NASA: We're sending humans to Mars

[Ken G]

That's an interesting analysis, but instead of plotting number of days for a given amount of shielding, they could equally plot the amount of shielding needed for a given number of days. That would seem to make more sense, and would not lead to such dire conclusions, merely a need for a small increase in shielding.

 

[marcus]

...
The large amount of energy required to heat and melt ice would melt several times as much common rock (Si, Al, Fe oxides).
...

You can melt ice with the waste heat from a power plant.
I don't know what kind of heating element you imagine being used to melt common rock. Might be more efficient to spend electric power to DRILL, in the case of rock.
In the case of ice you can use an electric powered drill to essentially the same effect, but also utilize waste heat at say 350 kelvin.

 

[marcus]

I think Ceres would be a better place to go, expected to have a thick mantel that is largely water ice. Nearly 1000 km diameter.
Humans could tunnel into the ice and make an underground habitat, safe from vacuum, radiation, space debris.
More interesting place than Mars. Dawn spacecraft is following Ceres along its orbit, gradually catching up with solar powered ion thrusters.
If successful should arrive at Ceres spring 2015, i.e. in a few months.

I favor robotic space exploration over human, as a general rule, but if humans are to colonize any time soon, don't bother with Moon or Mars, make it somewhere nice and icy.
http://neo.jpl.nasa.gov/orbits/fulltraj.jpg
You can see on the full trajectory map that the craft is now within 0.007409 AU of Ceres. the two dots are barely separable on the map. Here are some images from the craft's perspective.
http://dawn.jpl.nasa.gov/mission/live_shots.asp
I guess 0.007 AU is around a million km.

4 days ago (Thursday) when I posted last the Dawn craft was 0.007409 AU from Ceres, now the figure is 0.006721. The difference, 0.000688 AU, is 103,000 km
It is about 100 thousand kilometers closer to Ceres.
this 28 November entry is still the latest posting at the Dawn blog:
http://dawnblog.jpl.nasa.gov/2014/11/28/dawn-journal-november-28/#more-1533
The craft has been propelled almost exclusively by solar-powered xenon ion drive.

 

[mheslep]

The craft has been propelled almost exclusively by solar-powered xenon ion drive.

I would think a solar powered ion drive would not be useful past, say, Mars? And that therefore Dawn's ballistics were set well before approach to Ceres, with adjustments now made only by Dawn's hydrazine thrusters?

Ceres' orbit is 2.8AU, so solar insolation for Dawn nearby would be 1366/(2.8^2) or 174 W/m^2 if perfectly oriented. Assuming ~30% conversion PV, actual power collected is 52 W/m^2. Seems like weak sauce for an ion drive, and the remainder of the spacecraft power budget.

Edit: just watched a presentation by the Dawn Program Director:

...dominated by huge solar arrays... we're going far from the sun ... ion engines are power hungry. ... In fact when we launched, Dawn in 2007 this was the greatest tip to tip wingspan of any NASA interplanetary spacecraft : 65 feet from tip to tip...

http://www.jpl.nasa.gov/events/lectures_archive.php?year=2014&month=12

 

[zoki85]

Cool, but waste of money.

 

[marcus]

I would think a solar powered ion drive would not be useful past, say, Mars? And that therefore Dawn's ballistics were set well before approach to Ceres, with adjustments now made only by Dawn's hydrazine thrusters?
...

Apparently not so, though, Mheslep. The fulltraj link I gave earlier
http://neo.jpl.nasa.gov/orbits/fulltraj.jpg
shows that the ion thrusters have been on for almost the whole time since the craft left Vesta and started out for Ceres. And if you read the Dawn blog, e.g. http://dawnblog.jpl.nasa.gov/2014/11/28/dawn-journal-november-28/#more-1533
by Marc Rayman chief engineer and mission director, he reminds readers casually, but explicitly that it is the ion drive being used to get to Ceres.

Hydrazine is used primarily for controlling attitude. They had some mechanical trouble with one or more gyroscope wheels and had to use more hydrazine than expected to compensate, at one point. But it has never been the plan AFAIK to use hydrazine to, for example, get captured into orbit around Ceres.
You can see the very beautiful slow maneuver, ion-driven, that they plan to use, sketched in the 28 November edition of Dawn blog. I will get the link. Oh, already gave the link. Scroll down, the orbit plots are a ways down in the blog post.

 

[marcus]

The craft got out of its orbit around Vesta (using ion drive) in September 2012 and is now nearing Ceres. that is over 2 years. The solar powered ion thruster has been on nearly all that time. In the fulltraj map it looks like roughly halfway around the sun, a bit more, following an orbit intermediate between Vesta's and Ceres'. All that is well outside the orbit of Mars. Essentially all the impulse for that was solar-ion, not chemical.

If all goes as planned the craft will go into orbit around Ceres in March 2015 (using ion drive) So the solar powered thruster will have been on for about 2 and 1/2 years, getting it from Vesta to Ceres.

 

[mheslep]

Yes as I edited later, it appears Dawn has the most PV ever placed on an interplanetary craft (per Marc Rayman) something like 20 m^2 of PV, i.e. perhaps a kilowatt, largely to supply power to the ion drive. For thehttp://eo.ucar.edu/staff/dward/sao/fit/electric.htm (comparable?), a kilowatt apparently produced ~40 mN, or a delta-v of ~1300 m/s over a year for a 1000 kg craft (not counting the net gravitational forces).

 

[Monsterboy]

You can melt ice with the waste heat from a power plant.
I don't know what kind of heating element you imagine being used to melt common rock. Might be more efficient to spend electric power to DRILL, in the case of rock.
In the case of ice you can use an electric powered drill to essentially the same effect, but also utilize waste heat at say 350 kelvin.

How about Martian polar regions ? lots of water ice ,can be melted in order to build a base, right?

 

[marcus]

How about Martian polar regions ? lots of water ice ,can be melted in order to build a base, right?

Good thinking. I remember looking into that possibility some time back, to see if it had been studied. I tried to find information about the estimated depth, consistency (structural integrity) and year-round permanence of Mars polar ice.

that was before Google and Wikipedia :) so I spent a while at the Engineering library at the university campus near where I live. I didn't find much. Surely a lot more information about Mars "ice caps" is available now. Why don't you do some Google searches and see what can be found out.? Post some links for us.

For it to be interesting, the ice would need to be thick and solid enough that it would not develop leaks. It has to be able to contain a bubble of oxygen-containing atmosphere at pressure close enough to Earth normal for humans to breath comfortably.

The same structural concern applies to the idea of ice cave habitation on Ceres, which has the additional caveat about even lower gravity (3% of Earth normal).

A lot of information would need to be obtained about the actual composition and potential structural integrity of Ceres and or Mars polar ice material before people could actually seriously consider the ice cave idea. I still think it's quite interesting though.

I just checked the fulltraj page and saw that Dawn's distance to Ceres is now LESS than a million km.
http://neo.jpl.nasa.gov/orbits/fulltraj.jpg
Not much less, its range is now 0.977 million km.
You can see from the orbit map that from now on as it approaches it will be repeatedly turning OFF the ion thrusters for brief intervals. Little "blips" of zero thrust so as to gradually match speed. Not to overshoot when it arrives.
These show up as little gaps in the bright blue line on the map.

We should be able to tell something at least about the surface and mantel consistency from the pictures, assuming the craft makes its way successfully into orbit and starts taking photographs.

 

[Monsterboy]

Good thinking. I remember looking into that possibility some time back, to see if it had been studied. I tried to find information about the estimated depth, consistency (structural integrity) and year-round permanence of Mars polar ice.

that was before Google and Wikipedia :) so I spent a while at the Engineering library at the university campus near where I live. I didn't find much. Surely a lot more information about Mars "ice caps" is available now. Why don't you do some Google searches and see what can be found out.? Post some links for us.

For it to be interesting, the ice would need to be thick and solid enough that it would not develop leaks. It has to be able to contain a bubble of oxygen-containing atmosphere at pressure close enough to Earth normal for humans to breath comfortably.

The same structural concern applies to the idea of ice cave habitation on Ceres, which has the additional caveat about even lower gravity (3% of Earth normal).

A lot of information would need to be obtained about the actual composition and potential structural integrity of Ceres and or Mars polar ice material before people could actually seriously consider the ice cave idea. I still think it's quite interesting though.

I just checked the fulltraj page and saw that Dawn's distance to Ceres is now LESS than a million km.
http://neo.jpl.nasa.gov/orbits/fulltraj.jpg
Not much less, its range is now 0.977 million km.
You can see from the orbit map that from now on as it approaches it will be repeatedly turning OFF the ion thrusters for brief intervals. Little "blips" of zero thrust so as to gradually match speed. Not to overshoot when it arrives.
These show up as little gaps in the bright blue line on the map.

We should be able to tell something at least about the surface and mantel consistency from the pictures, assuming the craft makes its way successfully into orbit and starts taking photographs.

http://en.m.wikipedia.org/wiki/Planum_Boreum
The northern ice cap is about 3 kms thick and mostly water ice, the southern ice cap is also equally thick.
http://www.lpi.usra.edu/meetings/polar98/pdf/3048.pdf
It is said that dry ice will be too unstable to get that thick hence most of the ice cap must be made of water ice.

NASA could conduct experiments on Antarctica to build an underground(or under-ice) base , this might have been attempted already I don't know.

Maybe the next set rovers on Mars should be made to land on the poles and check out the ice.

Only reason why i don't feel comfortable with Ceres is that its gravity might reduce our bones to jelly and we will have to work out a lot to prevent that, Mars looks better on this aspect.

 

[mheslep]

I'm curious as to *why* the ion drive is cycled on and off, through out the entire mission per the trajectory map. I would guess to give time for heat rejection (ion drive grid?), but perhaps the cycling is a part of the trajectory scheme (which I don't understand).

 

[marcus]

I'm curious as to *why* the ion drive is cycled on and off, through out the entire mission per the trajectory map. I would guess to give time for heat rejection (ion drive grid?), but perhaps the cycling is a part of the trajectory scheme (which I don't understand).

Look at the fulltraj map record of the trip out to vesta and the trip from vesta to ceres (almost complete).

the ion drive (light blue) has been on for several months at a time. Evidently there is no need to operate intermittently.

it is only now as they are approaching Ceres that they plan to shut it off intermittently, less frequently at first, but more and more little breaks in operation as they approach the planet. It's a good lesson for us in how spacecraft with solar ion thrust operate, and maneuver.

I'm not sure but I think if someone is willing to learn (open to new concepts) they could also learn something from the 28 November Dawn block which shows plots of two different trajectories for approach to Ceres. the craft "eases" into the desired orbit in a rather graceful way. Several of us might enjoy checking that out.

 

[marcus]

Thanks for the links! 3 kilometers sources good!
You are right about under-ice experimentation. Pressurize to test for air retention. Measure factors involved in stability: stalactite growth, differential melt and freeze, structural strength and reliability, air-lock design for connection with surface, power plant operation with in-cave cooling. small nuclear power units as in submarines. Artificial light in the cave, to grow food. I haven't heard of any Antarctic experiments like that. Why don't you write a letter to someone in NASA?

...

NASA could conduct experiments on Antarctica to build an underground(or under-ice) base , this might have been attempted already I don't know.

Maybe the next set rovers on Mars should be made to land on the poles and check out the ice.

Only reason why i don't feel comfortable with Ceres is that its gravity might reduce our bones to jelly and we will have to work out a lot to prevent that, Mars looks better on this aspect.

I agree, a rover should land on one of the poles and check it out! this would be so fine! I don't understand why they have not done it already, the polar icecaps are the most interesting parts of Mars, in the long run.

About jelly bones, that is very serious, but humans are an adaptable species and might habituate to work out enough that they can thrive in 3% gravity.

Think about a circular bicycle track with almost vertical walls. If the radius of the circle is 10 meters then you have to pedal almost 10 meters per second in order to experience 1 gee. That is, V²/R. And if the radius is 20 meters, then you have to go 14 m/s. And there are those contraptions at the gymnasium.
Flying might help, not sure about that. Maybe with pedal-powered helicopters, and doing aerobatics. Vigorous airborne acrobatics. Challenging problems, requires creative solutions involving understanding what humans enjoy by way of exercise, mental emotional factors as well as anatomical.

 

[mheslep]

Look at the fulltraj map record of the trip out to vesta and the trip from vesta to ceres (almost complete).

the ion drive (light blue) has been on for several months at a time. Evidently there is no need to operate intermittently.

Probably so, though it may be that the lower solar loading on the spacecraft at Ceres' orbit allows for continuous operation.

 

[marcus]

Dawn's distance to Ceres now 900,000 km
More exactly
.006035 Astronomical Units = 902 823.15 kilometers
according to the current fulltraj update.
http://neo.jpl.nasa.gov/orbits/fulltraj.jpg

I'll check the mission director's blog ("Dawn Journal") to see if he has anything new:
http://dawnblog.jpl.nasa.gov/2014/
No, this 28 November entry is still the latest
http://dawnblog.jpl.nasa.gov/2014/11/28/dawn-journal-november-28/#more-1533

Ceres data:
http://en.wikipedia.org/wiki/Ceres_(dwarf_planet)

 

[Monsterboy]

Thanks for the links! 3 kilometers sources good!
You are right about under-ice experimentation. Pressurize to test for air retention. Measure factors involved in stability: stalactite growth, differential melt and freeze, structural strength and reliability, air-lock design for connection with surface, power plant operation with in-cave cooling. small nuclear power units as in submarines. Artificial light in the cave, to grow food. I haven't heard of any Antarctic experiments like that. Why don't you write a letter to someone in NASA?

This has not been done probably because NASA currently has no plans to build bases on Mars.
I don't know anyone in NASA ,perhaps some people in PF actually work in NASA ??

I agree, a rover should land on one of the poles and check it out! this would be so fine! I don't understand why they have not done it already, the polar icecaps are the most interesting parts of Mars, in the long run.

There was one attempt to land near the poles (Mars polar lander) ,it failed because it crash landed! ,i too don't understand why the polar ice caps remain unexplored ,perhaps there is some technical difficulty in landing something over the poles ?
If we land people on Mars ,it will mostly probably be near the poles right? radiation levels will be lower there and water will be available in the required quantity right?
If we ever find life on Mars ,that too is mostly likely to happen in the polar regions ,since several metres deep water ice can reduce radiation levels to that of Earth's hence photosynthetic life might be possible within the ice layers of the polar regions.

 

[Monsterboy]

http://astrobiology.nasa.gov/articles/2014/5/15/destroying-glycine-in-ice/
Now some astrobiologists say even under ice ,life is difficult to be sustained on Mars but the article doesn't mention depth of water ice required to sustain life.

 

[marcus]

It's really two questions. They were talking about photosynthetic life. that has to be near enough the surface of the ice to get light. So there is no question of going deep enough to be safe from radiolysis of glycine. Those are issues about the possibility of life emerging and evolving independently on Mars long ago, and issues about the preservation of traces of life, in the ice, from which we could learn about prior history.

But clearly those research issues do not affect the practicality of operating a base safely under Mars ice caps, only (indirectly) one of the motivations for doing so.

Thanks for the interesting links! I think you are right about all the points you made. I still suspect it would be more interesting to establish a human settlement on Ceres. Partly because there's expected to be a lot MORE ice---deeper and planet-wide---so room to expand and a good way to cool thermodynamic power cycles, if our species learns to thrive in 3% gravity. More place to go if you're successful.
Partly because the gravity is so weak it would be easier to land and take off.
Partly because IF our species ever finds reason to utilize or settle more parts of the solar system, Ceres could provide WATER MORE CHEAPLY than the Earth could. Water for life and industrial processes, hydrogen and oxygen for propulsion. So there is a long-range reason to want to utilize (if not actually settle on) Ceres.

We won't actually know much for sure about the place until the Dawn craft arrives in March 2015. So I'm just speculating. But it seems likely to be a ball largely of water ice (density estimated 2 g/cc) with escape velocity about 500 m/s, one is naturally interested :w

 

[Hercuflea]

Fabulous. Even though they could have done this in the 70s on nuclear thermal rockets...

I have more faith in private space companies.

 

[mheslep]

Fabulous. Even though they could have done this in the 70s on nuclear thermal rockets...
...

Do you have an example design in mind? Yes the nuclear power was available, the liftoff thrust was available, the specific impulse was an improvement over chemical rockets, but I don't know of anything in that era with the required specific impulse to go orbit hopping as has Dawn, i.e. an ion drive above 3000 seconds. Nuclear explosive propulsion (Orion) does not count.

 

[zoki85]

I think attempt to go to Mars in '70s had more chances to end in tragedy than not.

 

[HowardHughes]

So basically when NASA gets there, there will already be a fully established colony set up a decade before by SpaceX and co.

 

[marcus]

More about the conjecture that Mars might have a reservoir of subsurface ice in the "Northern lowlands":
http://science.nasa.gov/science-news/science-at-nasa/2014/19dec_marswater/

Dawn spacecraft distance from Ceres is now 787,000 km (i.e. 0.005261 AU)

As I recall it was 900,000 km from destination last Saturday, so in about 6 days it has closed in by more than 100,000 km. Seems to be on schedule to reach Ceres by 1 March. Will have to begin slowing down in order not to overshoot I suppose. Maybe gravity (orbital dynamics) will take care of that if it just turns off the solar-electric thrusters now and then.

 

[Kechel8]

Spectacular! Do we send matthew mcconaughey? ;)

 

[Firedog89]

Let's say we make to Mars, what will be the next step Europa? What about interstellar travel? Would that even be practical considering Einstein states that no man-made object can travel at the speed of light?

 

[Monsterboy]

http://www.universetoday.com/117384/nasas-curiosity-rover-detects-methane-organics-on-mars/

In how many ways can methane be produced on Mars non-biologically?

 

[progyan]

Setting foot on Mars would certainly be one of the greatest achievements of mankind since it would only be the second time since we ever set foot on any place besides our
planet.

 

[marcus]

http://www.universetoday.com/117384/nasas-curiosity-rover-detects-methane-organics-on-mars/

In how many ways can methane be produced on Mars non-biologically?

I'm not sure who here would be good to ask. Astronuc maybe? Almost certainly some of us have backgrounds in chem or chemical engineering. I don't know which would be the most likely pathways for producing CH₄ under Mars conditions. Nonbiological methane is common in outer solar system, e.g. moons of Saturn. Titan's atmosphere is largely methane, if I remember correctly. Hydrogen and Carbon are common elements and methane is a simple combination, likely to occur (in non-oxidizing conditions) and very stable (as long as there is not a lot of oxygen).

The catch is that oxygen, if present, will break down methane into carbon dioxide and water. If there free oxygen or oxygen molecules running around loose ready to react with stuff, it is called an "oxidizing environment". Methane tends not to form and does not readily accumulate under oxidizing conditions. But you can still have traces of it.
Mars is more oxidizing than not. So the question is: assuming no life, no biological action, what could have formed traces of methane in Mars atmosphere?

I'm no chemistry expert, but here's a unexpert suggestion to get the ball rolling. Mars has some water vapor in its atmosphere (it even has water ice at the poles) and
Mars has a lot of CO₂ in its atmosphere. Under the action of sunlight (especially UV) water vapor in atmosphere will slowly break down producing hydrogen and oxygen, and hydrogen will occasionally react with CO₂ to form methane, and water again.
As I recall, this reaction is even energetically favored, it would like to happen!
4H₂ + CO₂ --> CH₄ + 2H₂O

 

[marcus]

A Ceres Wonderland.
Due to mechanical wear, the Dawn craft lost "wheel control" after a number of years of voyaging---one or more of its gyroscopes (used for attitude control) wore out.
So when it needs to change orientation (to direct thusters, to keep solar panels in full sunlight etc. ) it has to use hydrazine. they mention that in the song.

Ceres is a huge H₂O resource with a surface escape velocity of only 500 m/s. From my perspective it has to be exciting that we are about to get a close look.
So ...

 

[Monsterboy]

Whether we find methane,chloro-benzene or any other organic compound ,only way to be certain about life on Mars is to directly FIND living organisms there ,or is it? Is there any organic compound that we are sure that it cannot exist without living organisms producing it? If there is any such thing ,we should start looking for that.

 

[phinds]

Whether we find methane,chloro-benzene or any other organic compound ,only way to be certain about life on Mars is to directly FIND living organisms there ,or is it? Is there any organic compound that we are sure that it cannot exist without living organisms producing it? If there is any such thing ,we should start looking for that.

It is my strong impression from what I have read that there are compounds that if seen in sufficient, sustained, quantities would indicate life forms as they would not as far as is known be producible/sustainable through geologic activity. I believe oxygen is one such but not the only one. No such concentrations of any have been seen on Mars. That absence does not guarantee that there are NOT life forms on Mars but it likely does mean that we're going to need direct observation to see if there is anything there.

 

[Monsterboy]

Lets have look at the hurdles for manned exploration of Mars.

http://www.space.com/25392-manned-mars-mission-astronaut-vision.html

Recently, scientists have begun realizing that spaceflight can cause serious and perhaps permanent vision problems in astronauts.

"Over the last 40 years there have been reports of visual acuity impairments associated with spaceflight through testing and anecdotal reports," a 2012 NASA report about spaceflight-related vision problems states. "Until recently, these changes were thought to be transient, but a comparison of pre- and postflight ocular measures have identified a potential risk of permanent visual changes as a result of microgravity exposure."

The problem is not confined to just a few isolated individuals, either. Postflight examinations performed on about 300 American astronauts since 1989 showed that 29 percent of space shuttle crewmembers (who flew two-week missions) and 60 percent of International Space Station astronauts (who typically spend five or six months in orbit) experienced a degradation of visual acuity, according to a report published this year by the U.S. National Academy of Sciences.

http://www.space.com/18980-radiation-manned-exploration-deep-space.html
http://news.discovery.com/space/history-of-space/mission-to-mars-health-risks-1107182.htm

Let us count the ways that the human body falls apart without gravity:

1) Bone loss of one percent per month.

2) Fainting spells (women more than men) after re-entering a gravitational field.

3) Cognitive problems including Alzheimer's-like symptoms.

4) Weakness and lack of cardiovascular fitness.

5) Muscle atrophy.

All of these medical conditions would make it tough for the crew to build a shelter when they land on the Red Planet, for example.

"What happens if they land on Mars and try to lift an object that's fairly or reasonably heavy, they could herniate their discs

Radiation:
The combined effects of background cosmic rays from extragalactic sources and extreme radiation events from the sun make space travel too hazardous for an estimated six months there and six months return.

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.

Pick astronauts that have never smoked, never been around smokers, and have a built-in genetic resistance to radiation damage. "We didn't know about this (ability) five or ten years ago, we should have an answer in another ten or 15 years,"

The crew needs either a small unit inside the ship or a vehicle design that rotates around a central pivot point (think 2001: A Space Odyssey). Hargens said a rotating arm of one-kilometer diameter will produce the equivalent of the gravity felt on the Earth at sea-level.
Smaller centrifuges have produced nausea among astronauts

Food:
However, studies show that radiation can damage the vitamins in food supplies, and the loss of even one vitamin in the food chain could cause serious health effects over a long trip. Little is known about the long-term effects of radiation on food supplies, since International Space Station (ISS) crews have been partially sheltered by Earth's magnetosphere.

Cabin Fever

Put six or seven people in a confined space for 18 months, send them to a place nobody's been before, with no way to escape, is likely to produce stress, tension and perhaps even severe psychiatric problems, according to NASA's 2009 Human Research Program report.

Based on studies in Antarctica and other isolated environments underwater, the report cited the risk of "increased human performance errors due to sleep loss, fatigue, work overload, and circadian desynchronization; and, increased errors due to poor team cohesion and performance, inadequate selection/team composition, inadequate training, and poor psychosocial adaptation."

Cosmonaut squabbles aboard the Russian Mir space station brought one mission home ahead of time, while NASA has also reported crew disputes among its astronauts

Some experts say the answer to all the medical, radiation, food and psychological issues is to get there faster.

Zubrin also went on the record to call VASIMR a "hoax."
"The insistence that we need a faster propulsion system just allows politicians to postpone a Mars mission,"

 

[mheslep]

Some experts say the answer to all the medical, radiation, food and psychological issues is to get there faster.

Zubrin also went on the record to call VASIMR a "hoax."
"The insistence that we need a faster propulsion system just allows politicians to postpone a Mars mission,"

I think Zubrin is a hoax

 

[Tsubaki]

I'm really pleased that they went to the Apollo-like design of the Orion Project. Upgradeable modules based on the greatest achievement in scientific history really can't fail us. It's an exciting time to be involved in science and engineering.