Orion is back on - sorta.

[shadron]

Well, looks like Obama has gotten the political word. Orion is back on the budget, but the Constellation boosters aren't. Instead, Orion will used as an escape pod for the ISS.

Is this a win? I'm really wondering. This news story is obviously biased as the capsule prime is Martin Lockheed, and the plant is a stone's throw from here. Heaven knows we have a lot of contenders for a booster, but...

What do you all think?

http://www.denverpost.com/frontpage/ci_14878671?source=rss

 

[BenBurch]

Anything but an SRB-derived booster. That was a fool's errand in my layman's opinion.

 

[3point14]

Anything but an SRB-derived booster. That was a fool's errand in my layman's opinion.

Genuine question:

Why?

 

[BenBurch]

Genuine question:

Why?

1. Solid fuel elements must be utterly perfect - if there is a crack, burning will proceed into the crack and the consumption rate and hence thrust will rise unpredictably. Solid bits of fuel can break off and be expelled and will change the total impulse of the vehicle. Chamber pressures can rise to bursting point in such a failure. - And if this happens there is no credible method of thrust termination.

2. The internal acoustics of even a properly-running SRB can cause thrust oscillation that can be really bad for the payload.

3. Even when it works perfectly, they are hard to configure to provide an even thrust profile.

4. Fuel production is really hazardous.

 

[TsarBomba]

Instead, Orion will used as an escape pod for the ISS.

[/URL]

I guess that assertion is based on this quote from the original article:

The vehicle will be able to launch within the next few years, creating what the administration said is an American crew escape capability that will increase the safety of space-station astronauts, reduce U.S. dependence on foreign providers and simplify requirements for other commercial crew providers

.

I think that they are saying that the "escape pod" will be one of many uses for the Orion capsule. Indeed, if you can launch it up to the ISS so that you can attach it to the station, you can use it as a normal astronaut transport. Right now they use a Soyuz as the escape vehicle, but escape is certainly not it's primary use.

 

[ellindsey]

1. Solid fuel elements must be utterly perfect - if there is a crack, burning will proceed into the crack and the consumption rate and hence thrust will rise unpredictably. Solid bits of fuel can break off and be expelled and will change the total impulse of the vehicle. Chamber pressures can rise to bursting point in such a failure. - And if this happens there is no credible method of thrust termination.

2. The internal acoustics of even a properly-running SRB can cause thrust oscillation that can be really bad for the payload.

3. Even when it works perfectly, they are hard to configure to provide an even thrust profile.

4. Fuel production is really hazardous.

Let me add a few more:

5. Solid fuel boosters have terrible ISP compared to nearly any liquid fuel. They're good for producing a lot of thrust for a fairly short period of time, but not for running long enough to reach orbit at reasonable acceleration rates.

6. Solid fuel boosters are much less abort-friendly. Aborting a liquid-fuel rocket in flight results in a cloud of burning fuel and small, lightweight fuel tank fragments that decelerate quickly and are easy for the capsule to outrun with an escape rocket. Aborting a solid-fuel rocket results in a cloud of multi-ton chunks of solid fuel still burning white-hot, and heavy fragments of the massive steel rocket casing. Getting the capsule out of the debris field safely is difficult, and may have been impossible for significant parts of the Ares ascent profile.

 

[3point14]

1. Solid fuel elements must be utterly perfect - if there is a crack, burning will proceed into the crack and the consumption rate and hence thrust will rise unpredictably. Solid bits of fuel can break off and be expelled and will change the total impulse of the vehicle. Chamber pressures can rise to bursting point in such a failure. - And if this happens there is no credible method of thrust termination.

2. The internal acoustics of even a properly-running SRB can cause thrust oscillation that can be really bad for the payload.

3. Even when it works perfectly, they are hard to configure to provide an even thrust profile.

4. Fuel production is really hazardous.

Thanks!

 

[Beerina]

Yikes, now even the very quiet Neil Armstrong's giving him hell.

Prove to Obama he won't, in fact, lose more votes cutting social spending a fraction than devastating the NASA budget.

 

[Andrew Wiggin]

1. Solid fuel elements must be utterly perfect - if there is a crack, burning will proceed into the crack and the consumption rate and hence thrust will rise unpredictably. Solid bits of fuel can break off and be expelled and will change the total impulse of the vehicle. Chamber pressures can rise to bursting point in such a failure. - And if this happens there is no credible method of thrust termination.

2. The internal acoustics of even a properly-running SRB can cause thrust oscillation that can be really bad for the payload.

3. Even when it works perfectly, they are hard to configure to provide an even thrust profile.

4. Fuel production is really hazardous.

To add a few more:

Hard to throttle: the thrust you get is what you get. Once the engine is lit, there's no way to change any of the burn parameters. It burns till its done burning, and it gives as much thrust as it gives. If you needed just a little less thrust, too bad.

Entire engine has to be reinforced to take maximum chamber pressure, because the combustion chamber is both engine and fuel storage. Liquid fuel engines only reinforce the actual combustion chamber and store the fuel in tanks that are basically big metal balloons. Less metal in the engine means more metal in the payload.

Reliable fuel delivery at a decent price means somewhere out there a company is always making it, and storing it for you so you can have it when you need it. Launch delays mean storing it longer, and in greater quantities. Google 'PEPCON disaster' to see that this is a real threat, or 'PEPCON disaster video' if you just like to see things go boom.

A

 

[Dr. Trintignant]

4. Fuel production is really hazardous.

Indeed:

Aborting a solid-fuel rocket results in a cloud of multi-ton chunks of solid fuel still burning white-hot, and heavy fragments of the massive steel rocket casing.

Yeah, that too:


- Dr. Trintignant

 

[DogB]

Getting the capsule out of the debris field safely is difficult, and may have been impossible for significant parts of the Ares ascent profile.

The main problem with this was that for almost a minute after launch the aborted capsule would still be inside the fireball at the point where it needs to deploy its fragile and inflammable parachutes. Nasty!

The solution was to beef up the abort rockets but there was already a weight issue to contend with. IMHO the system was never going to work as advertised.

It believe that the true intent was to defray the cost of the 5 segment SRB to the Ares I project thus reducing the overall price of the Ares V. Unfortunately the two ends refused to meet in the middle.

 

[Jimbo07]

Everyone catch the speech?

...

There's a lot of vitriol around the web regarding the new vision laid out for NASA over the past couple of days. However, I'm going to go out on a limb and make a prediction.

From the wider lens of history, this administration won't be regarded as the administration that killed human spaceflight, but rather one that actually gave it a kick in the pants.

- If, in fact, Constellation was a poorly conceived and executed program, it is good that it is terminated
- I've read the claim that "private industry" can do better... well... now we'll see
- Certainly, low launch rate experimental government boosters were not doing the trick of opening up spaceflight
- Obama's speech touched exactly on the need for a Heavy-Lift booster.
- It touched on all of the technologies that have been raised as requirements for trips to Mars (propulsion, radiation shielding, in situ resource utilization, etc.)

It's bold and it's scary. I think at times (much like his political success with health care reform - merits of the bill aside), it will appear that this strategy will falter, but in the long run, I bet it will be just the thing to lead to success.

NASA astronauts haven't broken Low Earth Orbit in almost four decades! It's not like this vision can do any worse than all previous... Now, at least, if people have fortitude to follow-through (and it's not just America, as the ISS will become dependent on the international partners) there may be a genuine chance at going beyond LEO.