Mars and Asteroids are a waste of time

[WannabeRocketScientist]

I agree.

By the way, I am going to go on a limb and say its going to be Mr. Bigelow that will have a Moon base first before anybody else.

Yep, color me crazy.

I have that feeling too... and good for him! He will have done what NASA should have done a few years ago :lol: .

 

[SpacexULA]

What is so not technologically feasible or costly about getting fuel and water from the ice we know is there. Honestly what is so technologically challenging about landing there, melting the ice, and performing electrolysis to separate the ice into usable fuel?

Electrolysis is a VERY energy intensive process. Currently the only power source developed that could be used on the Lunar surface are solar and Radioisotope thermoelectric generators. It would take decades to generate enough fuel to launch off the lunar surface using the output of these power sources, not counting the fact that we have yet to figure out how to store hydrogen without major leakage.

Developing an in space, triple redundant, radiation shielded and certified, serviceable in low g possibly using pressure suits Fission reactor will be a challenge.

Launching it from American soil will be even harder.

 

[DarkenedOne]

Electrolysis is a VERY energy intensive process. Currently the only power source developed that could be used on the Lunar surface are solar and Radioisotope thermoelectric generators. It would take decades to generate enough fuel to launch off the lunar surface using the output of these power sources, not counting the fact that we have yet to figure out how to store hydrogen without major leakage.

Developing an in space, triple redundant, radiation shielded and certified, serviceable in low g possibly using pressure suits Fission reactor will be a challenge.

Launching it from American soil will be even harder.

SO I just ran through some calculations to see how long it would take the ISS using an electrolysis device operating at 50% efficiency to manufacture the 735601 kg of hydrogen and oxygen used in the space shuttle external tank. One kg of hydrogen and oxygen produces 572 kJ when burned, so the 735601 kg in the external tank produces 420,763,772 kJ. Assuming a conversion efficiency of electrical power to chemical power of 50% you will need double the amount of electricity, which brings us to 841,527,544 kJ of electricity needed to perform the electrolysis. The ISS produces 110kW or 110 kJ per second from its solar arrays. Divide 841,527,544 kJ by 110 kJ you get 7650250.4 seconds. At this point I take a short cut and ask Google to convert that amount into years. The result is that it should take .2424 years for the ISS power supply of 110kW to produce enough LH2 and LO2 for the shuttle.

Thus clearly power is not a problem.

 

[MeteorWayne]

Of course, you haven't address the problem of how (and the cost) to transport the water you are going to elctrolicize to the ISS, how you are going to feed it into the new facility to do it that doesn't exist, and transport it up there, as well as the storage tanks, etc,etc,etc.

 

[scottb50]

Of course, you haven't address the problem of how (and the cost) to transport the water you are going to elctrolicize to the ISS, how you are going to feed it into the new facility to do it that doesn't exist, and transport it up there, as well as the storage tanks, etc,etc,etc.

You could store water in a simple balloon or a Bigelow container and Solar power is free to hydrolize it. Even if it has to go up as cargo, to begin with, it would be worth the cost. Hopefully asteroids or Comets will be able to provide water and the moon is a possibility, though gravity plays in there too.

As long as it is kept water it would last pretty much forever, and if it was used for other basic needs it would be recycled pretty easily. Fuel cells to provide electrical power would be a good example. Now you need Solar to produce the power and batteries to store it, with water you could provide Oxygen and Hydrogen gas using solar and fuel the fuel cells.

Water is one thing we have in abundance and could provide easily obtained propellants right now, everything else is speculation and years and years down the road.

 

[MeteorWayne]

OK, what would it cost to launch 735601 kg of water? And what would launch it?

 

[scottb50]

OK, what would it cost to launch 735601 kg of water? And what would launch it?

What would it cost to launch a Nuclear reactor or the equivalent mass of any other propellant? When you figure kerosene and LOX the require mass would be well past 1 million kg for the same results.

A Delta IV could do it in three or four launches.

 

[HopDavid]

Im not talking about fuel, because it doesnt much matter as we can get the fuel from earth! im talking about the spacecraft and astronauts going there!

Think of Delta-V budget as the money you need to spend for energy to reach specific destination in space. if any astranaut or spacecraft want to go to moon it needs to spend 16km/s Delta-V budget from earth, do you agree with this? so this doesnt make any difference if it refuels in moon because you still have to spend 16km/s Delta-V budget for it if you want to go to the moon! now if you want to refuel in moon and send the same spacecraft to mars or asteroids you will need to spend another 4km/s Delta-V budget so in total you need 20km/s Delta-V budget to go from earth to mars via moon. but it will only take you 12 kms/s Delta-V budget to go straight from earth to mars! so which one do you think is cheaper?! in fact fuel made in moon is gonna be more expensive than in earth so the price of launch is much higher than double that amount!!.. regardless of what you do, you have to spend money on two things: Rocket & spacecraft + Fuel. since we use the same spacecraft to refuel in moon the cost of rocket doesnt change, but fuel in here is more doubled! so this way of launch is much more expensive than straight from earth travel.


unless of course we use a smaller rocket from earth to send astranauts to moon while a bigger "moon made" rocket & spacecraft is waiting for them to take them from moon to mars and beyond, then yes it will be cheaper IF making rocket & spacecraft in moon is same price as making them on earth! ... anyway these are just cost terms, i still havent talked about complexity of doing it this way! imagine making a rocket factory in moon! )

This what I call the Tucson to Omaha by way of Austin argument against the moon.

Someone might argue that it's not worth it to gas up with Texas gas for a trip from Tucson to Omaha. But escapes their notice is that tankers deliver Texas gas to Alberquerque and Denver.

In a similar fashion Lunar propellent is only a short distance from LEO and EML1 in terms of delta V:

Here is a delta V map:

See how both LEO and EML1 are close to the moon? Lunar propellent could be delivered to these locations in single stage reusable rockets.

A Trans Mars Vehicle can be lofted to LEO with empty oxidizer tanks, this is a big mass savings. There it could get lunar oxygen in LEO depots. This would enable it to go to EML1 and gas up again. And EML1 has a 2.4 km/sec advantage over LEO.

 

[pathfinder_01]

your point about Moon being a good initial step is right, moon is a good place to colonise. but i dont understand how you could bring arguments of spaceflight, mars,astroid and ISS with this...

regardless of the planet you want to go to, you will need to escape earth's gravity, even for moon! infact going to moon means you need to spend even more energy as moons orbital velocity requires the spacecraft to reduce its speed AFTER it has escaped earth gravity. let me tell you the difference more clearly:


you will need about 16km/s Delta-V budget to go from earth to moon's orbit. (if you want to go from moon to mars you will need another 3-4km/s Delta-V budget!
you will only need about 11.5km/s Delta-V budget to go straight from earth to Mars' orbit.
maybe if we had a manufacturing plant to make the rockets and fuel and supplies in moon, then yes it would be more beneficial. but this is too costly and at the moment it is not feasible in technological term.

Delta V means change in acceleration. Propellant counts as mass. The more massive your craft the more propellant you need to move it. There are potential mass savings by offloading propellant you don’t need just yet. This is one of many reasons why I think propellant depots are needed. It makes the whole thing a bit more manageable.

Imagine how badly airplanes would be affected if they had to carry fuel for a return trip instead of having the option of landing at an airport and refueling. The airplane would unable to carry as much payload mass because of needing to carry the fuel. The airplane’s speed and range would likewise be affected. With refueling a single commercial jet liner can travel around the planet.

It is unknown wither lunar propellant would be cheaper than earth supplied propellant at EML. It could be due to lower launch costs from the moon depending on if you could get reusable tanker craft in use. I think the first use of lunar propellant would be for lunar landers. If the lander only needed to carry propellant for decent from LLO then there are big mass savings.

If you had depots at LEO, EML, Deimos and Phobos, you could launch a mars mission craft in a single HLV launch. Depots at LEO and EML would be useful for both moon and mars trips. A good example would be your 11.5km/s mars trip. If you start fully fueled with a 30 ton payload you will need about 367 tons of propellant assuming your engines had a specific impulse of 453(shuttle engines) and your trip started in LEO.

If you break it up into legs it becomes: 40tons to get from LEO to EML, 28tons to get from EML to Deimos, 85MT to get from Deimos to mars surface under propulsion (or 9.2 tons if you directly reenter). By refueling you only need at most 153MT of propellant, and you could save 75.8 tons more if you choose to reenter instead of go under propulsion to the mars surface. Your craft only needs to be big enough to hold the maximum amount of propellant (either 85MT or 40MT depending) and so instead of needing a monster rocket able to lift hundreds of tons into LEO, you only need to be able to lift 30. Instead of needing tanks that can hold 367 tons of propellant all at once you now only need tanks that can hold 85 or 40. Instead of needing a reaction control system that can handle 397 tons of craft your reaction control system now only needs to handle 115 or 70 tons of craft.

Now true it does cost propellant to move propellant and you may send more total mass up but it will be in more manageable amounts (i.e. Don’t need a 200MT HLV to move 28MT propellant to EML1) . In a perfect world you would have electric propulsion like Vasmir to move propellant from a LEO depot to EML1 and from EML1 on to Deimos. Thus a lunar supply line could enable a mars mission.

 

[EarthlingX]

OK, what would it cost to launch 735601 kg of water? And what would launch it?

735601 kg = 735, 601 t

Using 10t launcher = 73,5601 launches, or 74, and assuming 200 M$/launch = 74 * 200 M$ = 14,8 G$

Adjust per assumption.

It could be launched by anything that can get there, and you know it's a long list.

 

[sftommy]

I wouldn’t take a Mars and asteroid rendezvous too seriously. They are words of political necessity crafted to meet a political moment. Very little of the current budget seriously rises to either challenge, nor really appears to have any exclusivity toward such a goal. Once we have the heavy launch capability we can rethink where to apply it.

My opinion is that within the next several presidential-election cycles there will be a race to start claiming lunar resources. That race will force NASA to shift from Mars-Asteroid to Lunar-bases. My timing might be off but it’s the sort of challenge that would also motivate a broader political spectrum in the US.

The lunar technical challenges are not insurmountable. Each problem I’ve seen listed in the threads here has an engineering solution. If the Obama-Bolden development plan is real we can expect more cost effective ways to be coming so that the US will be well set for more serious lunar development by 2018 or so.

After we’ve figured out how to live on the moon, then would be a better time to go to Phobos or Mars and plant a longer-term human presence. The problems that pop up during our learning curve are better met five days away than six months.

In all this I still favor the asteroid visitation to keep the spirit of human exploration alive.

 

[rockett]

I wouldn’t take a Mars and asteroid rendezvous too seriously. They are words of political necessity crafted to meet a political moment. Very little of the current budget seriously rises to either challenge, nor really appears to have any exclusivity toward such a goal.

Agreed. Nothing more than spinning the exit from human spaceflight to satisfy a political agenda (which doesn't include human spaceflight), feed a fawning media, appease the critics, and con starry eyed admirers.

What is glaringly obvious about his "vision" is that it totally sweeps under the rug any mention of the lunar ice discoveries. That would be a game changer if the Obama Administration really had any interest in HSF.

Saw the same thing when Clinton shut down the SSC, and guess where all the scientists went? CERN, hence the LHC which is an updated quarter sized clone. We would have been 20 years ahead in the high energy physics game if anyone cared.