News We probably won't be going to Mars anytime soon.

[MattBaker]

Comet ISON's closest approach to Mars is coming up soon. That should be interesting.

Mars is passing the intersection before ISON so it won't be in it's tail. I think it's unlikely that there are big debris ahead of a comet.

 

[RGClark]

Mars is passing the intersection before ISON so it won't be in it's tail. I think it's unlikely that there are big debris ahead of a comet.

The latest I read was since ISON is such a large comet, Mars may actually pass through its coma.

Bob Clark

---------- Post added at 01:54 PM ---------- Previous post was at 01:46 PM ----------
Correction: it is Comet Siding Spring whose coma Mars is expected to pass through next year:

NASA to keep protective eye on Mars spacecraft as comets buzz by.
Leonard David Space.com
Sep. 24, 2013 at 6:08 PM ET
http://www.nbcnews.com/science/nasa-keep-protective-eye-mars-spacecraft-comets-buzz-8C11250212

Bob Clark

 

[Urwumpe]

The latest I read what since ISON is such a large comet, Mars may actually pass through its coma.

Bob Clark

What ever you read there... it isn't really scientific.

The biggest nucleus of a comet is just 72 km large, the visible part of the coma doesn't extend much ahead of the comet. The full coma can be easily 150 million km across - but most of this coma is thin hydrogen and only visible in Ultraviolet light.

By the time a comet crosses the Orbit of Mars, the coma is also already shrinking and getting blown away faster than vaporization of the nucleus fills it up.

 

[RGClark]

What ever you read there... it isn't really scientific.

The biggest nucleus of a comet is just 72 km large, the visible part of the coma doesn't extend much ahead of the comet. The full coma can be easily 150 million km across - but most of this coma is thin hydrogen and only visible in Ultraviolet light.

By the time a comet crosses the Orbit of Mars, the coma is also already shrinking and getting blown away faster than vaporization of the nucleus fills it up.

Ok, for ISON. But Siding Spring might be a different story.

Bob Clark

 

[Urwumpe]

Ok, for ISON. But Siding Spring might be a different story.

Bob Clark

Not really... does also not look like Mars will pass through its coma, at least not through the part that may contain bigger particles.

 

[BruceJohnJennerLawso]

Not really... does also not look like Mars will pass through its coma, at least not through the part that may contain bigger particles.

Too bad then. Will the pass offer a chance for anything besides a nice picture from MSL Curiosity?

 

[Urwumpe]

Too bad then. Will the pass offer a chance for anything besides a nice picture from MSL Curiosity?

Actually a lot of more than nice pictures. We also have probes in Mars Orbit. While the chance of any big meteor shower is low, dust particles could be sensed, that are freshly released from the comet.

 

[RGClark]

Not really... does also not look like Mars will pass through its coma, at least not through the part that may contain bigger particles.

Do you have a reference for that?

Bob Clark

 

[Urwumpe]

Do you have a reference for that?

Bob Clark

Look at the two body orbit elements, which show that the comet and Mars orbit don't even cross a bit, the comet passes radially to Mars. Even if you include a three-body situation, the high relative speed of the comet limits the effects of Mars gravity.

 

[RGClark]

Look at the two body orbit elements, which show that the comet and Mars orbit don't even cross a bit, the comet passes radially to Mars. Even if you include a three-body situation, the high relative speed of the comet limits the effects of Mars gravity.

The latest calculations show Mars will pass through the outer fringe of the coma of Comet Siding Spring. Likely there will only be small particles that will burn up before hitting the ground. But given the uncertainties with comets that can't be proven definitively at this point.

Bob Clark

 

[Admiral_Ritt]

Titan would be miserable. 6-7 years on a spacecraft one way to get there. Average temperature of -180C. Cloud cover so thick you'd never be able to see stars or the Sun or even Saturn. It may be true that Titan would be the easiest extra-terrestrial body in the solar system to establish long-term semi-independent habitation using ISRU, but it would be absolutely miserable.

.

From the photo of Titan's suface via Huygens craft it Looks better than Luna.
Mars always looks to me like Death Valley where it is a bit hilly.

Disadvantages to Titan
-Great distance conceeded
-Reactor Power Source for any bases (fusion power would nullify this)
-Double the negative temperature of the coldest recorded temp on earth.

Advantages
-No Radiation to worry about (well as long your reactor doesn't brew up)
-easy orbiting/deorbiting using much less fuel than Mars even less than Luna
-Great base construction materials available (propylene,acetyline,ethane)
-Ice at ground level
-Stable surface, Little evidence of massive resurfacing, or even meteor impacts.

But I think Titan's biggest edge is that it is easier to build habitats there by
either creating cavespace or bringing scafolding materials and use refrozen
water as 'concrete insulator'.

P.S. And IF hydrogen fusion ever comes to fruition The Saturn neighborhood will be THE player in Deuterium fuels, due to a much weaker radiation belt
and more tractable gravity for fuel harvesting ships.

 

[RGClark]

The radiation measurements by Curiosity in space pretty much confirmed what scientists already knew. Here's an article from 2006 that discusses the problem:

Shielding Space Travelers.
The perils of cosmic rays pose severe, perhaps insurmountable, hurdles to human spaceflight to Mars and beyond.
By Eugene N. Parker
Scientific American, February 20, 2006
http://engineering.dartmouth.edu/~d76205x/research/shielding/docs/Parker_06.pdf

Bob Clark

In addition to the radiation dangers, longer stays in space are now known to damage eyesight:

Does space travel damage eyesight?
An increasing number of astronauts who've spent a month or more aboard the International Space Station are visiting the optometrist.
By The Week Staff | March 14, 2012.
http://theweek.com/article/index/225533/does-space-travel-damage-eyesight

Astronauts And Mice Return From Space With Altered Eyes.
By Francie Diep Posted 10.25.2013 at 4:00 pm

When he rocketed up to the International Space Station in March 2009,
NASA astronaut Mike Barratt needed glasses to see things in the distance.
When he returned to Earth in October, he no longer had trouble seeing
far-off objects-but he suddenly needed reading glasses. By the time he
talked with CNN in 2012, his vision still hadn't returned to normal.
http://www.popsci.com/article/science/astronauts-and-mice-return-space-altered-eyes

The debilitating effects of zero-g for bone and muscle loss are also well known now. The bone loss in zero-g proceeds at a rate 10 times that of rate of the elderly suffering from osteoporosis.

Expedition 37 returned to Earth from the ISS Monday evening:

Karen Nyberg looked pretty wiped out after the landing. Luca Parmitano looked pretty energetic. Fyodor Yurchikhin was somewhere in between.
Karen also didn't appear at the news conference with the other two astronauts, on doctors orders:

I'm not making a comment about the effects of long space exposure on women, by the way. Sunita Williams seemed pretty energetic on her return from the ISS, while Chris Hadfield looked wiped out after his.
What I am arguing is that NASA should be focusing on short travel times for Mars missions. You can't afford to have 1/3rd of the crew members incapacitated for days or even weeks when the crew lands. Not even a 6 month travel time using nuclear propulsion that NASA scientists have proposed would be sufficient.
However, by first setting up propellant stations on the Moon, the travel time could be cut to weeks instead of months.

Bob Clark

 

[Donamy]

Simulated gravity, will probably be a must.

 

[N_Molson]

People seem to react very differently, regardless of their age and sex. There is probably a lot of things we still don't know about the effects of microgravity on the human body, and it's precisely why NASA and Roscosmos are conducting such long duration experiments. Its a very complex subject that mixes physics, biology, medicine, psychology, human factor... So there is work to do.

Currently the "official line" is to take the time to develop a high-Isp NTR tug to shorten the trip, which makes sense. But of course it's not going to be done soon.

 

[MattBaker]

1. Give more money to experimental physicists
2. Prove gravitons
3. Synthesize gravitons
4. Use it on your spaceship
5. PROFIT!!!

 

[Andy44]

All this reminds me of the (must-see) 1970 movie Marooned, which depicted long-term spaceflight as unhealthy for humans as a subplot. In the film, the crew had been aboard a Skylabesque space station for at most a couple of months; turns out that real life spaceflight takes a bit longer to do real harm, but the film was closer than thought at first glance.

 

[RGClark]

Karen Nyberg will be interviewed via satellite next week Wednesday:

NASA Astronaut Karen Nyberg Available for Satellite Media Interviews.
Press Release Source: Johnson Space Center Posted Wednesday, November 13, 2013
http://www.spaceref.com/news/viewpr.html?pid=41923

Bob Clark

 

[RGClark]

Nice explanation of the technical challenges of a manned Mars mission:

Why We Can’t Send Humans to Mars Yet (And How We’ll Fix That).
BY ADAM MANN 05.30.13 6:30 AM
http://www.wired.com/wiredscience/2013/05/actually-getting-to-mars/


Bob Clark

 

[Hlynkacg]

Curiosity measured 1.84 mSv per day.
Dennis Tito plans a roundtrip for two taking 501 days.

Which would expose them to 920 mSv. 100 mSv were already linked to higher cancer rates.

Not until 2025.

Is that really all that we're worried about, seems to me tha risk of cancer is a pretty small price to pay to walk on another planet.

besides 2-3 mSv a day is low enough that you could get away with taking anti-rad pills. Crap I got exposed to worse on a regular basis just flying around a carrier battle group.

 

[MattBaker]

Is that really all that we're worried about, seems to me tha risk of cancer is a pretty small price to pay to walk on another planet.

Even if I'd be an astronaut I'd prefer being a Buzz Aldrin over a cancer-patient Alan Shepard everytime. Going to Mars to die ten years later sounds worse to me than not going at all.