10 ms·
I know nothing about space - why are they doing tests, where the rocket could possibly explode or fail, with the payload on board?
by nateberkopec 10y ago
I know nothing about space - why are they doing tests, where the rocket could possibly explode or fail, with the payload on board?
- TylerE 10y agoThe payload is probably loaded in a clean-room type environment.
- yawz 10y agoThat was my first reaction. I thought they could create a dummy payload with the same dimensions and weight. But, then... unless the weight distribution of the payload is important.
- Klathmon 10y agoLoading the payload isn't a quick thing, it takes time and a lot of careful work to do. So doing it before the tests can save a lot of time and I'm guessing money.
- martindevans 10y agoLoading the payload also requires a load of work moving the vehicle about etc. If you want to be certain you didn't damage the vehicle in any way during all of that then you need to test again once the payload is attached. Of course normally a failure during a test would be something like minor thrust fluctuations - not a complete loss of vehicle and payload!
- fnj 10y agoUnderstood that mating the payload is a lot of work, but it is one hell of a lot less work than building a complete new payload.
- robryan 10y agoI think this kind of test is generally just looking at the performance of the engines. Certainly highly unusual for the rocket to explode as part of this kind of test.
- mayneack 10y agoMaybe they offer discounts to payloads on test flights
- 0xffff2 10y agoIt wasn't a test flight. The "hot fire" test is conducted on every rocket shortly before launch.
- manarth 10y agoAs an aside, when SpaceX do reuse a rocket for the first-time (I suppose you could describe that as a test-flight), they have apparently given SES a discount [1]. [1] http://money.cnn.com/2016/08/30/technology/spacex-rocket-reuse/ http://money.cnn.com/2016/08/30/technology/spacex-rocket-reu...
- ygra 10y agoSame reason anyone else does tests: Find potential and actual issues earlier than in production. The static fire they were doing is sort of a short integration / smoke (pun not intended) test whether the rocket as a whole (whether the payload is attached already depends on the customer; it reduces time between test and launch, though) works properly. Other tests are part of sort of a pre-flight checklist directly before launch and there have been launch scrubs due to issues at that point already. Every single engine is also fired for the full duration of the flight prior to installation in the rocket. There's a lot of testing, both in isolation and in integration with other components. The risk of the rocket exploding should actually reduce with each test. Note also that in this case the malfunction was most likely with the pad equipment, not the rocket, so not doing static fires would in this case probably just have meant that you'd have an explosion at launch time one day. EDIT: The static fire is more of a test for launch procedures, apparently: “The goal of the static fire is to provide a dress rehearsal for the launch team, culminating in a three second firing of all nine of the first stage Merlin 1D engines to validate the health of the rocket.” (https://www.nasaspaceflight.com/2016/09/falcon-9-explodes-amos-6-static-fire/ https://www.nasaspaceflight.com/2016/09/falcon-9-explodes-am...) Makes sense in that the rocket itself is tested quite a bit beforehand already.
- dmix 10y agoIs launch pad designed to take a hit like this? Or do you think it would have caused a lot of damage to Cape Canaveral.
- mitchty 10y agoUnlikely, it wouldn't be much of a launch pad if it couldn't handle failure modes for rockets (aka bombs with a hole in one end). Compare to this Saturn V launch. https://www.youtube.com/watch?v=DKtVpvzUF1Y https://www.youtube.com/watch?v=DKtVpvzUF1Y
- manarth 10y agoThe video points out two of the protection features, but they wouldn't do so well with a RUD. The tower features - the hold-down arms, etc - are painted with a sacrificial paint. The idea is that it's the paint that chars and burns, rather than the tower features. Then there's the water deluge system. In the video, the rocket and exhaust is clear of the tower, and the fires are out, within 30 seconds. Neither the sacrificial paint nor the water deluge are designed to handle long-duration fires from a RUD. After a 2014 Antares rocket failure, the launchpad at Wallops Flight Facility took 1 year and $15 million to repair [1]. [1] http://www.space.com/31412-virginia-launchpad-private-rocket-launches.html http://www.space.com/31412-virginia-launchpad-private-rocket...
- mabbo 10y agoThey do the tests to validate that this rocket won't turn into a cruise missile, headed for the nearest residential area. Not an impossible scenario. Lots of energy stored up in one of those rockets. Just like when we test software, they want to have everything as close to what they would expect on launch day as possible (2 days from now). All the stresses, the structure, etc. That means putting stage 2 and the payload on top of the main rocket before the test starts. They probably did a lot of tests before the payload was on board as well, and those didn't reveal whatever flaw has caused this issue. Yes, it sucks that the payload was lost but there will have been insurance to cover the loss. No human lives lost, no cruise missile scenario, no out of control fire... this is the best case scenario for a rocket failure.
- ygra 10y ago> They do the tests to validate that this rocket won't turn into a cruise missile, headed for the nearest residential area. In that case the rocket has a flight-termination system, though, which should activate as soon as it veers too far outside the planned/expected parameters of the flight.
- Gracana 10y agoThis discussion reminds me of the failure of the first Ariane 5 launch. The flight-termination system was activate erroneously, and the payload was not insured. Ouch. http://www.esa.int/esapub/bulletin/bullet87/cavall87.htm http://www.esa.int/esapub/bulletin/bullet87/cavall87.htm https://around.com/ariane.html https://around.com/ariane.html https://en.wikipedia.org/wiki/Cluster_%28spacecraft%29 https://en.wikipedia.org/wiki/Cluster_%28spacecraft%29
- twic 10y agoThat's not what happened - the rocket went out of control due to a software bug allowed by over-reliance on unit testing, and was quite properly deliberately destroyed. But yes, Cluster was run on the cheap, hence the use of the Ariane 5 test flight, and didn't have insurance.
- dr_zoidberg 10y agoThe Apollo 1 accident[0] was during a similar test (a "plugs out test", which tests the spacecraft independent of all the support systems on earth to verify that it works correctly on its own). The rationale behind all this tests is "better have a problem on the ground, where we can fix it, than have the spacecraft fail in space". If you get interest in this stuff, the HBO miniseries "From the Earth to the Moon" has an episode about Apollo1 (and the series as a whole, though slightly dated on the FX side, is amazing). [0] https://en.wikipedia.org/wiki/Apollo_1 https://en.wikipedia.org/wiki/Apollo_1
- dandelany 10y agoMy understanding is that it is up to the customer whether they want to integrate the payload before or after the hot fire test. Integrating before means higher chance of an incident like this, while integrating after means significantly longer turnaround between the hot fire and launch.
- nateberkopec 10y agoThanks, that's the answer I was looking for. Other commenters seemed to think I was asking why they test at all!
- robodale 10y agoWell, I know that In Space, No One Can Hear You Scream.
- WalterBright 10y agoBecause losing the payload amortized by the chance of its loss is less expensive than the 100% dead expense of a test rocket.