Jul 25 2013
In the decades prior to December 17, 1903, when the Wright Brothers flew for the first time at Kitty Hawk, the invention of the heavier-than-air flying machine was highly anticipated. There was a buzz. Many teams were working on the invention, and there were many false premature reports of sightings.
Today I get the same feeling about a mission to Mars. It seems that we’re just ready for such a mission, and multiple teams are proposing concepts for how to get there.
The latest proposal comes from scientists at the Imperial College London. They do not suggest any new technology or techniques, but simply put together a plan for addressing all the technical hurdles to such a mission. Their proposal is for a three person crew to travel to Mars and be safely returned home.
Here are the issues that need to be addressed on such a mission.
For most of the mission the astronauts will be in microgravity (whenever the ship is coasting and not accelerating). It will take months to get to Mars, during which time the microgravity will cause muscle and bone loss. By the time the astronauts get to Mars they will be in no condition to walk, let alone carry out any mission, even in the lower Mars gravity (which is 40% that of Earth).
The mission will require enough fuel to get to Mars, land on the surface, get back into Mars orbit, and then return to Earth. The so-called rocket equation makes this challenging – essentially, you have to carry the fuel you need in order to propel the fuel, so fuel needs increase dramatically for longer trips.
That is a long time to spend in a small space. The living quarters will have to be larger than an Apollo capsule, but probably won’t be as large as the International Space Station.
Perhaps the biggest hurdle is solar and cosmic radiation. In space the astronauts will not have the protection of the Earth’s atmosphere and magnetic field. Unshielded they will likely not survive, or will at least be at increased risk of cancer when the mission is complete. Further, if a solar flare or coronal mass ejection happens to be aimed in their direction, they could be killed outright.
The Imperial College London scientists address these issues. The microgravity problem is solved by using spin to generate artificial gravity. The ship will have two components, a main section and a crew compartment and lander. After the ship gets up to cruising speed the two sections can be separated by a long tether and made to rotate. The rotation will generate artificial gravity for the majority of the trip.
The fuel need is still a problem, but they address one major fuel use – getting back off the surface of Mars. They propose sending an earlier mission to Mars to land a launcher on the surface of Mars that can take the astronauts back up to the orbiter. The launcher will refuel by digging below the Mars surface for ice.
The radiation problem is addressed by adding shielding to the crew compartment. This can take the form of water stored in the outer hull. Further, they propose superconducting magnets to create a magnetic field to divert ionized particles around the ship.
If a CME or solar flare is headed their way, then then will pull in the tether and position the main section of the ship (the orbiter) so that it is between the lander and the incoming radiation. The hope is that this will provide enough additional shielding to protect the crew.
The proposal sounds conceptually solid, but I do not know if all the technical details add up. Broad concepts are one thing, technical specs are another. It sounds plausible, however. My biggest concern is for the radiation exposure. This could be a limiting factor, requiring heavy shielding that will be expensive to put into orbit and get to Mars and back.
Other Mars mission proposals are on the table as well. Inspiration Mars is a non-profit US company that wants to send a 2-person team to Mars in 2018. They write:
In 2018, the planets will literally align, offering a unique orbit opportunity to travel to Mars and back to Earth in only 501 days. Inspiration Mars is committed to sending a two-person American crew – a man and a woman – on an historic journey to fly within 100 miles around the Red Planet and return to Earth safely.
Elon Musk of SpaceX thinks a mission to Mars can be feasible within 12-15 years.
Perhaps the boldest plan is Mars One. They propose putting a permanent human settlement on Mars. They would solve the fuel problem by simply making the trip one-way. They plan to fund the entire project by making it a reality TV show, a kind of Survivor Mars.
Meanwhile, NASA remains all about sending robots to Mars and the rest of the solar system. There are those who maintain that humans are not built for space, but robots literally are. It is orders of magnitude easier to send robots to space than people, so why bother.
This is a valid position. I personally think we need to do both, but keep a proper balance, with perhaps the bulk of resources going to robotic missions. Robots, in my opinion, can pave the way for humans.
I do question the utility of a one-off mission of people to Mars. Perhaps we should concentrate on using robots to build an infrastructure on Mars first – pre-fueled ships, living quarters, supplies (food, water, oxygen, energy), and then send people for a permanent settlement.
Isaac Asimov argued that we should concentrate on the Moon first. Let’s build the Earth-Moon infrastructure, including bases and manufacturing facilities on the Moon. Once we have done that, Mars will be easy. The Moon, in essence, is our stepping stone to the rest of the solar system.
Think of it as a Sim game, the goal is to colonize the solar system. Which player is going to win – the one who builds a Moon infrastructure first, a Mars infrastructure first, the one who spends their resources on robots, or the one who puts a tremendous amount of resources into an early one-off personed mission to Mars?
I personally would like to see us (meaning humanity) progress towards colonization. It seems like a better idea to plan a long-term path to this goal, rather than focusing on individual missions that may not progress our long term goals beyond the experience of doing the mission.
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