I'd go with google. They're not perfect, but compared to Microsoft they are.
But a more sensible question is whether you want really want NASA to do it.
I mean are you one of the NASA selected 'elite'? If not- sorry, no space for you.
Atleast commercial launches are somewhat egalitarian- you have the cash, you get to go. And commercial pressures tend to push down on price, with NASA there's far less pressure to do that- that's a really bad thing. The price is way too high right now, particularly in NASA land. NASA is way too risk adverse; paradoxically, I think that caused Columbia and Challenger.
It's not as close as you might think, in terms of energy, starting at Mach 15 saves you about 5%
Actually, mach 15 saves you more like 30% energywise, but reaching orbit isn't predominately a n energy thing- it's a speed thing.
Mach 15 is about 4.5 km/s- that's about halfway to orbit. A relatively modest rocket on top of that would get you the rest of the way provided the scramjet wasn't outrageously heavy (say no more than 20% of the takeoff mass.)
The trouble is, mach 15 is too much to hope for right now from scramjets; even mach 10 is looking extremely difficult- and that makes a big difference- scramjets are heavy, and rockets hate heavy AND big delta-v. They're fine with heavy OR big delta-v.
It will always take that amount and to generate taht amount with fuel will always be expensive.
Um. Actually, fuel is fantastically cheap. Your typical rocket manages about a ratio of payload to gross liftoff weight of about 50.
But 50 kg of fuel costs only about $50 (if that). That's $50/kg of payload.
So, if you weigh 70kg, we can put you on orbit for about $3500; fuel cost. That's why rockets and other launch vehicles are not silly ways to get into space.
The operating altitude of the scramjet for this flight is 60 km.
60km is more than 180,000 ft. The article says 100,000, that's about 30km, which sounds more like it to me. It's my understanding that sonic booms do indeed reach down to the ground from that altitude.
I'm still quite sure that this vehicle gives a lot more drag. The only way to reduce the drag is to reduce the size, but Concorde is already tiny.
On the other hand, if I didn't mind the commute but wanted to live a little further out from the city, I could live in Los Angeles - my commute to Manhattan would still be just 33 minutes.
... and cost 30x the normal subsonic ticket price from LA to Manhattan. Going at mach many costs mucho. Good luck on paying that every day.
Atmospheric drag is a square law on speed. The drag has to be overcome by spending fuel unless you plan on leaving the atmosphere, but doing that means the scramjet stops working... it's all a bit self defeating really.
And then there's the slight problem of a sonic boom- didn't you learn anything from the commercial failure of Concorde? And that only went at mach 2.2.
I was under the impression that they were eventually hoping to get scramjets up to Mach 15 or so -- which isn't orbital velocity, but it's a hell of a lot closer.
If they were, it's looking very, very unlikely right now. Getting to mach 10 would be extremely impressive; mach 8.0 may very well be it.
But not having to carry oxidizer for a large portion of the trip to orbit is inarguably a Good Thing.
Nope. LOX is dirt cheap, pennies per kilogram; the tanks you store them in are incredibly lightweight; 1-3% of the weight of the contents (including pressurants and other extras).
The density of LOX is 10,000x greater than the atmospheric density of oxygen... that makes the pumps potentially 10,000x smaller... it's by no means inarguable, in fact some highly knowlegable people argue that airbreathing is a seriously bad idea (well for launch vehicles anyway- they have been known to inhale:-) ).
... but why weren't we doing this 40+ years ago? The X-43 seems to me like a logical evolution of the X-15, which is the kind of thing we should have been working on all this time.
My question is why anyone is doing this now. AFAIK there's still no useful way on the horizon that a scramjet can help you get to orbit, it's not obviously useful as a way of carrying passengers, it has a *really*, really horrible tendency to melt the vehicle, it maxes out at maybe mach 7.0-9.0 (n.b. orbit is mach twenty five!), the vehicle shape is deeply constrained and the materials to make this concept useful are pretty much beyond the state of the art.
I mean transportation? Concorde died because it was uneconomic and that ran at 3x lower velocity. Drag is a square law... you do the math.
Whatever you may think of rockets, they actually do work, whereas, right now, scramjets flat-out don't do anything useful.
Personally, I think the investment in this technology is missile related. That's the only thing small enough to fit into the shell, and one of the only things that can't leave the atmosphere because their target can't either.
Yeah, well, once you go black you never go back. But I don't think that X-33 would be successful even as a black project.
The trim problem is bad, the tankage problems are bad, the rumours on the linear spike is that it sucked (not confirmed- no firm data has been release AFAIK, which is suspicious.)
As I understand it, non cylindrical composite hydrogen tanks are more or less beyond the state of the art. Cylindrical liquid oxygen tanks are about the limit I think; Rotary Rocket demoed those anyway. I can't actually see why a black project would want to pick up the X-33; it wasn't even an orbital design, or even a good design.
Re:Unobtainium - air-breathing rockets
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The idea of cooling air down and then pumping it into a combustion chamber is great, but is likely to suffer from the problems of dust and condensed water and carbon dioxide in the 'plumbing'.
According to page 161 in SpaceFlight the liquid condensate problem has been solved, and they've successfully run the heat exchanger in a condensing atmosphere for 8 minutes (it only takes 4 minutes to leave the atmosphere).
Re:Don't count your chickens
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Yes, well; ultimately it depends on whether you think anything is being learnt along the way. Skylon doubtless has problems that they haven't solved yet (although I'm not aware of any), and it looks promising. Sure, lots of things have looked promising. Quite a few of the vehicles you mentioned had apriori bad problems; but still got built. (X-33 hydrogen tank [the project leader resigned!] and Shuttles tiles, Burans reliance on expensive boosters).
I don't know of any apriori reasons that this cannot work; with the possible exception of funding. But you never know; a military may like the look of SABRE or something. I believe that RASCAL is based on a roughly similar engine idea- and that has funding.
There is economics. Re:Arguments in favour of mann
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All that is fine for commercial missions, but it does little to advance the science.
No, look, who says that the reason for people to go into space is 'science'? It isn't. With a few exceptions when has 'science' ever been a reason to do anything? Ever?
The real reason to go into space is economic- we go into space because people like space. They like looking down at the Earth whizzing past below them, they like floating around in zero-g, they dig the funky roller coaster ride that is takeoff.
That in and of itself represents an economic argument- people are willing to pay to go into space, just like they are willing to go on cruises. The only current problem is that the current price is too high. That has to come down. There are lots of potential ways to do this, and lots of companies out there are working away at all of them right now. The chances of one of them succeeding is, in my opinion, extremely high.
Re:Unobtainium - air-breathing rockets
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The idea of cooling air down and then pumping it into a combustion chamber is great, but is likely to suffer from the problems of dust and condensed water and carbon dioxide in the 'plumbing'.
It doesn't have to last forever though, only a few minutes. It depends on details of exactly how the ice crystals form as to whether they stick to the heat exchanger or whether they get sucked through it. If the freezing is very rapid, as it would be here- the ice would be very tiny crystals and won't necessarily block the channels. Don't forget that the engine only has to last a few minutes- any ice would melt away again during reentry.
and who's going to make all those nanotubes for the space elevator?
Probably the patent holder or the licencee of the first person to actually make nanotubes with the right combination of strength/weight/length. But even space elevators aren't as cheap as is commonly supposed.
Re:Spaceflight as a religious endeavour
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Actually, as I understand it, the Red Giant won't envelop the Earth.
It would do, but in the intervening years the Sun will have lost enough mass that the Earth's orbit will have drifted outwards a ways; far enough that it should survive.
However, it's still going to get rather warm. You'd be well advised to hang onto your astbestos underwear- you're gonna need it; whatever the EPA says.
Re:Cost of Lifting Things
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Single Stage to orbit, airbreathing, lands and takes off like a conventional aeroplane. A snip at $10 billion (R&D- ticket price would be about a not-totally-unreasonable $100,000).
It doesn't seem to require any handwavium or unobtainium unlike (at the moment at least) the Space Elevator.
Incremental advances seem unlikely to do it - it requires an orders-of-magnitude shift in cost.
That may well happen though. Some new launchers like SpaceX promises to be quite a bit cheaper- a combination of higher launch volume and real reductions in price due to improved vehicle design very probably can drop us by that much.
Reminds me of the black humour on a concrete lid on a nuclear ICBM tube. Allegedly it's painted like a pizza box- with the words:
'Guaranteed delivery anywhere in world in 30 minutes'
'- or the next one's free'
:-)
I also liked the story on slashdot a few years ago about a decommisioned secret RSA listening station with a huge smiley face painted on the parabolic radio receiver dish saying 'hi' to the russians...
"What's in a name? That which we call a rose by any other name would smell as sweet".
Oh, ok, I suppose it's in space, and space is usually a pretty good vacuum, so doesn't smell. Unless you're in a space suit. In which case it wouldn't necessarily smell sweet. Might smell as sweat; but that's the smellor not the smellee asteroid. Hmm. Right.
But my point remains I think. Glad to have made it I think. Worth saying. Right. Good. Yes.
I don't think so. IPv6 has a reasonable degree of backward compatibility, unlike metric, and I suspect that soon you will be able to get IPv4 NAT gateways that give you IPv6 behind them- in otherwords you can tunnel your IPv6 home network out onto the big (IPv6) wide world across IPv4. Heck you can probably do that already, you just need more equipment and it's less convenient.
Energy is conserved, but some of it could be transferred to the massive object. How do you think gravitational "slingshotting" works? This is the same thing, except in reverse.
Um. Actually no. That's a three body process.
In order to actually enter orbit, it would be helpful to have other bodies nearby.
Essential.
But anyway, the basic point is that an asteroid can loop around a planet and emerge with more kinetic energy than it started with -- it just means that the kinetic energy of the planet has been reduced accordingly.
This turns out not to be the case; atleast from the point of view of the center of mass between the planet and the asteroid; unless there is a third body involved.
Jupiter and Neptune have a LOT more mass than Earth, so it might be easier for them to slow down an incoming asteroid and get it to stay in orbit.
The problem is that gravity is a 'conservative force' which means that it doesn't on it's own change the speed of incoming asteroids, which means they can't get captured.
What can happen though is that gravity can rearrange the energy among multiple moons- for example an incoming asteroid can bounce around the Jupiter system- interacting with half a dozen moons and gradually edge its way into a stable position.
A lone planet has *no* way of capturing moons. The origin of Deimos and Phobos is very problematic; it is an open research question.
But if that's the case, how does it work for those satellites that are considered to be "captured" by planets, like Neptune's Nereid? Does that involve the collision of two or more objects or something like that?
It's really not very well understood. What you are suggesting would probably work though.
Some planets like Jupiter- it has so many big moons that it's pretty easy to see how it can gain/lose moons; but the Earth and Mars with only one big moon and two tiny moons respectively; it's a bit hard to see how that came about.
Now, the question I have is, how close does an asteroid such as this have to pass so that it is captured by Earth's gravitational field and become a satellite?
It can't. The approach speed and retreat speed relative to the Earth has to be the same- due to conservation of energy. By definition, a meteorite approaching the earth arrives with higher than escape velocity so it is only going to be a visitor (unless it hits the Earth or the Moon).
There are only 2 ways that an object can end up in Earth orbit, and neither are likely to be stable:
a) just skimming the Earths atmosphere, deeply enough that it loses enough speed on the first pass to stay in Earth orbit (trouble is this orbit will still intersect the atmosphere on each pass- this means that its orbit will rapidly decay.)
b) be perturbed by the moons gravity and locked into orbit. However this too is likely to be only a short term thing, since the orbit that it would end
up on nearly intersects the orbit of the moon, and after a few months the moon will end up perturbing it again- the object will be ejected from the earth-moon system sooner or later, usually sooner.
That's actually why there aren't any rocks except the moon in Earth orbit right now- it's essentially impossible for them to be captured.
It could be useful to have a big rock in stable orbit.
Yes, but those regulations are really written for 35-70% peroxide which although rather more stable than HTP, is still very dangerous as it is capable of forming with several common hydrocarbons peroxides which turn out to be sensitive contact explosives. Also, below about 70% the water content absorbs much of the heat and stops it boiling away, and it is much more difficult to catalyse; and the 70% grade is typically packed with chemicals that poison catalysts.
The 85% HTP is a completely different animal, provided you keep it cool (below about 70C) and free from catalytic contaminants it's very stable. But it doesn't take much encouragement at all to turn into steam so you'd just catalyticaly decompose it on site to safely dispose of it.
I heard a story from the guys at Experimental Rocket Propulsion Society who were playing with high purity hydrogen peroxide (85% compared to the 3% you typically get in chemists).
Anyway the inspectors came around to check them out; and insisted on knowing what their cleanup method would be if they spilled the stuff.
"We don't need one."
At this point the inspector went into rant mode, threatening extensive punitive penalties if a cleanup methodology wasn't produced immediately.
... which was terminated only when the team pointed out that hydrogen peroxide, of this strength, when spilled on the local desert, immediately "pssssssssh" decomposed into a) steam b) oxygen... and they merely asked if they needed to worry about either contaminating the local groundwater. Upon careful consideration, the official waived this requirement, and elected not to penalise them.
(Indeed so effective was the desert at catalysing the peroxide, the team were jokingly considering abandoning their expensive silver catalysts, and using desert instead... but I digress.)
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But a more sensible question is whether you want really want NASA to do it.
I mean are you one of the NASA selected 'elite'? If not- sorry, no space for you.
Atleast commercial launches are somewhat egalitarian- you have the cash, you get to go. And commercial pressures tend to push down on price, with NASA there's far less pressure to do that- that's a really bad thing. The price is way too high right now, particularly in NASA land. NASA is way too risk adverse; paradoxically, I think that caused Columbia and Challenger.
Actually, mach 15 saves you more like 30% energywise, but reaching orbit isn't predominately a n energy thing- it's a speed thing.
Mach 15 is about 4.5 km/s- that's about halfway to orbit. A relatively modest rocket on top of that would get you the rest of the way provided the scramjet wasn't outrageously heavy (say no more than 20% of the takeoff mass.)
The trouble is, mach 15 is too much to hope for right now from scramjets; even mach 10 is looking extremely difficult- and that makes a big difference- scramjets are heavy, and rockets hate heavy AND big delta-v. They're fine with heavy OR big delta-v.
Um. Actually, fuel is fantastically cheap. Your typical rocket manages about a ratio of payload to gross liftoff weight of about 50.
But 50 kg of fuel costs only about $50 (if that). That's $50/kg of payload.
So, if you weigh 70kg, we can put you on orbit for about $3500; fuel cost. That's why rockets and other launch vehicles are not silly ways to get into space.
60km is more than 180,000 ft. The article says 100,000, that's about 30km, which sounds more like it to me. It's my understanding that sonic booms do indeed reach down to the ground from that altitude.
I'm still quite sure that this vehicle gives a lot more drag. The only way to reduce the drag is to reduce the size, but Concorde is already tiny.
That's actually a better way to make money here- point the asteroid at the Earth and extort money from governments :-)
Atmospheric drag is a square law on speed. The drag has to be overcome by spending fuel unless you plan on leaving the atmosphere, but doing that means the scramjet stops working... it's all a bit self defeating really.
And then there's the slight problem of a sonic boom- didn't you learn anything from the commercial failure of Concorde? And that only went at mach 2.2.
If they were, it's looking very, very unlikely right now. Getting to mach 10 would be extremely impressive; mach 8.0 may very well be it.
But not having to carry oxidizer for a large portion of the trip to orbit is inarguably a Good Thing.
Nope. LOX is dirt cheap, pennies per kilogram; the tanks you store them in are incredibly lightweight; 1-3% of the weight of the contents (including pressurants and other extras).
The density of LOX is 10,000x greater than the atmospheric density of oxygen... that makes the pumps potentially 10,000x smaller... it's by no means inarguable, in fact some highly knowlegable people argue that airbreathing is a seriously bad idea (well for launch vehicles anyway- they have been known to inhale :-) ).
My question is why anyone is doing this now. AFAIK there's still no useful way on the horizon that a scramjet can help you get to orbit, it's not obviously useful as a way of carrying passengers, it has a *really*, really horrible tendency to melt the vehicle, it maxes out at maybe mach 7.0-9.0 (n.b. orbit is mach twenty five!), the vehicle shape is deeply constrained and the materials to make this concept useful are pretty much beyond the state of the art.
I mean transportation? Concorde died because it was uneconomic and that ran at 3x lower velocity. Drag is a square law... you do the math.
Whatever you may think of rockets, they actually do work, whereas, right now, scramjets flat-out don't do anything useful.
Personally, I think the investment in this technology is missile related. That's the only thing small enough to fit into the shell, and one of the only things that can't leave the atmosphere because their target can't either.
The trim problem is bad, the tankage problems are bad, the rumours on the linear spike is that it sucked (not confirmed- no firm data has been release AFAIK, which is suspicious.)
As I understand it, non cylindrical composite hydrogen tanks are more or less beyond the state of the art. Cylindrical liquid oxygen tanks are about the limit I think; Rotary Rocket demoed those anyway. I can't actually see why a black project would want to pick up the X-33; it wasn't even an orbital design, or even a good design.
According to page 161 in SpaceFlight the liquid condensate problem has been solved, and they've successfully run the heat exchanger in a condensing atmosphere for 8 minutes (it only takes 4 minutes to leave the atmosphere).
I don't know of any apriori reasons that this cannot work; with the possible exception of funding. But you never know; a military may like the look of SABRE or something. I believe that RASCAL is based on a roughly similar engine idea- and that has funding.
No, look, who says that the reason for people to go into space is 'science'? It isn't. With a few exceptions when has 'science' ever been a reason to do anything? Ever?
The real reason to go into space is economic- we go into space because people like space. They like looking down at the Earth whizzing past below them, they like floating around in zero-g, they dig the funky roller coaster ride that is takeoff.
That in and of itself represents an economic argument- people are willing to pay to go into space, just like they are willing to go on cruises. The only current problem is that the current price is too high. That has to come down. There are lots of potential ways to do this, and lots of companies out there are working away at all of them right now. The chances of one of them succeeding is, in my opinion, extremely high.
It doesn't have to last forever though, only a few minutes. It depends on details of exactly how the ice crystals form as to whether they stick to the heat exchanger or whether they get sucked through it. If the freezing is very rapid, as it would be here- the ice would be very tiny crystals and won't necessarily block the channels. Don't forget that the engine only has to last a few minutes- any ice would melt away again during reentry.
and who's going to make all those nanotubes for the space elevator?
Probably the patent holder or the licencee of the first person to actually make nanotubes with the right combination of strength/weight/length. But even space elevators aren't as cheap as is commonly supposed.
It would do, but in the intervening years the Sun will have lost enough mass that the Earth's orbit will have drifted outwards a ways; far enough that it should survive.
However, it's still going to get rather warm. You'd be well advised to hang onto your astbestos underwear- you're gonna need it; whatever the EPA says.
Single Stage to orbit, airbreathing, lands and takes off like a conventional aeroplane. A snip at $10 billion (R&D- ticket price would be about a not-totally-unreasonable $100,000).
It doesn't seem to require any handwavium or unobtainium unlike (at the moment at least) the Space Elevator.
Incremental advances seem unlikely to do it - it requires an orders-of-magnitude shift in cost.
That may well happen though. Some new launchers like SpaceX promises to be quite a bit cheaper- a combination of higher launch volume and real reductions in price due to improved vehicle design very probably can drop us by that much.
'Guaranteed delivery anywhere in world in 30 minutes'
'- or the next one's free'
I also liked the story on slashdot a few years ago about a decommisioned secret RSA listening station with a huge smiley face painted on the parabolic radio receiver dish saying 'hi' to the russians...
Oh, ok, I suppose it's in space, and space is usually a pretty good vacuum, so doesn't smell. Unless you're in a space suit. In which case it wouldn't necessarily smell sweet. Might smell as sweat; but that's the smellor not the smellee asteroid. Hmm. Right.
But my point remains I think. Glad to have made it I think. Worth saying. Right. Good. Yes.
I don't think so. IPv6 has a reasonable degree of backward compatibility, unlike metric, and I suspect that soon you will be able to get IPv4 NAT gateways that give you IPv6 behind them- in otherwords you can tunnel your IPv6 home network out onto the big (IPv6) wide world across IPv4. Heck you can probably do that already, you just need more equipment and it's less convenient.
Um. Actually no. That's a three body process.
In order to actually enter orbit, it would be helpful to have other bodies nearby.
Essential.
But anyway, the basic point is that an asteroid can loop around a planet and emerge with more kinetic energy than it started with -- it just means that the kinetic energy of the planet has been reduced accordingly.
This turns out not to be the case; atleast from the point of view of the center of mass between the planet and the asteroid; unless there is a third body involved.
The problem is that gravity is a 'conservative force' which means that it doesn't on it's own change the speed of incoming asteroids, which means they can't get captured.
What can happen though is that gravity can rearrange the energy among multiple moons- for example an incoming asteroid can bounce around the Jupiter system- interacting with half a dozen moons and gradually edge its way into a stable position.
A lone planet has *no* way of capturing moons. The origin of Deimos and Phobos is very problematic; it is an open research question.
It's really not very well understood. What you are suggesting would probably work though.
Some planets like Jupiter- it has so many big moons that it's pretty easy to see how it can gain/lose moons; but the Earth and Mars with only one big moon and two tiny moons respectively; it's a bit hard to see how that came about.
It can't. The approach speed and retreat speed relative to the Earth has to be the same- due to conservation of energy. By definition, a meteorite approaching the earth arrives with higher than escape velocity so it is only going to be a visitor (unless it hits the Earth or the Moon).
There are only 2 ways that an object can end up in Earth orbit, and neither are likely to be stable:
a) just skimming the Earths atmosphere, deeply enough that it loses enough speed on the first pass to stay in Earth orbit (trouble is this orbit will still intersect the atmosphere on each pass- this means that its orbit will rapidly decay.)
b) be perturbed by the moons gravity and locked into orbit. However this too is likely to be only a short term thing, since the orbit that it would end up on nearly intersects the orbit of the moon, and after a few months the moon will end up perturbing it again- the object will be ejected from the earth-moon system sooner or later, usually sooner.
That's actually why there aren't any rocks except the moon in Earth orbit right now- it's essentially impossible for them to be captured.
It could be useful to have a big rock in stable orbit.
Most people call this 'the moon' :-)
The 85% HTP is a completely different animal, provided you keep it cool (below about 70C) and free from catalytic contaminants it's very stable. But it doesn't take much encouragement at all to turn into steam so you'd just catalyticaly decompose it on site to safely dispose of it.
Sadly though, it's a real ad for fake Klein bottles.
You can tell because on a true Klein bottle the bit where the neck goes through the side, it does this without touching the side.
If anyone knows of a source for real Klein bottles I would be very, very interested :-)
Anyway the inspectors came around to check them out; and insisted on knowing what their cleanup method would be if they spilled the stuff.
"We don't need one."
At this point the inspector went into rant mode, threatening extensive punitive penalties if a cleanup methodology wasn't produced immediately.
(Indeed so effective was the desert at catalysing the peroxide, the team were jokingly considering abandoning their expensive silver catalysts, and using desert instead... but I digress.)