Is It Time for a Moon or Mars Mission?

[drag]

Greetings !

If he's trying an engine run before the end of the year, there must be something to it. As far as energy consumption goes, I'm looking up some facts now...

Another article:

http://www.space.com/scienceastronomy/solarsystem/deepspace_propulsion_000816.html

"Easy on xenon

Yet Deep Space 1's engine only consumes 3.5 ounces (100 grams) of xenon per day, taking about four days to use up just 1 pound (0.4 kilogram). Its solar panels generate just 2.5 kilowatts of power, the equivalent of 25 100-watt light bulbs."

From the Deep space 1 press kit:

Weight of 1080 pounds (490kg)
Power: 2400 watts

I dunno, it doesn't seem like it would take "megawatts" to power something to orbit. Sure, it'll take more time the less energy is used until a small amount atmospheric friction overcomes the power of the ion thruster, but it can be done.

Also, that DS1 was powered with solar energy. If the blimps use some kind of alternative power source, more thrust could be had along with a faster time to orbit.

But what is the respective mass of the blimp with payload? I doubt we're talking about a 1000 fold difference in power requirements.

Yep, I'm a bit familiar with the IBT on DS1.
For full power mode at nearly 2.5 KW it produced a maximum thrust
of 0.092 N at exhaust velocities of about 32 km/sec with 70% power efficiency.

Now, Enigma mentioned here just one of the MANY other apparent
problems. You have drag, power sourse, mass of power source/collector/
transformers, propellant and thruster mass, cargo mass, drag and
size and strutural integrity of such a system and more.

But, just sticking to one small aspect of ion propulsion power:
Suppose you have exhaust velocity of 20 km/sec and you need
thrust of 10,000 N (which is a joke of course compared to
what you'll really need as a minimum for something of that
size even at such altitudes for ascent). Assume 70% efficiency.
Power is : 10,000 * 20,000 / 2 / 0.7 = 143 MW.
Now that should take some pedalling.
(Propellant mass flow is then: m = 10,000/20,000 = 0.5 kg
which gives you 1,800 kg per hour - 17.6 tons of weight. )

This JP Aerospace site has a PDF on this which is just full
of pretty pictures (what are NASA's high altitude research
baloon pics doing there ?) and zero information. Now, I'm
always for space initiatives and technologies - but I prefer
the real thing.

Peace and long life.

 

[aeroegnr]

Aha!

So I guess there are a plentitude of problems that aren't addressed, at least in the public.

I wonder what will happen to the test run later on...

Aside from that, couldn't this be used almost like a really high launch platform to a realm with much lower drag than sea level? Or are the effects of low altitude drag on current launch vehicles not a significant fraction of energy used?

I'm curious and open on all of this, I start getting into the real details of this stuff next spring semester.

 

[drag]

Greetings aeroegnr !

So you're studying AE too, what semester are you ?
(I'm just finishing my second right now. It'll take a few
more before I can get into this stuff too. )

Anyway, launching from high up does allow to reduce propellant
mass and may allow to skip a rocket stage - have
two instead of three for example, and use smaller engines.
As far as I remember there are at least two X-Prize teams -
a UK and Isreali, that designed baloon based launch concepts.
But, even if they make it work, these are just for small sub-orbital
craft, or micro and nano settelite launchers, like the Hercules
dropped rocket launcher for very small settelites designed by
Israeli students.

Other than that, it doesn't seem very practical to get something
really big up there. You'll need enormous helium volume and
if something goes wrong before egnition or after there's lesser
overall safety, and there's probably more. Anyway, the advantage
probably isn't that big here if any, and it would require whole new
designs to implement.

Now, a jet powered first stage is a much better idea, I think.
You can fly any size of payload from a standard airfield to high
altitude right along the equator, if you wish, where you gain
about 1.5 Mach due to Earth's rotation plus 1-2 Mach from the
jet engines. You then ignite your rocket engines and separate.
The jet engine stage flies back and lands and is totally reusable.
(There're also ideas of parachuting the jet engines, but that
doesn't seem very practical - they could get damaged, you need
to recover them, and besides you'll need wing and other sections
as part of this first stage anyway.) Why this hasn't been
implemented so far, I don't know. It's safe, cheap by comparisson,
reusable and highly configurable for different launcher sizes/masses/
orbits/launch locations. I guess that NASA just aimed too high
in the past 15 years, and hopefully that'll change now.

Live long and prosper.

 

[aeroegnr]

Hey there!

I'm entering my junior year this fall. I've had all of the basics. I'm actually ahead of most everyone that entered the same time I did. So, I'm taking control theory in the fall, a couple of labs, and finishing a physics minor. They combined the mechanical and aerospace program here, so I haven't seen really much anything geared toward aerospace in particular. Another thing is I would already be taking aerodynamics, astrodynamics, and maybe a couple others in the fall, but due to courses only being offered once a year or worse I can't do that.

Anyway, yeah jet engines seem like a good idea for a first stage. NASA did look at this, along with a bazillion other launch designs. ( I have a full color book containing information and pictures on all of the designs leading to the shuttle, it's interesting but after awhile it just starts to get into tedium)

Personally I think a design of the shuttle without a lifting body design would be better. Why bring up all that extra weight when you can just plunk it down in the water or land a different way, delta V style? I guess predictability with landing sites can be bad, but if some control method for parachutes were implemented...

 

[Integral]

The theme of your post is that we should not waste our time with space travel.

Nonsense! I am all for space exploration. But it needs to be done with intelligence. For all of your words you still have not explained to me why a HUMAN must journey into space. We can learn everything we need, we can can harvest any resources discovered without the necessity of wasting fuel and space on catering to the needs of a human.

If all that travels into space is hardware we lose nothing and gain much. We gain more missions for the same money, we gain flexibility. If something unexpected is encountered a Earth side team can be gathered to deal with it. This is EXACTLY what any space tourists would have to do. The difference is that there would not be any emergency in which human lives would be at risk. (Not counting driving to and from work!)

To compare this exploration to the journeys taken by the Europeans of the 15th and 16th century's is simply ludicrous and really does not even deserve response.

 

[russ_watters]

http://www.popsci.com/popsci/science/article/0,12543,577754,00.html

EARNSHAW'S THEOREM--stable magnetic levitation was thought impossible for 150 YEARS, until the 1990's.

There is a difference between 'we don't know yet' and theoretically impossible. There is a difference between 'wrong' and 'incomplete.' From your own link:

It turns out that Earnshaw's theorem is absolutely correct, but it has a couple of loopholes large enough to drive all sorts of stable magnetic levitation devices through...

Same goes for QM.

All new theories must at least in part incorporated existing ones as special cases. They must: existing theories wouldn't be accepted unless experimental data supported them.

 

[drag]

Greetings !

Personally I think a design of the shuttle without a lifting body design would be better. Why bring up all that extra weight when you can just plunk it down in the water or land a different way, delta V style? I guess predictability with landing sites can be bad, but if some control method for parachutes were implemented...

Well, personally I doubt that it's a good idea. I do not believe
that the shape of the SS greatly affects it's mass. Besides,
without actually being able to maneuver and get some considrable
lift, the whole reentry process would be different. Right now the
SS slows down along some 8,000 kms and it can manuever right
to the landing strip. Them manned space capsules just drop
and you never know where they might end up, like that Russian
capsule recently - blew the predicted landing site by a few hundred
miles. It's also far from safe, both due to the way you land and
the possible misses I've mentioned above. And then you have to go
there and perform a rescue of all that equipment and people every
time, so it doesn't end up very cost effective either, I suppose.

Physics - that's great ! My second or third (with EE) choice after AE.

Nonsense! I am all for space exploration. But it needs to be done with intelligence. For all of your words you still have not explained to me why a HUMAN must journey into space. We can learn everything we need, we can can harvest any resources discovered without the necessity of wasting fuel and space on catering to the needs of a human.

If all that travels into space is hardware we lose nothing and gain much. We gain more missions for the same money, we gain flexibility. If something unexpected is encountered a Earth side team can be gathered to deal with it. This is EXACTLY what any space tourists would have to do. The difference is that there would not be any emergency in which human lives would be at risk. (Not counting driving to and from work!)

You know, I believe I said that before too, you're absolutely right.
Same can go for deep underwater exploration. But what can
we do if the dumb general public just loves them fine dressed
astranauts, who wan'na go too, running out there. Dumb, isn't it ?
Maybe we should move to Vulcan with'em logical dudes...

And another thing, NASA is not a private company and it's purpose
is not just purely exploration, but also development of related technologies. You know much better than I do that unless you actually build something very sophisticated like a manned spacecraft and see it perform, you can't move on and design new and better ones. You can't just put your new and untried technologies and theories in a very long list and one day wake up and say - "hey, let's build a spaceship out of all of that".

Live long and prosper.

 

[drag]

Just to lighten-up the depressing atmosphere around here...
Just 3 days left now:
http://www.spacedaily.com/news/xprize-04h.html
Space will never be the same.

 

[Adriaan Steenkamp]

Mining Space

Mining space is not strictly profitable for the first time you do it. The reasons for this is manifold but mainly since it is extremely expensive (energy wise) to send vehicles from the Earth's surface to Low Earth Orbit, from there on the cost decrease substantially. The idea is to actually mine a Near-Earth Object for ice and use the available solar energy to make fuel from the water ice. Even a few tons of fuel will make further mining a very lucrative prospect since no fuel needs to be sent up from Earth. Once a fuel base has been established in Earth's orbit one can start looking at mining metals, forget about gold and silver those are practically useless, the real prize is almost pure iron, nickel and aluminium in large quantities. There will also be no mining involved since the ateriods are made up of these metals.

Being from South Africa, one of the world's leading metals producers I know that the main costs in forge's like ISCOR's is electricity to actually melt and work the metal or to produce alloys. Energy is free in space, you have a constant high-density energy source in the form of solar power and the zero-G conditions will allow manufacturers to produce cheap, high-grade alloys with much less imperfections and impurities than those produced on Earth. In fact the zero G consitions will allow the manufacture of very rare steel alloys in bulk. The first country to reap the benefits will be the next superpower. I personally believe that it will not be the US since the very fact that they have NASA precludes them from starting a program that will need the rerouting and cancellations of mission that were planned a decade ago.

Cheers

 

[Kojac]

You know, off-world colonization isn't totally out of the question...as y'all might think via the laws of physics. 1:cryogenics. If we successfully froze a population of about 100,000, I'd say colonization would be much closer to our grasp. 2: identifying a 'second Earth' this could be done through deep-space probes (as long as they have an accurate telemetry) 3:building a large craft. this would have to be done in orbital docks, and the craft would need a large, sustainable powersource. people could be awaken every few years for maintenance, but in general, the thing needs to propel itself and not need too much help to find where it's going. a few hundred years doesn't sound so bad to establish a first colony. (assuming we can find a planet that close)