There’s been a lot of celebration this holiday season of the fiftieth anniversary of the Apollo 8 mission, the first time humans went into (relatively) deep space and orbited another body, the moon. I’m glad to see Apollo 8 getting some recognition. It’s usually overshadowed by Apollo 11, the first mission to actually land on the moon, but Apollo 8’s accomplishment should be remembered. When the S-IVB Saturn stage fired, initiating the translunar injection, it was an incredible leap into the void for those astronauts.
But for some, the celebration has been marred a bit due to comments made by one of the astronauts from that mission, Bill Anders:
According to one of the astronauts aboard NASA’s 1968 Apollo 8 mission, it would be “stupid” and “almost ridiculous” to pursue a crewed mission to Mars.
“What’s the imperative? What’s pushing us to go to Mars? I don’t think the public is that interested,” said Bill Anders, who orbited the Moon before returning to Earth 50 years ago, in a new documentary by BBC Radio 5 Live.
Anders argued that there are plenty of things NASA could be doing that would be a better use of time and money, like the uncrewed InSight rover that recently touched down to study Mars’ interior.
A lot of the reasons behind Anders remark seem to focus on criticism of NASA and its focusing on crewed missions at the expense of the more scientifically oriented robotic ones. Those robotic missions have done far more for science than anything from the crewed missions.
I think Anders has a point. Sending a crewed mission to Mars is problematic. The difficulties in getting there are enormous. With present technology, it would require a crew to spend nine months in transit, a year or so exploring, and then nine months coming back: a three year mission.
The problem is keeping astronauts healthy for that long. No human has spent that much time in space. We know about some of the health effects from astronauts living in the ISS (International Space Station). They involve bone loss, vision impairments, and other changes. Astronauts returning from the ISS typically have to go through a recovery period before they can function again on Earth. We should expect a three year span to exacerbate these effects.
And the ISS can lead to overconfidence. The ISS orbits only a few hundred kilometers above the Earth. It receives regular resupply runs from Earth, so we haven’t really been testing our ability to provision people to live independently for years in isolation. And with the crews safely ensconced in Earth’s magnetic field, we haven’t had to deal with the effects of long term radiation exposure.
Impatient space enthusiasts who get most of their information from science fiction will often counter that all of these things can be handled. We just need to spin the spaceship for artificial gravity, have sufficient storage space for supplies, and provide solid shielding for radiation. The problem is that all of these things add mass, and given the tyranny of the rocket equation, every additional kilogram is extraordinarily expensive.
Myself, I think Mars crewed missions should wait until we’ve had a chance to improve drive technologies, notably the various types of ion thrusters, which may be able to bring the transit times down substantially, say a month or two instead of the nine month time frame. Such a technology might reduce a round trip mission down to a few months, or a year if we decide it’s best to wait until Earth and Mars are near each other for the return trip. That still leaves major challenges, but it starts to look more achievable.
This might enable us to get to the point of eventually establishing scientific research stations on Mars. Personally, that’s as far as I think things are liable to go for a long time. I doubt humans will ever colonize Mars, at least not in any significant numbers. The reason is economics.
Living on Mars would be outrageously expensive. Mars habitats would be dependent on long tenuous supply lines from Earth. The idea that they could be self sufficient in any meaningful way is mostly fantasy. We’re vitally dependent on Earth’s biosphere. Self sufficiency would require generating a replacement biosphere, something we currently don’t know how to do. And even if we did, maintaining such a biosphere farther out from the sun, where there is far less free energy available, would always be more expensive than doing it on Earth.
We won’t colonize Mars, or space in general, until there’s a major economic interest that drives us to do it. People often talk about mining being the economic interest, but with the cost of doing anything in space being so high, that interest may not be enough.
Overpopulation sometimes gets mentioned as a motivator, but setting aside the biosphere dependency, before colonizing Mars, we should first look at colonizing Antarctica, the ocean floors, or underground. Yes, life in these locations would be difficult, dangerous, and expensive, but not nearly as difficult, dangerous, or expensive as living on Mars or anywhere else in the solar system. And all in all, it’s a lot cheaper to solve the overpopulation issues in other ways.
So I think Anders has a point. The public may be enthusiastic for crewed space missions, but they’re a lot less enthusiastic for the associated costs. This is shown in the fact that crewed Mars exploration is always a couple of decades in the future. When I was a boy in the early 1970s, the Mars mission was supposed to happen in the 1980s or 90s. By the 1980s, it was supposed to happen in the first years of the 21st century. For the last decade or so, it’s been supposed to happen by the 2030s. I won’t be shocked if by 2022 it hasn’t slid to the 2040s.
To me, the question is whether crewed scientific missions into deep space will become viable before they get obviated by advances in artificial intelligence. From the beginning, the pioneers in space have been the robots. It may be that we’ll have a solar system populated far more by robots than by humans, at least of the biological sort.
Unless of course I’m missing something?