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SpaceX launches first U.S. national security space mission

reuters.com

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Re: SpaceX launches first U.S. national security space mission

#51

Post by meepmorp »

xvilka wrote: post #49
Phlarp wrote: post #38

Earlier quoted context omitted.

Civilian use is wide yes, but this is only because it is provided for free by DoD. None of those uses would be economically viable if they had to bear the costs of developing, launching and maintaining the system. Keeping track of the boats and missiles pays the bills. Everything else is just a happy accident of zero marginal use cost.

Galileo GNSS proves you wrong, since initially was designed primarily for civilian use.

Galileo’s being primarily civilian in focus has no bearing on GPS’ main purpose. GPS is a US system, funded and directed by the military.

Re: SpaceX launches first U.S. national security space mission

#52

Post by xvilka »

meepmorp wrote: post #51
xvilka wrote: post #49

Earlier quoted context omitted.

Galileo GNSS proves you wrong, since initially was designed primarily for civilian use.

Galileo’s being primarily civilian in focus has no bearing on GPS’ main purpose. GPS is a US system, funded and directed by the military.

You are right, but it proves that GNSS system can be civilian primarily and would be still feasible.

Re: SpaceX launches first U.S. national security space mission

#53

Post by InclinedPlane »

5436436347 wrote: post #11
_0w8t wrote: post #9

SpaceX had to use a fully expendable Falcon for this launch. What makes a GPS satellite so heavy?

Two things: 1. A GPS satellite is in a very high orbit compared to LEO, and so all stages were requested to burn to completion, to ensure the satellite has enough margin to reach that orbit. 2. The second stage ends at a ~800 km orbit, while the satellite itself needs to increase this to ~12,000 km (I'm rounding these numbers). The sat has to carry enough on-board propellant to raise it's orbit that much which necess…

3. USAF requires the upper stage do a deorbit burn to avoid long lived high altitude space debris.

Re: SpaceX launches first U.S. national security space mission

#54

Post by enraged_camel »

xvilka wrote: post #52
meepmorp wrote: post #51

Earlier quoted context omitted.

Galileo’s being primarily civilian in focus has no bearing on GPS’ main purpose. GPS is a US system, funded and directed by the military.

You are right, but it proves that GNSS system can be civilian primarily and would be still feasible.

Nice goal post moving.

Re: SpaceX launches first U.S. national security space mission

#56

Post by peter303 »

briandear wrote: post #7
sneak wrote: post #4

How is an upgraded GPS satellite a “national security” mission? Yes, I understand that precise and reliable global navigation is essential to fighting wars and guided weapons, but such uses pale in comparison to the billions of people who rely on GPS every day to do non-war, non-USA stuff. It is neither national nor security. Or do they just mean “in the role of defense contractor”?

The reason GPS came to exist is because of the US military. That billions use it now for other purposes is a happy side effect. Also it is very much “national” as the US taxpayer pays for the GPS system billions of people use for their non-war, non-USA stuff. And it’s definitely security because if that GPS system were to go down, there’s be a serious and immediate economic effect. Protecting and improving GPS is eve…

My neice once missed work when her phone broke and she hadnt learned they way there. I imagine there would be thousands if not millions in a similar situation should GPS go down.

Re: SpaceX launches first U.S. national security space mission

#57

Post by burfog »

xvilka wrote: post #49
Phlarp wrote: post #38

Earlier quoted context omitted.

Civilian use is wide yes, but this is only because it is provided for free by DoD. None of those uses would be economically viable if they had to bear the costs of developing, launching and maintaining the system. Keeping track of the boats and missiles pays the bills. Everything else is just a happy accident of zero marginal use cost.

Galileo GNSS proves you wrong, since initially was designed primarily for civilian use.

Galileo GNSS is publicly justified as being primarily for civilian use.

Navstar-GPS works fine though, so there must be some other reason.

Possibilities: military use, jobs program, pride, etc.

Re: SpaceX launches first U.S. national security space mission

#58

Post by ChuckMcM »

More importantly it is SpaceX's 21st launch of the year. Making 2018 the year with the most launches ever. One of the things that contributes to this is a stock of 'previously flown' boosters that allowed for more launches without having to build more engines and boosters. As the cadence improves the financial picture for SpaceX only gets better as far as I can tell.

Re: SpaceX launches first U.S. national security space mission

#59

Post by gameswithgo »

dlgeek wrote: post #48
trhway wrote: post #6

no employee protests against DOD projects :)

Not going to happen with SpaceX. Their work force skews very conservative/nationalist. They used to chant "USA! USA!" during every successful launch - you can hear it on their old webcasts. I think this got some media attention a while back and they mostly stopped for the more recent launches.

I would have chanted USA USA along with them but would never vote for a conservative American political candidate (at present)

Re: SpaceX launches first U.S. national security space mission

#60

Post by elihu »

pilsetnieks wrote: post #45
the8472 wrote: post #39

Earlier quoted context omitted.

> while the satellite itself needs to increase this to ~12,000 km (I'm rounding these numbers). The sat has to carry enough on-board propellant to raise it's orbit that much which necessarily increases it's wet-weight due to the rocket equation. Looks like they use a liquid fuel thruster lift it to its final orbit[0]. Some other missions have used ion engines for orbit raising[1]. I wonder why that wasn't incorporate…

Ion engines still need propellant, you might be thinking of the so far unproven EM drive.

Ion engines need propellant, but they need a lot less of it to achieve a similar result as a traditional rocket engine.
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