Planning Out a Trip to Mars

16:28 minutes

A member of the HI-SEAS mission. Credit: C. Heinike
A member of the HI-SEAS mission, a long-term Mars simulation on Hawaii. Credit: C. Heinike

In a recent op-ed, President Barack Obama renewed his call, first made in 2010, for Americans to reach Mars by the 2030s. And in late September, Elon Musk, the CEO of SpaceX, gave a blockbuster speech in which he outlined a proposal not just to send people to Mars, but to colonize it with a million people — making humans “a multiplanetary species.” How close are we to getting to Mars — and staying there?

Robert Zubrin, founder and president of the Mars Society, says that Musk’s proposal has “a lot of useful and interesting ideas,” but that the designs for SpaceX’s Interplanetary Transport System, a rocket and spacecraft combo, aren’t quite ready for launch. For one, Zubrin doesn’t think they make the most efficient use of “payload” — or fuel, which, on Mars, will need to be produced on-site, from methane and oxygen.

Zubrin walks us through the logistics: Musk is proposing a “two-stage vehicle” wherein the first stage is reusable, and it returns to Earth. Meanwhile, the second stage goes into orbit and gets refueled. “Now, this is a very large vehicle. It is about four times the takeoff thrust of a Saturn V, so it’s like a Saturn XX. And the upper stage is like a Saturn V. And he refuels that on orbit and then shoots it all the way from low-Earth orbit to the surface of Mars, where it is carrying a very large passenger compartment, which stays on the ship. He unloads the passengers, then he refuels the ship and shoots it back to Earth.”

The giant spaceship is delivering hardly any payload permanently to Mars: “The engines on this upper stage weigh 60 tons. That could be 60 tons of payload.”

Instead, Zubrin suggests jettisoning the (spent) upper stage just before the ship escapes Earth’s gravitational field. This would lighten the ship’s load as it heads for Mars with just a small propulsion system for landing, and it would also get the stage moving back towards Earth for snappy reuse.

It would be back in low-Earth orbit in a week as opposed to two and a half years, and the returned stage could be used five times every Mars “launch window” (about every 26 months), he says.

The habitat needed to make human travel to Mars possible should stay put, on the planet. “You should unload that [habitat] — the colonists are going to need it. Just keep a small cabin on board the ship and shoot that back to Earth with the pilots and maybe a few colonists who want to go home.”

This would reduce fuel-making requirements for sending the payload back, by at least a factor of five, he says.

Zubrin reasons that with alterations to its designs, SpaceX could have people on Mars by the end of the 2020s. But the capability may be even closer than that: Zubrin says that with support from the new president of the United States this spring, we could get to Mars by the end of his or her second term.

“From a technical point of view, we are much closer today to being able to send humans to Mars than we were to being able to send men to the moon in 1961, when Kennedy started the moon program — and we were there eight years later,” he says.

For one, Zubrin points out that technology-wise, we’ve already done some heavy lifting.

By going to the moon, we’ve mastered hydrogen-oxygen rocket engines, multistage heavy-lift vehicles, in-space life support, spacesuits — the list goes on and on. “What we have to do now for the Mars mission is scale a few things up, modify some things, but we’re working within a craft that has already been developed. We’re advancing a craft instead of creating a craft.”

While experts like Zubrin say that our technology may soon be ready for a trip to Mars, others are mulling another crucial aspect of the mission: Are we ready to live on the Red Planet? Sheyna Gifford, now a scientist at the Saint Louis Science Center, was a medical officer on HI-SEAS, NASA’s yearlong simulated mission to Mars. She says that colonizing a new planet will be exhausting work.

“If you thought owning a house on Earth was a time suck, try owning a house in space,” Gifford says. “Everything takes longer because half the time, you don’t have what you need and running to the corner store is not an option. So you either have to ‘science it,’ or 3-D print it, or invent it.”

And while a Mars colony would eventually have enough people to provide “backup” for all the work to be done, crew members on the first few Mars missions won’t have that luxury.

“We were at work for 366 days straight … and that’s a problem,” Gifford says. “Humans need a break. Unfortunately, you still have to get up and water the crops and check the computer system, make sure the air compressors and filters are working. There’s no way to take a break. At the same time, you must. And this is one of these questions we have to answer before we go [to Mars], even if the technical ones are solved.”

— Julia Franz (originally published on PRI.org)

Segment Guests

Robert Zubrin

Robert Zubrin is founder and president of The Mars Society, and the author of The Case for Mars: The Plan to Settle the Red Planet and Why We Must. He’s based in Colorado.

Sheyna Gifford

Sheyna Gifford is a scientist-in-residence at the St. Louis Science Center in St. Louis, Missouri. She was Health and Safety Officer on HI-SEAS, NASA’s 1-year mission to simulated Mars.

Segment Transcript

IRA FLATOW: This is Science Friday. I’m Ira Flatow. We’re talking about space travel and we are going to talk about what it’s like to go to Mars.

Maybe you’ve thought about going to Mars. You saw this week where Elon Musk outlined his ideas about sending humans to Mars and not just to visit but to colonize. He wants to put a million people on Mars to form a self-sustaining civilization there and make that, quote, humans a multi-planetary species.

Well, my next guest is no newcomer to this idea. He has been plotting for years how the humans could settle Mars. Robert Zubrin is founder and president of the Mars Society, also president of Pioneer Astronautics an aerospace R&D company. He joins us from Colorado Public Radio studios in Denver. Welcome to Science Friday.

ROBERT ZUBRIN: Thanks for inviting me.

IRA FLATOW: You’re welcome. You’ve been thinking about, what, how many years have you been thinking about settling Mars?

ROBERT ZUBRIN: Well, I’ve been thinking about settling Mars since about 1957, but I’ve been working on it professionally for about 30 years.

IRA FLATOW: Wow. And what do you think of Elon Musk’s proposal? Did he get it right, did he get it wrong? The good and the bad.

ROBERT ZUBRIN: Well, there were a lot of useful and interesting ideas in his mission plan, but he didn’t put them together right, that is the architecture that he showed was suboptimal. For example, he’s got a two stage vehicle that goes to orbit. The first stage is re-useable, comes back to Earth. That’s great and SpaceX is demonstrating it now.

The second stage goes to orbit, where it is refueled. Now, this is a very large vehicle. It is about four times the takeoff thrust of a Saturn 5. So it’s like a Saturn 20. And the upper stage is like a Saturn 5.

And he refuels that on orbit and then shoots it all the way from low Earth orbit to the surface of Mars, where it is carrying a very large passenger compartment which stays on the ship. He unloads the passengers, then he refuels the ship and shoots it back to Earth.

So what you have is this giant spaceship that you’re refueling to send back to Earth, which is delivering hardly any payload permanently to Mars. The engines on this upper stage weigh 60 tons. That could be 60 tons of payload.

What he needs to do is the following. First of all, that upper stage, he can reuse it in the way he says, but he should stage off of it just before Earth escape. So it would loop out about as far as the moon and come back and be back in low Earth orbit in a week instead of in 2 and 1/2 years.

So it could be used five times every Mars launch window, which occurs every two years instead of once every four years. You get much more use out of it, you get 10 times as much use out of it. And you don’t have to drag that heavy stage all the way to Mars and back.

And then, the big habitat that you shoot to Mars, you don’t send it back to Earth. What goes to Mars should stay on Mars. You should unload that hab, the colonists are going to need it. Just keep a small cabin on board the ship and shoot that back to Earth with the pilots and maybe a few colonists who want to go home.

And if you do it that way, then the fuel making requirements that you need to do on Mars to shoot the payload back drop by at least a factor of five, perhaps a factor of 10, putting much lower burden on the base.

So these are some modifications. And in fact, the really interesting though, about the architecture, is that if you do do it the way I just said, where you can use that upper stage five times per opportunity instead of one time every other opportunity, you’re increasing its payload by a factor of 10, which means you could deliver the same payload by reducing the booster size by a factor of 10.

IRA FLATOW: You have though about this.

ROBERT ZUBRIN: Yeah. But just one more thought. Right now, that booster delivers 500 tons to orbit, Reduce it by a factor of 10, you’re delivering 50 tons to orbit, which is what the Falcon Heavy will actually be able to do next year.

IRA FLATOW: Well, given all these options, how soon do you think, if you were in charge, you could get us to Mars?

ROBERT ZUBRIN: Well, if I were in charge, and if Hillary Clinton was to say in the spring if her first term, she’s committing the nation to send humans to Mars, I could be there before the end of her second term. From a technical point of view, we are much closer today to being able to send humans to Mars than we were to being able to send men to the moon in 1961 when Kennedy started the moon program. And we were there eight years later.

IRA FLATOW: Because we don’t have to create new technology?

ROBERT ZUBRIN: We don’t have to create as much new technology, that’s for sure. The challenges we mastered going to the moon, developing hydrogen-oxygen rocket engines, multi-stage heavy lift vehicles, in-space life support, spacesuits, orbital rendezvous techniques, in-space navigation techniques, communication systems, soft landing systems, re-entry systems. You could go on and on and on. The whole bag of tricks we developed during Apollo.

What we have to do now for the Mars mission is scale a few things up, modify some things. But we’re working within a craft that has already been developed. We’re advancing a craft instead of creating a craft.

IRA FLATOW: What about once we get to Mars? Setting up a colony, growing food, things like that. How much work needs to go into that?

ROBERT ZUBRIN: Well, some, certainly. But first of all, I don’t think the concept is that we launch 1,000 spaceships and send 100,000 people to Mars each time and rapidly send a million people to Mars as fast as we can. That’s not how America was settled, for example.

We send first, four people. And they establish a greenhouse. And then we send six people, and then 10 people, then 20 people, because as you go, you’re building up the infrastructure on the ground to support larger and larger number of people.

So the task before us, in our generation right now, is first, to send that first exploratory human expeditions to the surface of Mars. And I can talk in a minute about some of the things they can do besides preparing the way for colonists, scientific things. But then, perhaps 10 years after the first landing, start establishing a permanent base, which will be more devoted towards developing the technologies that make Martian raw materials into resources for settlement.

IRA FLATOW: Do you think anybody has a leg up on this? Do you think NASA’s going to get there first, or is there going to be Elon Musk or Jeff Bezos? Who’s going to get there do you think? Who would you like to go with? Place your bets.

ROBERT ZUBRIN: I would like to go with any of them. Right now, I would say that the Musk organization has a great deal of credibility. It’s showing a great deal of determination to want to make this happen. Musk not using problems as excuses for not going. He attacks them head on. And that’s something.

So I don’t think that the first SpaceX expedition to Mars is going to go in this giant spaceship. I think that is something for later. That is something for a future. Columbus didn’t sail on the Queen Elizabeth, he sailed in a much smaller ship.

I think, if they take that architecture that Musk outlined, scale it down by a factor of 10, and do some of the tricks that I mentioned. SpaceX could have people on Mars by the end of the 2020s.

IRA FLATOW: Let me get one call here. See if we can get a call in before we have to go. Rachel in a Portland, Oregon. Hi, Rachel, welcome to Science Friday.

RACHEL TILLMAN: Hi, there, Ira and Bob. This is Rachel Tillman with the Viking Mars Mission Education Preservation Project. And good to talk to you again, Bob. And nice to be on.

ROBERT ZUBRIN: Good to talk to you.

RACHEL TILLMAN: One of the things that I was thinking about in knowing that you were coming onto the show was, we have this immense challenge that’s not just a scientific challenge but an environmental challenge that specifically relates to missions being anywhere from 10 to 20 years in a necessary lifespan, whereas our political construct is really chunked up to the four year bits and /

How can you address, Bob, that challenge that we’ve talked about before in collaborating with lots of different entities, educational entities, such as ours, NASA, a global community of providers that will be necessary to make that exploration occur?

IRA FLATOW: All right. Yeah, it takes a village to do this, doesn’t it?

ROBERT ZUBRIN: Right. Well, as far as NASA’s concerned, a number of people have pointed out that it could use a more stable basis for its funding. And it has occasionally been advanced by various legislators to create a basis for NASA funding that didn’t go up and down and sideways every other year and having the rug pulled out from programs halfway through. So that clearly should be done. That would help.

Apollo was successful because we had bipartisan commitment. We had serious commitment by the political class, no one wanted to– I mean, a few people– but by and large, there was very strong support, and they carried it all the way across. Although, once again, they had the advantage that they weren’t trying to do it over 30 years, they were doing it over 10.

And I think, if we want to go to Mars, the next president has to get up and say, we’re going to do this within my two terms, not we’re going to do it in 30 years. That’s leaving too much to chance.

Having private organizations in the game can help as well. Look, what Musk is doing and what Bezos is to do are developing flight systems. They’re developing substantial parts of the Mars hardware set that’s needed. And so if the political class starts to address this, and they see that half the flight systems have already been developed, that allows us to do this, not only at a lower cost but on a much faster schedule.

IRA FLATOW: I want to bring out someone who can add to our conversation about talking about what would a trip to Mars be like? Shauna Gifford can give us some idea. She was a medical officer on NASA’s High Seas Program. That was a one year simulated mission to Mars. She’s now scientist in residence at the St. Louis Science Center. Welcome to the program.

SHAUNA GIFFORD: Thank you, Ira. Dr Zubrin, how are you?


IRA FLATOW: Describe this project. What? You had six people in one simulated Martian habitat for a year. What was that like?

SHAUNA GIFFORD: That’s right. Six people, 1,200 square feet. It was like a bunch of scientists farmers. It was like space camp for real. It was a lot of fun and a lot of challenges and very educational, very worthwhile and very productive.

IRA FLATOW: And what was the main questions you were trying to answer or a single question?

SHAUNA GIFFORD: The single question. So Dr Zubrin’s addressing the technical aspects of getting there, as is Elon and Jeff Bezos. We’re addressing the human aspects of how to get there psychologically, keeping people well physically, keeping people well.

We also did some experiments in feeding people, growing food using volcanic soil and little cyanobacteria. We also cultured food. We exercised. So I’m working on the human part, and Bob and the rest are working on the technical aspect.

IRA FLATOW: There have got to be conflicts that break out when six people are put together for a year in 1,200 square feet.

SHAUNA GIFFORD: Sure. Show me a roommate situation where there are no conflicts.

IRA FLATOW: How were they resolved?

SHAUNA GIFFORD: Expeditiously, if possible. If not possible, you give yourself an adult time out. These things are very important, even in space. You can always go out the hatch as needed. You just need five minutes to decompress and permission from mission control to take an EVA. If you really need to go for a walk, you take a walk.

IRA FLATOW: So there has to be some downtime allotted to you away from the crowd, some space for that?

SHAUNA GIFFORD: Yes, absolutely. And in fact, scheduling, how to schedule space time, time in space, is a very strange thing, because you can never take a break in space. We were at work for 366 days straight, Ira. And that’s a problem.

Humans need a break. Unfortunately, you still have to get up and water the crops and check the computer system, make sure the air compressors and filters are working. There is no way to take a break, at the same time, you must. And this is one of these questions we have to answer before we go, even if the technical ones are solved.

IRA FLATOW: Well, for six people, is it possible to scale that up? What it would be like for a thousand, a million people in a Martian colony?

SHAUNA GIFFORD: Absolutely. Its possible to scale it up. We were, I believe, at a minimum for our skill set. We had one of everything. One commander soil scientist, one engineer, one architect, one astrobiologist, one physicist, and one physician. It would be tough to scale down and still retain the resources and the talents you need to make the mission run, but you could definitely scale up.

IRA FLATOW: We had Mike Massimino. Let me just remind everybody this is Science Friday from PRI, Public Radio International.

We had astronaut Mike Massimino on talking about what it was like on the shuttle to work. And he said, you know, I discovered– and he writes this in his book– things take so much longer, missions, things, just turning a bolt, whatever, takes so much longer than we thought we would need. Did you find that true?

SHAUNA GIFFORD: It’s so true, it’s incredible, Ira. You spend so much longer cooking and cleaning and cleaning yourself and mending the clothing and repairing the hab. If you thought owning a house on Earth was a time suck, try owning a house in space. It’s that to an order of magnitude.

Everything takes longer, because half the time, you don’t have what you need. And running to the corner store is not an option. So you either have to science it or 3D print it or invent it. It’s basically very much science on the fly. And everything takes much, much longer.

IRA FLATOW: Robert Zubrin, do you agree that have to make plans for contingencies you don’t expect and bring stuff along that you might not have or is 3D printing a great idea too?

ROBERT ZUBRIN: 3D printing, bringing extra stuff, bringing people who can adapt, bringing people who can roll with the punch, bringing people who have a sense of humor.

We, at the Mars Society, we have a simulated hab too. We have a team in our desert station right now that’s going to be there for 80 days and then in the Arctic for 80 days. And the one thing though, that we do find is that having an active program of field exploration completely relieves these pathologies associated with boredom that a lot of simulations that have just looked at isolation have caused in the crew. Give them something to do, and there’ll be a lot happier.

IRA FLATOW: Have we figured out about the risk from radiation out in space?

RACHEL TILLMAN: We do know But we do know quite a bit about that thanks to Mars Curiosity Rover, we have the reports from the first 200 days. It looks like it’s not as bad as it could have been. It’s certainly something worth worrying about during big events worth worrying about. And certainly, there’s always micrometeorites.

There is a little bit of Martian atmosphere, just enough to be a bit of a buffer. But at the end of the day, I think we’ll probably be safer and happier living underground on Mars. I know it’s very picturesque to put the dome on the surface. But there are huge lava tubes, they provide all kinds of shelter and all kinds of other resources. So that may be where we end up setting up shop.

IRA FLATOW: What about the dangers from the trip out there? Bob, do you think this is going to be a one way trip because–

ROBERT ZUBRIN: Well, the initial missions, you could do it one way, but I think the initial mission should be round trip exploratory missions. Ultimately, we will do one way missions. Settlement is a one way mission.

I should say, by the way, that the actual health effects that we have seen in space have not been radiological in their origin. They have been caused by zero gravity. And we can counter zero gravity by engineering techniques such as rotating the spacecraft. The radiological effects have been quite secondary and not really noticeable.

SHAUNA GIFFORD: We would like to believe that. I agree that we don’t actually know what the long-term health effects are. The cardiovascular state of our poor Apollo astronauts is not good. And we just know that they have not fared as well as their peers. Why? Is it because they were exposed to zero gravity, where two liters of your body fluid floats up into your torso and is now pulsing through your heart, or is it radiation, or is it something else?

IRA FLATOW: All right. We’re going to have to leave it there, because we’ve run out of time. I want to thank both of you, Shauna Gifford and Dr Robert Zubrin.



SHAUNA GIFFORD: Thank you, Ira.

IRA FLATOW: –President of the Mars Society and she’s scientist in residence at the St. Louis Science Center.

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  • Jeffrey Haran

    A near term manned mission to Mars may well prove to be the greatest ecological disaster ever perpetrated by mankind. Mars may contain life. It may be the only place in the solar system where extraterrestrial exists, all the speculation about Europa and Enceladus not withstanding. We have done only paltry searches for Martian life to date. So now we plan to send human beings with guts full of microbes that we haven’t even completely classified yet to a potentially pristine ecosystem. If life is found on Mars after human contamination, what do we do if we find that it is very similar to what we find here on Earth? How would we disambiguate it from human contamination? How can we be confident that contamination from terrestrial microbes won’t have deleterious effects on Martian life?

    We have contaminated countless pristine ecosystems on Earth with our presence in the name of “human exploration” and today’s terrestrial ecosystem is much poorer because of it. We should thoroughly explore Mars for the presence of life using sterilized robotic missions before we send people lest future generations judge us to be in same ilk as the sailors who wiped out the dodo bird. Mars will be available for future human colonization for eons. There is no need to rush here, other than the greed of aerospace contractors.

    Jeff Haran
    Fremont, CA

    • Carney3

      This is insane.

      We can tell family members apart via DNA. Given such close relations being distinguishable, any life we find on Mars, even descended from pre-human interplanetary transfer, will be obviously identifiable as local or not.

      There’s no remotely plausible scenario where humans could introduce bacteria that would crowd out local life anyway. The Martian surface is a multiple overkill, redundant sterilization system that would make a hospital operating room seem like a fetid tropical latrine.

      Finally, putting bacteria above humans is, again, insane. Listerine users are not mass murderers.

  • Tom Higgins

    I consider it unethical for people to bring or bear children in space or another planet given the current state of knowledge and level of risk. Adults are capable of taking responsibility for becoming fully aware of and taking (for themselves only) such an enormous risk without ethical conflict. But children are not capable of taking such responsibility. The only ethical solution is for all persons who would populate another planet to be sterilized. Otherwise, despite all good intentions, plans and agreements, an unintentional pregnancy is bound to occur.

  • Joel Corley

    Zubrin is a very smart guy. But in his staging discussion, I don’t think he is considering the difficulty in landing a large, manned craft on Mars. Musk is proposing to solve that by repulsively landing that craft (and having it be a large lifting body), so you need to have fuel tanks and engines on-board. With that said, I do agree that he might be able to optimize the mission by making it three stages, where the second stage would be jettisoned (and returned to Earth) just before achieving Earth escape. But I imagine SpaceX examined this option and discarded it for reasons that I don’t see at the moment.

    I also think returning the transport and landing craft is not really negotiable for Musk because he doesn’t want to design a mission with throw-away components. His position is that fuel is cheap, hardware is expensive. Throwing any of the hardware away is a huge waste that sets a higher floor on the cost of each seat.

    As for having no option to take a break – having more people and more automation would let you do that. The problem we have now is that we have a small number of people in space and not having someone else to rely on is difficult. It’s very like running a small homestead farm during planting season – it’s all up to you and if you don’t get up and do everything that needs to be done each day you have few people to fall back on.

    Also living on the space station or anywhere in space is complicated by a lack of gravity. Mechanically and by training, we’re used to living in Earth’s gravity well. A lack of gravity makes doing a lot of things extraordinarily difficult. But Mars has a respectable gravity well. It just don’t have a breathable atmosphere – and that’s where the biggest risks come for the colonists.

    As for the comments about having children, I think that is a ridiculous red herring. Ultimately having children born on Mars is desirable. Having grown up there, they will be best suited to the relatively low gravity. Radiation is only a problem if you spend a lot of time on the surface relatively unprotected. As they were discussing here, habitats are likely to be built underground such as in lava tubes (some of which likely could accommodate an entire city). Radiation will only be a small problem for colonists making the trip. Most will experience no adverse effects. But a knee jerk reaction such as requiring them all to be sterilized in advance would have long-lasting consequences on the viability of the colony.

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