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- Newsgroups: sci.space.shuttle
- Path: sparky!uunet!cs.utexas.edu!torn!utzoo!henry
- From: henry@zoo.toronto.edu (Henry Spencer)
- Subject: Re: A new orbiter? (dont think so--was Re: National Space Plane)
- Message-ID: <BtnKJH.Jv9@zoo.toronto.edu>
- Date: Thu, 27 Aug 1992 17:28:28 GMT
- References: <l9025rINN1a2@west.west.sun.com> <1992Aug18.134803.1800@murdoch.acc.Virginia.EDU> <kdawson.14@AFIT.AF.MIL> <1992Aug19.102235.14319@athena.mit.edu> <BtGory.EwA@zoo.toronto.edu> <RUCA.92Aug25122029@pinkie.saber-si.pt> <BtLvy1.KHt@zoo.toronto.edu> <BtM0HB.us@news.cso.uiuc.edu> <BtM6oy.p6@zoo.toronto.edu> <BtML5q.7Ln@news.cso.uiuc.edu>
- Organization: U of Toronto Zoology
- Lines: 64
-
- In article <BtML5q.7Ln@news.cso.uiuc.edu> jbh55289@uxa.cso.uiuc.edu (Josh 'K' Hopkins) writes:
- >>For one thing, I don't
- >>consider anything with large solid boosters "man-rateable" :-).
- >
- >I'm skeptical myself, but NASA and ESA seem to disagree.
-
- NASA has changed its mind; they've said recently that they don't want
- to see solid boosters on future man-rated launch systems.
-
- >What you want is an Atlas II series at a lower price...
-
- It may be a little small, but it probably matches the requirements as well
- as anything we've actually got right now. Slightly greater lift might be
- had by small liquid-fuel strap-ons a la Ariane 4.
-
- >a little extra (well, okay, a factor of 2) because I didn't think you could
- >get a crew vehicle and a tug on the same rocket with only 10 tons...
-
- I haven't done detailed estimates on weight, but I don't think it should
- be that hard. Remember, my reentry vehicle is not an all-singing-all-dancing
- craft that supports a crew for a week and doubles as a laboratory; taking
- them up and down is its only job. Occupied lifetime of perhaps 24 hours.
- The cargo load is a toothbrush apiece. :-) It needs a heatshield, attitude
- control, retrorockets, a gliding parachute, crushable foam as a shock
- absorber, an air supply, and not much more. It's hardly worth trying to
- make it reusable; re-use the subsystems and throw away the structure.
- If I were really being minimalist, I'd put the crew in spacesuits and
- wouldn't even bother to pressurize it. (Remember, if they're staying
- up for any length of time, they've got a habitation module or they're
- heading for an already-existing base camp.) Think "airport shuttle bus",
- not "motor home".
-
- We can certainly do the reentry vehicle for 1500kg/man, because at that
- weight we can simply give each one his own Mercury capsule! I would
- hope we could do it for a few men at 500kg apiece, just off the top of
- my head.
-
- And my tug isn't a big husky thing meant to move comsats into Clarke
- orbit. Its job is rendezvous and docking for payloads that have already
- been fairly carefully inserted into essentially identical orbits. Its
- job is assembly, not major orbit changes. At an exhaust velocity of
- 3000m/s (good fuels but not liquid hydrogen), assuming a 1000kg tug
- carrying 5000kg of fuel, we can impart about 280m/s to each of five
- 10000kg payloads. I don't know offhand what rendezvous+docking needs,
- and five payloads is somewhat arbitrary, but my gut reaction is that
- this ought to be adequate.
-
- That's a fully-fuelled tug plus an eight-man reentry vehicle in 10 tons.
- The reentry vehicle probably doesn't need to be that big, and we can
- get by with a minimally-fuelled tug if we must (the first payload
- includes a tank module for the tug), so there's margin. If worst comes
- to worst, we launch the tug separately and remote-control it long enough
- to r+d with the first payload, which is the reentry vehicle plus some cargo.
- Cut the fuel load in the tug a bit, and we can do that with a 5-ton launcher.
-
- >Maybe we can both agree that Ariane 5 is the closest real-world hardware to
- >what you want but is still sadly lacking.
-
- Actually, I think a (possibly somewhat souped-up) Atlas is the closest
- match in current hardware, and a bulk buy might get the costs down to
- something approaching practicality.
- --
- There is nothing wrong with making | Henry Spencer @ U of Toronto Zoology
- mistakes, but... make *new* ones. -D.Sim| henry@zoo.toronto.edu utzoo!henry
-