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SES-8 – Falcon 9 GEO Transfer Mission

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Re: SES-8 – Falcon 9 GEO Transfer Mission

#31

Post by arrrg »

jccooper wrote: post #21

Saw the 1st stage doing some RCS maneuvers right after separation, but they cut the camera away from that shot pretty quick so I couldn't see exactly what. They're not supposed to be trying to "land" this one, but I bet they're getting aero data in support of the F9-R. All in all, looks like a good launch. Can't wait to hear about the second burn, which was last flight's sticking point.

They turned it around to see when it falls apart if not re-lit but falling down the right way (engines first).

Re: SES-8 – Falcon 9 GEO Transfer Mission

#33

Post by tocomment »

unspecified wrote: post #26
aidos wrote: post #10

Velocity of 1.2km/s - rockets are just awesome.

As Randall Munroe says: But getting to space is easy. The problem is staying there. http://what-if.xkcd.com/58/

Edit: I'm going to try to rephrase this whole question since it got so unpopular. (I also said moon when I meant sun)

Lets say we fly a rocket up to earth sun L4 at a really slow speed. When we reach L4 we fire retro rockets to slow down as to not overshoot.

It seems to me that we never have to reach a high speed to stay in space at that point. The two bodies would be holding us there?

Is that correct? Is there a certain speed to fly out to L4 which uses less fuel than speeding up to 8km/s like you would need to stay in space orbiting earth?

Re: SES-8 – Falcon 9 GEO Transfer Mission

#34

Post by MrMeker »

tocomment wrote: post #33
unspecified wrote: post #26

Earlier quoted context omitted.

As Randall Munroe says: But getting to space is easy. The problem is staying there. http://what-if.xkcd.com/58/

Edit: I'm going to try to rephrase this whole question since it got so unpopular. (I also said moon when I meant sun) Lets say we fly a rocket up to earth sun L4 at a really slow speed. When we reach L4 we fire retro rockets to slow down as to not overshoot. It seems to me that we never have to reach a high speed to stay in space at that point. The two bodies would be holding us there? Is that correct? Is there a cer…

If you did that you would have a huge relative velocity to the Lagrange point. You'd shoot right past it unless you could kill all your relative velocity, which would mean you would have enough delta-v to achieve orbit anyway.

Re: SES-8 – Falcon 9 GEO Transfer Mission

#35

Post by tocomment »

MrMeker wrote: post #34
tocomment wrote: post #33

Earlier quoted context omitted.

Edit: I'm going to try to rephrase this whole question since it got so unpopular. (I also said moon when I meant sun) Lets say we fly a rocket up to earth sun L4 at a really slow speed. When we reach L4 we fire retro rockets to slow down as to not overshoot. It seems to me that we never have to reach a high speed to stay in space at that point. The two bodies would be holding us there? Is that correct? Is there a cer…

If you did that you would have a huge relative velocity to the Lagrange point. You'd shoot right past it unless you could kill all your relative velocity, which would mean you would have enough delta-v to achieve orbit anyway.

I updated my question to explain it better I think.

Re: SES-8 – Falcon 9 GEO Transfer Mission

#36

Post by InclinedPlane »

tocomment wrote: post #33
unspecified wrote: post #26

Earlier quoted context omitted.

As Randall Munroe says: But getting to space is easy. The problem is staying there. http://what-if.xkcd.com/58/

Edit: I'm going to try to rephrase this whole question since it got so unpopular. (I also said moon when I meant sun) Lets say we fly a rocket up to earth sun L4 at a really slow speed. When we reach L4 we fire retro rockets to slow down as to not overshoot. It seems to me that we never have to reach a high speed to stay in space at that point. The two bodies would be holding us there? Is that correct? Is there a cer…

It takes more speed to get high enough to reach an Earth-Moon lagrange point (L1 would be the closest, at about 90% of the Earth-Moon distance) than to simply get into Earth orbit.

Re: SES-8 – Falcon 9 GEO Transfer Mission

#38

Post by bane »

physcab wrote: post #27

I know HN readers have a love affair with SpaceX but my dad's company is launching a rocket on Thurs at Vandenberg and it should be fun to watch: http://www.noozhawk.com/article/atlas_v_set_for_launch_from_...

I'd also like to add that Orbital Sciences is another great space launch company that's often forgotten about. They're HQ is also on "Warp Dr.".

Re: SES-8 – Falcon 9 GEO Transfer Mission

#39

Post by dredmorbius »

pbosko wrote: post #25
latchkey wrote: post #24

Just curious, what is the purpose of the 4 towers around the launchpad?

Lightning rods

Trivia: Apollo 12 was struck by lightning, twice, after leaving the pad.

http://www.nasa.gov/offices/oce/appel/ask-academy/issues/vol...

This knocked out command module electrical systems, and it took some damned fast thinking from ECOM (electrical and environmental systems) who recalled an earlier incident and gave the instruction "SCE to AUX", resetting electrical systems.

Actual launch: http://fixyt.com/watch?v=eWQIryll8y8

Dramatization: http://fixyt.com/watch?v=TMYNy3JsHTE

Re: SES-8 – Falcon 9 GEO Transfer Mission

#40

Post by jccooper »

pvarangot wrote: post #22
jccooper wrote: post #21

Saw the 1st stage doing some RCS maneuvers right after separation, but they cut the camera away from that shot pretty quick so I couldn't see exactly what. They're not supposed to be trying to "land" this one, but I bet they're getting aero data in support of the F9-R. All in all, looks like a good launch. Can't wait to hear about the second burn, which was last flight's sticking point.

Here, look at the left frame at about 3:30. It looks like RCS maneuvers, some guy on reddit claims he saw a relight from his backyard but its not visible in the official video. http://youtu.be/cXEJLhAh-Kg?t=3m15s

A bit better. Yeah, that stage was working pretty hard on something. Hard to say but it may have been turning around, like the F9R would for its first retro burn. Some extra practice wouldn't hurt.
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