Now if only...
we as a species could stop squabbling over petty things like whose cosmic wizard is the least silly and focus our efforts and resources we might actually stand a chance of making it out of this solar system...
Top boffins working at a NASA spinoff company are thrilled to announce that their plasma drive technology – potentially capable of revolutionising space travel beyond the Earth's atmosphere – has checked out A-OK in ground tests. The VX-200 blasting Argon at full bore in ground trials. Credit: Ad Astra Rocket Co What …
Let the space wizard worshippers stay here while us sensible humans jet off into the stars. They seem quite happy for everything to stay exactly as it is or even better - regress back to medieval times.
They hate new technology so I think they would probably be happy if we all left them to it.
Maybe we'll check in on them after a couple of hundred years if we fancy a laugh.
The "teach a man to fish" guys are spot on here. 5.7 newtons of force applied to a 100 ton spaceship, you're talking a 10 millionth of a g force. Paltry, but if you apply the force continuously in the right direction, VERY useful. In the ISS it would let them cheaply and effortlessly raise or lower their orbit. For long range missions, add more motors and ramp up the power - apparently the VASIMIR scales very nicely.
Best thing to happen to space science in 40 years.
F=ma, where 'F' is force (5.7 Newtons in this case), 'm' is the mass being accelerated and 'a' is trhe resulting acceleration.
Rearranging gives a=F/m
As an interplanetary spacecraft is likely to have a mass in the order of a few tonnes, 'a' is going to be very, very small.
The advantage of this type of engine is it can apply this tiny acceleration for days, weeks and months at a time rather than the few seconds of a more powerful but less fuel efficient 'firework' type engine.
5.7N(force) cannot be translated to G (acceleration) without a mass component (f=ma).
the simple way to visuallise 5.7N is to imagine how much Mass it could hold against G. ie m=f/a therefore 5.7N can hold 0.581KG steady (levitate it) in 9.81m/s^2 gravity. ie this engine could hold 581grams in a hover. Hopefully you can visulise holding 581g in your hand, that is 5.7N force in earths gravity 1G = 9.81m/s^2.going further of all the items on my desk in front of me, the metal stapler is closest to 580g.
> what does a sustained 5.7N translate to in G?
It doesn't. The Newton is a unit of force, "g" is a measure of acceleration.
If we were to assume a mass of one tonne for the drive unit (it was described as about the same size as a small car), we'd get an acceleration of 5.7mm/s^2, or approx 0.00058g.
Not as quick as my bike, but likely to go a bit further without refuelling...
Gravity is an acceleration. Newtons are a unit of force. The standard equation between them is
Force (N) = Mass (g) x Acceleration (m/s/s)
The closest relevant unit is the gram-force ((g*m)/(s*s)), which uses the Terran gravity constant (G) for acceleration. Based on calculations, 5.7N equals 581.238241397 gram-force.
As the article states and as the example illustrates, 5.7N isn't exactly a huge force, but if allowed to exert over a long period, it can still translate into a LOT of acceleration.
First off, M/AM reactions emit all usable energy as photons. So this gives you two choices:
1) Capture the photons for use as electricity (our extant technology here is inefficient)
2) Use the photons to superheat a propellant, sort of like...and ion engine!
Given the mass of the equipment you'd need to create antimatter containment bottles, M/AM RA type engines wouldn't be more efficient than fission/ion engines even if you could recover 100% of the energy from the conversion of both the matter and the anti-matter. Problem is...we can't recover 100% of the usable energy from a M/AM reaction...and 50% of it escapes as neutrinos anyways!
When you figure out how to capture neutrinos and derive power from them, we'll talk. Also, you'll have solved all of humanity’s power problems until the end of time. Until then, give me a fission reactor, baby!
Hell, give me one next door to my house. Anything’s better than these toxic coal plants. We don’t get enough sunlight at my latitude for photovoltaic to be useful (if it actually is anywhere,) and windmills seem to consume more energy in their manufacture than we actually could extract from the atmosphere here. Hydro and fission, baby: only way to go!
And in space, the hydro is all frozen…
"..no one can hear you scream. So why are the radiators(?) on that uber-rocket thing streamlined?
Grips my tits when spacecraft are made to look and manoeuvre like aircraft..."
Presumably because they need to be transported to space through the earths atmosphere before their interstellar jaunt. I agree, once up there, a ruddy great cube (ala Borg) would be fine and dandy (barring the sparse hydrogen getting draggy when travelling at silly speed*), just getting it there would be an arse
(*this thing seems fast, but I don't think it would be fast enough for this to be an actual issue)
When Lewis mentions "nuclear", he frequently deliberately omits the distinction between nuclear fission reactor technology and radioisotope generators, perhaps because he's riding some nuclear high horse or other. That various missions might use the latter technology is nothing new - I guess that's what the Mars Rover references are suggesting - but although the former technology is also nothing new, it's also controversial for the reasons you give and others: look up RORSAT on Wikipedia, for instance.
Yes, that would be the way to go. Also un-used enriched Uranium fuel rods aren't a serious hazard. Enriched Uranium is only a few times more radioactive than natural Uranium, and Uranium oxide pellets in Zirconium tubes are pretty robust. We'll be OK just as long as a well-used reactor never re-enters, with all its accumulated fission by-products. Dump used fuel rods into the Sun?
actually i am curious about this, i have been for years, obviously blasting used fuel rods in to space on chemical rockets isnt a smart idea given that the rockets are essentially a barely contained explotion that quite often do blow up but in all seariousness assuming we could get that stuff in to space what would be the effect of blasting it in to the sun, it wouldnt get anywhere near the sun before burning up and everything around there is somewhat hazardus to us anyway.
before the eco folk go on about not dumping our waste in to some other backyard which i would agree with, just think for a second what would actually be left? i dont know the answer so im just asking the question
All the basic research for nuclear powered engines was done from the late 50's to the beginning of the 70's when atmospheric nuclear tests were banned. Although they were never tested in space, projects like XE-Prime did in-vacuo test firings on earth, so we know the 40 year old technology works. If it wasn't for public concern over transporting inert reactor cores on conventional rockets (so they could be fired a long way from earth) we'd have had 2-way expeditions to Mars decades ago.
The actual acceleration depends on the mass of the ship (see above), but yeah, that's the idea. Let that small amount of push add up and add up until you're halfway there, then turn around.
VASIMIR has a ridiculously high specific impulse compared to chemical rockets, which makes getting up to that kind of velocity practical. Google "rocket equation".
You can use the gravity well at the other end as a brake. In theory, it's easy to calculate by doing things in reverse. You pick a stable orbit around the mass, work out the escape velocity and then project that out to find a few points on the escape trajectory and the associated velocities at each of those points. Then, since you can reverse the time component of the equation, you know that if you approach the mass along the given trajectory with a given velocity, you will end up in a stable orbit, without necessarily needing to slow down.
In practice, things are going to be a lot more complex, though. The first issue, which isn't that difficult is that depending on the mass of the planet that you're trying to achieve orbit around, you'll find that there's a maximum velocity that you can be travelling at, above which you'll never be captured by its gravity well unless you hit it, which is probably not desired. Then there's the issue of navigation and having accurate sense of where the craft is at any given moment along with position and velocity relative to the target planet and any other major masses in the area. A lot of this can be pre-computed, but things might not go completely to plan (eg, differences between observed and theoretical velocities of other deep-space probes) so on the fly adjustments will need to be made, thus necessitating good telemetry data and the ability to recompute trajectories as needed.
The major problem, as I understand it (and this is only from pre-University level Applied Maths and some other reading I've done) is that while specific trajectory equations are reversible, the general equations aren't. That is to say we can easily come up with a trajectory which will escape or be trapped by the planet's gravitational field, there's no easy way to figure the best or most efficient approach. As I understand it (again) it's a problem of sensitive dependence on initial conditions (as per Lorentz or Mandelbrot). We might find lots of trajectories which will bring us into orbit, but it might take a long time for us to reach a stable orbit or, worse, our trajectory will cause us to collide with the planet or its atmosphere.
If the general set of equations aren't reversible (since, unlike a 3-D Lorentz attractor, we're dealing with a 4-D system and that isn't generally solvable, AFAIK) the only thing we can do is to run many simulations, trying out lots of different target orbits and "escape" velocities until we find one that's good enough. Only then can we plan the trajectory and hope to hit it without too much margin of error...
For extra shits and giggles, there's nothing to stop you from including acceleration/deceleration at various points along the flight path, too, of course. But to get back to my previous point, strictly speaking there may not be any need to decelerate at the half-way point or even any later point.
Like I said, this is just as I understand it. I wouldn't mind being corrected by someone more knowledgeable if I am, in fact, wrong on any of these points... cheers
This article on a new form of space propulsion has cheered me up no end, as have your musings on gravity well braking... nice to know there are clever people out there and that humanity's brains haven't all been turned to porridge by us all watching X-Factor.
I am wondering though if there will be some high g-forces involved that would rip the spaceship/occupants appart during breaking?
Won't the target body's gravity actually (initially) add energy to the system rather than take it away? The only way to slow down without reverse thrust is either a very careful velocity control on the way in, i.e. not exceeding the target body's escape velocity, or to use atmospheric braking (possibly repeatedly)?
I think you have covered most of it, but from what I understand, the velocity to get there very quickly is too high for capture, so deceleration or aero-braking may be used where you deliberately fly into the atmosphere to help slow you down for capture. Of course that only works for a single craft; something like the ISS built in space wouldn't survive.
Of course you missed out a major issue with ensuring capture, and that is make sure that you measure your distances always using metres. Using El Reg standard units of measure (or even crazier things like furlongs and inches) means you might not end up where you think you want to be (ask Nasa).
Admittadly I am not an expert in this because I work on the things themselves, not the trajectories.
You're not starting from a standstill when you leave Earth Orbit, you're most likely in a stable Earth orbit. If you were going to a same sized planet, then you'd turn around half way there and arrive with the right amount of speed to re-establish that same orbit around the target planet.
If the object you're heading to is larger than Earth you can keep some of your hard earned speed, but if it's smaller you need to lose some of the speed from the orbit you held around Earth too. So you might need to start slowing down before half way!
Unfortunately you're ignoring the fact that your craft and both planets are in orbit about the Sun. Doing a reverse slingshot (which is what Frumious Bandersnatch is suggesting) involves making use of the relative velocities of the interacting bodies in creative ways. In the situation you're describing the craft will always gain velocity as it approaches its destination - size notwithstanding.
Paris, because she's being known to make creative use of relative velocities.
Great shame and missed opportunities in some respects - in other regards it may have been for the best that 60,000 ton spaceships aren't blasting off from the planets surface to the stars.
Honestly - if you want an idea of what could be done, and what may have happened if it wasn't for the SALT treaty then take a look at project Orion.
Scary and fascinating at the same time.
...but iirc, wasn't Orion designed to have been launched by lighting its nuclear propellant source straight off the pad, i.e. nuclear launch from the surface of the Earth? I believe they were considering a site known as Jackass Flats, Nevada. I'm sure if they'd tried it, it would've given a whole new meaning to the name "Jackass Flats":
Jackass Flats was where the nuclear rockets like Kiwi and Nerva were tested. A book (Astronautics in the Sixties?) shows a firing vertically *into* the air of Nerva before being dragged back to the assembly building for dis assembly by remote tele-operators (or Waldo's if you're of a certain age) by a remote control locomotive.
I'm not sure they got as far as picking out a launch site for Orion. Although big, flat and isolated would probably be a *very* good idea.
This time they'll make an engine module unit that can be serviced/refilled from inside the space station.. it'd be good to just send up a tank of argon every few cargo flights and have the guys on board change the canister in the engine room when required.. rather than having to loft a whole engine modeul each time it needs a refill...
This is just the sort of engine the ISS needs to maintain a decent orbit. perhaps now they will think twice about dropping it. As reboosting will no longer be required I think they have just halved the maintainance costs involved in keeping the ISS 'up' a bit longer...
It's a shame this was not invented 30 years ago, or that politicians had the imagination and balls to use the nuclear option.
What they should do is fix a big one onto the ISS, power it using the power plant from a Nuclear sub and send it on a tour of the solar system.
Then maybe the ISS might actually be useful.
Of course politicians and the senior types at NASA lack any serious will or imagination.
This invention is likely to be assigned to the 'we could if we wanted to' bin of inventions like 'Hotol'.
39 days to Mars as opposed to 6 months. Marvellous!
The real question is: who has the guts to back this project financially and not get the jitters and pull the funding the next time the banks hit the skids?
What's needed is large scale international cooperation at all levels. Will we see it? Sadly, I don't think so.
What could we have done with the 376 trillion dollars thrown at the banks in the past 2 years?
NASA's budget is something like 20 billion dollars per year which is something like 14 billion pounds.
And british banks were bailed out to the tune of 100 billion.....
SO we could have funded a NASA sized space agency for 8 years on the bailout cash
Perhaps we should measure the bailout in better units... such as 14 NASAs, or 47 hospitals, or 4 high speed rail lines, or 287 royal weddings....
I know lots of people have suggested that here at one time or another, but I'm not sure the module connections and truss structure of the ISS were really designed for that kind of acceleration stress load.
I do recall at least one Mars flyby-ship design which was basically a beefed-up version of a SkyLab/MORL concept, using S-IVB stages mated in series, retrofitted spent S-IVBs and existing Apollo hardware for the crew re-entry module. No nuke propulsion option, though, that I'm aware of.
"I know lots of people have suggested that here at one time or another, but I'm not sure the module connections and truss structure of the ISS were really designed for that kind of acceleration stress load."
Going with a nerva style nuclear thermal system probably not. Very dramatic in a film. Nonsense in real life. The joints will fail.
But VASIMIR thrust levels are *much* smaller than the hypergolic thrusters used for orbit correction at present (long and low Vs short but high thrust) so with a big enough long lived power source perhaps.
But ISS life support is *not* closed cycle (there are European test sections to work on this) and the modules do leak so you'd need to stock up a *lot* with the present level of life support tech.
"What they should do is fix a big one onto the ISS, power it using the power plant from a Nuclear sub and send it on a tour of the solar system"
hard to believe but this *is* quite a big one.
"What they should do is fix a big one onto the ISS, power it using the power plant from a Nuclear sub and send it on a tour of the solar system."
While sub power plants are *relatively* compact the system that converts raw heat into electricity is *very* substantial. You're looking at IIRC a 60-120Mw steam turbine. This is not that small or light. The fact it's heavy is no big thing on a sub (you want it to sink easily, don't you?).
"This invention is likely to be assigned to the 'we could if we wanted to' bin of inventions like 'Hotol'."
Hotol might be dead but it's spawn is very much alive. Look up reaction engines ltd.
Ever since my college days, I've been a proud member of any number of groups opposing nuclear power, nuclear weapons and the "weaponization" of spaceflight.
That said... about fifteen years ago, one of the groups I worked with was organizing protests related to the then-upcoming Cassini Probe launch -- a march and rally here in DC, and a presence at KSC for the launch -- and I told them flat-out how silly they were being, and that while they may have their shit together on nuclear weapons/power and "Star Wars" space systems, they'd totally failed to do their homework on RTGs, in terms of what they are and how they work, and that all of the Apollo lunar expeditions carried RTGs to power certain surface experiment packages with no ill effects on the crews. These goddamn' people were acting as if Cassini were launching with a slab of plutonium duct-taped to the spaceframe or something. At the meeting, I came right out and said that if I were able to make it to KSC at all for this launch, I was going to be not outside the gates pissing and moaning, but inside in the general-public viewing area, cheering the booster as it cleared the tower. I reminded them that not only was the amount of radioactives aboard barely negligible, but also that the goddamn' probe was going to Saturn -- SATURN, f'crissake -- where there's no known life to be affected by any radiation hazard, real or imagined, from the RTG power source aboard Cassini, and to do some homework and get a goddamn' grip, already.
Now, I _am_ a bit concerned about the use of reactors aboard interplanetary manned craft, although a quick look through the Encyclopaedia Astronautica reveals that the designers of all of the proposed systems seemed to have considered this problem fairly thoroughly.
If they could propel a complete manned spacecraft and keep it accelerating at 1G for like, uhh, 6 months (or 1 year?), it would reach c. That c, from E=mc2.
I vote for building a spacecraft propelled by that and placing just a small radio transmitter on it, and watch it reach 0,99c or so. Physics experiment on a large scale FTW.
Call it Sputnik 2, please.
PS. An initial nudge from a Saturn V rocket fired from orbit might help with some V0.
Why would you be concerned about reactors on interplanetary manned craft?
These ships will have LOTS of shielding to keep the interstellar subatomic golfballs / the odd solar flare out and shielding the reactor will be listed under "bugs to fix later". Not even talking about cancerogenic chemicals that will probably accumulate in the closed-cycle systems.
The astronauts they will probably have their reproductive organs pickled away before the trip or something.
I wouldn't even be concerned about a slab of plutonium taped to the outside of an exploding shuttle. It's not going critical, and it's not like anyone is going to inject the debris into his bloodstream. You would probably find it back in one piece; it's just metal.
The main concern "non technical" people have appears to be to do with the launch process. Having seen plenty of footage of exploding rockets - some even from the last half-century - their thought process goes something like: Rocket goes <bang>, reactor explodes, nuclear fallout everywhere, planet glows in the dark and everybody dies. I'll leave it as an exercise to list the number of fallacies in this train of thought (I make it 4).
The main concern that technical people have is to do with orbits. Basically, in space everything is in orbit - and it'll come back to where it started from at some time or other. Now, uranium is pretty dam' close to inert in its pure form. It has a half-life of 100's of millions of years, so _provided any neutrons from the occasional decay_ doesn't hit another uranium nucleus and start a chain reaction, it's close to failsafe UNTIL THE REACTOR IS INITIATED. After that all the decay products start to accumulate in the core and they are friggin nasty little isotopes. If the nuclear rocket misfires, when it does come back it'll be one glowing ball of nastiness (TM Microsoft: 1981). And orbits being closed, at some point it'll arrive back where it came from ..... The trick is to make the start-point of the mission a long way from Earth, which means you have to haul the whole mess out to L1 or somesuch, using a chemical rocket. As with nuclear power, the big problem with nuclear rockets is safe disposal of the (expended) core after the mission. It's not practical to capture them and reprocess the fuel - though at some point it will be, but for now: nah. So each mission puts another glowing ball of nastiness up there, going somewhere, that has to be tracked in case it comes back to bite us in the arse.
I seem to recall that the nuclear reactor can actually be used *as* shielding *for* the crew.
The ship has a pretty much unshielded nuclear reactor and VASIMR drive at one end, with a long pole connecting it to the crew module at the other. Inverse squares deals with the neutron flux from the reactor. The real danger for the crew is a solar storm. In which case, shut down the drive and orient the ship so the reactor is precisely between the crew module and the incoming radiation.
Incidentally the pole can be pretty flimsy by terrestrial standards. It doesn't ever get subjected to as much as a milligee!
Good points; thanks for filling me in.
As I recall, the people getting their panties in a bunch over the Cassini launch were worrying about a launch failure. I remember at the time thinking that if it were being launched by the Russians -- whose interplanetary launch record, iirc, was less than stellar -- I might've been worried about shit going south. As it is, _our_ interplanetary launch record was at least a bit better than theirs at the time (especially their record for Mars launches), so I wasn't really all that concerned. Add to that the fact that the Apollo 13 ALSEP RTG actually came all the way back to Earth -- as the LM was used as a lifeboat and the ALSEP never deployed on the Moon -- surviving re-entry intact and resting comfortably under 4 or 5km of ocean water, and I really couldn't get that worked up about the Cassini launch.
Leaving aside your guesstimate of how long it'd take to reach c at a constant acceleration, which I'm pretty sure you didn't calculate, you're not going to get anywhere near c thanks to special relativity and Relativistic mass. The relativistic mass approaches infinity as speed approaches c, meaning that you approach infinite energy to apply any more acceleration on it at all.
Also, we already had Sputnik 2. It was the one with the first astro-dog, Laika.
...the closer you get to c, the less acceleration you get for a given force. This is because, from the equation you've stated, as you put more energy into the system, you gain mass, thus going back to the force equation (F = ma), you either lose acceleration or need to pump out more force to maintain the same rate.
It would never reach the speed of light, not matter how long you accelerated at 1G. From the occupants point of view they will still feel the same force, but measured from any other frame of reference, it might appear to get ever closer to the speed of light, but it won't get there. Also if they measure the speed of any other object, they won't see that moving at the speed of light either.
Not all is lost though - from the occupants point of view, they will apparently get to the destination quicker due to time dilation than would appear to be the case from those in the frame of reference of the starting point.
That's the special theory of relativity for you.
The only way that anything with rest mass can get to the speed of light is essentially to convert that rest mass to energy, hence Einstein's famous equations. Short of matter/anti-matter anilation, it won't happen.
300.000km/s = 300.000.000m/s
1 g = 9.8 m/s
v= v0 + a. t where v = final speed v0= initial speed a=acceleration t= time.
or better (v-v0)/A = t
v= 300.000.000 m/s
v0 = 0
a = 9,8m/s2
t= 300.000.000 / 9,8
t= 30.612.245 seconds = 8503,4hours = 354,3 days
Yes, the guessing of 1 year sounds plausible, if Newton had anything to say about it.
But stil, the whole mass gaining puzzles me. Would I become fat as I got faster? What happens at 0,98c which is plenty possible even for Einstein? Did you care to do the math too?
In short, a ship that keeps 1G acceleration during a trip cannot do that for 1 year flat-out. 11 months, maybe, then things could get wonky.
Feel free to vote down.
No, they can't propel a spacecraft with 1G for 1 year. Not even for 6 months. Not even with a 1oz. radio payload. Not on present tech.
5.7N vs a 10 tonne vehicle in the absence of any other forces.......
a = 5.7/10,000 = 0.00057m/s^2 = fat end of fuck all..........
after an hour 2m/s approx 4mph
after a day 49.25m/s approx 100mph
after 4 weeks 1378.94m/s approx 2500mph
after a year 17926.27m/s approx 36000mph
36000MPH quick enough for you?
'(It will not have escaped the notice of solar-powered Mars rover fans that despite the machines' tremendous longevity they have still not travelled as far as the much shorter-lived Soviet Moon rovers of the 1970s did.)'
It's nothing to do with the amount of power. The Mars rovers haven't travelled as far because their moves have to be calculated and pre-programmed before they go for their next trundle. When they get there, that location is surveyed and the results passed to the team in charge of the next leg. Lunokhod was remote controlled from Earth by humans, so it could be driven further and faster.
Not bragging, but my father was a real "Rocket Scientist", working for such companies as Cornell Aeronautic Labs, Thiokol and Bell Aerospace. He worked as a program manager and engineer on solid and liquid fueled rocket engine projects that helped to "defend against the communist menace", land Man on the moon, boost the Shuttle into orbit and control the position of the Moon Lander, Shuttle and many satellites.
He has long since passed away, but I'm sure he's up there between the Stars, smiling at the work of the folks responsible for the plasma drive.
On this day, let us give thanks to all the forward thinking men and women that made the Space Program possible. The technology that has been spun off from these programs have paid for the investments several fold, regardless of the naysayers and doom bringers objections.
Just think, if we can get enough people off this rock so they can see just how small and insignificant we are, maybe some of the resulting humility will result in cooperation instead of conflagration.
When we stand so close to the brink of war in Korea, it becomes even more urgent to get a survivable population of humanity as far away from the Earth as possible. Those who leave Earth will have no choice but to cooperate for their collective survival and will be better for leaving.
Would be interesting to work out how long one of these would take to reach some ludicrously fast speed, if you just bolted it to a power source and let it go.
Makes for a much more interesting bit of relativity revision than the standard problems I've been given...
Would also need the ejection rate of the fuel
On a side note, look at the second video from the bottom here: http://www.adastrarocket.com/aarc/VX200 , it even SOUNDS like something straight out of a science fiction movie!
Ion drives have long been known to have really high values for specific impulse. That basically means that a rocket using that as its propulsion system can carry a lot of fuel for its weight.
But they have a very low ratio of thrust to mass. So the efficiency of an ion drive has the price that it can't be used to lift off from the ground, and it can't be used to go anywhere fast. As long as life support is the critical problem, that makes it irrelevant to manned exploration.
We could perhaps send larger instrumented probes to Mars and beyond with ion drive, as long as we're willing to have them take much longer to get there. It's a technology worth researching, but it may end up being a solution in search of a problem.
Thus the article says it's a worthy thrust system once you're already out in space. However, to start the initial thrust from 0 to escape velocity requires at least a couple orders of magnitude improvement in the thrust-to-weight ratio, and I think there are a few physics limitations in the way of improving it by one order at the moment.
Give this is just the test version, how about we speculate on how much more powerful / fuel efficient this thing could get with bunch of development chucked at it. So, it's only .57 today, what about after a few years of investment?
Seems like it has a lot of potential.
First rate LOX/kerosene engine 100:1
Good LOX/LH2 engine 60:1
Poor but re usable Peroxide/kerosene 40:1
Modern jet engine 10:1 (the wings make a *big* difference).
Nuclear thermal c1.1:1
Bottom line overall travel time is shorter and there will be no spine grinding multi g turns.
You will note even Nerva could not lift itself (that's optimistic that its thrust exceeded its weight, but not that of the vehicle carrying it.
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