Some intelligent decisions for future spacecraft (1 Viewer)

[Andrew Testa]

More for the space buffs, our corporate newsletter also cribbed the following, which is actually a very good thing. New requirements for crew safety and escape systems for all future spacecraft:

NASA Sets New Safety Standards for Future Spacecraft: NASA issued new safety standards for future space vehicles that will require crew escape systems and methods of aborting troubled launches -- features that were rejected by the agency as impractical or too costly for the existing fleet of space shuttles. The new guidelines were drafted to provide "the maximum reasonable assurance" that future mission failures would not automatically imperil the crew, according to NASA. As the agency pushes to resume operations of the grounded shuttles, officials added, its engineers will scour the guidelines for safety features that might be adapted to the three remaining spacecraft. "Crew survivability is critical, no matter what the system might be," said Allard Beutel, a spokesman for NASA. "These standards strengthen our commitment to safety by getting engineers, designers and everyone else involved in long discussions of crew safety and analysis . . . well before you ever turn the first screw."

The new standards are largely aimed at the development and production of future space vehicles, such as a proposed orbital space plane and the next generation of launch systems for long-distance space travel. They were made public about a month before the board investigating the Feb. 1 Columbia accident is expected to issue a final report that will include scathing criticisms of NASA's safety standards for the shuttles and its own recommendations for averting future catastrophes. According to the new NASA "Human-Rating Requirements and Guidelines for Space Flight Systems," future spacecraft should be designed to enable crews to make a rapid escape during pre-launch procedures and to abort a mission or make an emergency escape during the ascent.

Currently, it is impossible for astronauts to abort a launch or escape from the shuttle once the powerful solid rocket boosters ignite. The new regulations state that any flight termination system should include design features, such as "thrust termination," that allow sufficient time for "safe human escape prior to activation of the destruct system." "Crew escape systems are required on ascent, regardless of analytical risk assessments, due to the highly dynamic nature of the ascent flight regime and the increased likelihood of catastrophic, uncontainable failures," the regulations state. The new standards call for sufficient redundancy in flight systems so that no two mechanical failures or human errors during operations or in flight maintenance will result in "permanent disability or loss of life." There are also new standards for computer software, which NASA describes as an integral part of the overall space flight safety system.
"There is obviously no 100 percent guarantee, but the point is to try to build in as much safety as we can," NASA's Beutel said.

I'm very happy to hear this.

Andy

 

[Jack Briggs]

Same here.

One thing I really liked about the ill-fated, super-ambitious VentureStar SSTO design was that crew survivability was a major consideration. I also came across a story on the Internet about Sean O'Keefe seeking congressional approval to fast-track the OSP into service as soon as 2008. I'll post it here when I find it.

One thing's for sure: No matter what design is selected for OSP and no matter what vehicle eventually replaces the STS, there never again should be a manned spacecraft system with so many Criticality One components.

I think your bosses are slowly coming to the realization that extending the STS's service life to as long as fifty years total is wildly unrealistic (and irresponsible).

(It's going to be interesting when the CAIB releases its final report next month.)

 

[Mark Hedges]

I think it is critical that any program to replace the space shuttle have as few reusable components as possible. The craft should be concerned with taking the cargo (and crew, if neccesary) into space, and if there is a crew returning them safely. It should not be concerned with returning the vehicle intact. Reuseability in a spacecraft really makes little sense, except maybe politically.

 

[Andrew Testa]

Well, reusability makes a great deal of sense in a high volume environment, but none in a low volume one. If the wildly unrealistic flights per year original promised (as you pointed out, Mark) had actually been attained then economies of scale would have made a reusable a no brainer. Imagine having to throw away an aircraft after every flight. But for only a handful of flights, then expendables make much more sense. Even a hybrid would make more sense: such as a reusable capsule atop an expendable Atlas 5.

I feel the best and most economical approach is to aim for reusable SSTO (Single Stage to Orbit) vehicles. Staging adds a huge burden to getting into space, whatever the design. An SSTO would move us more towards the paradigm of a commercial aircraft: a single vehicle that can be reused with a minimal amount of maintenance. The technology to do this is still out of reach, but we can get our fingertips on it enough to start designing and testing what may be required. It won't be the next genration manned vehicle, but I hope to see it done in my lifetime.

Andy

 

[Lee L]

I agree that they should make a safer vehicle but is it realistic that they can eliminate all criticality one components so that any combination of 2 things can fail and not lead to the loss of the crew?

Also, going back to the Challenger, I've never understood why they did not make the crew cabin strong and its attachment relatively weak. At least that way in a catastrophic accident, the cabin would at least break free and not have to absorb all the stress from the rest of the orbiter breaking up. Still no guarantee of survival especially on reentry but certainly more that the current design.

 

[Jack Briggs]

Lee, the crew compartment was one of the last things to have been destroyed during STS-51L. If you will recall, it detached largely intact well after the ET and Orbiter exploded, rising still higher, arcing, and then plummeting into the Atlantic. Dick Scobee's emergency oxygen pack had been activated (by Judith Resnick, probably), as was Mike Smith's. The crew probably survived until the moment of impact with the ocean.

NASA is being much more silent regarding the crew compartment on Columbia, and, out of respect for its fallen heroes and their families, not going into much detail about the forensic aspects of STS-107 (you've read, of course, that the crew compartment remains are being stored separately from the rest of the Orbiter in the hangar).

But forensics evidence has played a significant role in the CAIB's work in determining the precise nature of the Orbiter's break-up sequence.

My point: The crew compartment is damn sturdy, and is, based on two catastrophic accidents, one of the last things to come apart.

 

[Andrew Testa]

Lee, the short answer to your first question is no. Crit one will always be with us. There will always be situations where a single failure leads to loss of vehicle and crew. No way around it.

Regarding the crew cabin, it just wasn't possible to design the entire cabin as a separate escape pod. While it is sturdy as a result of the pressurization requirement, there's no way to make it survive a separation, reentry, or landing without a huge hit on weight and space. Everything is a trade-off. Like it or not, cost and human survival have to be reconciled. Human survival at all costs is not achievable.

Latest word making the news is that Columbia's crew may have survived up to a minute after contact was lost. I've heard nothing here beyond that. Challenger's crew survived the entire incident, and were killed on impact with the ocean.

Andy

 

[Jack Briggs]

Crit One will always be with us, true, but I hope less so than in the current system. And one just cannot help but wonder what it was like in the crew cabin in that final minute of awareness of something having gone horribly wrong.

Yet note what their families are saying, almost in lockstep: The program must continue.

Reminds me of the line of text that ends journalist Robert S. Lewis's definitive history of the American manned space effort up to Apollo 11, Appointment on the Moon (1969):

"There may be many starts and stops in going forward, but there is no going back — and no forseeable end to such a beginning."

The mainstream media keep talking about Apollo having been the "golden age" of manned spaceflight. Jeez louise, people, we haven't even seen the golden age of space travel yet. The best is yet to come. And with the vastness of interstellar space potentially awaiting us as our destiny, each new step will be a new "golden age."