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Author Topic: NASA ATK CRS-8 launch in less than half hour! (obsolete)  (Read 933 times)

de_la_Nae

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See subject.

It's not a super sexy launch, but if you are awake go to https://www.nasa.gov/nasalive if you want to watch.
(let's hope this goes better than yesterday, where with less than 1.5 minutes to launch, a wayward aircraft entered the airspace, so they scrubbed and rescheduled. very frustrating)
« Last Edit: 12 Nov 2017, 04:31 by de_la_Nae »
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Case

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Re: NASA ATK CRS-8 launch in less than half hour!
« Reply #1 on: 12 Nov 2017, 04:00 »

See subject.

It's not a super sexy launch, but if you are awake go to https://www.nasa.gov/nasalive if you want to watch.
(let's hope this goes better than yesterday, where with less than 1.5 minutes to launch, a wayward aircraft entered the airspace, so they scrubbed and rescheduled. very frustrating)

Well f**k, why not - haven't watched a launch live since ... Columbia's first one in 81, I believe?

EDIT: Cute mission patch ...
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Case

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Re: NASA ATK CRS-8 launch in less than half hour!
« Reply #2 on: 12 Nov 2017, 04:11 »

"TEL is armed ..."


"Ssst ... Mike? Hey Mike! ..."

"What? Kinda busy here ..."

"What is TEL?"

"Telemetry, duh ..."

"And why do we arm it?"

"It's NASA, dude ...."

"So?"

"Sounds cooler ..."
« Last Edit: 12 Nov 2017, 04:18 by Case »
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Case

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Re: NASA ATK CRS-8 launch in less than half hour!
« Reply #3 on: 12 Nov 2017, 04:51 »

Hope you enjoyed too!

Sure did!

Wondering about the apogee/perigee difference after stage 2 separation: 300+ km/200 km - so going +/- 50 km in one rotation? Does the ISS have the same elliptical orbit?

If not - Can they still correct this to a circular orbit? (I mean: Sure they can, if they still have a thruster aboard the craft) Or are they simply so gung-ho about their orbital mechanics kung-fu that they figure they can complete the docking in the respective window of time?
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BenRG

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Re: NASA ATK CRS-8 launch in less than half hour!
« Reply #4 on: 12 Nov 2017, 05:31 »

Wondering about the apogee/perigee difference after stage 2 separation: 300+ km/200 km - so going +/- 50 km in one rotation? Does the ISS have the same elliptical orbit?

No, the ISS is in a ~300km circular orbit. However, because of the way orbital mechanics work, OA-8 will be travelling faster than the ISS and will thus be able to slowly match positions at apogee. The Cygnus freighter will then use its' main propulsion system to raise its perigee so that it is just below 300km whilst the apogee is just above 300km but the orbital period being identical to the ISS's orbit. So, relative to the ISS, OA-8 will be 'orbiting' the station at a distance of a few kilometres. Finally, the spacecraft will slowly move in to a distance of about 20m by limited use of its reaction control thrusters to slowly match apogee and perigee with the station. Once the spacecraft is close enough to the space station, its propulsion system is shut down and then it is collected by the station's remote manipulator arm (SSRMS) and towed to the Node 2 Nadir berthing port.

There are several reasons for using this method, one of the most important of which is that it avoids leaving the derelict Castor-60 upper stage floating about in the ISS's orbit. An elliptical orbit of this kind decays quickly, moving the debris out of the way. Another reason for targeting an orbit that is close to but not precisely similar to the ISS is that the exhaust plumes from the main engines would damage the ISS's solar panels and thermal waste radiators, so you want all main engine burns to be on a different orbital altitude so the particles disperse before long reaching the ISS.

"What is TEL?"

I would have thought that TEL is Transporter Erector Launcher. That's the big arm attached to the side of the of the rocket that swings back when it launches. It also supports the rocket when it is being rolled out from its assembly building to the launch pad and is used to lift the rocket up to vertical for launch.

Well f**k, why not - haven't watched a launch live since ... Columbia's first one in 81, I believe?

If you thought that was good, wait until you get a load of this!

« Last Edit: 12 Nov 2017, 05:46 by BenRG »
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Akima

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Re: NASA ATK CRS-8 launch in less than half hour! (obsolete)
« Reply #5 on: 17 Nov 2017, 13:47 »

I couldn't find TEL in this list of NASA initalisms and acronyms, but if BenRG is correct about the launcher arm (and Wikipedia says this), that could provide an explanation for the "armed" business other than the cool factor. There might be explosive bolts used to ensure a fast, clean detachment on launch, requiring a detonating circuit.

P.S. That video of the SpaceX launch/landing video is seriously cool!
« Last Edit: 17 Nov 2017, 14:11 by Akima »
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