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2. The latest United States "space policy" declares that it will "deny access to space" to those players it deems hostile, which translates to pre-emptive attack on non-US space objects and their supporting ground infrastructure.

Western news dispatches from Moscow, reporting on Russian official complaints about the policy, stated that it asserted the right "to deny adversaries access to space for hostile purposes," and that it claimed the right (some say "tacitly") for the US to deploy weapons in space. Vitaly Davidov, deputy head of the Russian Space Agency, complained: "They [the US] want to dictate to others who is allowed to go there."

But the actual policy document makes no such claim and displays no such intent to "deny" access. The Russian anxiety, echoed on the editorial pages and in news stories around the world, is apparently based on some over-wrought page 1 stories in US newspapers, written by people too careless to actually read the original US document and subsequent official US government clarifications, or too eager to misinterpret it in the most alarmingly stark terms.

NASA is in the awful position of trying to pretend that Bush's lunar program is real. Congress isn't going to appropriate the money. Smart people aren't going to come to work on the program. The date is always a decade or two off. It's vaporware. So they futz around with stuff like this, lacking the money or capability to develop a new launch vehicle.

NASA barely has a manned launch capability. The Shuttles will be retired in three years, and the "Crew Exploration Vehicle" program is vaporware. The General Accounting Office was very critical of the program in 2006: NASA has attempted several expensive endeavors such as the National Aero-Space Plane, the X-33 and X-34, and the Space Launch Initiative, among others. While these endeavors have helped to advance scientific and technical knowledge, none have completed their objective of fielding a new reusable space vehicle. We estimate that these unsuccessful development efforts have cost approximately $4.8 billion since the 1980s." The original schedule called for contract award for the CEV in 2006 after the preliminary design review, but although a contract has been awarded, the PDR has been pushed back to 2008.

Originally, the CRV was supposed to fly in 2014. Unlikely at this point.

It's sad to note that the Big Gemini spacecraft, proposed in 1967 and mocked up by McDonnell Douglas, was intended to take 9 people to a space station in low orbit. If that had been built, reusing the Gemini technology (which was quite good), the US would have had a low-end crew vehicle. So NASA is now trying to replicate 1967 technology. But with the second team; who goes to work for NASA today?

Realistically, the US manned space effort ends in 2010.

Uh... no. The most powerful booster rocket engine being manufactured in the ex-USSR right now AFAIK is the RD-170 used in the Zenith and Sea Launch vehicles. Which were designed for Energia, which is more recent than the Shuttle. Those modified N-1 engines you were talking about, the NK-33, are a toy compared to them.

Uh... no. The most powerful booster rocket engine being manufactured in the ex-USSR right now AFAIK is the RD-170 used in the Zenith and Sea Launch vehicles. Which were designed for Energia, which is more recent than the Shuttle. Those modified N-1 engines you were talking about, the NK-33, are a toy compared to them.

Secondly, it opens up an arms race in space, with money thrown into space weapons research, testing, and bigger and heavier weaponry.

Why do people keep thinking this is new? It's not. The only new thing is that it's China doing it.

The USA successfully tested an anti-satellite missile over twenty years ago. And when I mean "successfully tested," I mean we did just what the Chinese did here: destroyed an actual satellite in actual orbit around the actual earth. And it wasn't something like NMD, where we had to test it a dozen times to get a single kill. There was one test, and it just worked.

The Soviets had a working anti-satellite program even earlier than that, basically big fragmentation warheads that they'd launch into a matching orbit and then maneuver into kill range of the target satellite. Seven interceptions. Hell, the Soviets even launched (unsuccessfully) an armed orbital battle station.

All of this was decades ago. So why the fears of opening up an arms race?

Secondly, it opens up an arms race in space, with money thrown into space weapons research, testing, and bigger and heavier weaponry.

Why do people keep thinking this is new? It's not. The only new thing is that it's China doing it.

The USA successfully tested an anti-satellite missile over twenty years ago. And when I mean "successfully tested," I mean we did just what the Chinese did here: destroyed an actual satellite in actual orbit around the actual earth. And it wasn't something like NMD, where we had to test it a dozen times to get a single kill. There was one test, and it just worked.

The Soviets had a working anti-satellite program even earlier than that, basically big fragmentation warheads that they'd launch into a matching orbit and then maneuver into kill range of the target satellite. Seven interceptions. Hell, the Soviets even launched (unsuccessfully) an armed orbital battle station.

All of this was decades ago. So why the fears of opening up an arms race?

Little Joe wasn't a strap on booster. It was a launch vehicle used to test the launch abort system on the Mercury.

In fact the Shuttle was the first us in the US of large solid boosters in the US.

Little Joe wasn't a strap on booster. It was a launch vehicle used to test the launch abort system on the Mercury.

In fact the Shuttle was the first us in the US of large solid boosters in the US.

Little Joe wasn't a strap on booster. It was a launch vehicle used to test the launch abort system on the Mercury.

In fact the Shuttle was the first us in the US of large solid boosters in the US.

Little Joe wasn't a strap on booster. It was a launch vehicle used to test the launch abort system on the Mercury.
Here is a good link to about the "Little Joe" http://www.astronautix.com/lvs/litlejoe.htm
The Little Joe is a long time favorite of scale model rocket builders.
They never used strap on boosters for Mercury flights. In fact the Shuttle was the first us in the US of large solid boosters in the US.
There where plans to us them with the X-20 and MOL but they where never flown.

So.
1. No they didn't use lots of stages in early rockets just to get into orbit they used about the same as they do now two or three. Well excluding the Jupiter-C that is.
2. They didn't use strap on boosters for the Atlas Mercury Flights.
3. The Little Joe wasn't a strap on booster.

CEV/Constellation is becoming our "traditional" launch system.

Hehe... no I don't. XCOR is keeping the numbers close to their chest. As they should... the numbers belong to NASA under contract. But you can back out a rough guesstimate since they gave you the thrust.

Here's a link to an old plan for Mars operations leveraging the ease of obtaining methane and oxygen on Mars.

Wasn't there something about the Iraqi Supergun?

from the link one of its key objectives:

As an anti-satellite weapon. It would launch a special shell in space that would explode near the target satellite, covering it with sticky material and blinding it.

The thing is much bigger than I expected. I would guess with a 2m radius and 4m height. It is quite fat, so I guess they are using spherical or ellipsoidal propellant tanks. The shape reminds me of the Kankoh Maru and the shell seems to be made of composites or plastic. I guess the blunt nose makes sense because the thing is suborbital and they do not have a wide cross range requirement like the Delta Clipper had.

I am not an expert, but the burn looked too clean, I guess it is a pressure fed mono propellant. Perhaps H2O2 (Hydrogen Peroxide) like someone else said. Much like what Carmack tried to do with Armadillo. I counted 3 x 3 = 9 thrust chambers in that setup.

The man requested someone with experience in cryogenic turbopumps. Even mentioned the RS-68 explicitly. So it seems to me he is going for a pump fed LOX/LH2 engine. It makes much more sense to me than the H2O2/Kerosene rumours I heard before. Why risk it all by going for an engine no one has built before? I mean the only rocket engine with that combo I remember is the one in the British Black Arrow rocket from the 70s. Beal killed himself by going with a risky H2O2/Kerosene combo and a filament wound shell.

A LOX/LH2 engine with a variable mixture ratio would do the trick. H2O2 is IMO overrated and finicky. LOX is cheaper than high purity H2O2 and has pretty good density. You have to go for LH2 if you wanna go orbital anyway for the ISP AFAIK (unless you use a lot of stages, which I guess is what they do not want).

The thing is much bigger than I expected. I would guess with a 2m radius and 4m height. It is quite fat, so I guess they are using spherical or ellipsoidal propellant tanks. The shape reminds me of the Kankoh Maru and the shell seems to be made of composites or plastic. I guess the blunt nose makes sense because the thing is suborbital and they do not have a wide cross range requirement like the Delta Clipper had.

I am not an expert, but the burn looked too clean, I guess it is a pressure fed mono propellant. Perhaps H2O2 (Hydrogen Peroxide) like someone else said. Much like what Carmack tried to do with Armadillo. I counted 3 x 3 = 9 thrust chambers in that setup.

The man requested someone with experience in cryogenic turbopumps. Even mentioned the RS-68 explicitly. So it seems to me he is going for a pump fed LOX/LH2 engine. It makes much more sense to me than the H2O2/Kerosene rumours I heard before. Why risk it all by going for an engine no one has built before? I mean the only rocket engine with that combo I remember is the one in the British Black Arrow rocket from the 70s. Beal killed himself by going with a risky H2O2/Kerosene combo and a filament wound shell.

A LOX/LH2 engine with a variable mixture ratio would do the trick. H2O2 is IMO overrated and finicky. LOX is cheaper than high purity H2O2 and has pretty good density. You have to go for LH2 if you wanna go orbital anyway for the ISP AFAIK (unless you use a lot of stages, which I guess is what they do not want).

The thing is much bigger than I expected. I would guess with a 2m radius and 4m height. It is quite fat, so I guess they are using spherical or ellipsoidal propellant tanks. The shape reminds me of the Kankoh Maru and the shell seems to be made of composites or plastic. I guess the blunt nose makes sense because the thing is suborbital and they do not have a wide cross range requirement like the Delta Clipper had.

I am not an expert, but the burn looked too clean, I guess it is a pressure fed mono propellant. Perhaps H2O2 (Hydrogen Peroxide) like someone else said. Much like what Carmack tried to do with Armadillo. I counted 3 x 3 = 9 thrust chambers in that setup.

The man requested someone with experience in cryogenic turbopumps. Even mentioned the RS-68 explicitly. So it seems to me he is going for a pump fed LOX/LH2 engine. It makes much more sense to me than the H2O2/Kerosene rumours I heard before. Why risk it all by going for an engine no one has built before? I mean the only rocket engine with that combo I remember is the one in the British Black Arrow rocket from the 70s. Beal killed himself by going with a risky H2O2/Kerosene combo and a filament wound shell.

A LOX/LH2 engine with a variable mixture ratio would do the trick. H2O2 is IMO overrated and finicky. LOX is cheaper than high purity H2O2 and has pretty good density. You have to go for LH2 if you wanna go orbital anyway for the ISP AFAIK (unless you use a lot of stages, which I guess is what they do not want).

The thing is much bigger than I expected. I would guess with a 2m radius and 4m height. It is quite fat, so I guess they are using spherical or ellipsoidal propellant tanks. The shape reminds me of the Kankoh Maru and the shell seems to be made of composites or plastic. I guess the blunt nose makes sense because the thing is suborbital and they do not have a wide cross range requirement like the Delta Clipper had.

I am not an expert, but the burn looked too clean, I guess it is a pressure fed mono propellant. Perhaps H2O2 (Hydrogen Peroxide) like someone else said. Much like what Carmack tried to do with Armadillo. I counted 3 x 3 = 9 thrust chambers in that setup.

The man requested someone with experience in cryogenic turbopumps. Even mentioned the RS-68 explicitly. So it seems to me he is going for a pump fed LOX/LH2 engine. It makes much more sense to me than the H2O2/Kerosene rumours I heard before. Why risk it all by going for an engine no one has built before? I mean the only rocket engine with that combo I remember is the one in the British Black Arrow rocket from the 70s. Beal killed himself by going with a risky H2O2/Kerosene combo and a filament wound shell.

A LOX/LH2 engine with a variable mixture ratio would do the trick. H2O2 is IMO overrated and finicky. LOX is cheaper than high purity H2O2 and has pretty good density. You have to go for LH2 if you wanna go orbital anyway for the ISP AFAIK (unless you use a lot of stages, which I guess is what they do not want).

Tin foil hat time.

You're right of course, the link to lostcosmonauts.com was a weak one, yet keep in mind that PBS took it seriously enough to run a show on the Ilyushin incident, which brings the ballgame to a higher level. BTW, correcting three mistakes of mine, proving that memory isn't as strong as a bit of research:
a) It's Ilyushin, not Ilushyn,
b) It was on PBS, but not on Nova, and
c) The show was run in 1999, not the early nineties.

Here's a stronger link: http://www.astronautix.com/astros/ilyushin.htm

The crew compartment was finished, its just that the test regimine called for an unmanned flight first.

The life support system was not installed and no software was installed on the CRT displays.

Flight 5 (3K1) - 1994 or 1995 - first flight of third orbiter. First manned flight; the third orbiter was the first outfitted with life support systems and ejection seats.

I was reminded of Gerald Bull, one of the great "mad scientists" of our day, and Project HARP. :) Check out the plume leaving the barrel of their research gun. That had to be quite something to see in person.

Of modern ballistic launch mechanisms, there are lots of neat options ranging from light gas guns to ram accelerators. I also find the concept of ballistically-launched scramjets to be pretty nifty. :)

Go for MOOSE short for "Man Out Of Space Easiest". Which may be "easy", but certainly would not be unscary.

The idea is to re-enter from orbit wearing nothing more than your space-suit, a foldable foam heat-shield, a small hand-held rocket-motor with sufficient trust to make you slow orbital speed until you touch the atmosphere (from which point air-friction does the rest)

After entering in your own personal 6-foot-diameter flaming fireball, you'd jettison the heat-shield, deploy the parachute and proceed from there.

Now *that* would be hell of a ride.

Okaaaay...How 'bout this?

It's called a rockoon, and it's been used since the earliest days of the space race.

http://www.astronautix.com/lvs/rockoon.htm

And risk another Otrag? No thanks.

The "intended" launch rate for the Atlas V and Delta IV was 20 vehicles per year. They are right now flying 5/year. The cost of the metal in the machines is not the issue. The Atlas V especially is a very simple machine with far fewer elements and components than an equivalent Falcon. Costs are in the people to support the missions and keep the machine alive through years.

I see you're not counting the development costs for the early ICBM days of the Atlas series. Encyclopedia Astronautica claims that part is another $2.23 billion in 1965 dollars. Using the GDP deflator, that becomes more than $10 billion in today's dollars. So total development cost is around $12 billion, assuming you're right about the Atlas I through V costs and those costs are in current dollars.

And while an Atlas V doesn't have as many engines as the Falcon V design would have, visual inspection of pictures indicates that the Atlas's engines are far more complex than the proposed Falcon 9 engine (or here for a CAD drawing). There's a lot less plumbing associated with SpaceX's Merlin engine meaning if SpaceX can maintain that level of complexity, they'll have an engine that is far easier to assemble than the RD-180 that the Atlas V uses.

The "intended" launch rate for the Atlas V and Delta IV was 20 vehicles per year. They are right now flying 5/year. The cost of the metal in the machines is not the issue. The Atlas V especially is a very simple machine with far fewer elements and components than an equivalent Falcon. Costs are in the people to support the missions and keep the machine alive through years.

I see you're not counting the development costs for the early ICBM days of the Atlas series. Encyclopedia Astronautica claims that part is another $2.23 billion in 1965 dollars. Using the GDP deflator, that becomes more than $10 billion in today's dollars. So total development cost is around $12 billion, assuming you're right about the Atlas I through V costs and those costs are in current dollars.

And while an Atlas V doesn't have as many engines as the Falcon V design would have, visual inspection of pictures indicates that the Atlas's engines are far more complex than the proposed Falcon 9 engine (or here for a CAD drawing). There's a lot less plumbing associated with SpaceX's Merlin engine meaning if SpaceX can maintain that level of complexity, they'll have an engine that is far easier to assemble than the RD-180 that the Atlas V uses.

they really should bring back Energia that can take up to 200tons of useful weight up in one piece.

Wow! It looks like it will be crowded on the moon with all of these bases:Japan, Russia, China. But lets face it folks. The only credible plans for lunar exploration are coming out of the USA. The rest are just angling to hitch a ride.

Imagine how great these new Apollo style capsules will be with 40 years of materials science improvements.

Alas, politics is the fountain of compromise, and compromise is the enemy of engineering.

Ion propulsion is too low thrust to solve the major problem IMO. The major problem IMO is getting off the Earth's surface into LEO for cheap. To do this, I believe the only reasonable alternatives, using presently known physics, are beamed propulsion, nuclear and space elevators/tethers.

Space elevators/tethers have basic material constraints which I doubt will be solved any time soon. Nuclear propulsion is possible but politically impractical. So that leaves beamed propulsion using, for example, lasers or microwaves.

Here: http://www.astronautix.com/articles/womspace.htm
Go thou and read, Read, READ.

So if you think some other woman got into space first, put up or shutup, She was and she was american.

The Soviet cosmonaut Valentina Vladimirovna Tereshkova was first, in 1963. Even if one doesn't remember her exact name, any of us nerds should know something of the history of the space program, like the fact that the Russians put a woman up there first.

Attempt to use BFG to get into orbit - mostly successful, damn politics though.
http://www.astronautix.com/articles/abroject.htm

While one should be skeptical that pressures as great as 12.50G let alone 20.00G would ever be experienced during space travel

While one should be skeptical that pressures as great as 12.50G let alone 20.00G would ever be experienced during space travel

The proposed bigger model, the Falcon 9-S5, is comparable to the modern Atlas V. 6 launches to date, 100% success rate. About 2x the price the new guys claim, but then, the Atlas is a proven product.

But the commercial launch market has collapsed. Iridium is done, and nobody wants to launch that many sats again. The geosync comsat market is saturated; everybody is going fibre optic. There's just not that much going up.

The proposed bigger model, the Falcon 9-S5, is comparable to the modern Atlas V. 6 launches to date, 100% success rate. About 2x the price the new guys claim, but then, the Atlas is a proven product.

But the commercial launch market has collapsed. Iridium is done, and nobody wants to launch that many sats again. The geosync comsat market is saturated; everybody is going fibre optic. There's just not that much going up.

Here's another way to view the math - if you start at standstill (i.e. v(0)=0) and expect to be moving at 11km/s at the exit of the tube, your average velocity is Vaverage = (v(exit) - v(0))/2 = 5.5km/s. Using this number you can calculate the time to traverse the launch tube: t = distance/Vaverage = 11km / 5.5 km/s = 2 seconds. You can also calculate the acceleration: a = v(exit)/t = 11km/s / 2 = 5.5km/s^2. So relative to 1 g = 9.8m/s^2, your launch system will require occupants and payload to sustain about 561 g's for the 2 second launch.

For electrical and mechanical payloads, that's achievable. Many small atmospheric-study payloads have been gun-launched to orbital altitudes, but on ballistic trajectories. Cited accelerations are on the order of 12000-14000 g's for very short durations.

For people and critters: pink goo.

Actually von Braun thought the Saturn V was a mildly interesting side road - his real interest was in reuseable shuttlecraft.

People keep repeating this, but it just isn't true. The Space Shuttle concept was an offshoot of the Dynasoar which was an offshoot of the Silbervogel (Silverbird). The Sibervogel was Eugen Sänger's baby, not Von Braun's

Von Braun actually believed that the Saturn V was the future to space access, and became a big believer in a Saturn V launched Orion. His idea was that the SatV would get the craft up there, then the Orion would take us to other planets.

If the Space Shuttle had been Von Braun's baby, then he wouldn't have resigned in protest when the government cancelled the Saturn V program.

In fact, NASA has (by-and-large) been following von Braun's Shuttle-> Station-> Moon-> Mars plan since the day it changed it's name from NACA.

This has always been NASA's vision as a whole, and has not had all that much to do with Von Braun himself.

Von Braun was working to make good on that vision, but he had his own ideas about how it should be accomplished. Most of them featured the Saturn V prominently.

Actually von Braun thought the Saturn V was a mildly interesting side road - his real interest was in reuseable shuttlecraft.

People keep repeating this, but it just isn't true. The Space Shuttle concept was an offshoot of the Dynasoar which was an offshoot of the Silbervogel (Silverbird). The Sibervogel was Eugen Sänger's baby, not Von Braun's

Von Braun actually believed that the Saturn V was the future to space access, and became a big believer in a Saturn V launched Orion. His idea was that the SatV would get the craft up there, then the Orion would take us to other planets.

If the Space Shuttle had been Von Braun's baby, then he wouldn't have resigned in protest when the government cancelled the Saturn V program.

In fact, NASA has (by-and-large) been following von Braun's Shuttle-> Station-> Moon-> Mars plan since the day it changed it's name from NACA.

This has always been NASA's vision as a whole, and has not had all that much to do with Von Braun himself.

Von Braun was working to make good on that vision, but he had his own ideas about how it should be accomplished. Most of them featured the Saturn V prominently.

Actually von Braun thought the Saturn V was a mildly interesting side road - his real interest was in reuseable shuttlecraft.

People keep repeating this, but it just isn't true. The Space Shuttle concept was an offshoot of the Dynasoar which was an offshoot of the Silbervogel (Silverbird). The Sibervogel was Eugen Sänger's baby, not Von Braun's

Von Braun actually believed that the Saturn V was the future to space access, and became a big believer in a Saturn V launched Orion. His idea was that the SatV would get the craft up there, then the Orion would take us to other planets.

If the Space Shuttle had been Von Braun's baby, then he wouldn't have resigned in protest when the government cancelled the Saturn V program.

In fact, NASA has (by-and-large) been following von Braun's Shuttle-> Station-> Moon-> Mars plan since the day it changed it's name from NACA.

This has always been NASA's vision as a whole, and has not had all that much to do with Von Braun himself.

Von Braun was working to make good on that vision, but he had his own ideas about how it should be accomplished. Most of them featured the Saturn V prominently.

Personally I think the company that will make the most headway and profit in space is the one which devises a way to get us there for much less per kg. Even the lightest space station weighs in the tons and at $20k/kg it's quite difficult to make a profit. There was a German company a while back that had some great ideas (http://www.astronautix.com/lvs/otrag.htm) but we need to make serious inroads here before space will *really* become profitable.

Hmm. A smaller version of MOOSE would almost do the trick for the reentry one. Would need a bit of avionics though.

(Goes off to look up old General Electric patents)

When did the Soviets land on the moon?

Not sure how much "less-efficent" the J-2 is.

http://www.astronautix.com/engines/ssme.htm
Manufacturer Name: RS-24. Designer: Rocketdyne. Developed in: 1972. Application: . Propellants: Lox/LH2 Thrust(vac): 232,301 kgf. Thrust(vac): 2,278.00 kN. Isp: 453 sec. Isp (sea level): 363 sec. Burn time: 480 sec. Mass Engine: 3,177 kg. Diameter: 1.63 m. Length: 4.24 m. Chambers: 1. Chamber Pressure: 204.08 bar. Area Ratio: 77.5. Oxidizer to Fuel Ratio: 6. Thrust to Weight Ratio: 73.1197829645898. Country: USA. Status: In Production. First Flight: 1981. Last Flight: 1998. Flown: 279 . Comments: Used in Shuttle Orbiter. Space Shuttle Main Engine. Staged combustion, pump-fed. Originaly specification was vacuum specific impulse of 455, but not achieved in the final design.

http://www.astronautix.com/engines/j2.htm
Manufacturer Name: J-2. Designer: Rocketdyne. Developed in: 1960. Application: . Propellants: Lox/LH2 Thrust(vac): 105,352 kgf. Thrust(vac): 1,033.10 kN. Isp: 421 sec. Isp (sea level): 200 sec. Burn time: 475 sec. Mass Engine: 1,438 kg. Diameter: 2.01 m. Length: 3.38 m. Chambers: 1. Chamber Pressure: 30.00 bar. Area Ratio: 28. Oxidizer to Fuel Ratio: 5.5. Thrust to Weight Ratio: 73.1801112656467. Country: USA. Status: Out of Production. First Flight: 1966. Last Flight: 1975. Flown: 87.
Used in Saturn IVB stage in Saturn IB and Saturn V, and Saturn II stage in Saturn V. Specific impulse and thrust is for final flight version; J-2 had a specific impulse of 418 sec/thrust of 90,700 kgf/mix ratio of 5.00 on LV's SA-201 through 203, and 419 sec/thrust of 102,040 kgf on SA-204 through 207 and SA-501 to 503. Sea level versions with reduced expansion ratio proposed for Saturn II first stage use. Upgraded toroidal aerospike versions (J-2T-200K and J-2T-250K) studies for upgrades to Saturn upper stages. Modestly improved J-2S was tested and provides basis for X-33 linear aerospike engine thirty years later. Proposed for use in Nova A-2; Saturn IVB; Nova NASA-3; Nova B-2; Saturn II; Jarvis-2; Saturn MS-II-1; Saturn S-II-8; Saturn S-IVC; Nova 60-8-3; Saturn S-II-C3; Saturn S-II-4; Saturn S-II. Saturn V S-ll & S-IVB Stage Engines, Saturn IB S-IVB. Upper Stage Engine. Gas generator, pump-fed.

Thier thrust to weight ratios are similar with the J-2 capable of a longer burn

Not sure how much "less-efficent" the J-2 is.

http://www.astronautix.com/engines/ssme.htm
Manufacturer Name: RS-24. Designer: Rocketdyne. Developed in: 1972. Application: . Propellants: Lox/LH2 Thrust(vac): 232,301 kgf. Thrust(vac): 2,278.00 kN. Isp: 453 sec. Isp (sea level): 363 sec. Burn time: 480 sec. Mass Engine: 3,177 kg. Diameter: 1.63 m. Length: 4.24 m. Chambers: 1. Chamber Pressure: 204.08 bar. Area Ratio: 77.5. Oxidizer to Fuel Ratio: 6. Thrust to Weight Ratio: 73.1197829645898. Country: USA. Status: In Production. First Flight: 1981. Last Flight: 1998. Flown: 279 . Comments: Used in Shuttle Orbiter. Space Shuttle Main Engine. Staged combustion, pump-fed. Originaly specification was vacuum specific impulse of 455, but not achieved in the final design.

http://www.astronautix.com/engines/j2.htm
Manufacturer Name: J-2. Designer: Rocketdyne. Developed in: 1960. Application: . Propellants: Lox/LH2 Thrust(vac): 105,352 kgf. Thrust(vac): 1,033.10 kN. Isp: 421 sec. Isp (sea level): 200 sec. Burn time: 475 sec. Mass Engine: 1,438 kg. Diameter: 2.01 m. Length: 3.38 m. Chambers: 1. Chamber Pressure: 30.00 bar. Area Ratio: 28. Oxidizer to Fuel Ratio: 5.5. Thrust to Weight Ratio: 73.1801112656467. Country: USA. Status: Out of Production. First Flight: 1966. Last Flight: 1975. Flown: 87.
Used in Saturn IVB stage in Saturn IB and Saturn V, and Saturn II stage in Saturn V. Specific impulse and thrust is for final flight version; J-2 had a specific impulse of 418 sec/thrust of 90,700 kgf/mix ratio of 5.00 on LV's SA-201 through 203, and 419 sec/thrust of 102,040 kgf on SA-204 through 207 and SA-501 to 503. Sea level versions with reduced expansion ratio proposed for Saturn II first stage use. Upgraded toroidal aerospike versions (J-2T-200K and J-2T-250K) studies for upgrades to Saturn upper stages. Modestly improved J-2S was tested and provides basis for X-33 linear aerospike engine thirty years later. Proposed for use in Nova A-2; Saturn IVB; Nova NASA-3; Nova B-2; Saturn II; Jarvis-2; Saturn MS-II-1; Saturn S-II-8; Saturn S-IVC; Nova 60-8-3; Saturn S-II-C3; Saturn S-II-4; Saturn S-II. Saturn V S-ll & S-IVB Stage Engines, Saturn IB S-IVB. Upper Stage Engine. Gas generator, pump-fed.

Thier thrust to weight ratios are similar with the J-2 capable of a longer burn

• The famous Mathematica report *was* rosy on the savings from a reusable craft, but that was hardly the extent of NASA's reports. NASA's cost figures changed as the design changed. The goal that Nixon wanted was all the needs of NASA and the Military for $8 billion a year or less.
• While NASA did a study into 20 tonnes of payload or more just before Nixon took office, it actually pushed heavily for 6 tonnes of payload, and low cross range ability.
• Fletcher rammed through the military's demands after Nixon appointed him head of NASA. At the same time, Nixon also told NASA to make due with 3.2 billion per year, of which only 1 billion could be spent on the shuttle.

Hmmm...Project Orion...he's so dreamy...

*rolls eyes*

You do know that Wernher Von Braun went along with the plan to launch an Orion on the Saturn V, right?

Von Braun was intially skeptical of the Orion design, thinking it to be a fanciful idea. However, after he witnessed the Putt-Putt test, Von Braun changed his tune. He was still enamored with his chemical rockets for liftoff, but he began to envision the Orion being used as interplanetary transportation. Thus the Mini Orion was born. If things had gone as planned, the Orion would have been the space transport of the future. Sadly, the Saturn V program was shut down before the plan could be fully executed, and Von Braun resigned in disgust.

Cargo weight to Earth orbit of Saturn V was about 259,000 lbs, of Shuttle about 60,000 lbs (excluding Orbiter weight -- we're talking cargo you can leave in orbit)

This is a pointless distinction to make when you're comparing engines and raw lift ability. The Shuttle lifts more mass to orbit despite a lower liftoff mass. Period, end of story. The details over what's cargo and what's ship are completely ancillary to this discussion.

Sure, Shuttle-derived cargo designs that use e.g. engine pods rather than an orbiter can rival Saturn V's lift to LEO -- but then Saturn V derived designs exist to put much larger payloads in orbit -- eg the Saturn V-D (a 1968 MSFC design) had a payload of 720,000 lb to LEO, and a couple of other S-V derived designs went to a million pounds to LEO.

Granted. However, none of those designs went into production. Instead they were funnelled into the tech that built the Space Shuttle. And if we're going to compare studies, there was also the Sea Dragon study which would have taken 550 tonnes to orbit. Until these are built, there's no way to tell if any of them would have actually succeeded.

In comparison, we already know that the all the shuttle components work and can carry well over the cargo capacity of the SatV. Designing an HLV based on the shuttle components is thus a no-brainer.

To be sure. And introduces many known issues of its own (parallel vs inline stack, problems of large segmented solid boosters, unexpectedly short lifespan of a high pressure engine, etc).

If it weren't those issues, there would have been others. The entire point is to keep gaining experience. What's interesting is that the CEV and HLV crafts will simplify and eliminate several of the issues inherent in the shuttle design. For example, the parallel stack is outright eliminated. Replaced with a fully inline stack. The SSMEs will be treated as either disposable or limited lifespan components. The SRBs will have the latest in NASA's sealing technologies. So on and so forth.

Yes, many of those have been overcome (although they're still working on the problems of a parallel stack), but then Shuttle has had over 100 more flights and nearly 20 more years of flight experience than Saturn V (114 vs 13 and 24 vs 5).

It's not like it's been idle in that time, though. The Saturn V taught us how to build high powered LHOx engines that don't oscillate like they're on Red Bull. It also taught us how to use computer control, staging, and gave us engineering info on power curves. But that was all very basic stuff. The Shuttle has taught us so much more. As long as we learn from it rather than running off to build the next pie-in-the-sky vehicle (I'm looking at you X-33), the experience is far from wasted.

A follow-on vehicle -- which is long overdue -- needs to combine the lessons and technology of both Saturn and Shuttle.

You're right here. We should be sitting on a shiny new rocket platform that is both more powerful and capable of anything we've built before. Unfortunately, the pie-in-the-sky platforms are very much what killed it. NASA research thought they could leapfrog the economic cycle of the common rocket and move straight on to unproven technologies. Unfortunately, it doesn't work that way. And now we're in a pickle because we need a new spacecraft in a hurry. "Project Constellation" (aka CEV Program) at least moves us forward. Perhaps not as fast or as well as we should have, but it will get the job done, it will get it done fast, and it will get it done right.

Personally I'd like to see more work done on SSTO, VTOVL and aerospike engines -- and have done ever since I read Bono and Gatland's book back around 1970.

I'm also a fan of SSTOs. Unfortunately, I don't think they're going to happen until there's a justifiable reason for developing one. The Space Shuttle was supposed to be an SSTO. It failed because it had to be upgraded to c

I think the most interesting example of military space was the USSR's Polyus orbital weapons platform:

http://www.astronautix.com/craft/polyus.htm
http://en.wikipedia.org/wiki/Polyus_spacecraft

The USSR launched this back in 1986, but it had a launch "accident" and was unable to successfully deploy.