I heard that French wine (red wine) uses cow blood to give it color.
To filter it, you mean? That's been forbidden in Europe since 1997 (see for example a related urban legend); other animal substances are used now.
Re:Each has their own advantages
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Shuttle Politics
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You design something that does deorbit a ton or two (it's not that hard to do). I'd bet that that could be done cheaper than the cost of a few shuttle flights.
I assumed the question was something earlier in the thread, "there is nothing a shuttle can do that soyuz + iss can't, and then some." (Generalizing "Soyuz" to Soyuz capsules and unmanned launchers.) If you start designing new vehicles, then surely you can replace the shuttle. Whether you can design that cheaply is another matter, but I tend to agree if you keep it off NASA's management.
Hell, if memory serves the Titan IV is cheaper per shot than a shuttle launch
That's difficult to say since shuttle launch cost estimates vary, maybe between 250 and 400 M$, while a Titan IV-B might cost 400-450 M$. There aren't many left anyway, and the Delta IV Heavy, while cheaper, won't reach the same performance.
Re:Each has their own advantages
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Shuttle Politics
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· Score: 1
No, the now quite old quip that "If the space shuttle was the answer, what was the question?" still applies.
How do you bring back more that a few hundred kg from orbit?
How do you repair/upgrade a (LEO) satellite?
How do you launch people at less than 56 degrees inclination? (OK, launch a Soyuz from Kourou...)
I agree that the need for those capabilities is debatable, with the first being the most apparent (sample return from ISS). Repairing GEO satellites would be interesting, but is way outside the shuttle's reach.
Do the shuttle's on-board engines/fuel provide any capability for changing orbits? I'm assuming it can all be used up since the orbiter is going to be scrapped.
Yes, as long as it stays in the same orbital plane. That is, if the initial orbit is a circle around the Earth, the shuttle can widen or shrink or elongate the circle (altitudes could range 200-600km, maybe 800-1000 if all the fuel is used), but not warp it or incline it significantly (perhaps a couple of degrees).
The ISS was going in a circle roughly the same size, but in a different plane, which is why Columbia could not have gone there.
Since I've got the ear of someone who understands orbital mechanics,
Ah, I would have turned you over to Google, but I can't seem to find an appropriate FAQ... <g>
I have to ask the awful question: could the ISS not be deorbited to meet up with the shuttle? Theoretically speaking
First, it's not a question of going "up" or "down", which is easy enough, but "sideways". To take another example, imagine you are sliding down a pole; it is easy to speed up or slow down, but even if you let go of it, you can't reach far from the pole itself.
Second, the ISS has even less maneuvering capability than the shuttle. More mass, smaller engines, not that much more reserve fuel. So, theoretically speaking, yes, if you can send a few hundred tonnes of fuel there first.
I've read it contains station-keeping thrusters and it would be working towards the Earth's gravity well, presumably costing significantly less than working against it.
I'm afraid it doesn't work like that; the orbit is already a free-fall trajectory, which just happens not to pass through the atmosphere or the Earth. The only way not to work against gravity is to keep that orbit.
By the way, notice that the shuttle has to use the atmosphere to shed all its velocity (28,000km/h to 0) before it can land. If there was no air, it would have to slow down the same way it accelerated: with a whole ET's worth of hydrogen and oxygen. And if that fuel was available, reentry would be safer, since the shuttle could go in much more slowly--witness Scaled's SpaceShipOne, which has little thermal protection if any; although it will reach comparable altitudes, it won't go anywhere as fast as a satellite nor undergo the same kind of stress.
Let me try to explain better. There's a usual range of orbits the shuttles get into, to service satellites, and such, right? The ISS is not in that typical range, hence the short-term survival problem.
Now I see what you meant. But there is something you missed: the orbits which can be reached by the shuttle are not at all the same as those orbits which it can reach after being launched into a different orbit.
Imagine you are making a trip with a car, and a bike inside the car. Assume that no gas stations are available, and that you want to consume the car's whole tank and then ride around with the bike. You can go a few hundred km with the car, say either from Paris to Geneva or from Paris to Brussels. But once you have arrived in Brussels, you can't change your mind and use the bike to get back to Geneva.
It's the same with the shuttle: it can go to the ISS, but you have to decide on it before launch. Afterwards, your fuel is gone, it's too late.
So the problem with your idea is that you would have to park and maintain boosters or fuel tanks at every possible orbit that the shuttle might want to reach, which makes a lot of them.
Basically a really-big satellite full of solid rocket fuel/oxidizer. I assume it would have to be launched by a shuttle being that big, so it would be volume limited to the size of the shuttle's cargo bay. Of course, I'm ignorant of the relevant energy densities/energy necessary for orbital changes.
A shuttle can launch 20-30tonnes of payload to low Earth orbit depending on the orbital inclination (the higher the more difficult except below the latitude of Cape Canaveral, which is impossible when launching from there). Last winter's event would have required 120-160tonnes of fuel to get to the ISS--with a moderate-efficiency engine such as the OMS or a kerosene-oxygen one; solid motors are not as good. But you could station a full tank every few degrees and use several of them, each getting you to the next one.
Expensive but not impossible--that could be interesting once we develop a space-based infrastructure, with materials and fuel coming from nearby asteroids or maybe the Moon or even Mars.
And, of course, this doesn't solve the problem of keeping everybody alive more than a few days at the ISS.
How about just parking some booster rockets in permanent orbit for use if the occasion should arrive?
I don't understand. Do you mean something like systematically launching to a space station, where boosters--or, more easily, fuel--would be stored, and changing orbit from there?
It's an option if you want to go further than the shuttle can in a single launch; actually, you could keep spaceships there and use shuttles only for Earth-space ferry. (No, the ISS does not fit the bill for that kind of refueling station: its orbital inclination is too high, which reduces the payload a given launcher can haul up there.)
However, if it is to be used for "exceptional" LEO missions, then it would be much more expensive, since you'd have to keep the station supplied: think, for each mission to another orbit, you'd have to launch several shuttles' worth of fuel in advance. It makes more sense to just launch into the right orbit from the beginning.
Well, there was no contingency plan. The Soyuz on the ISS has enough fuel for a complete deorbital burn; would that be enough to drop to LEO and the shuttle, and then reascend?
No. The ISS is in LEO (400km altitude; neither shuttle nor Soyuz can get much higher), it's a question of orbital inclination, which takes as much fuel to change as it took to get the spacecraft in orbit in the first place. (Well, roughly; I had calculated that 120-160tonnes were needed, the external tank at launch holds 2000, and the Soyuz less than1...)
But I imagine if you abandon the idea of a deorbital burn on the shuttle and instead use the fuel to get to a higher orbit
Not even close, I'm afraid.
I don't know if you could squeeze all seven astronauts into a three person capsule either.
Not for a return to Earth (the seats are form-fitting and the landing quite hard), otherwise possibly, but the more people aboard, the more fuel is required to get anywhere...
Maybe multiple trips would have been required. Can the shuttle and the Soyuz even dock?
No. And they don't use the same docking ports on the ISS either.
That might have required EVA's...in any event, I think that with all of those resources in orbit, something could have been worked out if NASA had committed to a solution.
No. The best bet, provided that the danger were known at the beginning of Columbia's mission, was to conserve power so as to last maybe an extra week or two in orbit, and rush Atlantis through launch preparations, bypassing a number of safety regulations to have it ready in less than a month. And only because it happend to be already sitting on the pad.
Sorry to sound rude like that, but I hear this kind of misconceptions so often...
This may all seem pointless, but it's not: at some point, we will encounter this situation again in some form. "Orbit to ISS" is not part of the any shuttle mission profile; perhaps it should be from now on.
It is said to be in the cards. Not that it would help (the ISS can't hold that many people for long), but no mission was planned elsewhere except for the last Hubble repair before its planned end of life, and all interesting places to go are out of the shuttle's reach anyway.
Okay, sorry for the slight rant there. The shuttle rocked but it is time to move on. Why haven't we? If NASA had a budget that was maybe, at the least, equal to the increase in defense spending for 2003 we might be able to do this.
An appealing idea, but a good number of people happen to think that:
NASA is at the point that a significant budget increase is unlikely to result in a comparable increase in results, because they tend to inflate costs;
if costs remain high, then only huge government agencies can afford anything involving space, hampering a real space conquest where many people actually get to go;
since NASA's survival appears to be linked to 2, then 1 seems to be in their best interests.
Even the HTML encoding of addresses can not stand up to this exploitation. When scouring a website for addresses, everyone knows you look for all occurrances of '@' in the source. Encoding it with HTML merely substitutes one search character with the short string '@'.
Correct, but very few spambots bother with entities. As a matter of fact, I thought the manna of unobscured addresses was enough that spambots would be satisfied with them for the time being. Unfortunately at least one went through my test page, and each of my HTML-obscured spamboxes was "visited"--although much less than the others.
Probably the best defense is to randomly insert undisplayed '@'s and '@'s all over the place within a webpage. That way, there would be too many false positives for them to work out. People are lazy and won't bother with such garbage. The irony of this would be that spammers would need to use anti-anti spamming filters. Then we'd need anti-anti-anti filters, etc.
That would work for humans, but I don't think spambots ever had a problem with information overload. You know, with all those 42-gazillion email address CDs, guaranteed without duplicates, for which you get half a dozen spams in your mailbox...
5. Obscuring an e-mail address is an effective way to avoid spam from harvesters on the Web or on USENET newsgroups. Even when posted in publicly accessible areas, none of the addresses we obscured -- whether in English ("example at domain dot com") or in HTML -- received a single piece of spam. Users who want to avoid spam should consider obscuring their addresses when possible.
FYI, about HTML-obscured addresses (user@domain): according to my own measurements, they are still efficient but not 100% any longer. One single spam in little less than a year, for every such obscured address, none of which have been posted any other way. Oh, bother...
Boeing have a rather nice alternative ready for production. It's another delta-wing that looks as cool as concorde, and is rated for mach 0.95. It is almost as fast as concorde, but much cheaper to run.
Sources, please? The only similar concept Boeing had that I knew of was the Sonic Cruiser, which they recently shelved (even before the paper study was completed, I think -- let alone "ready for production").
Oh, and the Concorde flies (flew) at Mach 2. Mach 0.95 is not "almost as fast"...
IANAReal Computer Scientist, but aren't all current microprocessors and computers Turing machines? Aren't Von Neumann machines self-replicating devices, which AFAIK we don't have?
So, when is this new shuttle going to be rolled out?
There isn't any. The only new project in that field is the Orbital SpacePlane, whose primary purpose is to stay docked at the ISS for 7+ crew rescue. A recent tacked-on requirement is that it could be launched on a conventional rocket with people aboard and possibly go beyond Earth orbit, but with virtually no cargo.
This is interesting, but not a replacement for the shuttle, although it will likely be just as expensive to operate. The current plans call for it to fly in 2010 in addition to current shuttles, which could remain in service through 2020.
But according to the latestcouple of updates of the Space Access Society, don't hold your breath, since NASA hasn't managed to design any new vehicle since said shuttle...
Also if you could send up fuel for the OMS and have a way of refuling that in flight you might be able to make it to the ISS where it could be secured *and* eventually repaired (EVA vehicles, which the Columbia did not have on board would be necessary).
Not even close, I'm afraid. Changing orbital inclination is expensive; the amount of fuel necessary for the mere 15 that would have been required, according to my back-of-the-envelope calculations, is 1.5 to 2 times the mass of the shuttle itself, 120-160 (metric) tons. Nobody on Earth has the capability to launch that in less than maybe five launches (think months of preparation).
Furthermore, the ISS has no repair facilities; they would have to be shipped--by Progress, since only one shuttle can dock at a time--and before supplies ran out, with three times the normal crew...
I believe the European Space Agency's Aryan 5 (if I spelled that right) was ready to lift off...
Not quite, Ariane 5 was still grounded after last October's failure of the first uprated one. There was talk about chancing it anyway for launching Rosetta, since the basic version seemed to be unaffected, but the unusual flight profile was deemed too risky.
However, shuttle Atlantis was due for launch the following month. They might have tried to race for it.
Any number of things could have been done. Even with Columbia, knowing there was a disaster in the offing, I'd expect some creativity under pressure, if only sending up Soyuz to take them off.
There is a limit to what creativity can do. In this case, the shuttle's orbit was not inclined enough to be reachable by Russian rockets--unless they launched from elsewhere that Baikonur, but their pad in Kourou won't be in service for years.
One possibility would have been to launch Atlantis a couple of weeks early, but they would have to have known about the seriousness of the damage early in the mission (so that Columbia's crew could conserve power and have resources left to stretch). But this was luck (what if no shuttle was waiting?), and it would still imply to skimp a few safety procedures; gamble, one shuttle and seven crew lost, or two shuttles and nine crew?
And in future, I expect that NASA will have a contingency plan or two availible, with fuel and supplies to implement it.
They're speaking of scrapping all shuttle missions not going to the ISS--not that there were many--except the final Hubble servicing. In other words, don't build a safer vehicle, don't take risks, reduce our capabilities...
So ruling out Europa doesn't mean that there is no life in the Jovian system.
Besides, I still can't see how the Europa torus could hamper life there. On the surface, yes, but that was pretty much already known. Life would be underwater, in an ocean tens of kilometers deep, the radiations won't penetrate that far. So don't rule out Europa.
Tomorrow the UK government will announce it's going to "get serious" about renewable energy
[8<]
the current situation is "unsustainable". On the bright side, it's mentioned that sustainable energy sources are less susceptible to terrorist attack.
Renewable or sustainable? Nuclear fission is not renewable, but is sustainable in the long run (possibly with breeder reactors) and looks like the only way to reduce CO2 emission levels while keeping the energy production comparable to the current levels.
(Solar/photovoltaic consumes almost as much energy to make solar cells as they produce over their entire lifetime and yield toxic waste, solar/thermal has a poor ration of conversion to electricity, windmills and dams need to be spread over very large areas -- think whole countries -- to produce the same quantities...)
And nuclear reactors would still be vulnerable to terrorism. But they are not PC anyway.
I just wonder how on earth can one single space shuttle launch cost an average of 470 million dollars?
Most of these costs are fixed: the payroll of the standing army of people who check and rebuild each shuttle between missions.
$470M probably assumes about 5 launches a year (a little over $2G/yr), say half of it is 20,000 workers at $50,000/yr, plus hardware for the remaining half. Figures.
>And even if it did, you are still looking at a six-to-eight-year mission, at least.
No. More like 3 years.
Er, I messed up, I meant six to eight months. Three years would be the duration of a "conventional" mission, following minimum-energy orbits, with a one-year stay at Mars. (Not the minimum, there is also a two-year-total, one-month-stay scenario, I think.)
Can't you use all that gobs of power to seperate the water into it's component elements and eject something sightly more energetic than steam?
Sure, but I can't see any use; better use all the available energy in kinetic form (blast the exhaust molecules out as fast as possible) rather than breaking molecular bonds.
Slashdot Mirror
Everybody, I mean, nobody knows the real crash took place 100 miles north of Fairbanks, Alaska in 1978.
To filter it, you mean? That's been forbidden in Europe since 1997 (see for example a related urban legend); other animal substances are used now.
I assumed the question was something earlier in the thread, "there is nothing a shuttle can do that soyuz + iss can't, and then some." (Generalizing "Soyuz" to Soyuz capsules and unmanned launchers.) If you start designing new vehicles, then surely you can replace the shuttle. Whether you can design that cheaply is another matter, but I tend to agree if you keep it off NASA's management.
That's difficult to say since shuttle launch cost estimates vary, maybe between 250 and 400 M$, while a Titan IV-B might cost 400-450 M$. There aren't many left anyway, and the Delta IV Heavy, while cheaper, won't reach the same performance.
I agree that the need for those capabilities is debatable, with the first being the most apparent (sample return from ISS). Repairing GEO satellites would be interesting, but is way outside the shuttle's reach.
Yes, as long as it stays in the same orbital plane. That is, if the initial orbit is a circle around the Earth, the shuttle can widen or shrink or elongate the circle (altitudes could range 200-600km, maybe 800-1000 if all the fuel is used), but not warp it or incline it significantly (perhaps a couple of degrees).
The ISS was going in a circle roughly the same size, but in a different plane, which is why Columbia could not have gone there.
Ah, I would have turned you over to Google, but I can't seem to find an appropriate FAQ... <g>
First, it's not a question of going "up" or "down", which is easy enough, but "sideways". To take another example, imagine you are sliding down a pole; it is easy to speed up or slow down, but even if you let go of it, you can't reach far from the pole itself.
Second, the ISS has even less maneuvering capability than the shuttle. More mass, smaller engines, not that much more reserve fuel. So, theoretically speaking, yes, if you can send a few hundred tonnes of fuel there first.
I'm afraid it doesn't work like that; the orbit is already a free-fall trajectory, which just happens not to pass through the atmosphere or the Earth. The only way not to work against gravity is to keep that orbit.
By the way, notice that the shuttle has to use the atmosphere to shed all its velocity (28,000km/h to 0) before it can land. If there was no air, it would have to slow down the same way it accelerated: with a whole ET's worth of hydrogen and oxygen. And if that fuel was available, reentry would be safer, since the shuttle could go in much more slowly--witness Scaled's SpaceShipOne, which has little thermal protection if any; although it will reach comparable altitudes, it won't go anywhere as fast as a satellite nor undergo the same kind of stress.
Now I see what you meant. But there is something you missed: the orbits which can be reached by the shuttle are not at all the same as those orbits which it can reach after being launched into a different orbit.
Imagine you are making a trip with a car, and a bike inside the car. Assume that no gas stations are available, and that you want to consume the car's whole tank and then ride around with the bike. You can go a few hundred km with the car, say either from Paris to Geneva or from Paris to Brussels. But once you have arrived in Brussels, you can't change your mind and use the bike to get back to Geneva.
It's the same with the shuttle: it can go to the ISS, but you have to decide on it before launch. Afterwards, your fuel is gone, it's too late.
So the problem with your idea is that you would have to park and maintain boosters or fuel tanks at every possible orbit that the shuttle might want to reach, which makes a lot of them.
A shuttle can launch 20-30tonnes of payload to low Earth orbit depending on the orbital inclination (the higher the more difficult except below the latitude of Cape Canaveral, which is impossible when launching from there). Last winter's event would have required 120-160tonnes of fuel to get to the ISS--with a moderate-efficiency engine such as the OMS or a kerosene-oxygen one; solid motors are not as good. But you could station a full tank every few degrees and use several of them, each getting you to the next one.
Expensive but not impossible--that could be interesting once we develop a space-based infrastructure, with materials and fuel coming from nearby asteroids or maybe the Moon or even Mars.
And, of course, this doesn't solve the problem of keeping everybody alive more than a few days at the ISS.
I don't understand. Do you mean something like systematically launching to a space station, where boosters--or, more easily, fuel--would be stored, and changing orbit from there?
It's an option if you want to go further than the shuttle can in a single launch; actually, you could keep spaceships there and use shuttles only for Earth-space ferry. (No, the ISS does not fit the bill for that kind of refueling station: its orbital inclination is too high, which reduces the payload a given launcher can haul up there.)
However, if it is to be used for "exceptional" LEO missions, then it would be much more expensive, since you'd have to keep the station supplied: think, for each mission to another orbit, you'd have to launch several shuttles' worth of fuel in advance. It makes more sense to just launch into the right orbit from the beginning.
No. The ISS is in LEO (400km altitude; neither shuttle nor Soyuz can get much higher), it's a question of orbital inclination, which takes as much fuel to change as it took to get the spacecraft in orbit in the first place. (Well, roughly; I had calculated that 120-160tonnes were needed, the external tank at launch holds 2000, and the Soyuz less than1...)
Not even close, I'm afraid.
Not for a return to Earth (the seats are form-fitting and the landing quite hard), otherwise possibly, but the more people aboard, the more fuel is required to get anywhere...
No. And they don't use the same docking ports on the ISS either.
No. The best bet, provided that the danger were known at the beginning of Columbia's mission, was to conserve power so as to last maybe an extra week or two in orbit, and rush Atlantis through launch preparations, bypassing a number of safety regulations to have it ready in less than a month. And only because it happend to be already sitting on the pad.
Sorry to sound rude like that, but I hear this kind of misconceptions so often...
It is said to be in the cards. Not that it would help (the ISS can't hold that many people for long), but no mission was planned elsewhere except for the last Hubble repair before its planned end of life, and all interesting places to go are out of the shuttle's reach anyway.
An appealing idea, but a good number of people happen to think that:
What about browsers without JavaScript support (missing, deactivated, or forbidden)?
Correct, but very few spambots bother with entities. As a matter of fact, I thought the manna of unobscured addresses was enough that spambots would be satisfied with them for the time being. Unfortunately at least one went through my test page, and each of my HTML-obscured spamboxes was "visited"--although much less than the others.
That would work for humans, but I don't think spambots ever had a problem with information overload. You know, with all those 42-gazillion email address CDs, guaranteed without duplicates, for which you get half a dozen spams in your mailbox...
FYI, about HTML-obscured addresses (user@domain): according to my own measurements, they are still efficient but not 100% any longer. One single spam in little less than a year, for every such obscured address, none of which have been posted any other way. Oh, bother...
Sources, please? The only similar concept Boeing had that I knew of was the Sonic Cruiser, which they recently shelved (even before the paper study was completed, I think -- let alone "ready for production").
Oh, and the Concorde flies (flew) at Mach 2. Mach 0.95 is not "almost as fast"...
IANAReal Computer Scientist, but aren't all current microprocessors and computers Turing machines? Aren't Von Neumann machines self-replicating devices, which AFAIK we don't have?
There isn't any. The only new project in that field is the Orbital SpacePlane, whose primary purpose is to stay docked at the ISS for 7+ crew rescue. A recent tacked-on requirement is that it could be launched on a conventional rocket with people aboard and possibly go beyond Earth orbit, but with virtually no cargo.
This is interesting, but not a replacement for the shuttle, although it will likely be just as expensive to operate. The current plans call for it to fly in 2010 in addition to current shuttles, which could remain in service through 2020.
But according to the latest couple of updates of the Space Access Society, don't hold your breath, since NASA hasn't managed to design any new vehicle since said shuttle...
Not even close, I'm afraid. Changing orbital inclination is expensive; the amount of fuel necessary for the mere 15 that would have been required, according to my back-of-the-envelope calculations, is 1.5 to 2 times the mass of the shuttle itself, 120-160 (metric) tons. Nobody on Earth has the capability to launch that in less than maybe five launches (think months of preparation).
Furthermore, the ISS has no repair facilities; they would have to be shipped--by Progress, since only one shuttle can dock at a time--and before supplies ran out, with three times the normal crew...
Not quite, Ariane 5 was still grounded after last October's failure of the first uprated one. There was talk about chancing it anyway for launching Rosetta, since the basic version seemed to be unaffected, but the unusual flight profile was deemed too risky.
However, shuttle Atlantis was due for launch the following month. They might have tried to race for it.
There is a limit to what creativity can do. In this case, the shuttle's orbit was not inclined enough to be reachable by Russian rockets--unless they launched from elsewhere that Baikonur, but their pad in Kourou won't be in service for years.
One possibility would have been to launch Atlantis a couple of weeks early, but they would have to have known about the seriousness of the damage early in the mission (so that Columbia's crew could conserve power and have resources left to stretch). But this was luck (what if no shuttle was waiting?), and it would still imply to skimp a few safety procedures; gamble, one shuttle and seven crew lost, or two shuttles and nine crew?
They're speaking of scrapping all shuttle missions not going to the ISS--not that there were many--except the final Hubble servicing. In other words, don't build a safer vehicle, don't take risks, reduce our capabilities...
Besides, I still can't see how the Europa torus could hamper life there. On the surface, yes, but that was pretty much already known. Life would be underwater, in an ocean tens of kilometers deep, the radiations won't penetrate that far. So don't rule out Europa.
Renewable or sustainable? Nuclear fission is not renewable, but is sustainable in the long run (possibly with breeder reactors) and looks like the only way to reduce CO2 emission levels while keeping the energy production comparable to the current levels.
(Solar/photovoltaic consumes almost as much energy to make solar cells as they produce over their entire lifetime and yield toxic waste, solar/thermal has a poor ration of conversion to electricity, windmills and dams need to be spread over very large areas -- think whole countries -- to produce the same quantities...)
And nuclear reactors would still be vulnerable to terrorism. But they are not PC anyway.
Mariner 4 was launched at the end of 1964. 1965 is the date of the actual flyby.
Most of these costs are fixed: the payroll of the standing army of people who check and rebuild each shuttle between missions.
$470M probably assumes about 5 launches a year (a little over $2G/yr), say half of it is 20,000 workers at $50,000/yr, plus hardware for the remaining half. Figures.
One of the Mariners, I guess, but the CO2 data seems to date from 1969, not 1966. I don't know.
Er, I messed up, I meant six to eight months. Three years would be the duration of a "conventional" mission, following minimum-energy orbits, with a one-year stay at Mars. (Not the minimum, there is also a two-year-total, one-month-stay scenario, I think.)
Sure, but I can't see any use; better use all the available energy in kinetic form (blast the exhaust molecules out as fast as possible) rather than breaking molecular bonds.