…may have more fresh water than on all of earth. Seems in many ways more habitable than Mars.
16 thoughts on “Ceres”
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…may have more fresh water than on all of earth. Seems in many ways more habitable than Mars.
Comments are closed.
I love the depiction of the asteroid belt as an impassable mine field like in The Empire Strikes Back.
No crewed vessel has ever survived a trip through the asteroid belt, perhaps because human reaction times just aren’t fast enough. If we ever do make it through that obstacle (may I suggest we go over the belt, assuming humans can take the kind of altitudes required to accomplish that), then the next big problem is relying on nothing but inertial navigation to make it through the Oort cloud, where we won’t have any visual references – because it’s a giant cloud.
er, what? No crewed vessel has ever survived a trip through the Asteroid Belt because no crewed vessel has ever left cislunar space. It’s never been tried.
It is an amazing time we live in.
” more fresh water than on all of earth. ”
Most of the water on Earth is salt water anyway, there’s less that 3% fresh water.
http://en.wikipedia.org/wiki/Fresh_water
> Seems in many ways more habitable than Mars.
Seriously asking here . Which is easier to achieve full-gee artificial gravity on? A low gravity body such as Ceres or a moderate gravity body like Mars. You would think Mars because you’re already 3/8ths of the way there. But that 3/8ths creates downward torque on any swing arm creating an engineering problem. Yet the partial gravity means that one can have a lower rpm and shorter swing arm thereby less torque…
I would definitely say that Ceres would be easier, not only because of the tiny fractional G on the thrust bearings, but because there’s no atmospheric drag on whatever you spin up. For a Ceres mission it would even make sense to have your entire rotating ship just land on the surface (Ceres only has a 510 m/sec escape velocity) and keep on spinning as it normally does. Given the 0.028 G gravity on Ceres, it would feel like your floor only tilted 1.6 degrees, which you’d hardly even notice.
Ceres is a particular interesting colonization target because it’s not in a very deep gravity well, the escape velocity is only 510 m/s (orbital velocity would be around 360 m/s). Take something like the Saturn V first stage, it could put about 17,000 tonnes into orbit around Ceres from the surface and then have enough fuel to return. Obviously you’d want to switch to LOX/LH2 so you could use locally produced propellants, or perhaps NTRs or even pulsed plasma thrusters. The point being that the resources on Ceres are far, far closer to orbit than the resources on Earth or Mars. So it may not make any sense whatsoever to build habitats on the surface of Ceres since the surface is only a short hop to orbit. Orbit where it would be easier to create 1g artificial gravity, provide radiation shielding, etc.
LEO to Ceres surface is about 9.4 km/s and that’s not including the hefty plane change expense that would come from the ~10 inclination of Ceres’ orbit.
LEO to Mars surface is about 5.7 km/s, not including the aerobraking savings Mars’ atmosphere can give.
Ceres may have a shallow gravity well but it still takes more delta V to reach than Mars.
Sorry, rereading your post I believe you’re saying Ceres resources are much closer to Ceres orbit than Mars or earth resources are to their orbits. That’s correct.
Moreover it has a 9 hour day. With such a shallow gravity well and a higher angular velocit it’d be a piece of cake to build Clarke towers on Ceres (at least in comparison to beanstalks or earth or Mars).
It’ll be interesting to see how Ceres vs. Mars fare in terms of colonization. Mars is obviously a very promising colonization target for a lot of reasons, but Ceres has its advantages as well. The fact that you can build in orbit while still having prompt and easy access to the resources on the surface is intriguing.
Power on Mars is slightly problematic because of the dust and the general problems of solar energy on any surface. Ceres would receive perhaps 1/4 as much sunlight as Mars but on Ceres it would always be direct, easily tapped using capital equipment that lasts for decades (as have comsat solar power systems), and always on 24/7. Ceres has plenty of water so there’s no issue in terms of supplying basic consumables and manufacturing propellant. The truly important questions are how easy it will be to mine chondrite and other minerals. With Mars’ abundance of CO2 it becomes almost trivially easy to make CO which can then be used to smelt Iron and so on. Bootstrapping Martian industry would be easy, within a decade or so Martian colonies could be manufacturing fuel, food, concrete, and steel. I’m not sure what the bootstrapping process for industry on Ceres would be though.
To get back to the ease of transport between the surface and orbit of Ceres, the payload capacity of a single stage rocket delivered to Ceres would be about 100x the dry mass of the rocket. Meaning that a 10 tonne vehicle sent to Ceres could put twice the mass of the ISS into orbit around Ceres. Without atmosphere as an issue an RLV on Ceres would be much simpler than one needed to work on Mars or Earth, and it would have a considerable lifetime due to the low delta V, lack of aerodynamic loading, and low gees. That puts propellant production and cargo loading as the main gate in such a situation, even with a very paltry amount of capital equipment.
Earth gets about 33 tons space material falling in it per day- so 12045 tons a year.
Some of it, say more than 1% would be H2O- so more than 100 tons of water added per
year seems to me like the least it could be.
“Here is what scientists think is happening: when Ceres swings through the part of its orbit that is closer to the sun, a portion of its icy surface becomes warm enough to cause water vapor to escape in plumes at a rate of about 6 kilograms (13 pounds) per second. When Ceres is in the colder part of its orbit, no water escapes. – See more at: http://dawn.jpl.nasa.gov/feature_stories/HerschelTelescope_DetectsWater_Ceres.asp#sthash.KEw2yi4K.dpuf
Ceres perihelion is and 2.55 AU and aphelion is 2.97 AU
http://en.wikipedia.org/wiki/Ceres_%28dwarf_planet%29
So first it would spend more time in winter [ near aphelion] than perihelion
Second it doesn’t seem like much difference in amount solar energy at such distance
and generally it doesn’t make much sense to me.
But anyhow, roughly if 6 in summer and 0 in winter one has less than 3 kg per second
average.
So in an Earth year of 31.5 million second one less than 94.6 million kg [94,600 tonnes]
lost water [water at near escape. Or why all water gas go at escape velocity. And/or why would all molecules go in one vector. Plus it going somewhere, and some could return Ceres. Or rocks near Ceres. Or basically since water molecule not very hot which don’t travel fast.].
So Ceres escape velocity from dwarf planet is 0.51 km/s. Earth atmospheric gas has average velocity if .4 km/s [400 m/s] . So if jump off Ceres at 400 m/s you don’t escape, but with such velocity
one get into orbit or have suborbital trajectories. Comparatively slow orbits or suborbital trajectories.
But so say go 600 m/s and escape Ceres, you aren’t going to escape the Sun’s gravity- the molecule is going to say in similar orbit as Ceres. And likewise return eventually to Ceres Or maybe Ceres has moon or other asteroids passing near Ceres. So water may go to some rock in region, vaporize again
and return to Ceres.
So, large part of 94,600 tonnes of water vapor may be recycled.
The final point is new material like with Earth is being added per Earth year. And if you in the main asteroid belt, do get more of this “new material” as compared how much Earth gets?
Isn’t this all good news for future (admittedly, somewhat distant future) terraformers of Mars, Venus, the Moon? At least the material is there — how to get it to the objects to be terraformed is merely a matter of engineering. Well, engineering and money.
Going back to sci-fi for a moment, this makes the main plot of the classic miniseries “V” pretty silly. Well, sillier anyway.
Go for it. Go for the entire solar system. My charter works everywhere because economics is universal.
The advantage Ceres has is solar will not be enough. Nuclear power makes everything possible.
Let me know your wagers. I still bet on mars… and soon somebody will owe me a soda!
“The advantage Ceres has is solar will not be enough. Nuclear power makes everything possible.”
I think at Ceres distance one gets about same much solar energy as you get in Germany.
And lack solar energy in Germany did not deter Germans from becoming the “solar energy capital
of the world”. As in ““[Germany] has more than 50% of the world’s solar power [production], but they don’t have as much sun,” said Jamie Hahn”
http://www.bbc.com/capital/story/20140106-renewable-energys-bright-future
So I mean that at earth distance one gets about 10 times more solar energy as one get at Ceres when it’s Aphelion {2.97 AU}.
Or at Ceres distance or if in Germany one gets less than 1/10th the solar energy one gets at Earth distance.
So in 24 hours at 1360 watts it’s 32.6 kilowatts per square meter. At Earth distance.
And in Germany or Seattle an average day gets about 2 kilowatts hours.
And at Ceres distant one might get about 3 kilowatts in 24 hours. Of course if you on a planet with half the time in night, one would get less than one gets in Germany or Seattle.
But it seems possible one could be on the planet Ceres and manage to do better than 50% day and 50% night.
If you are at it poles, perhaps one can get something like you get at the moon’s poles- so something
like 80% of the time- thereby do slightly better than Germany.
Unless there clouds, eruption, weather or something on Ceres.
Here’s something in regards to Dawn spacecraft:
“Over the course of the exercise, the arrays were positioned at five angles, each for an hour, and the main computer recorded their output power and other pertinent measurements. Initially, when the wings were pointing directly at the sun, a glowing orb 2.48 AU (371 million kilometers, or 230 million miles) away, together they could generate more than two kilowatts. The ion propulsion system then was thrusting at level 53, consuming 1,368 watts. When the arrays were tipped to their maximum angle of 47 degrees, the insolation was the same as it would be at 3.00 AU (449 million kilometers, or 279 million miles), and the system yielded more than 1,300 watts”
http://www.planetary.org/blogs/guest-blogs/marc-rayman/20130730-dawn-journal-craving-power.html
Now, one could say the Germans are crazy and so this doesn’t argue for Ceres becoming the
solar capital of the solar system. And that nuclear power would as safe and cheap on Ceres, as would
be in Germany.
Regarding Dawn’s solar panels:
” Each of the two solar arrays is 27 feet (8.3 meters) long by 7.4 feet (2.3 meters) wide. On the front side, 18 square meters (21.5 square yards) of each array is covered with 5,740 individual photovoltaic cells. The cells can convert about 28 percent of the solar energy that hits them into electricity. On Earth, the two wings combined could generate over 10,000 watts.”
– See more at: http://dawn.jpl.nasa.gov/technology/ion_prop.asp#solar
Let’s do math, so 18 times 1360 is 24,480, and times .28 is 6854.4 watts. And two arrays 13708.8 watts.
So did they mean noon clear sky on Earth- 1000 watts? Yeah that would just over 10,000 watts.
But it seems Ceres at furthest distance from sun is about 1/10 the solar energy as at Earth distance.
And if, one could near constant sunlight at Ceres, it would much better than Germany as location
to harvest solar energy.