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A US military exercise to launch a satellite on short notice

arstechnica.com

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Re: A US military exercise to launch a satellite on short notice

#71

Post by dh2022 »

blauditore wrote: post #33
kimixa wrote: post #23

Earlier quoted context omitted.

No, not even close. The issue is simply exhaust velocity and reaction mass, that leads us into the tyranny of the rocket equation - in that you have to carry that reaction mass with you and accelerate that mass too. Even if you had magic infinite energy - e.g. it's supplied externally by a laser or similar. Using the theorized maximum of 31km/s exhaust velocity of project orion (much higher than any current high impu…

And why not accelerate using swing-bys on moons and planets? Of course this gets harder the faster you're already moving, but IIUC Voyager 1 has roughly 0.01% c, and this was launched 50 years ago.

Is there a short snd simple explanation for how these planetary slingshots work? To me the gravity that increases the vehicle speed on the way to the planet will decrease the speed on the way away. Thanks!

Re: A US military exercise to launch a satellite on short notice

#72

Post by jocaal »

wat10000 wrote: post #59
jocaal wrote: post #34

Earlier quoted context omitted.

Funny how people complain about federal debt, when the people complaining benefitted the most from the system. It is your children who will be paying the interest, while the older folk enjoyed a heated economy with high government spending. Economics is just as fundemental as physics. There are conservation laws that cannot be violated. However you can make other people hold the bag.

What are those conservation laws?

It's simple accounting. Net money in must be more than or equal to net money out when adjusting for any temporal changes in the face value of the assets. If you use more than you produce, either you are going to have to pay in the future, or in the case of the government, you can die and let your children pay.

Re: A US military exercise to launch a satellite on short notice

#73

Post by rcarr »

WarmWash wrote: post #10
ck2 wrote: post #4

Can we swap the US Military and NASA budgets for just one year please? Just one year It would be AMAZING Or even what we fund Israel's 2/3 of all their weapons are bought by US We'd have 10% speed of light probes going outside of solar system already Well at least Nancy Grace Roman L2 Telescope is launching, hope it goes perfectly

The military budget is a jobs program that also keeps a (near bare minimum) level of industrial capacity afloat. Its why no politician left or right is really interested in cutting it. If you browse open contracts, you'll see they that they overwhelmingly buy rather banal things and spend comparatively little on the "killing people" parts.

Here's a Ken Livingstone quote from the foreword of "Drama Games: For Those Who Like To Say No":

> In the early 1980s, when the GLC (Greater London Council) was trying to save and create jobs to mitigate the impact of Thatcher's recession, we discovered that the most labour-intensive form of public spending was the arts, and so during the five years from 1981 to 1986 we increased spending on arts and recreation from £l6 million to £160 million. Virtually every actor, painter, poet, sculptor and, in particular, community artist was in work, and it made London a much more exciting city to live in. As well as taking orchestras from the Royal Festival Hall to play in the canteen at Ford's Assembly Plant in Dagenham, we particularly tried to reach disaffected youth. It's against that background that I was able to understand Chris Johnston's book. (Oh, and by the way, if you want to know which is the least labour-intensive form of public spending, it is the military.)

Maybe if we stopped pushing insane amounts of money into fossil fuels and the military industrial complex, and instead redirected it into the arts and sciences then, just maybe, we might actually end up with a happier, more employed, more fulfilled, and more equal planet.

Re: A US military exercise to launch a satellite on short notice

#74

Post by akiselev »

somat wrote: post #62
senthil_rajasek wrote: post #26

Also,the mission to rescue the Swift telescope made news this week. Soon I'll be seeing a sign for a "Joe's Satellite Repair Service" shop right next to the local autobody shop. https://www.mos.org/article/space-news-deep-dive-saving-swif...

Here is a good video on the swift rescue mission. https://www.youtube.com/watch?v=Up0LNTMPnjI Pegasus to the Rescue: 'The Edge of Feasibility' (Alexander the ok)

I remember working with the Pegasus at Caltech in the early 2010s for a tech demo that was never going to launch.

I'm amazed it's still operational.

Re: A US military exercise to launch a satellite on short notice

#75

Post by dh2022 »

brookst wrote: post #69
dh2022 wrote: post #67

Earlier quoted context omitted.

As proven so well during this whole debacle in the Hormuz strait.

Hard to see that as an indictment of military capability when it is so overwhelmingly a reflection of political incompetence.

Hmmm, the US is not able to control the Hormuz strait. Iran decides who goes through it. Yesterday Iran shot at a vessel [0]. We can argue the semantics of “control” but I think this whole debacle showed the limits of US military power.

[0] https://www.npr.org/2026/06/26/nx-s1-5871963/un-agency-pause...

Re: A US military exercise to launch a satellite on short notice

#76

Post by wat10000 »

jocaal wrote: post #72
wat10000 wrote: post #59

Earlier quoted context omitted.

What are those conservation laws?

It's simple accounting. Net money in must be more than or equal to net money out when adjusting for any temporal changes in the face value of the assets. If you use more than you produce, either you are going to have to pay in the future, or in the case of the government, you can die and let your children pay.

There's no law of conservation of money. It can be pretty trivially created and destroyed. It may not be a good idea, but it's entirely doable.

Re: A US military exercise to launch a satellite on short notice

#77

Post by Schiendelman »

exe34 wrote: post #70
Schiendelman wrote: post #64

Earlier quoted context omitted.

If anything, we've been letting the killing parts languish dangerously for decades - to the point where we may not be able to defend our allies in a serious conflict.

Good thing you don't have that many allies left, so it should make the job easier.

Hopefully we elect a sane executive next election so we can start figuring out how to keep the executive from fucking over our allies. We can make a lot more of our partnerships with allies into ratchet mechanisms that are far less easily undone.

Re: A US military exercise to launch a satellite on short notice

#78

Post by kimixa »

dh2022 wrote: post #71
blauditore wrote: post #33

Earlier quoted context omitted.

And why not accelerate using swing-bys on moons and planets? Of course this gets harder the faster you're already moving, but IIUC Voyager 1 has roughly 0.01% c, and this was launched 50 years ago.

Is there a short snd simple explanation for how these planetary slingshots work? To me the gravity that increases the vehicle speed on the way to the planet will decrease the speed on the way away. Thanks!

It mostly works because the object you're sling-shotting with is moving relative to the initial origin of the probe - if you can line it up so the object is moving in the direction you want to accelerate in you can get it to "drag" your probe along a bit.

The end result is the probe isn't moving any "faster" leaving the slingshot object than it arrived from that object's point of view, but it may well be faster from the origin reference frame.

The thing is to remember that the bodies you're launching from, and then slingshotting against, are moving very fast relative to each other already. It's like throwing a bouncy-ball against a moving car - when it bounces off it may be moving faster relative to you than when you threw it, but it's actually a lower velocity relative to the moving car's reference frame.

Re: A US military exercise to launch a satellite on short notice

#79

Post by brainwad »

rcarr wrote: post #73
WarmWash wrote: post #10

Earlier quoted context omitted.

The military budget is a jobs program that also keeps a (near bare minimum) level of industrial capacity afloat. Its why no politician left or right is really interested in cutting it. If you browse open contracts, you'll see they that they overwhelmingly buy rather banal things and spend comparatively little on the "killing people" parts.

Here's a Ken Livingstone quote from the foreword of "Drama Games: For Those Who Like To Say No": > In the early 1980s, when the GLC (Greater London Council) was trying to save and create jobs to mitigate the impact of Thatcher's recession, we discovered that the most labour-intensive form of public spending was the arts, and so during the five years from 1981 to 1986 we increased spending on arts and recreation from…

This only works if you can force every state to do it, lest naive states be defenseless against those that don't disarm. But any such compulsion would be self-terminating, and thus unstable.

Why not just do it all? Fund the military and the arts and the sciences.

Re: A US military exercise to launch a satellite on short notice

#80

Post by JTbane »

zer00eyz wrote: post #24
ck2 wrote: post #4

Can we swap the US Military and NASA budgets for just one year please? Just one year It would be AMAZING Or even what we fund Israel's 2/3 of all their weapons are bought by US We'd have 10% speed of light probes going outside of solar system already Well at least Nancy Grace Roman L2 Telescope is launching, hope it goes perfectly

> Can we swap the US Military and NASA budgets for just one year please? It would be nice. There is a pretty well known interview of Admiral Grace Hopper by David Letterman, where she talks about her famous "nanosecond" and explaining (to Generals) why it takes so long to get a message to a satellite. https://www.youtube.com/watch?v=oE2uls6iIEU (As an aside, Grace was a name she lived up to in a way few others could,…

I hope I am not alone in thinking the military needs to be defunded in the USA. Nuclear weapons mean that there is zero strategic threat and any future wars will be regional. Drawdown of oversea bases is long overdue.
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