Why not Mars?
Sending people to Mars is not a done deal no matter the level of commitment and and extent of funding.
A fair number of non-trivial obstacles lay squarely across our path.
Here are the ten stumbling blocks that come to mind…
Propulsion — The voyage out and back with conventional propulsion is on the order of six to eight months each direction. A significant improvement in rocket propulsion might cut this substantially. Still it would be months in transit and right now we have no way to improve this very much.
Landing — All of those pretty picture of large spacecraft on final approach to Mars are complete fiction. The martian atmosphere presents a dilemma with respect to landing. The air is too thin to land like an airplane and too thick to land like the Apollo missions to the Moon.
In short — we have no idea how to land a craft heavier than a metric ton.
A massive amount of fuel could be used to slow the craft before reaching the upper atmosphere and from there a lot more fuel to wind down through the last dozen kilometers or so. Yet this is more fuel than any reasonable-sized mission to Mars could afford to carry from Earth.
Radiation — Cosmic radiation and solar storms would be lethal without proper shielding. There are theoretical ways to shield enough to survive — especially while on the martian surface. Shielding would be extremely heavy, requiring far more launches from Earth and much more propulsion than we can imagine from ordinary chemical rocketry to reach Mars.
Even with extensive shielding, the crew would still be exposed to more radiation than allowed by any occupation on Earth. If the crew survives this dose during the mission, their cancer risk will be huge after returning home.
This is not something even close to resolved.
Food Supply — It is not possible to bring enough food. Much of this will need to be grown on the way and on the surface of the Mars. No one has done this away from the Earth in quantities remotely sufficient to support an entire crew of six or ten astronauts for months on end. It’s hard enough to keep plants happy on the Earth where they evolved. Making them productive in space and on Mars is not going to be easy.
Air Quality — Maintaining a breathable indoor atmosphere for nearly three years will be a chore to say the least. Carbon dioxide filters will need to work well the whole time as will oxygen generators. Plants will help, yet aren’t likely to absorb enough carbon or supply enough oxygen. Martian soil and water may also release toxic fumes. Some of these we have already seen in robot data. Others likely are yet to be discovered.
Toxic Minerals — Mars is not simply a drier version of Earth. Chemical processes are different leaving a stew of minerals toxic to people. It is possible that water found on Mars may be polluted by earthly standards in ways that we hadn’t anticipated, or soil toxic to plants people planned to grow on Mars. It may be possible to purify martian water, yet that would require equipment that cannot fail.
Hardware Reliability — The International Space Station is comparable in complexity to a martian base and it has key equipment failures all the time. There can be only just so much redundancy and other reliability tricks before nothing can be done to improve the odds. If the ISS has a major failure, new parts can be sent up from Earth. The astronauts can even bug out and return to Earth in a matter of hours, in a truly dire emergency. A major life-support failure anytime during a Mars mission would be deadly.
Wear and Tear — Equipment such as space suits will have durability issues no matter how well built. Miners don’t wear the same safety equipment for 540 days straight. On earth we replace worn parts and gear as a matter of routine. On Mars we’ll need to know exactly what will wear out and bring a warehouse full of spares and replacements – yet not more than we need.
Who knows what to bring? What if we forget a key part? What if a tank leaks and we can’t store enough air or water? What if our rover dies fifty miles from our home base and our back up rover dies during the rescue?
Isolation – Even with careful selection and lots of preparation, living almost three years away from Earth is a level of isolation beyond human experience. The whaling ships of past centuries voyaged similar lengths of time, yet they put into ports along the way.
There is no way to say how well people will cope. Any mission lasting this long will be a grind. There will be down time and ways to relax, yet there will be a constant level of anxiety in a world without a breathable atmosphere filled with dreadful dust storms where the warmest nights are comparable to the coldest places on Earth.
Medical Care — There is no way to plan for every medical emergency. No one will catch a seasonal flu, yet there could be broken bones or other injuries (including chemical and radiation poisoning). If enough of the crew were incapacitated, there may not be enough hands on deck to maintain equipment or fly their spacecraft home when the time comes.
On the other hand…
We have solved a number of issues in recent decades — especially in areas of long duration flight and ways to maintain a measure of physical fitness. Bone mass is still an issue, yet with martian gravity, this is likely not a problem.
We’ve also gained experience assembling large spacecraft in space and are gathering a track record on ways to make key life support systems more reliable — or at least learning how long it should last once repaired.
Beyond this we’ve been sending a stream of robotic missions to Mars and have been collecting a much better picture of the martian environment — thereby removing a number of mysteries regarding soil quality and other key factors for living on the planet.
All of this will require a high degree of inventiveness, courage and considerable up-front research mostly within our grasp.
Would I want to be a member of the first crewed mission to Mars?
Hell no. But then, I don’t do things a lot safer either — like parachuting or scuba diving. So just because there are chickens like me doesn’t preclude a caliber of people with the right stuff. I’d wish them well, and as long as I’m working in the field of spacecraft systems engineering I’ll do my part in surmounting the hurdles.
- – - – - – -
[...] Why Not Mars? Possibly related posts: (automatically generated)Russia to launch 520-day mock mission to Mars – CNN.com [...]
Mars Mission Radiation « No Stone Left Unturned said this on June 23, 2010 at 3:25 pm |