are thrown out there by opponents of going to Mars to try to scare people into not supporting a mission.
Can you tell us a little bit more about the other work Explore Mars does?
Explore Mars is a US-based nonprofit corporation that was founded in 2010. We’re not a membership group, but instead we run technical projects. One is called ExoLance, which is developing penetrator probes to try and get below the Martian surface to do experiments, and potentially look for life as well. We are also doing a student project called Time Capsule to Mars, where
we’re trying to send a small cubesat to Mars and drop a tiny digital time capsule onto the surface.
We do a lot of programs like the Humans to Mars summit, which is the biggest annual conference dedicated to human missions to Mars, and we do a lot of topical workshops, all to bring the space community together to try and build a coalition and try to solve some of the problems that have kept the different Mars groups apart over the last several years. We also do science and technology education programs as well. We do a wide range of activities, as well as policy work for trying to advance the goal of getting humans on the surface of Mars by the mid-2030s.
Our founders, including myself, used to be with the Mars Society. I was actually the executive director of the Mars Society for a few years, and we’re still good friends with a lot of people there, but we haven’t collaborated much over time, and I think it’s time to interact more with them. What makes our organisation succeed is that we collaborate with a large number of different groups within the space community and also groups that are not related to space.
Will astronauts actually land on the surface of Phobos? Not Phobos. It doesn’t have much gravity, so it wouldn’t be practical to colonise. Popular opinion is that Phobos and Deimos are actually captured asteroids, so we could use them for other things instead of setting up a base. First off, we could do Mars sample-return missions from either moon because there is a lot of debris from Mars on those moons. This is because over billions of years Mars shot up debris from the surface thanks to now-dormant or extinct volcanoes and meteorite impacts, so scientists think we could find an awful lot of samples of Mars on the surface of Phobos and Deimos using robots to search for them. Another reason scientists want to go to the moons is to better understand asteroids.
One of the discussions we’ve had in the US for over a decade now is whether we should stop at an asteroid before going to Mars. If you go to Phobos or Deimos you’re killing two birds with one stone, because if they are asteroids you can learn about both Mars and about small asteroidal bodies by going to them. To land a robot on Phobos, you would need some kind of system of harpoons and drills like the lander on the Rosetta probe had and do a lot of thruster moves because there isn’t enough gravity to land like you would on Mars.
“Popular opinion is that Phobos and Deimos are actually captured asteroids”
Will astronauts go to Mars directly from Phobos?
For the first mission they would certainly not go to the surface of Mars and the surface of Phobos on the same visit – it’s not even certain they would go to the surface of Phobos, just into orbit. Based on the JPL plan, it would be several years before they land on Mars, and they wouldn’t stop at Phobos along the way in that second mission. The main goal is to get onto the surface of Mars, and even JPL folks who have talked about going to Phobos or orbiting Mars in general, their goal is to get to the surface, but we figure that we need to have at least one stepping stone along the way to allow them to test out key technologies.
Will current spacecraft orbiting Mars select the landing site, or will this be done closer in time to the landing by future orbiters?
The European Space Agency is actually beginning to review potential landing sites even at this stage, despite landing on Mars not being likely to take place until after
2035. But either the current satellites we have around Mars or the ones that come after will help choose the landing site, and hopefully in the next 20 years we’ll have far more advanced orbiters that can take much more detailed photographs and much more accurate readings of the climate and the chemical nature of the Martian atmosphere, which we already have a good sense of. It will be interesting to see what spacecraft we will have around Mars in advance of sending humans.