NASA says it still sees a manned mission to Mars in the works for sometime in the 2030s. But, current politics (including GOP reluctance to spend on about anything with the word "science" in it, as noted in the story, are part of why I'm skeptical. The only realistic way to do it, fiscally,
is through international cooperation, and given the recent fun with Vladimir Putin, I'm sure US officials want to keep Russia at arms' length.
The other reason?
Per actual science, I don't think we're there yet.
|
Properly measuring and protecting against Martian radiation will be key
to any manned mission to Mars./Space.com photo |
Despite
Dennis Tito saying a year ago that he plans on having a manned mission to Mars by 2018, we're nowhere near that close, as I blogged
a couple of years ago,
unless Tito wants nothing but an unscientific, one-way trip, and a high
likelihood of cancer to boot. That said, that's probably all Tito cares
about.
That's because, as Space.com notes
in this great piece,
we're just starting to figure out what we need to know about cosmic
rays. And, the problems will be on Mars, not just in flight. Nothing in the USA Today story, at top link, convinces me that NASA has fully addressed these issues yet. It is working on addressing things like
how to slow down a manned capsule for landing, as Curiosity's detachable retros, and older balloon systems, are out of play. But, I'm still not convinced NASA is adequately addressing radiation issues, let alone crew redundancy-safety or crew size issues.
(Update, April 24: Wired has
a piece of its own on the cosmic rays issue.)
Let's take a peek at it, before doing an update on the possibility, and needs, of an actual scientific mission:
The Mars rover Curiosity
has allowed us to finally calculate an average dose over the 180-day
journey. It is approximately 300 mSv, the equivalent of 24 CAT scans. In
just getting to Mars, an explorer would be exposed to more than 15
times an annual radiation limit for a worker in a nuclear power plant.
So,
double that for the return trip. Add 50 percent, off the top of my
head, for time on Mars. That's 60 CAT scans, or 37.5 times the power
plant worker's limit. Or, 750 mSv, which is 75 rem.
Per Wikipedia, we're at a lifetime dose for a nuclear power plant or similar worker.
In
short, while a trip to Mars isn't going to turn an astronaut into the
cosmic-ray version of Frankenfood, without at least some shielding, it's
going to definitely increase his or her likelihood of cancer. And,
especially with men, it's going to increase the likelihood of sterility.
That said ...
Is this doable? Yes? Any time this decade? No.
It
is a big sum to do this, unless we want a one-way trip, which somebody
likely would volunteer to do. I think setting a target date of about
2035 allows out years to fatten that budget, do the R&D on radiation
shielding, use more
robotic missions to focus what a manned mission should do, etc. That
also allows NASA plenty of time to work out details of a joint effort
with Roscosmos, the European Space Agency, and maybe other partners.
Also,
our current rockets are too small, specifically capsule size. As I've
blogged before, unless you want to do the 1-day stop-and-return to have
the lowest-energy return trajectory, you've got to have more than three
people on that mission. And, that adds up to additional weight, space
and food, plus additional weight and space for the exercise area. Mars'
gravity is enough more than the moon's that, without adequate exercise
in flight, an astronaut is liable to break a leg on landing.
That 2035 tracks pretty closely with the "30 years away" of my original blog post.
Wikipedia has an entry entitled "
Manned mission to Mars."
Since I started writing my thoughts independently of looking at it, I'm
going by what I have written, with brief references to it.
Shorter
take? Illustrations of such a trip look great, don't they? Well, drool
away, because those illustrations are about as close as we're getting in
your lifetime or mine to landing people on Mars, in my opinion.
There's
three main reasons why "cool" images are all we'll be seeing in the
foreseeable future. They're called space psychology, space safety and
space engineering.
And, most of those are connected
with the idea that, at minimum, we're talking 1.5 years of travel, with
distances far greater than lunar travel. And, the low-fuel journey, for
one-quarter of what the "fast" trip takes, involves 2.8 years, more than
half of that on Mars.
This will tax engineering,
certainly tax human psychology, and without massive advances in
shielding from cosmic rays, will kill astronauts -- not on the actual
trip, but more surely, and with at least as much life reduction on
average, as smoking two packs of Camels a day.
In
short, beyond the illustration, we have to do R&D on human
physiology for a long journey in "zero gravity," a certain amount of
exploration into 1/4 Earth gravity, then a long journey back into zero
gravity. We have to do the psychological R&D, more rigorous
than Russia's mock trip to Mars, on a capsule of as many as seven people
confined together for 6 months or more, and, on Mars, as far away as 20
minutes, one way, by communications link.
Details on the "why" of all of this below the
fold, updated to reflect how NASA's current manned mission planning is
woefully inadequate, starting with the spacecraft.
1.
Space psychology. A trip to Mars will take about 400-450 days round
trip. Once on Mars, astronauts either have to wait about 1.5 years for
an optimal window for return, or else burn much more fuel to get back to
Earth after a relatively short one-month stay. Details of both options,
as well as a faster outward trip, are
here.
Having to burn 3x as much fuel for a faster outward trip, and 5x as
much for an earlier return is not a negligible consideration.
Here's the bottom line:
A. Hohmann transfer both ways plus 1.5 years on Mars
= 2.8 years.
B. Fast trip out plus 1 month on Mars plus slow trip home = 1.5 years.
So,
we've got astronauts away, well away, from Earth for a minimum of 1.5
years. And, if we want to maximize the "return" on going to Mars, we've
got them there three years.
Even in near-Earth orbit,
and with less than a year's time, we've seen psychological stress on
some outer space crews. Yes, there have been simulated Mars trips, but,
given the many minor things that can go wrong in real space, and the
simple psychological factor of knowing that Earth is "just outside the
door," I'm not sure how well you can simulate the psychology of such a
trip. The Russian mockup was far short of that. First, they had the
knowledge they could bail. Second, it only simulated a one-way trip; the
time on Mars and the return time was not in the simulation.
2.
You certainly can't simulate space health effects. As for the effects
of solar wind? In its articles on magnetospheres and solar wind, Wiki
talks about Mars' lack of magnetic field and results thusly:
Mars, with
little or no magnetic field, is thought to have lost much of its former
oceans and atmosphere to space in part due to the direct impact of the
solar wind, with an atmosphere now 1/100 that of Earth.
Venus,
with its thick atmosphere is thought to have lost most of its water to
space in large part owing to solar wind ablation. (The solar wind
stretches the "downwind" side of Venus' atmosphere almost to Earth.)
For
just about all the trip, astronauts will be outside the protection of
Earth's magnetosphere. Dangerous, in terms of radiation? Yes, enough to
make some people
rethink the whole idea as potentially fatal:
"The estimate now is you would exceed acceptable levels of fatal
cancer," said Francis Cucinotta, chief scientist for NASA's space
radiation program at the Johnson Space Center in Houston. "That's just
cancer. We also worry about effects of radiation on the heart and the
central nervous system."
Cucinotta says these estimates do take into account protective
shielding around a crew vehicle, probably some form of polyethylene
plastic. Lead shields actually create secondary radiation when struck by
cosmic rays, while water, perhaps the best form of protection, would
have to be several meters thick to get enough protection. ("Houston
calling Water Balloon 1, do you copy?")
Lead and water, in any case, are very heavy for the quantities
that would be required, making them an expensive shielding to launch.
And
then, there's the gravity issue. We'd have either 450 days of zero
gravity and one month of 1/4 Earth gravity, or 450 days of the former
and a little more than that of the latter.
At the same
time, while Mars' gravity is low, low enough to not be "good" for
Earth-accustomed astronauts, it's heavy enough to be problematic after
225 days of no gravity, as the story above notes;
"What happens if they land on Mars and try to lift an object that's
fairly or reasonably heavy, they could herniate their discs," said Alan
Hargens, an orthopedic surgeon at the University of California San Diego
who studies the effects of gravity on astronauts. "One of the main
issues is that when they arrive at Mars, there's nobody there to take
care of them. If they have some issue due to de-conditioning in that six
month period, they'll definitely have a problem."
It's
true. Even with treadmills and other gravity simulators on the
spacecraft, in the first few days on the Martian surface, there would be
a high risk of muscle pulls, muscle and tendon tears, hernias and
broken bones, and possibly heart attacks due to stress.
Because
you'd definitely need "backup," that means not just one, but two
members of each crew would have to be physicians. (One could be a
psychiatrist, to address issues under point No. 1. We're going to need a
psychologist anyway.
There's also another medical problem that's already hit some shuttle/ISS astronauts:
Vision problems.
According to one NASA survey of about 300 astronauts, nearly 30 percent
of those who have flown on space shuttle missions — which usually lasted
two weeks — and 60 percent who completed six-month shifts aboard the
station reported a gradual blurring of eyesight.
It's
obviously progressive. A trip to Mars would have worse effects on a
higher percentage of astronauts. It's fairly serious, and so far,
recovery has not been complete in those who have suffered it.
3. Space engineering. This is going to subsume several things.
Let's
start with a bottom line that also relates to point 1: the
communication time gap. When Earth and Mars are at opposition, it's 20
minutes one way for communication.
So, if an Apollo 13 type event happens, during almost all the journey, astronauts are on their own.
That
affect Earth engineering. We can't have an Apollo 13 problem, as far as
improvised fixes, of trying to mate square canisters and round holes or
vice versa. Can't have it. That means that the U.S. government, U.N.,
EU, a consortium or whatever, has to ride a very, very heavy herd on
private contractors. That, in turn, ramps up the price.
Second,
radiation shielding. Unless you have astronauts who sign "death
sentence waivers," our current engineering simply can't protect against
it. Period.
Third, crew composition. Let's say we have a crew of seven.
As
I noted above, we have to have two M.D.s, one a psychiatrist. Both to
study human changes in space and explore Martian life, person No. 3 is a
Ph.D. biologist, of course. No. 4 is a mechanical engineer who's spent
time at all those private contractors' sites. (Every astronaut, though,
for reasons mentioned above, will have a crash course in engineering.)
No. 5 is a geophysicist. No. 6, whether military or not, as commander,
has to have a leader's presence. No. 7 is No. 2 in charge, and No. 1 in
piloting skills. These two may have some backup training in sciences,
but, their primary backup training will be the leads, along with person
No. 4, in engineering and constructing a Martian base, on the first
flight, which will be the high-fuel, quick-return version.
Of
course, we' re not getting there anyway. But, that would be a minimum.
Arguably, even on the first flight, you'd want an eighth person, another
engineering/construction person. That then said, what crew capsule size
are we talking about? And, are we conforming a crew to a capsule or
vice versa? In either case, seven is a minimum, I think.
Don't
forget all the food that means. All the water conversion and air
filtration that means, with multiple redundancies on systems.
Meanwhile, NASA's Orion crew vehicle
only seats four.
NASA's skimping a LOT on both human backup needs, legitimate crew needs
and space psychology issues. More reason to say both that we're not
going to launch a manned mission to Mars any time soon, and we
shouldn't, at least not under current planning.
However, Boeing's new capsule (update, May 8, 2015) does seat seven, and does so in comfort, style and modernity,
as this story details, complete with the photo and more at the link.
Details note that the pilot's seat has had traditional switchgear replaced with tablet-like interfaces. In turn, that reduces cabin clutter.
Plastic has replaced metal in a lot of places, which reduces weight.
It generally looks much more ergonomic.
Now, this is being targeted to low-Earth orbit, for flights to the International Space Station and commercial use. But, the size is right and general design elements are right. No reason why something based on this couldn't be the Mars craft.
There's
one more "engineering" option. Let's call it "financial engineering."
Throwing aside radiation, building a spaceship that can offer some
exercise protection against zero-G debilitation, be big enough to offer
some small bit of buffer against space psychology, be big enough to,
over a few trips, carry Mars base construction raw materials, etc. ....
Will cost at least $1 trillion in today's money to build and launch.
The
U.S. is not doing that alone. See above, all the various links.
Partnerships
also need to to "research and development" on the willingness of even the biggest
government joint venture to shell out that much, or even international cooperative efforts to shell that out.