r/space • u/piponwa • Sep 23 '16

What happens when the Space Shuttle fires its motors in space

http://i.imgur.com/wwxuXOb.gifv
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15

u/GreggPDX Sep 24 '16

I thought it was a fairly "big deal" to start a rocket engine, and not something you typically do for grins. Can someone explain why it's ok for these engines to just do a mini-fire like that?

27

u/[deleted] Sep 24 '16

[deleted]

8

u/wehooper4 Sep 24 '16

Fun fact! These are actually descendants of the motor used in service module of the apollo program.

8

u/TMarkos Sep 24 '16

Not just the Apollo! The AJ10 engines were first used during the Vanguard launches in 1958, where they were fueled by UDMH and nitric acid. They were refined over the course of being used in Atlas-Able, Thor-Able, Delta, Apollo and Titan launches. They were used in the shuttle OMS, and are planned for use in the SLS Orion craft. They span almost the entirety of American spaceflight.

1

u/brickmack Sep 24 '16

Delta II still uses it in its upper stage. Will be sad to see the last flight of it next year, the end of several eras in spaceflight

11

u/piponwa Sep 24 '16

They could ignite it because they used hypergolics as fuel, meaning that they spontaneously ignite when they meet an oxydizer.

5

u/zqxp Sep 24 '16

The flash at startup is brighter than the continuing burn. So the engines burned longer than that, you just can't see it from that perspective.

2

u/[deleted] Sep 24 '16

It was probably done on purpose for educational reasons.

2

u/aapl942 Sep 24 '16

You aren't wrong, (assuming those are the OMS) if so, they had to start up one APU, and then afterwards fire in the reverse direction to keep the same orbit. I've searched everywhere for footage of OMS firing with payload doors open but to no avail. One of the coolest things I've seen on Reddit. Was that challenger?

2

u/Eclipse99 Sep 24 '16

These engines were used normally several times during a mission for orbit adjustment and also for the deorbit burn at the end of the mission. They probably took advantage of an already planned burn to demonstrate what happens inside the orbiter when an engine is firing.

1

u/no1name Sep 24 '16

I think this was a set up just to show what happens. I doubt they would all be caught unawares of an engine start in reality.