Griffin Favors Shuttle Solid Rocket Booster for Launching CEV

Space News ^ | 29 June 2005

[Magnum44]

Griffin Favors Shuttle Solid Rocket Booster for Launching CEV NASA Administrator Mike Griffin said Monday that he favors launching the proposed Crew Exploration Vehicle (CEV) on a single solid rocket booster based on the ones that for the past two decades have helped lift the space shuttle off the launch pad.

The so-called single stick approach, which refers to the use of a single solid rocket booster, has been touted by solid rocket maker ATK Thiokol as the safest and simplest solution to launching the CEV. The solid rocket would require an upper stage engine.

Boeing and Lockheed Martin, meanwhile, have been pushing their respective Evolved Expendable Launch Vehicles (EELVs) -- the Atlas 5 and Delta 4 respectively -- as the right choice for CEV.

Griffin has said on numerous occasions that he believes a shuttle-derived launcher is the right choice for the agency's heavy-lift needs -- lofting payloads weighing 100 metric tons or more on their way to the Moon or beyond. But on the issue of launching the CEV, which is expected to weigh 25 metric tons or so, Griffin had so far declined to show a public preference.

But in an interview Monday at NASA Headquarters, Griffin said that, all things considered, shuttle-derived looks to be best choice for both heavy lift and CEV.

"There would be a bunch of changes that would have to be made to the EELV to human rate it. I don't know that that would be the most fiscally sound path for NASA to go down, and frankly I don't know that the EELV community would welcome us getting into their production lines in order to make those kinds of modifications," Griffin said, "so all that would need to be thought through very carefully. Right now [the path] we think is the most favorable is the shuttle - derived path in part because it gives us the best work force transition issues."

Griffin said that given the likelihood that NASA will pursue development of a heavy lifter built from space shuttle components, the agency would have to keep Thiokol's solid rocket production line open anyway.

The single - stick approach also bodes well for ensuring safe operation of the space shuttle through the very last flight, he said. "You fly the last shuttle safely if the work force on the last shuttle feels there is a path to the future for them."

"All in all the best path for NASA appears to be the shuttle-derived approach," Griffin said.

A new U.S. space transportation policy issued by the White House in January requires NASA and the Pentagon to coordinate a joint recommendation on the nation's next heavy-lift launcher and leaves it to the president to decide.

[Magnum44]

Griffin has good arguments, inspite of it flying in the face of commercial launch development. The man rating issue is a big and expensive one. Solid rockets would be safer and less expensive, though less capable lift wise than liquid. But CEV may not need that much. Enjoy

[boris]

They worked so well on Challenger, too.

[Magnum44]

While the solid motor leaked on Challenger, it was the ignition of the liquid hydrogen that doomed that crew. had only the solid been present, the catastrophic failure would not have occurred. There is the issue of how to throttle back a solid if there is a problem. I defer to solid rocket motor experts to address this.

[jnaujok]

The booster worked fine. In fact, in a single-stick configuration, the booster would have flown to altitude. The problem was that the leaking o-ring was losing about 10,000 pounds of thrust. That, across a 30 foot lever-arm, applied about 300,000 foot-pounds of torque on a thin aluminum fuel tank. The tank ruptured and the hydrogen fuel hit a 5,000 degree flame cone. Boom.

In a single stick configuration, they would have more clearly seen the loss of power, and might have scrubbed the mission early on. On Challenger, the computer saw the 10,000 pound difference and just gimbaled the main engines to make up for it, thereby putting counter-torque on the fuel tank.

Frankly, having seen the burn-through vs temperature at launch graph, NASA should never have used the boosters at temperatures under 55 degrees. It was 22 degrees that morning. You figure it out.

[ariamne]

Could you add me to your NASA ping list?
thanks.

[Lx]

I believe that an Air Force study after the Challenger disaster stated that the Air Force expected a burn through or failure in 1 out of 50 launches! which was acceptable to them since there wasn't any human cargo. Obviously, we've gotten a much better failure rate.

Also, Aerojet offered their proposal to use one piece boosters which would have been made in a local plant in Florida which they would have built. The head of Nasa at the time I believe was James Fletcher from Utah so for some unknown reason, Morton Thiokils's multi segmented design was chosen. Morton Thiokil is/was in Utah.

[Magnum44]

they would have more clearly seen the loss of power, and might have scrubbed the mission early on.

This seems more your area than mine. So I will pose the question from earlier to you. In such a scenario, what options would a single stick crew have, since to my knowledge, you cant throttle back a solid motor?

[Magnum44]

I really don't have a ping list. There are some Space Ping lists out there and I am happy if someone picks this up on one.

Regards,

[Question_Assumptions]

Expect someone to bring up polution. They Hydrogen-Oxygen liquid rockets produce water. What do the solid booster pump out?

[Magnum44]

What do the solid booster pump out?

Nasty stuff, but they already do that under the current config, so its a losing argument.

[boris]

"The booster worked fine..."

Yeah, it only killed seven people.

[ariamne]

Oh, okay. thanks though for this story; I am reading everything I can on the Mercury/Gemini/Apollo missions and astronauts and anything related to NASA. What a fascinating and hopeful era that was for this country; an outstanding counterpoint to the smelly protesting traitorous hippies of the time.

[boris]

"While the solid motor leaked on Challenger, it was the ignition of the liquid hydrogen that doomed that crew."

I love this logic:

1. If a solid fails, it is the liquid's fault.
2. If a liquid fails, it is the liquid's fault.

I guess we should just abandon those dangerous liquid rocket engines!

--Boris

[Magnum44]

This has been explained to you twice now. If you have some personal beef here, say so.

[boris]

"This has been explained to you twice now. If you have some personal beef here, say so."

You have explained nothing; only made excuses for man-killers. How many people have liquid rocket engines killed?

--Boris

[RightWhale]

Solid boosters are a rough ride.

[wyattearp]

How many people have liquid rocket engines killed?

Ever heard of the ME-163?

[Phsstpok]

There is the issue of how to throttle back a solid if there is a problem.

As I understand it, you can't throttle a solid, particularly not the kind used on the STS.

But the counter to that supposed requirement is to ask how many times we've had the opportunity to throttle the Shuttle back as a way to deal with a problem? I believe the answer is none. I also believe that we've never used the "throttle back in case of a problem" in any manned launch that I can remember. Doesn't mean it hasn't happened, but I can't remember it.

We have had catastrophic failures, however. And in none of those cases would throttling back have been of any help.

I've always liked BDB. This sounds about as big and dumb as anything I've heard of. No moving parts whatsoever (OK, steerable nozzles, but nothing in the motor itself).

Of course, I also like the Rutan inspired T/Space proposal to build a man rated launcher to low earth rendesvouz with the CEV and having the CEV launched empty on something that therefore doesn't need to be man rated. They want to make a bigger, wingless, craft along the lies of Space Ship One and drop it from beneath a much larger version of the White Night carrier (or a modified 747). If we went with that approach we would instantly create a viable commercial human orbital launch capability.

I think it's an interesting proposal. It's even possible that Griffin is mentioning using Thiokol solids to forestall a lot of the arguments Boeing and the other big contracters might be ginning up against the T/Space proposal.

[BenLurkin]

http://www.atk.com/




http://chart.finance.yahoo.com/c/2y/a/atk

[BenLurkin]