Unanswered Questions - Answered

Here is a short list of questions I got from some of the students in the outreach program - I will try to answer them over the next few days.

Is it possible to use nuclear or solar power on Mars?
-Yes. Usually nuclear power is preferred for human Mars missions, because the power requirements for life support systems are usually high - they are often estimated at 20 kW peak. If the life support system is highly closed (meaning that it recycles more air and water), it will require more power than an open system. If we want to have power to run the life support system, conduct science experiments, communicate with Earth, and create rocket propellant for a return trip, we will need a lot of power. Solar arrays can't generate as much power at Mars as they can at Earth, because sunlight is less intense there. But improved solar arrays designs and lower required power levels may mean that solar power for a Mars mission will become feasible.

How are carbon, oxygen, and nitrogen recycled in Mars habitats?
-Nitrogen will probably not be recycled. The only use for nitrogen on a spacecraft or in a surface habitat is to maintain pressure inside without relying on a purely oxygen atmosphere (which can be dangerous). So nitrogen will be pumped into the habitat or spacecraft to make up for minor leaks (like at seals) or for air lost when astronauts go through the airlock for extravehicular activity. It will be supplied from tanks, rather than recycled.

Are the EVA suits hot? Heavy? Hard to put on? Are they like real EVA suits?
-The EVA suits at MDRS are very hot. Fortunately, it is usually cold at MDRS when crews go there. They are heavy, especially the backpacks, and they are hard to use. In this sense, they are like real EVA suits, although the MDRS suits are not pressurized. The MDRS suits, while they are hard to put on, are not quite as hard as real suits.

If a trip to Mars takes three years, is it feasible that we will go?
-A lot of people hope so. NASA's plan for the next fifteen or twenty years is to go to the Moon, which is much closer to Earth, and practice staying there for a long time, up to six months or a year at a time. That will allow us to practice for trips to Mars. If you're worried that a three-year trip is a long trip, consider that the trip from England to America by sailing ship took weeks, and Magellan's voyage around the world took three years. Furthermore, a lot of people who sailed to the New World stayed for the rest of their lives - much more than three years, and in conditions much less safe and much more harsh than will be the case on a trip to Mars.

What are the psychological effects of living together in a small space?
-While some interpersonal friction is possible given the sometimes-stressful (it's very work-oriented) environment and close quarters, generally there are no major detrimental psychological effects. I can report that our crew functioned generally well, and this can be attributed to two main factors: the professionalism of all the crewmembers, and the willingness to accommodate others that crewmembers showed when required. The first factor is a typical side effect of years of education in science or engineering (there are many other ways of acquiring a professional attitude, of course, but a lot of hard-working science and engineering types come to it through their work), the second usually a personality characteristic. This plays some role in crew selection, and although sometimes prickly aspects of personality will not manifest themselves completely right away, usually there are signs whether a given person will get along well with others or not. I feel that I displayed these signs when I described my childhood - I was the first-born of seven kids, so I had no choice but to eventually learn to get along well with others (there were a lot of others running around my house by the time I left).

Is there a limiting factor on crew size?
-Not of which I know. If you have the technology and money to send fifty people (we have the technology, certainly), you can send fifty people. If you have the technology to send two hundred people, you can send two hundred people. Obviously, it's very expensive to send just one person, so most estimates place the size of the first crew to visit Mars at 4 to 6 people. This is for a round trip, however. I once estimated that the same amount of mass needed to send six people to Mars and back could send 24 people to Mars and supply them for two years . . . it's a rough estimate. But large groups of people do live in tight, dangerous quarters for long periods of time while working hard for non-spectacular pay . . . just look at the Navy. An aircraft carrier may have a crew of up to 3000, and may cruise for months at a time. If it were the biggest, coolest, most expensive spaceship ever instead of a carrier, we could send it to Mars instead.


How do we prevent disease on a trip to Mars?
-Send healthy people, and send good doctors and medical supplies along too. Make the crew wash their hands often and practice good sanitation and hygiene. Ideally, this is the same way we prevent disease on Earth, except that the environment in a spaceship or a Mars habitat can be controlled much more closely.

Do we need to go to Earth orbit first to get to Mars? How about the Moon?
-Nothing can leave Earth without passing through the volume of space usually called "Earth orbit," but it isn't strictly necessary to stop there. We usually do, just to check things out before we leave. It isn't necessary at all to send a ship to the Moon, have it stop there, and then go to Mars - in fact, that's way more expensive than just sending it to Mars in the first place. Anytime a spaceship lands on or leaves a planet's or moon's surface, it uses a lot of fuel (and a lot of money). The cheapest path between any two planets is almost always directly from the surface of one to orbit, from that orbit to the other planet's orbit, and then down to that planet's surface. The only reason to stop at the Moon before going to Mars would be if there were already a rocket base, with a fuel depot and construction facilities, already there. Launching from the Moon is cheaper than launching from Earth, so we could just send humans in a small spaceship to the Moon, where they would meet the big rocket with all its supplies and then fly to Mars. Of course, we cannot yet make these supplies on the Moon, or build rockets there, so it doesn't make sense to stop there first. If we could grow food, synthesize rocket fuel, and refine and cut aluminum on the Moon without shipping it from Earth first, then things would be different.

How do we use the bathroom in space? How much recycling is there?
-A special toilet is used in space. Usually we try to recycle as much as possible, because then we don't need to bring more supplies from Earth. Water is especially desirable to recycle, as astronauts usually use more of it than of food, oxygen, packaging, or anything else. Right now, the Space Station recycles some of its water, mostly from wash water. Eventually, we hope to have enough equipment on the station to recycle nearly all the water.

What do we wear in the EVA suits? What do we wear in the Hab?
-In the simulated EVA suits, we wear something that's comfortable but a little bit warm - some of my crewmates wore sweatpants, while I chose to put on an exercise shirt and board shorts - athough I did wear a nice fuzzy hat, both to keep my head warm and to keep from getting sunburned. The glass of the helmets can intensify the light uncomfortably, and don't offer any shade. I wore a lot of sunblock as well. In the Hab, we wear whatever we want . . . although usually not for more than a few days in a row. We don't have laundry facilities, so when clothes get too smelly, they are tied up in a bag for taking home and turb-washing after the mission is over.