Why not colonize Ceres?

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Re: Why not colonize Ceres?

Postby Tass » Thu Apr 07, 2011 8:59 am UTC

idobox wrote:What Izawwlgood is saying, is that we have the technology to build a livable habitat on Earth.
Radiation shielding and thermal insulation are not difficult issues. Carrying all the stuff we need to build one in space is a major issue though, but no one contested that point.


Once we have a moon base producing fuel and solar panels, infrastructure to move stuff from the moon to earth orbits, better electric propulsion, and have cut launch costs by an order of magnitude, then we should be able to build it from mostly space materials.

I hope it happens within not too many decades.

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Re: Why not colonize Ceres?

Postby idobox » Thu Apr 07, 2011 3:13 pm UTC

The thing is you need factories in space to build habitats, and you need habitats to build factories.
At one point, someone will have to invest an absurd amount of money, time and effort to build the first step.
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Re: Why not colonize Ceres?

Postby HopDavid » Thu Apr 07, 2011 4:27 pm UTC

idobox wrote:What Izawwlgood is saying, is that we have the technology to build a livable habitat on Earth.


The question is, do we have technology to build a livable habitat in space?

The I.S.S. is a step in that direction. However we still haven't attained what we'd need for an MTV or other long journeys.

idobox wrote:Radiation shielding and thermal insulation are not difficult issues.


You can't get much better insulation than hard vacuum. Dumping waste heat can be problem though.

Radiation shielding and radiating heat can add substantial to your hab mass which is an important issue.

idobox wrote:Carrying all the stuff we need to build one in space is a major issue though, but no one contested that point.


Well, that point alone is a show stopper at this time. However it's not a show stopper for trips to the moon, as these take less than a week.
Last edited by HopDavid on Thu Apr 07, 2011 4:52 pm UTC, edited 1 time in total.

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Re: Why not colonize Ceres?

Postby HopDavid » Thu Apr 07, 2011 4:49 pm UTC

idobox wrote:The thing is you need factories in space to build habitats, and you need habitats to build factories.


At first all habs will be built on earth and lifted from earth's gravity well. We will not have the infrastructure in space to do this sort of challenging manufacturing for some time to come.

However In Situ Resource Utilization can reduce hab mass. At the lunar poles there is water. Which can be used for radiation shielding and drinking. You can split it to hydrogen and oxygen. Oxygen is useful for breathing. Hydrogen and oxygen is useful for propellant. A propellant source high on the slopes of our planet's gravity well could be immensely useful in enabling space transportation.

Further, the moon is close enough that much of the work can be accomplished with telerobots. Not so for NEOs or Mars.

idobox wrote:At one point, someone will have to invest an absurd amount of money, time and effort to build the first step.


It's my contention that building lunar infrastructure is plausible while NEO and Martian infrastructure much less so.

Let's review the metrics:

Delta V
Trip time
Frequency of launch windows
Communication light lag

Delta V has a huge impact on vehicle size, complexity and reusability. Local propellant resources can break the delta V budget into several parts. In terms of delta V and trip time, lunar propellant is quite close to EML1, EML2, GEO, LEO as well as other orbits in the earth-moon neighborhood.

Lunar propellant has the potential for enabling transportation to all parts of our solar system as well as within the earth moon neighborhood. Martian propellant has the potential to enable trips from Mars to earth, but little else.

Most of the metallic asteroids likely have no exploitable volatiles that could be used for ISRU propellant. If their platinum takes a 20 km/sec round trip for delivery to earth market, they will never be profitable.

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Re: Why not colonize Ceres?

Postby Izawwlgood » Thu Apr 07, 2011 5:12 pm UTC

Wait, I'm confused: HopDavid, you're citing thin glass as a reason why artificial environments won't work in vacuum, but a few pages ago were advocating for lunar green houses... I obviously didn't mention Biosphere2 to suggest we should build it, as is, off Earth, but to point out that the technology for enclosed ecosystems has been tested and played with a bit, fairly effectively, about 20 years ago.

Your 'without maintenance from Earth' still stands with Biosphere2; it was sealed for 16 months before construction flaws and crew idiocy lead to failure. Sealed. As in, only sunlight in.
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Re: Why not colonize Ceres?

Postby idobox » Thu Apr 07, 2011 6:50 pm UTC

I was just trying to defend Izawwlgood on the subject of fully enclosed ecosystems there.

Building an habitat on Earth is doable. Building something similar on the moon, for example, is not much more difficult, once you have carried all the materials and personnel there. Of course, sending all that on the moon is a project considerably larger than any other space project ever.
Doing it on Ceres or any NEO would be even more difficult and expensive.

That's why I believe first habitats will not be fully enclosed ecosystems like the biosphere, but a mix of ecological and chemical treatment.

By the way, there is a price at which mining platinum from m-type asteroids becomes profitable. It might be unreasonnably high, but there is a threshold at which it happens.
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Re: Why not colonize Ceres?

Postby Meteorswarm » Thu Apr 07, 2011 7:40 pm UTC

HopDavid wrote:I wrote "without supply or maintenance trips from earth". That gives a hint I was thinking of a habitat in space.


Nobody is saying that it would be easy. Stop harping on the weight issue - everybody acknowledges it. Our point is that it is a matter of expense, and not a matter of possibility - we can and have built systems that are independent for months, which means that, with relatively little research, we can build systems that are independent for much longer. Getting them to orbit or to another planet is obviously extremely difficult and expensive.
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Re: Why not colonize Ceres?

Postby HopDavid » Thu Apr 07, 2011 8:10 pm UTC

Izawwlgood wrote:Wait, I'm confused: HopDavid, you're citing thin glass as a reason why artificial environments won't work in vacuum, but a few pages ago were advocating for lunar green houses...


Earlier I had cited New Light on the Lunar Poles

I wasn't advocating lunar green houses. I was countering your belief that lunar bases must suffer 14 day nights.

Further, I wasn't arguing thin glass is a show stopper for artificial environments. I was citing it as one of the many differences between biosphere and a plausible Mars Transfer Vehicle.


Izawwlgood wrote:I obviously didn't mention Biosphere2 to suggest we should build it, as is, off Earth, but to point out that the technology for enclosed ecosystems has been tested and played with a bit, fairly effectively, about 20 years ago.


Okay, I acknowledge there are closed ecological life support systems that have kept people alive for more than 8.5 months. As I've acknowledged before, earth is such a life support system. It's kept humans alive for many generations.

Were you trying to make the case for a Mars Transfer Vehicle? If so, citing biosphere doesn't come close.

Izawwlgood wrote:Your 'without maintenance from Earth' still stands with Biosphere2; it was sealed for 16 months before construction flaws and crew idiocy lead to failure. Sealed. As in, only sunlight in.


Were we talking about a transfer vehicle between earth and Mars? Or between earth and an NEO?. I had thought by context it was obvious I was talking about a hab in space.

Show me a hab in space that has been sealed for 16 months without supply or maintenance trips and been keeping humans alive all the while? Or is citing Biosphere supposed to demonstrate that an MTV would be an acceptable risk with present state of the art?
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Re: Why not colonize Ceres?

Postby HopDavid » Thu Apr 07, 2011 8:12 pm UTC

Meteorswarm wrote:
HopDavid wrote:I wrote "without supply or maintenance trips from earth". That gives a hint I was thinking of a habitat in space.


Nobody is saying that it would be easy. Stop harping on the weight issue - everybody acknowledges it.


And there are other differences besides weight between a CELSS on earth and a CELSS in space. Not sure if you got that.

Meteorswarm wrote:Our point is that it is a matter of expense,


In the real world budgets are limited. Money is finite.

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Re: Why not colonize Ceres?

Postby Izawwlgood » Thu Apr 07, 2011 9:55 pm UTC

I see where my miscommunication occurred; I was speaking more of permanent planetary habitats. But that said, small scale enclosed systems aren't unheard of or difficult. I'm not sure why an artificial rotating green house is out of the question for small scale foodstuffs and oxygen generation. The ISS has more internal space than the scale I'm imaging for this.
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Re: Why not colonize Ceres?

Postby HopDavid » Thu Apr 07, 2011 10:33 pm UTC

Izawwlgood wrote:I see where my miscommunication occurred; I was speaking more of permanent planetary habitats. But that said, small scale enclosed systems aren't unheard of or difficult. I'm not sure why an artificial rotating green house is out of the question for small scale foodstuffs and oxygen generation. The ISS has more internal space than the scale I'm imaging for this.


Once you have the ability to exploit local resources, life support can be much easier. This is true of the lunar poles as well as Mars.

However for the trip there and back, all consumables must be carried aboard the vehicle.

With present state of the art, vehicles that can carry people to the moon are plausible. Vehicles that can carry humans for 8 months for an interplanetary trip less so.

In the event of a system failure at a lunar hab, it's possible to people back to the earth in less than a week. People on Mars would need to wait for the next Mars to earth launch window.

If you have an unlimited budget, vehicles that can carry people for 8 month interplanetary trips are no problem. I would agree that the laws of physics don't prohibit such vehicles.

If you throw in plausible budgets as a constraint, permanent NEO or Mars bases are extremely unlikely.

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Re: Why not colonize Ceres?

Postby Wolfkeeper » Sun Aug 02, 2015 8:27 pm UTC

Looks like the Ceres probe has thrown up some new info.

It's likely, but not proven yet, that the spots on Ceres may be ice volcanos; if so that may change the equation.

If you collect the ice that comes out of the volcanos, you can store it as propellant.

Once you've collected enough you can launch it into orbit, and then use it to put propellant on a return trajectory towards Earth, which takes 1 year and 3 months, and the propellant can aerobrake when it gets there. The rest of the vehicle can do a fly past Earth and return to Ceres to get more propellant.

Because the surface gravity and escape velocity of Ceres is so small, and the delta-v to put propellant onto aerobraking returns are all much less than lunar, it looks like all this might be very low cost, and perhaps can all be done with robotic equipment.

A main point of it could be to collect propellant for use for other things, to allow humans to go to the moon or whatever, but it looks like it could be much easier to use Ceres for mining the propellant.

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Re: Why not colonize Ceres?

Postby oxoiron » Wed Sep 16, 2015 2:48 pm UTC

How are you going to use ice as a propellant? Heat it and expel it as steam?
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Re: Why not colonize Ceres?

Postby Sizik » Wed Sep 16, 2015 2:55 pm UTC

Electrolyse it into hydrogen and oxygen?
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Re: Why not colonize Ceres?

Postby speising » Wed Sep 16, 2015 3:59 pm UTC

Sizik wrote:Electrolyse it into hydrogen and oxygen?

And then burn it again? How is that different from heating it directly?

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Re: Why not colonize Ceres?

Postby Wolfkeeper » Wed Sep 16, 2015 8:35 pm UTC

You can do either; you can heat it and expel it as steam, or electrolyse it, and liquefy it then burn it. It might be even possible to use it in an ion drive, but it's not very energy efficient to do that, heavy molecules work better in ion drives.

The second option has much higher exhaust velocity (~4.5 km/s) compared to steam (~1.9 km/s) but the equipment to electrolyse and liquefy liquid hydrogen and liquid oxygen- it's really very surprisingly heavy with lots of heat exchangers and huge power plant requirements; and at least one analysis I've seen suggests that in most cases you're best off just throwing more steam out the back than going the LOX/LH2 route; there was orders of magnitude improvement in how much payload you could deliver with steam- for cislunar and Mars trips at least; for any given outbound earth-launched mass.

But if you have a high delta-v missions; LOX/LH2 is unequivocally better due to the exponential in the rocket equation.

If you have a very high delta-v mission, then the ion drive route might be best even though the energy efficiency is poor. The exhaust velocity would probably be ~15km/s.

Edit: it looks like the return from Ceres burn to get on the Earth transfer orbit is just over 4km/s, so using steam would be practical for that; the propellant load would come in to Earth orbit pretty hot, not sure how the aerobraking practicalities look to achieve capture for minimum outbound mass; possibly some kind of carefully shaped layered plastic bag that sacrifices some of the water as 'ablative' might well work.

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Re: Why not colonize Ceres?

Postby commodorejohn » Wed Sep 16, 2015 10:19 pm UTC

If I remember junior-high science correctly, splitting water into hydrogen and oxygen is trivial. We just need to find an asteroid made out of yeast.
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Re: Why not colonize Ceres?

Postby Wolfkeeper » Wed Sep 16, 2015 11:07 pm UTC

Splitting useful amounts of hydrogen and oxygen for rocketry purposes is indeed completely trivial if you have an absolutely humongous powerplant connected to your electrolysis cell :wink: which you would have to send to Ceres on a freaking enormous rocket.

But if you ask yourself whether sending a LH2/LOX plant to Ceres or using steam cycle propulsion gets you more propellant back to Earth, for the same rocket. The answer is that the second one gets you back tens of times more for you buck.

It's not only the powerplant, you have to liquefy it afterwards, and liquid hydrogen needs lots of heavy equipment to make even once you have the hydrogen.

Here's a website that covers it:

http://www.neofuel.com/index_neofuel.html

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Re: Why not colonize Ceres?

Postby Neil_Boekend » Thu Sep 17, 2015 9:12 am UTC

Also, steam based space travel would make many steampunk enthousiasts very happy.
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Re: Why not colonize Ceres?

Postby gmalivuk » Thu Sep 17, 2015 12:17 pm UTC

I think only if we also adopt their bad clothing fashions and start making more things out of brass.

After all, much if not most of the world's electricity is generated in some way by steam, and yet they don't seem to see that fact as fitting in with their aesthetic.
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Re: Why not colonize Ceres?

Postby Neil_Boekend » Thu Sep 17, 2015 2:39 pm UTC

That might be more of a question of marketing. Must non-technical people don't realize steam is still used that extensively. It's mostly hidden (although it was quite clearly audible when a powerplant near to my work had a ruptured steam pipe. The pressurized steam escaping made a flute-like tone, just a bit more audible (must have been clearly audible at 10 km distance))
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Re: Why not colonize Ceres?

Postby speising » Thu Sep 17, 2015 2:41 pm UTC

The central thing about steam punk is that steam is used *instead of* electricity. Generating electricity via steam doesn't count.

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Re: Why not colonize Ceres?

Postby commodorejohn » Thu Sep 17, 2015 2:55 pm UTC

Unless there are Tesla coils involved.
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Re: Why not colonize Ceres?

Postby Wolfkeeper » Thu Sep 17, 2015 4:24 pm UTC

Steampunk To Ceres!!!

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Re: Why not colonize Ceres?

Postby drachefly » Fri Oct 02, 2015 6:45 pm UTC

commodorejohn wrote:Unless there are Tesla coils involved.


Or Van de Graaf generators?

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Re: Why not colonize Ceres?

Postby Wolfkeeper » Fri Oct 02, 2015 8:14 pm UTC

I've been trying to work out the burn needed to return to Earth from Ceres.

It's actually a bit complicated.

Deadfrog has an excellent delta-v map here:

http://www.projectrho.com/public_html/r ... frog42.png

This gives a return to Earth burn from Ceres escape as 4.39 km/s.

But unfortunately it assumes everything is coplanar, whereas Ceres is 10.59 degrees to the ecliptic, which is pretty bad.

Given the orbital velocity of Ceres (17.905km/s) if you just did a mid course burn it would add at least ~17.905*sin(10.59) = 3.29km/s on top of the 4.39km/s = 7.68km/s which is quite a lot, given the exponential in the rocket equation.

But you can probably do somewhat better than that in many cases.

For example if Ceres happens to be at the intersection point between the two planes (the Earth has to be at the right place in its orbit also) when you want to do the burn to go onto the transfer orbit, then you can do both burns in quadrature, giving SQRT(3.29^2+4.39^2) = 5.48 km/s.

There's probably other multi burn strategies that also give a big improvement even when you're not starting at the intersection point. For example if you did a small burn to lower periapsis and decrease the orbital period, and then did your bigger quadrature burn later, it might not be too bad.

It would be interesting to know what the minimum and maximum burns might be. Has anyone ever calculated this?

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Re: Why not colonize Ceres?

Postby dimitriye98 » Sun Oct 11, 2015 7:24 pm UTC

About the yellow (Earth-LEO) stage never being reusable: I have significant hope for SSTO technology.
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Re: Why not colonize Ceres?

Postby Wolfkeeper » Sun Oct 11, 2015 8:04 pm UTC

Whether or not SSTO is successful, we need to 'live off the land'; if a source of off-earth propellant can be located, that would be stupidly useful; Ceres is looking plausible as a source for that.

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Re: Why not colonize Ceres?

Postby dimitriye98 » Mon Oct 12, 2015 8:32 pm UTC

Wolfkeeper wrote:Whether or not SSTO is successful, we need to 'live off the land'; if a source of off-earth propellant can be located, that would be stupidly useful; Ceres is looking plausible as a source for that.

Well, yes, I didn't dispute that. I was just saying that the Surface - LEO stage could easily be made reusable, since it was brought up that that stage may not be reusable.
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