Some news on the NASA Front

[GT98]

Hmm K6-III is gonna like this one:

NASA Looking at resurrecting Apollo style capsules

[KRSESQ]

The study notes actual Apollo equipment would not be suitable for use, nor would its blueprints, because manufacturing techniques and equipment have changed significantly since the capsules were built in the 1960s. Rather, contractors could tap an extensive library of drawings, technical reports, test results and qualifications, as well as retired Apollo-era engineers, to design a derivative system.

(Dream mode on)

Now all they have to do is design a "dirivative" of the Saturn rocket to boost massive payloads.

(Dream mode off)

Kevin

[Dr Mordrid]

As noted in the article there are also major limitations to the capsule idea;

1. rougher re-entry because of higher G's than a winged spaceplane.

2. rougher "normal" landings than a spaceplane. Just ask the last Soyuz crew.

3. both 1 and 2 make capsules a poor choice if a crew member is sick or injured, which is not what you want in a "lifeboat".

4. limited payload capability for experiments, many of which may also be negatively affected by 1 & 2.

5. just using capsules doesn't necessarily guarantee launch safety ratio greater than the shuttles since all boosters fail; some with regularity.

About the only safety feature they add is the ability to use an escape tower rocket, and even they have problems. One major one is that a good escape depends on the main booster automatically shutting down when a failure mode is detected, which is unlikely if the problem is a catastrophic mechanical failure that results in an explosion

Dr. Mordrid

[Nowhere]

Dr Mordrid, but when something malfunctions, they're safier during reentry - though it isn't very comfortable then (espacially for wounded, as you pointed), but most probably they'll make it...

for example when once soyuz's reentry capsule didn't separated from service module - the whole thing performed much of its reentry facing completely opposite direction that it should - with hatch in front - yet (barely thought) the one who was in it survived...

and as for limited payload capability for experiments - you always have iss or (in case when you don't want to dock with iss/perform experiments there) you can for example launch two capsules which will form "mini space station" on orbit. but of course the problems with higher g's remain...

[RedRed]

closer to the Russian model in more than one way....

The Soyutz works! It has done for many, many years.... its relatively cheap to produce (less than the servicing costs of a shuttle, I would imagine!). The Russians tend not to develop a new system unless it necessary to develop a new system. The mish-mash of technologies which is the shuttle has probably done more to stunt the worlds drive into space than any disaster...

It looks like the shuttles will be a while before they rise again... and with the scrapping of the existing plans for the reuseable pod, there is no way to keep american presence in space, without hitching a ride with the Russians.... (embarrising). The Chineese will almost certainly be next to develop the tech. US pride (or national interest) should prevent China/Russia form dominating space !!!!

I would love to see a derivative of Saturn V comming back - but I doubt it... (China will have to build one though - if their plans for research stations on the moon in 40 years are to be possible....) What is the load of that big russian superlifter? is there not an Ariane variant planned with significant mass lifting capabilities?

this is one stage of the race where the US could loose....
I do think that some of the powers that be have lost REAL interest in whole challenge....

RedRed

[Dr Mordrid]

Safer duriung re-entry? As in the several examples of when a capsules heat shield has come loose, seals failed or any of the other problems both NASA and the Russians have had?

There is nothing magical about capsules other than they are cheaper and sometimes a simple one (Mercury for example) can do a ballistic entry without a guidance or electrical system (Coopers flight).

IMHO: NASA should take a long look at Rutans solution.

Dr. Mordrid

[Nowhere]

currently safer

I didn't hear about any major accident for a looong time - I guess the ones that are in use are pretty mature now.

[Brian Ellis]

Doc

If an SFBR (solid fuel booster rocket) fails during launch, there is NO WAY that it can be shut down, no way whatsoever. Once the fuel is lit, it stays alight until it is all burnt out. I've done some work with the Thiokol guys in Utah, who make the shuttle boosters and I know the chemistry of the fuel and how it is put in the casings and have seen small samples ignited. Incidentally, the hangar where the sections are fuelled have really ferocious emergency escape hatches for the workers. If one did take fire, I'd guess the guys would have less than 1 second to evacuate the building. I was told that only one person has tried using one of the hatches and broke both legs (which I can well believe), although I don't know whether the anecdote is true or simply village wisdom.

[MultimediaMan]

Good points here:

The Orbiter is/was a Horse designed by comittee: NASA didn't want SRBs (Solid Rocket Boosters) originially, but the budget precluded building liquid-fuelled boosters.

The Tiles were always a sticking point for the shuttle: Columbia had her tiles replaced three times before she flew into orbit for the first time...

As far as the Soyuz goes it is a good platform, but not a great one...a fair number of Cosmonauts have died in them...the total body count they will admit to is four, but some sources suggest there might have been more.

The biggest problem with Capsules is the problem that came up 10 days ago: They are not steerable. Mid Course corrections, even collision avoidance are simply not an option. Some Soyuz capsules ended up in lakes, upside down or took enough damage to need tools to open the hatch. Not good.

Rutan's Space plane, by Burt's own admission, is a purpose-built vehicle...it is a suborbital craft, not an orbiter. But the concept of using a conventionally-powered aircraft to get a space vehicle into position for orbital insertion has merit.

The problem with orbiters is the raw speed with which they need to attain orbit. You have to slow down somehow to get back home. You can do it by using drag (Like we do now), or you can expend a bunch of fuel and slow down to the point of near-freefall: this method, while safer from a structural standpoint, is expensive and risky in it's own way. Spacecraft designers have grappled for decades with materials vs. mass vs. fuel usage.

Obviously, they thought they had the materials problem licked, and really, they did. They just need now to make a more robust platform. One than can land in the rain. (Shuttles don't do Rain.)

[Dr Mordrid]

Brian;

I suggest NASA should take a long look at the concepts behind Burt Rutans X-Prize entry; SpaceShipOne

http://www.scaled.com/projects/tierone/index.htm

It's a 3 man space plane drop-launched from a dedicated launch vehicle (White Knight). This is a very viable alternative to ground boost. SPOne's engine is a hybrid SRB that can be shut down and re-started.

Fuel: HTPB (a rubber)
Oxydizer: NO2 (Nitrous Oxide)

Turning off the NO flow allows engine shutdown. Turning it back on comnbined with an internal igniter lighting up re-starts the engine. Lots safer than the alternatives.

It also has a unique re-entry profile: spiraling in with the wings rotated up like a shuttlecock, with most deceleration happening at high altitudes. This not only limits G loads but also makes SPOne self-aligning.

Rutan's supposed to start flight tests of SPOne early this summer. White Knight has already flown.

If this system works a scaled up version for ferrying a few astronauts might be just the ticket. Put in a smaller engine (just for retro-fire) and more seats and you have a crew return vehicle.

Dr. Mordrid

[MultimediaMan]

NASA's original dream for the Orbiters was to have a completely liquid-fuelled propulsion system. Unfortunately, the military stepped in and requested the orbiter be built large enough to deploy and retrieve surveillance satellites. This of course was a good thing because it meant more money for NASA, and the Hubble got built, too. But there were added problems: the SRBs got the nod after it became clear that they weren't going to have the money to build liquid-fuelled boosters capable of lifting that much mass.

A 100% liquid-fuelled shuttle would have been safer, and arguably, would not have resulted in the Challenger disaster nor the Columbia disaster. The acceleration curve of a liquid-fuelled spacecraft is much gentler than the SRBs.

It is nearly impossible to beat Liquid Hydrogen/Liquid Oxygen in terms of raw Thrust to Mass. SRBs are efficient because their mass tapers off so quickly, and they are vastly cheaper.

[Dr Mordrid]

Liquid fuels sound good and have a high specific impulse, but get leaks or turbopump failures and you have an explosion. Happens several times a year....just ask the folks running Ariane

Also; a high specific impulse isn't as important if you have a launch vehicle (White Knight, a B-52 etc.) doing the heavy lifting to a high altitude. This simplifies the requirements for the orbital insertion engine.

The problem with Colombia's damage from foam falling off the booster tanks was more due to enviro-wackos getting their way with a water soluble insulating foam than anything else. With the older "dirty" formulation this wasn't an issue since it adhered better and didn't have such a tendency to having internal bubbles and weak spots.

Dr. Mordrid

[K6-III]

Rutan's vehicle is suborbital.

Its peak velocity is about 1km/s, far less than the appx 8km/s you need for orbit. His only goal is to reach 100km, not to go to orbit.

Capsules make sense when flight rates are low. Reusables are only justifyable when the flight demands already exist.

Resurrecting Apollo would mean little, other than using existing aerodynamic data and cooling systems. Reworking the spacecraft would probably cost the same or more than just starting over.

Personally, I see many uses for a variety of capsules:

A small one man mercury-class capsule to be launched on the upcoming Falcon or Falcon-heavy booster from SpaceX. We could bring down passenger costs to under $10 million.

A two or three passenger gemini-class capsule to be launched on the Indian GSLV, which can take up 5000kg to LEO, well within range for a 3800kg Gemini capsule.

As for OSP, which is to be launched in 2010 and the EELV man-rated by 2012, that is a farce.

Private industry can do much better.

The trick is for a private company to design and build a capsule that can be pitched not only at NASA for use with the EELV's, but also at the Japanese with the H-IIA and the Europeans with the Ariane5.

I personally like the GSLV-gemini combination for an inexpensive way to get to ISS or send up tourists.

A GSLV currently costs $14 million. Assuming a 3 person capsule would cost about 60% of the booster, the total cost would be some $23 million. Dividing that by 3, one has a cost-per-passenger of about $8 million.

It'd probably end up costing about the same per passenger as the Falcon-mercury combo, but you could have two of the passengers be less trained on a 3 passenger capsule, making it a more feasible tourist vehicle.

Cost of development, however, would probably be much better for a Mercury-style ballistic capsule.

With Soyuz, they lost two vehicles. Soyuz 1 was lost because the chute didn't deploy. (launched vehicle even though it wasn't ready). The crew of Soyuz 11 was lost because the cabin depressurized and the cosmonauts weren't wearing space suits. Thereafter, they returned to a 2 cosmonaut configuration with pressure suits. It would not return to 3 until Soyuz TM.

If you want to read about Soviet coverups of losses in space, check out www.lostcosmonauts.com

Capsules are simpler than reusables. There are simply fewer systems to deal with. Your TPS can be a single peice ablater, for better reliability. You don't have wings and landing gear to worry about. And, on top of that, a capsule can land ballistic, while computer loss on a winged vehicle is not suvivable.

Reusables will have their day for orbital vehicles. Today just isn't that day. I hope that Space Island Group survives until that day, with their fusion of the best elements of Shuttle and Buran, as well as readily available parts from private industry superior to both.

As for suborbital, reusables are the only way to fly, unless you're the Rocket Guy, Brian Walker: www.rocketguy.com

He's currently building a one-man capsule and monopropellant 90% hydrogen peroxide rocket to take himself upto 100km in his back yard. He already has done some very interesting work, including the most powerful private centrifuge in the world.

[K6-III]

High specific impulse is always important for the upper stage of an orbital vehicle.

If one wants to build a liquid vehicle without a turbopump, the best way to go is pressure-fed, using a separate helium or nitrogen tank to pressurize the fuel tanks.

It means thicker and heavier tanks and lower ISP, but better reliability and cost.

Makes sense to make a big pressure-fed first and second stage, with a pump-fed third stage...

[K6-III]

Oh, and as for the latest Ariane5 ECA explosion, that was due to a faulty valve for coolant flow to the nozzle, leading to a deformation of the nozzle and the rocket flying off course.

Mission control was forced to explode the rocket.

The main problem with Shuttle is that it flies in a lateral configuration, which will always allow things to fall off and hit the sensitive TPS.