Moon, Mars, or Asteroid? Which is the best goal?

[scottb50]

The water would have to be replaced.

What is used for propulsion would have to be replaced or, more aptly, carried throughout the mission. That used for crew use and other uses would generally be recycled.

 

[HopDavid]

I've suggested launching it as water and processing it using Solar power as it is needed. Water is stable and easily storable and could also be used internally by vehicles and Platforms for electrical power environment and sanitation and recycled for repeated uses.

Takes a lot of power to split H2O. Unless you have lots of PV, it will take a long time to split. If splitting takes a long time, you'll be back to storing hydrogen anyways.

What mass of PV cells do you hope to launch?

 

[HopDavid]

How about Centaur with bigger tank, Sundancer, and Orion for command and decent module ?

Centaur would have to be refuelled, of course, and using LH doesn't make me happy, due to evaporation problems.

And how to launch the fuel?

With whatever is cheapest, can bring it there, and not bust the explorer vehicle. Buy it on the market.

You'd ship the fuel on the explorer vehicle and not in a separate trip?

If return trip propellent must be carried, you're looking at a substantially higher delta V budget.

 

[scottb50]

I've suggested launching it as water and processing it using Solar power as it is needed. Water is stable and easily storable and could also be used internally by vehicles and Platforms for electrical power environment and sanitation and recycled for repeated uses.

Takes a lot of power to split H2O. Unless you have lots of PV, it will take a long time to split. If splitting takes a long time, you'll be back to storing hydrogen anyways.

What mass of PV cells do you hope to launch?

It would take a lot more then ISS has, but in transit there is plenty of time to store Hydrogen and Oxygen and electrical power to keep it cryogenic. If it was part of continuous water cycle it could be siphoned off from what is used for normal operations.

I'm thinking of alternating hydrolysers and fuel cells, they're the same thing anyway and temperature control would be easier.

 

[rockett]

Takes a lot of power to split H2O. Unless you have lots of PV, it will take a long time to split. If splitting takes a long time, you'll be back to storing hydrogen anyways.

What mass of PV cells do you hope to launch?

Actually there is a method that is well suited for this application I think:
High-temperature electrolysis
http://en.wikipedia.org/wiki/High-temperature_electrolysis
Solar mirror focused on a boiler, solar cells for power. My son actually did this as a science project with a home built rig and a foot long by 4 inch wide solar array. It was surprisingly efficient even in the winter...

 

[rockett]

You'd ship the fuel on the explorer vehicle and not in a separate trip?

If return trip propellent must be carried, you're looking at a substantially higher delta V budget.

For initial exploration, I can't see any other way. We are a (VERY) long way from ISRU for asteroids...

 

[EarthlingX]

You'd ship the fuel on the explorer vehicle and not in a separate trip?

If return trip propellent must be carried, you're looking at a substantially higher delta V budget.

For initial exploration, I can't see any other way. We are a (VERY) long way from ISRU for asteroids...

What makes you think that ?

 

[HopDavid]

You'd ship the fuel on the explorer vehicle and not in a separate trip?

If return trip propellent must be carried, you're looking at a substantially higher delta V budget.

For initial exploration, I can't see any other way. We are a (VERY) long way from ISRU for asteroids...

What makes you think that ?

Lack of knowledge. We know very little about the NEOs.

I have long advocated launching a fleet of prospector probes to gather an inventory of asteroid resources. Also beefing up the Deep Space Network to accommodate the flow of data these probes would send back. Given such a fleet, I believe we would find accessible NEOs with icey interiors.

But we don't have a fleet of prospector probes, nor does it seem likely such a fleet will be funded in the near future. Any usable NEO propellent remains unknown.

On the other hand, we have an abundance of data from Chandrayaan-1, LRO, etc. indicating the presence of water on the moon. There is also good evidence of massive ice sheets at the lunar poles.

Getting propellent on an airless world would be hard rock mining. Mining is an activity where many unforeseen problems come up -- you can count on Murphy's Law. Autonomous robots aren't up to this task, you need human oversight. The only plausible robotic asteroid mining scheme I know of is the Kuck Mosquito. But even this requires drilling which can easily go wrong without oversight. And Kuck Mosquitoes require an accessible body with an icey interior. Let me know when we find such an asteroid.

On the moon you can have oversight via telepresence (light lag is only 2.7 seconds). Actual human presence is also much easier. You have a launch window opening every two weeks and trip time is days to weeks.

Rarity of launch windows and long trip times are an obstacle to sending humans. For teleoperated mining equipment, light lag can be minutes to half an hour, a much less acceptable reaction time than 2.7 seconds.

 

[oldAtlas_Eguy]

I have long advocated launching a fleet of prospector probes to gather an inventory of asteroid resources. Also beefing up the Deep Space Network to accommodate the flow of data these probes would send back. Given such a fleet, I believe we would find accessible NEOs with icey interiors.

There are NASA whitepapers on how to modernize the deep space network by turning it into an Internet like system with network nodes placed at various planets like Mars, Jupiter, Saturn etc. so that exploration robots can use shorter range communication systems at high data rates.
http://www.universetoday.com/21206/nasa ... -internet/
By using swarm methods, small robots that communicate short distances ~1million km to a network node in long range communication with Earth, several bodies can be investigated simultaneously or multiple robots can investigate a body rapidly and then move on to the next.

 

[neilsox]

Has anyone built a 1000 kilogram rover that might make hydrogen from cactus juice in a typical Earth desert? Could it make even one kilogram of hydrogen per hour? Is the output higher if it has to use damp sand as the water source? Obviously the rover needs to be very versatile as a small lake is very improbable. Can the rover dig a well 100 meters deep to get below the surface water? Neil

 

[HopDavid]

Is the output higher if it has to use damp sand as the water source? Obviously the rover needs to be very versatile as a small lake is very improbable. Can the rover dig a well 100 meters deep to get below the surface water? Neil

The mini-SAR radar seems to indicate sheets of relatively pure water ice at least two meters thick on or near the moon's surface. If the ice were deeply buried, there'd be no elevated CPR.

So far as I know, no such NEO ice has been discovered.

 

[HopDavid]

I have long advocated launching a fleet of prospector probes to gather an inventory of asteroid resources. Also beefing up the Deep Space Network to accommodate the flow of data these probes would send back. Given such a fleet, I believe we would find accessible NEOs with icey interiors.

There are NASA whitepapers on how to modernize the deep space network by turning it into an Internet like system with network nodes placed at various planets like Mars, Jupiter, Saturn etc. so that exploration robots can use shorter range communication systems at high data rates.
http://www.universetoday.com/21206/nasa ... -internet/
By using swarm methods, small robots that communicate short distances ~1million km to a network node in long range communication with Earth, several bodies can be investigated simultaneously or multiple robots can investigate a body rapidly and then move on to the next.

That'd be a dream come true for me. I believe this would reveal lots of other resources besides minable volatiles. I happen to believe the little bodies are the most interesting objects in the solar system. It would yield many surprising and interesting discoveries, I'd wager.

Until then, known lunar ice trumps possible asteroid volatiles, in my opinion.

 

[Yuri_Armstrong]

Why not explore the the moons of Mars? Let's go to Phobos. Look at the monolith that was put there. It would be a good compromise between the parties involved in this thread. We would be landing on a moon, an asteroid, and in the vicinity of Mars. The time to get to Phobos would be about 6 months. This would be a lot better than a mission to an NEA!

Why not a near Earth asteroid? Many reasons. First, most asteroids are not as easy to get to
as the moons of Mars. A few Near-Earth Asteroids (NEA) with low inclination have been
identified; however, most of these do not have low-energy opportunities at frequent regular
intervals. The advantage of the moons of Mars is they are available every two years. Most
important, however, the moons of Mars are near Mars. They are both a path to Mars, and a point
from which to study Mars. Exploration of an asteroid, however interesting scientifically, is not a
step that leads directly to the desired goal of Mars exploration.

 

[EarthlingX]

Why not explore the the moons of Mars? Let's go to Phobos. Look at the monolith that was put there. It would be a good compromise between the parties involved in this thread. We would be landing on a moon, an asteroid, and in the vicinity of Mars. The time to get to Phobos would be about 6 months. This would be a lot better than a mission to an NEA!

Why not a near Earth asteroid? Many reasons. First, most asteroids are not as easy to get to
as the moons of Mars. A few Near-Earth Asteroids (NEA) with low inclination have been
identified; however, most of these do not have low-energy opportunities at frequent regular
intervals. The advantage of the moons of Mars is they are available every two years. Most
important, however, the moons of Mars are near Mars. They are both a path to Mars, and a point
from which to study Mars. Exploration of an asteroid, however interesting scientifically, is not a
step that leads directly to the desired goal of Mars exploration.

most asteroids are not as easy to get to as the moons of Mars

You don't need to start with more than one, and don't have a need to go directly to Mars. I prefer Jupiter, though Saturn might be more friendly, and Neptune gives a very nice view from the dining room. I'll stop here, but i hope you get an idea.
This ground-hugging makes me sick. All that trouble to get to LEO and then double trouble to land in the next gravity well is just putting things off in some far away (20 years+ usually), never to be, future.

Anyway, Phobos mission doesn't need a lander (10 extra years and too much money), gets us deep space vehicle, and not to mention 'minor' science that could be done there. If explorer can 'dock' with Phobos, it can 'land' on Deimos too, and could orbit Venus as well.

If teleoperating, which 'just' needs to get spaceworthy, is by that time practised on the Moon, one could do a lot of sniffing on Mars, Venus and between, much easier with very small lag.

If there is a NEO, which is closer, and vehicle is ready, it would be a real shame to pass it though, and i have a strong confidence many such will be found, perhaps not so glamorous, but very important anyway, since we don't know enough about them, and their numbers are huge.

This whole discussion is a bit off, because nothing of this will happened on this side of 10-15 years, that's why i'm arguing for something that can go anywhere, and when it's ready, just set the course.

 

[Yuri_Armstrong]

You don't need to start with more than one,

I wasn't saying we needed to explore both. I was just picking Phobos because I think it would be more interesting than Deimos. More debate on that subject will be necessary though.

and don't have a need to go directly to Mars. I prefer Jupiter, though Saturn might be more friendly, and Neptune gives a very nice view from the dining room. I'll stop here, but i hope you get an idea.

Woah, woah, woah there. I was not talking about the outer solar system, the destinations you mentioned would be a lot more difficult to get to than Phobos.

This ground-hugging makes me sick. All that trouble to get to LEO and then double trouble to land in the next gravity well is just putting things off in some far away (20 years+ usually), never to be, future.

I'm confused what you're saying here. What's wrong with landing on a planet with a deep gravity well? Sure you need more force to escape from it but the planets and moons are the most interesting destinations. Besides, Phobos' gravity is measured in thousandths of a g. No gravity well there.

Anyway, Phobos mission doesn't need a lander (10 extra years and too much money), gets us deep space vehicle, and not to mention 'minor' science that could be done there. If explorer can 'dock' with Phobos, it can 'land' on Deimos too, and could orbit Venus as well.

All of which are good reasons to support a Phobos mission.

If teleoperating, which 'just' needs to get spaceworthy, is by that time practised on the Moon, one could do a lot of sniffing on Mars, Venus and between, much easier with very small lag.

If there is a NEO, which is closer, and vehicle is ready, it would be a real shame to pass it though, and i have a strong confidence many such will be found, perhaps not so glamorous, but very important anyway, since we don't know enough about them, and their numbers are huge.

Why would you rather go to an asteroid in deep space somewhere that will take the same amount of time if not more than to get to Phobos? If you're on Phobos you're on the moon of another planet and in Mars' orbit! I bet you will find a lot more support for that than a NEO mission.

This whole discussion is a bit off, because nothing of this will happened on this side of 10-15 years, that's why i'm arguing for something that can go anywhere, and when it's ready, just set the course.

Isn't Obama's asteroid mission supposed to be before 2025?

 

[EarthlingX]

You quoted Geofrey Landis, with whom i disagree on the quoted point as written. Try reading again.

What's wrong with landing on a planet with a deep gravity well?

You have to launch too, for one. With that amount of deltaV you could get much further out.

Why would you rather go to an asteroid in deep space somewhere that will take the same amount of time if not more than to get to Phobos?

Because i would like to got to an asteroid for which it will take less amount of time than to get to Phobos. I have nothing against Phobos, it's just that there are asteroids which are closer, and we are just beginning to find them.

Before any ISRU gets to the point where on-site resources could be used in a mission, a lot of flying can be done.

Simplest solution for LH evaporation is to not use it. RP-1 could very likely do much better, and as a result bring better overall Isp. There are also satellites in the orbit, which have propellant for 10-15 and more years, and they somehow don't have problems with evaporation.

I like very much the idea for a robotic lunar base, which could go in parallel, at not very high costs. It would also prove technologies needed for later human landing and stay, on this or other moons. Mars has some serious problems with landing heavier stuff, like thin atmosphere. No need to wait for that problem to be solved before moving out.

 

[rockett]

In either mission, asteroid or Mars moons, you are forgetting:
1. LENGTH OF MISSION - We can't even sustain the ISS THAT LONG without resupply yet.
2. Fuel to boost all those supplies. Gonna cost no matter how you go about it.
3. If anything goes wrong, we have dead astronauts. No way we could mount any kind of rescue mission in time.

 

[oldAtlas_Eguy]

In either mission, asteroid or Mars moons, you are forgetting:
1. LENGTH OF MISSION - We can't even sustain the ISS THAT LONG without resupply yet.
2. Fuel to boost all those supplies. Gonna cost no matter how you go about it.
3. If anything goes wrong, we have dead astronauts. No way we could mount any kind of rescue mission in time.

The only way to solve the rescue problem is to have a high g/high delta-v maneuver robot to rendezvous with the Human spacecraft with the required equipment to fix whatever went wrong. This robot rescue vehicle would cost almost as much as the original mission and still take up to several months to reach the Human craft. The normal method of redundancy to lower the risk also doubles the cost: redundant living space, redundant landers, redundant orbit injection boosters.

 

[SteveCNC]

Why not send a robotic redundancy/supply vessel ahead of time to orbit , so you can verify it is there and operational before sending a human crew .

 

[Yuri_Armstrong]

In either mission, asteroid or Mars moons, you are forgetting:
1. LENGTH OF MISSION - We can't even sustain the ISS THAT LONG without resupply yet.

How long could the ISS run without resupply ships? I agree this is a pretty big issue so we may need a bigger ship that is able to grow its own food over long durations. I'm sure the folks preparing for the asteroid mission have been working on this though. I think the latest solution is to dock two Orions together and use one of them as crew quarters and the other as storage.

2. Fuel to boost all those supplies. Gonna cost no matter how you go about it.

We may need several launches and dock the separate craft together. It's going to cost a lot of money, but I don't think anybody was expecting this would be cheap.

3. If anything goes wrong, we have dead astronauts. No way we could mount any kind of rescue mission in time.

And that's how its been for every single space mission ever since Gagarin. I don't think there's ever been an instance of one ship going to rescue another. Apollo 13 is a perfect example of mission control rescuing the crew from disaster. Others in this thread have suggested sending an unmanned rescue ship ahead of the manned ship that the crew could rendezvous with in case of disaster. This, I think, would be a good idea. It's just a matter of how far we are willing to go to ensure crew safety in relation to cost.

 

[scottb50]

To land on a moon of Mars you would first have to establish Mars orbit then match the moons orbit. That sounds like a lot of work to reach, an asteroid.

 

[MeteorWayne]

What has been done a number of times? I only recall one little probe landing on one asteroid.

Hayabusa orbited Itokawa for months and landed upon it at least twice. NEAR Shoemaker landed, more or less, on 453 Eros. The moon, Venus, Mars and in a matter of months Mercury have all been landed on, the mechanics and physics are the same.

Exactly what mission is going to land on Mercury within a matter of months???

 

[Yuri_Armstrong]

To land on a moon of Mars you would first have to establish Mars orbit then match the moons orbit. That sounds like a lot of work to reach, an asteroid.

In what way is it "a lot of work"??? Are you seriously suggesting that we should not do a deep space mission because it will be "too hard"???

 

[scottb50]

To land on a moon of Mars you would first have to establish Mars orbit then match the moons orbit. That sounds like a lot of work to reach, an asteroid.

In what way is it "a lot of work"??? Are you seriously suggesting that we should not do a deep space mission because it will be "too hard"???

No, just pointing out it would be simpler and cheaper to get to other asteroids. Both moons of Mars appear to be captured asteroids. Having to deal with Mar's gravity just adds to the complexity. Once a transit Station is in Mars orbit both moons will be easily reached anyway. By a lot of work I refer to propellant needs.

 

[scottb50]

Exactly what mission is going to land on Mercury within a matter of months???

Yeah I got a little carried away! In orbit though and that's a big part of a landing anywhere.