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SpaceX launch webcast: Orbcomm-2 Mission [video]

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Re: SpaceX launch webcast: Orbcomm-2 Mission [video]

#101
post #5

Lots of eggs in this basket.

Yay! Successful egg deployment, as well as perfect basket landing :-) I can't stop smiling!

Hehe, me neither. This will be with me for days if not longer. I feel really terribly lucky. When I was 4 my dad got me out of bed to watch the moonshot and the landing, now many years later I get to watch the next real step in the humans-in-space saga.

Re: SpaceX launch webcast: Orbcomm-2 Mission [video]

#102

"Congrats @SpaceX on landing Falcon's suborbital booster stage. Welcome to the club!" Oy... someone needs to tell Bezos it's a whole different scale than what he did. https://twitter.com/JeffBezos/status/679116636310360067

He knows, but the public doesn't and he can say what he wants to twist the perception in his favor and give the impression that the feats were equally challenging. Not to remove any merit to Blue Origin's achievement, but it's nowhere near what SpaceX just pulled off.

The public that cares about this achievement (or Blue Origin's) likely understands the difference.

Re: SpaceX launch webcast: Orbcomm-2 Mission [video]

#103
post #50

I must have missed it, but can anyone explain why Orbcomm wants 11 satellites in the same orbit? The stage 2 engine isn't firing in between letting the satellites go.

Leo, they are so low they don't cover a whole lot of territory. The oribits may be at slightly different altitudes simply because of the inertia of the second stage, I really should have monitored that altitude indicator during the releases, were they identical?

Maybe there was a secondary thruster somewhere to provide some separation.

I went back and recorded the release speed (km/hr), altitude (km) for each drop:

25960 626

25954 627

25950 628

25944 630

25937 632

25935 632

A circular orbit at that height is about 29000 km around; 25 km/hour of difference between release 1 and 6 would give them a separation of 6 degrees longitude/day, or ~50 days until the faster satellites 'lap' the slowest one.

Not any sort of rocket scientist, but I gather the strategy with these kind of LEO satellites is to just throw a pile of them up there semi-randomly, and count on at least one being in the neighborhood when you want to talk to it.

edit: Last paragraph is wrong. See my comment two levels down for the answer.

Re: SpaceX launch webcast: Orbcomm-2 Mission [video]

#104

AMAZING THEY DID IT :) hah! Tears in my eyes here this is absolutely incredible to watch. I stayed up for this, I hope I didn't wake up the neighbours and it will take days to wipe the grin of my face.

I had to stay late at work to finish last tasks before my vacation time; I was worried I'll miss it, but I managed to tune in just few minutes before the landing. I have a huge grin on my face that won't go off easily. I've been waiting for this moment for a long time, and I'm going to be an insufferable person tomorrow, yelling to everyone in the earshot about it!

EDIT: To quote my friend's reaction,

"HAPPY FEET, WOMBO COMBO!

Let's Kerbal the shit out of Space."

Re: SpaceX launch webcast: Orbcomm-2 Mission [video]

#107

"Congrats @SpaceX on landing Falcon's suborbital booster stage. Welcome to the club!" Oy... someone needs to tell Bezos it's a whole different scale than what he did. https://twitter.com/JeffBezos/status/679116636310360067

"Welcome to the club"? Wow, that was classless. What Blue Origin did was impressive, but it was utterly trivial compared to what just happened with this flight.

Really, 'classless'? The achievement is landing a space-capable booster vertically, after an actual mission above 100km, which can then be reused. And, Blue Origin managed that first, no two ways about it. I think it's probably pretty classless to imply that what Blue Origin managed to do was 'trivial'. Just because SpaceX is the current hacker's favourite, doesn't mean you have to downplay everyone else. I think Musk's tweet about the difference between 'space' and 'orbit' was actually pretty pointless hair-splitting. Now, you can get technical and say that the achievement is landing a booster that is part of an orbital launch system but really, what the rest of the system does has no real part to play in the landing of the rocket stage, and I think everyone else understands that.

Re: SpaceX launch webcast: Orbcomm-2 Mission [video]

#108

Earlier quoted context omitted.

Leo, they are so low they don't cover a whole lot of territory. The oribits may be at slightly different altitudes simply because of the inertia of the second stage, I really should have monitored that altitude indicator during the releases, were they identical?

Maybe there was a secondary thruster somewhere to provide some separation. I went back and recorded the release speed (km/hr), altitude (km) for each drop: 25960 626 25954 627 25950 628 25944 630 25937 632 25935 632 A circular orbit at that height is about 29000 km around; 25 km/hour of difference between release 1 and 6 would give them a separation of 6 degrees longitude/day, or ~50 days until the faster satellites…

The satellites themselves usually have small thrusters but I'm not sure what kind of orbital change the can effect, usually they are there for detailed maneuvering and to boost the satellite to a slightly higher orbit as it decays. When it runs out of fuel it dies so you'd try to use as little of that as possible during launch.

Re: SpaceX launch webcast: Orbcomm-2 Mission [video]

#109
post #100

Earlier quoted context omitted.

http://www.space.com/21386-spacex-reusable-rockets-cost.html ~75%.

The money quote: > Musk said that a rocket's first stage accounts for three-quarters of its total price tag, so a vehicle with a reusable first stage can be produced at far less cost — assuming the hardware is fully and rapidly reusable. ~75% savings seems like a "best case scenario" number.

Good enough for me. Even if it is only 25% in practice they'll own the market.

Re: SpaceX launch webcast: Orbcomm-2 Mission [video]

#110
post #27

Earlier quoted context omitted.

Completely amazing! I'm sure I heard a "holy shit" or two there in the audience. :) EDIT: One question for the rocket scientists here: exactly how reusable do they expect these returned first stage rockets to be? What is the process of certifying that a returned rocket is fit to fly, and what components are most likely to need repairing/replacing with each launch?

NARS but probably comparable to shuttle engines and body.

The shuttle's main engines were extremely high-performance. They were marvels of engineering but required a lot of work between flights. Just like cars can be optimized for performance or reliability (think Honda Civic versus Ferrari) rocket engines can be made more maintainable and tolerant to long use periods. Not saying Spacex engines are Hondas, but they are probably way less trouble than SSMEs.
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