SpaceshipTwo crashes shortly after Mojave test flight • Hacker News Board

Re: SpaceshipTwo crashes shortly after Mojave test flight

#281

Post by robryk » Sat, Nov 01, 2014, 9:45 AM UTC

zepolud wrote: post #168

smackfu wrote: post #137

Earlier quoted context omitted.

Fair point, but the failure modes of flying seem to be more addressable than those of rockets. Like if the airplane engine is essential, add enough that you can tolerate a failure. If control surfaces are essential, add redundant systems. Whereas the failure mode of rockets tends to be exploding, and that's pretty hard to mitigate.

The failure modes of rocket engines could be explosions but nobody says you can't have multiple redundant engines on a single rocket. In fact, in 2012 Falcon 9 demonstrated exactly that: one of their 9 Merlin engines blew up but the rest redistributed the load and the rocket successfully delivered the payload to the ISS[1]. [1] http://blogs.discovermagazine.com/badastronomy/2012/10/08/sp...

According to the article you are quoting the engine didn't explode; it's just failed. I'd be very impressed if a rocket survived an explosion of one of its engines (they are much closer together than jet engines on a passenger plane and even i such planes an explosion of one engines can damage others due to shrapnel).

Re: SpaceshipTwo crashes shortly after Mojave test flight

#282

Post by stefanix » Sat, Nov 01, 2014, 10:18 AM UTC

marze wrote: post #69

mixmax wrote: post #23

What this weeks events show us is that space travel is hard. Really hard. Most systems operate in extreme conditions, sometimes bordering on the improbable. Thousands, sometimes millions of horsepower in an engine smaller than a car, cryogenic liquids at -200 degrees celsius cooling a nozzle that is 3000 degrees celsius 5 millimeters away, heatshields designed to absorb obscene amounts of heat, the list just goes on…

Some say this is an "inevitable" result of pushing boundaries. No. This is the result of a poorly managed program. What they are doing is much easier than the Apollo program, which was well managed and had no in-flight failures that resulted in loss of life, while accomplishing an infinitely harder task. This is a tragedy, obviously. But the program is about six years behind schedule, been going for 10 years. The mos…

Software development fuckups can be just as fatal as manned space flight. Software is actually the cause of many space flight accidents. To think of software as some isolated system that does not affect peoples' lives is absurd. It's critical in many areas and can fail with fatalities.

https://en.wikipedia.org/wiki/List_of_software_bugs

- radiation therapy machine kills 5 - clock drift in Patriot system caused 28 killed - Chinook helicopter killed 29 due to bug in engine control - Toyota's electronic throttle control system caused dozens of fatalities

Re: SpaceshipTwo crashes shortly after Mojave test flight

#283

Post by marze » Sat, Nov 01, 2014, 10:27 AM UTC

chris_wot wrote: post #278

marze wrote: post #275

Earlier quoted context omitted.

"Almost pointless" due to the vast differences in scale and complexity but still worthwhile, as a contrasting example of a solid safety culture employed by the Apollo engineering and operations teams. Although the Virgin 60,000 lbf rocket is small by the standards of Apollo, it is still an extremely challenging problem. There are no problem-free or inherently safe options, so safety needs to be engineered in from the…

If there are no inherently safe options, then that tends to preclude engineering in safety. I really don't think you know what you are talking about.

A propulsion system that was "inherently safe" wouldn't have dangerous failure modes. Although Virgin has tried in the past to paint their hybrid prolusion system as being "inherently safe", it isn't. No 60klb rocket engine is. To make any such system operate safely and reliably is a big engineering challenge. I think you don't understand the meaning of the term "inherently safe" in an engineering context.

Re: SpaceshipTwo crashes shortly after Mojave test flight

#284

Post by badname » Sat, Nov 01, 2014, 12:09 PM UTC

adamfeldman wrote: post #185

This is a time when you re-read Gene Kranz's famous speech to the flight control division after the Apollo 1 fire. Gene Kranz is the gentleman sitting in the flight director's chair in the Apollo 13 movie, wearing the white vest. He helped create the Mission Control organization at NASA. "Spaceflight will never tolerate carelessness, incapacity, and neglect. Somewhere, somehow, we screwed up. It could have been in de…

...and then it was Enterprise, Atlantis etc. No matter how tough and competent the organization is, failures cannot be eliminated when we are talking about so complex systems/operations.

Re: SpaceshipTwo crashes shortly after Mojave test flight

#285

Post by exDM69 » Sat, Nov 01, 2014, 12:54 PM UTC

marze wrote: post #270

vacri wrote: post #264

Earlier quoted context omitted.

Speaking of perspective, the Apollo was fully-backed by the government of the most powerful economy in the world at the time - 4% of the federal budget was directed towards it, with 34,000 NASA employees and 375,000 third-party employees, with a cost of ~$140B of today's dollars. How the hell is a private company supposed to compete? Not even Apple's famed $100B in cash could pay that bill. http://en.wikipedia.org/wi…

Another difference, the Apollo astronauts carried slide rules to do calculations during the mission.

They had slide rules in addition to the most sophisticated digital computers of the time. Both, in the spacecraft and on the ground.

Re: SpaceshipTwo crashes shortly after Mojave test flight

#286

Post by lotsofmangos » Sat, Nov 01, 2014, 1:03 PM UTC

marze wrote: post #243

termain wrote: post #215

Earlier quoted context omitted.

Aviation Week reported it back in May. So, yes. I'll keep an eye out for the accident report. http://m.aviationweek.com/space/new-fuel-boost-spaceshiptwo

Well you could be right, but it is very hard to imagine that being true since the plastic hybrid has only been tested once on the ground. Doing a flight test so soon would be totally insane. In any case, the disaster was undoubtably a result of inadequate ground testing. Problems like these are almost always the result of management pushing things faster than the engineering progress warrants.

Officials decided this spring to modify the space plane’s rocket motor to use a different type of fuel. Instead of burning a rubber-based fuel mix known as HTPB used on SpaceShipOne and SpaceShipTwo’s initial test flights, Virgin Galactic selected a new propellant grain known as polyamide which officials said offered improved performance.

“This was a new fuel formulation that had been proven and tested on the ground many times,” Mickey said in a press conference.

http://spaceflightnow.com/2014/10/31/virgin-galactics-spaces...

Re: SpaceshipTwo crashes shortly after Mojave test flight

#287

Post by lotsofmangos » Sat, Nov 01, 2014, 1:09 PM UTC

venomsnake wrote: post #115

sliverstorm wrote: post #92

Earlier quoted context omitted.

Some say this is an "inevitable" result of pushing boundaries. No. This is the result of a poorly managed program. Some of the boundaries that are being pushed are how much oversight, how meticulous, etc you have to be. In other words, how well you have to manage the program, how tight a ship you keep. Keeping a tight ship raises costs, and isn't the big emphasis of all this privatized space travel on reducing costs?

Costs are fixed. It is up to the culture to choose whether to pay in blood or treasure.

Well I'm going to pay in phone apps and home-made chocolate. I think you will do alright on the treasure, but you might find it hard to shift the blood.

Re: SpaceshipTwo crashes shortly after Mojave test flight

#288

Post by JabavuAdams » Sat, Nov 01, 2014, 3:14 PM UTC

marze wrote: post #69

mixmax wrote: post #23

What this weeks events show us is that space travel is hard. Really hard. Most systems operate in extreme conditions, sometimes bordering on the improbable. Thousands, sometimes millions of horsepower in an engine smaller than a car, cryogenic liquids at -200 degrees celsius cooling a nozzle that is 3000 degrees celsius 5 millimeters away, heatshields designed to absorb obscene amounts of heat, the list just goes on…

Some say this is an "inevitable" result of pushing boundaries. No. This is the result of a poorly managed program. What they are doing is much easier than the Apollo program, which was well managed and had no in-flight failures that resulted in loss of life, while accomplishing an infinitely harder task. This is a tragedy, obviously. But the program is about six years behind schedule, been going for 10 years. The mos…

This is two fatal accidents, so far. There was widespread speculation in the space community over Scaled Composite's seemingly blasé attitude to Nitrous Oxide, after their cold-flow test fatalities.

Re: SpaceshipTwo crashes shortly after Mojave test flight

#289

Post by JabavuAdams » Sat, Nov 01, 2014, 3:18 PM UTC

atlantic wrote: post #30

mixmax wrote: post #23

What this weeks events show us is that space travel is hard. Really hard. Most systems operate in extreme conditions, sometimes bordering on the improbable. Thousands, sometimes millions of horsepower in an engine smaller than a car, cryogenic liquids at -200 degrees celsius cooling a nozzle that is 3000 degrees celsius 5 millimeters away, heatshields designed to absorb obscene amounts of heat, the list just goes on…

> This is commendable, and is what drives the human race forward. Without these fearless men we wouldn't have gone to the moon. We wouldn't have explored the depths of the ocean. We wouldn't have flown the skies. That's one way of looking at the matter. Another is that without this untrammelled technological evolution (I hesitate to use the word "progress") we wouldn't be living through the greatest mass extinction e…

Boring.

Re: SpaceshipTwo crashes shortly after Mojave test flight

#290

Post by JabavuAdams » Sat, Nov 01, 2014, 3:23 PM UTC

revscat wrote: post #70

atlantic wrote: post #30

Earlier quoted context omitted.

> This is commendable, and is what drives the human race forward. Without these fearless men we wouldn't have gone to the moon. We wouldn't have explored the depths of the ocean. We wouldn't have flown the skies. That's one way of looking at the matter. Another is that without this untrammelled technological evolution (I hesitate to use the word "progress") we wouldn't be living through the greatest mass extinction e…

You are getting downvoted, but I actually agree with you. Space travel is awesome, but so is living, and right now we are not living in a way that is sustainable over the short term. Space travel is, for me, an anachronistic hold-over from people who grew up with Heinlein, Asimov, etc., but is not something that is realistic given the environmental situation. Realistically, any vehicle that is dependent upon currentl…

Fundamentally, we don't know where our resources would be best spent. We need to try all the things.

The biggest lever we've got right now is computation, so yeah maybe it would be more efficient to develop AI / IA first and then mass space travel, but we can't be sure.

Also, fundamentally we can accept a few billion deaths. That sounds and is grotesque, but it wouldn't be the end of humanity. I don't see how climate change kills us all in the next 100-500 years.