Thursday, August 6, 2009
On the Mars Vacation post, Brian Shiro of HI commented: Lessons learned from simulated Mars field science activities like FMARS is that astronauts need to arrive on Mars in good physical condition to carry out work. This precludes the idea of traveling 6 months in micro-gravity. The Mars ship carrying people needs to be spinning to produce artificial gravity.
The laws of physics don’t rule this out, but the size involved is cost-prohibitive; I also hear about the engineering and communication challenges that a "spinning" ship presents. Somewhere between science and science-fiction, I keep hoping there will be a practical compromise.
Anyone ever read Ben Bova’s Mars series? He envisioned a realistic craft that would slowly acclimate the passengers’ bodies to Martian gravity (38% of Earth’s force) over the mission duration. A good idea for the trip, but what about when they return home? Unanswered questions, all.
At any rate, this point highlights how different simulations address the various challenges in reaching Mars. The Mars500 tackles psychological effects and self-sufficiency, NASA bed-rest studies seek counter-measures to bodily problems brought on by low gravity, and field expeditions like Brian’s remind us of what is necessary upon reaching Mars: we need our explorers to be healthy, sane and able to withstand rigorous physical activity!
Recently on Devon Island, the arctic "Mars analog" environment, Brian logged nearly 29 hours in a space suit, and covered a distance of 80.5 km in 9 EVAs – the most of any crew member. He also installed a seismometer and conducted an electromagnetic ground water survey. Other members of the sim team tested aerial surveying technologies, resource recycling, medical treatments, communications and image geo-tagging.
And he’s right, fatigued people with brittle bones won’t be useful if we cannot keep them healthy on the way. For those interested in truly in-depth simulations performed by astronauts-in-training, see Brian's blog, Astronaut For Hire. He has awesome videos of the whole FMARS team!
Gilda F. of Ohio emailed: (Edited for length!) My 8-year-old and I read your blog. I try to encourage his interest in science, and it’s keeping us occupied over summer break! He asked how they could have a martian rock on display? We haven't been there yet, and I thought, that's a good point.
Good question – one I also asked when I heard a NASA coordinator mention that one of their brethren spent a season in Antarctica, looking for meteorites that might prove to be from Mars. How do you spot a "Martian" meteorite? And how the heck would it get here? No samples have been returned from any landers, and anything reaching Earth’s atmosphere would have drifted for millions of years. Would a long trek through the vacuum of space affect its composition? Once here, wouldn’t it immediately be contaminated by terrestrial bacteria?
The shergottite on display in Houston has undergone chemical examination; using varying dating techniques, oxygen isotopes, and powerful electron microscopes, it was determined that the minerals inside this solidified lava matched the 200-million-year old volcanic basalt known to be prevalent on (and unique to) Mars.
It is believed that 34 meteorites found on Earth came from Mars… a miniscule number considering how many are catalogued annually! Scientists don’t agree on all of them, so a “Martian” label is not given lightly. Many are still under analysis, and any new find tends to create a fresh firestorm about origin, authenticity, and what constitutes proof of “life.”
There are other clues that help geologists determine meteorite origins: Minerals inside some rocks show signs of shock, which could be from the impact that blew the materials off the surface of Mars. Specimen interiors can contain gases consistent with the composition of the Martian atmosphere and lastly, all show signs of having formed in a weaker gravitational field than that of planet Earth.
For further reading, you can see the Jet Propulsion Lab's SNC page, which has a list of all commonly accepted Martian rocks (shergottite, nakhlite, chassignite). The collection of articles describe some of the details, many of the mysteries and all of the controversy!
Posted by PillowNaut at 9:03 AM