Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Unmanned U.S. Air Force space plane lands after secret, two-year mission

reuters.com

Post reply on HN
Print view View original

141–150 of 177 posts

Re: Unmanned U.S. Air Force space plane lands after secret, two-year mission

#141

Post by daemin »

rocqua wrote: post #134
pavement wrote: post #131

Earlier quoted context omitted.

Kinetic impactors are not missiles. Repeat: Kinetic impactors are not missiles. https://en.wikipedia.org/wiki/Kinetic_bombardment These are not things that get fired. You don't launch them. They don't follow a trajectory. They might just travel straight down from a geostationary orbit, depending on implementation. Yes, a guidance package might be necessary (depending on target discrimination, and precision, which in…

> They don't follow a trajectory. They might just travel straight down from a geostationary orbit That's not how orbiting works. If you want your projectile to travel straight down, you need to cancel all it's orbital velocity. For geostationary orbit, that's 3km/s of delta V needed. Obviously, you can de-orbit with less delta-V, but then guidance starts becoming necessary. > The slug is simply released with no indic…

I am wondering, what kind of impact would the wind have on these projectiles? Or even on ballistic missiles?

I would imagine a nuke having such a large explosion that missing the target by a kilometre won't matter too much. But with a kinetic projectile that kind of deviation would not be acceptable (unless we are talking about seriously big projectiles, like in Tunguska etc).

Re: Unmanned U.S. Air Force space plane lands after secret, two-year mission

#142

Post by shortsightedsid »

sytelus wrote: post #138

So why are they publishing this super secret mission with photo containing people wearing hazmat suit? This doesn't look like a leak, it's full blown press release!

It's a form of propaganda. Release just enough information to pip curiosity and speculation. Then call the rest of it classified. For all you know it could be having a dummy payload but call it classified and the bad guys would think that it has some advanced technology.

Re: Unmanned U.S. Air Force space plane lands after secret, two-year mission

#143

Post by iaskwhy »

joshschreuder wrote: post #80
tammer wrote: post #20

Surprised nobody's mentioned this possibility as it usually comes up re: the X-37B. Terrifying but I think not out of the question given the strategic potential of such a weapon. https://en.wikipedia.org/wiki/Kinetic_bombardment

> During the Vietnam War, there was limited use of the Lazy Dog bomb, a steel projectile shaped like a conventional bomb but only about 1" long and 3/8" diameter. A piece of sheet metal was folded to make the fins and welded to the rear of the projectile. These were dumped from aircraft onto enemy troops and had the same effect as a machine gun fired vertically.[3][4] Observers visiting a battlefield after an attack…

Adding to this: all war is utterly terrifying. People like to pretend it's not but it is. It's not "only" soldiers being killed in all crazy ways but other people being killed, raped, tortured, etc. Babies included like when the Japanese would throw them in the air and let them fall on their katanas. That's reason enough to avoid war.

Re: Unmanned U.S. Air Force space plane lands after secret, two-year mission

#144

Post by tomdz »

pavement wrote: post #131
nradov wrote: post #111

Earlier quoted context omitted.

No that's all wrong. Firing a missile from orbit has less surprise value than firing from a submarine because satellites can't hide. There's no difference in kinetic effects; a non-nuclear ballistic missile can hit just as hard at a lower cost (do the math). A kinetic projectile launched from a satellite is no harder to intercept than a ballistic missile in the terminal phase, and satellites themselves are highly vul…

Kinetic impactors are not missiles. Repeat: Kinetic impactors are not missiles. https://en.wikipedia.org/wiki/Kinetic_bombardment These are not things that get fired. You don't launch them. They don't follow a trajectory. They might just travel straight down from a geostationary orbit, depending on implementation. Yes, a guidance package might be necessary (depending on target discrimination, and precision, which in…

>They don't follow a trajectory. They might just travel straight down from a geostationary orbit

So you're just going to target the equator then?

Re: Unmanned U.S. Air Force space plane lands after secret, two-year mission

#145

Post by josefresco »

tammer wrote: post #20

Surprised nobody's mentioned this possibility as it usually comes up re: the X-37B. Terrifying but I think not out of the question given the strategic potential of such a weapon. https://en.wikipedia.org/wiki/Kinetic_bombardment

"Rods from God" - spent way too much time on Friday on Wikipedia reading about these, and other Kinetic concepts.

Re: Unmanned U.S. Air Force space plane lands after secret, two-year mission

#146

Post by pc86 »

tomdz wrote: post #144
pavement wrote: post #131

Earlier quoted context omitted.

Kinetic impactors are not missiles. Repeat: Kinetic impactors are not missiles. https://en.wikipedia.org/wiki/Kinetic_bombardment These are not things that get fired. You don't launch them. They don't follow a trajectory. They might just travel straight down from a geostationary orbit, depending on implementation. Yes, a guidance package might be necessary (depending on target discrimination, and precision, which in…

>They don't follow a trajectory. They might just travel straight down from a geostationary orbit So you're just going to target the equator then?

It's gotten a pass for too long.

Re: Unmanned U.S. Air Force space plane lands after secret, two-year mission

#147

Post by nradov »

pavement wrote: post #131
nradov wrote: post #111

Earlier quoted context omitted.

No that's all wrong. Firing a missile from orbit has less surprise value than firing from a submarine because satellites can't hide. There's no difference in kinetic effects; a non-nuclear ballistic missile can hit just as hard at a lower cost (do the math). A kinetic projectile launched from a satellite is no harder to intercept than a ballistic missile in the terminal phase, and satellites themselves are highly vul…

Kinetic impactors are not missiles. Repeat: Kinetic impactors are not missiles. https://en.wikipedia.org/wiki/Kinetic_bombardment These are not things that get fired. You don't launch them. They don't follow a trajectory. They might just travel straight down from a geostationary orbit, depending on implementation. Yes, a guidance package might be necessary (depending on target discrimination, and precision, which in…

This is 100% wrong. You don't understand orbital mechanics. Everything follows a trajectory until force is applied. When you release something in orbit it doesn't fall down. It continues orbiting until an attached rocket motor does a de-orbit burn. Rocket motors are subject to manufacturing variations plus there are a lot of atmospheric effects on the way down to the surface so any missile would require a sophisticated guidance system to have any chance of striking a target.

Re: Unmanned U.S. Air Force space plane lands after secret, two-year mission

#148

Post by rootbear »

gibsjose wrote: post #18
jfoutz wrote: post #14

Earlier quoted context omitted.

My guess was to refuel spy satellites. I imagine those sats are tough and can survive a long time. But when they get low on gas they can only do station keeping. If you can count of fuel coming, there's a lot more freedom to shift the track a half a degree as needed. It may be all electronic surveillance. I guess, you can count on satellites not changing after they're launched, so the electronics package would be goo…

On-orbit satellite servicing and refueling has not been performed as of yet, but we are currently working on it: https://sspd.gsfc.nasa.gov/restore-l.html

I thought Restore-L was one of the missions who's funding was cut in the budget proposal. I'm partly funded by PACE, which is toast.

Re: Unmanned U.S. Air Force space plane lands after secret, two-year mission

#149

Post by secfirstmd »

JshWright wrote: post #36
jcims wrote: post #12

Earlier quoted context omitted.

I always imagine it creeping up on unsuspecting satellites like some kind of space puma. All up close and personal like, giving them a sniff and then slipping away undetected.

It's tough to be sneaky in space...

Wasn't there a story somewhere awhile back that the Russians had launched satelites and yet strange movement of the supposedly jettisoned pieces was detected?

Re: Unmanned U.S. Air Force space plane lands after secret, two-year mission

#150

Post by marsRoverDev »

jfoutz wrote: post #14
hendzen wrote: post #6

Earlier quoted context omitted.

Probably a space equivalent of the USS Jimmy Carter - i.e. hacking/surveilling unfriendly satellites.

My guess was to refuel spy satellites. I imagine those sats are tough and can survive a long time. But when they get low on gas they can only do station keeping. If you can count of fuel coming, there's a lot more freedom to shift the track a half a degree as needed. It may be all electronic surveillance. I guess, you can count on satellites not changing after they're launched, so the electronics package would be goo…

I think you might be right on this one.

Recent US spy satellites such as PAN (https://en.wikipedia.org/wiki/USA-207) have started using much, much more aggressive manoeuvring strategies in order to do line-of-site microwave dish spying and spying on commercial sats.

This is unusual for "geostationary" satellites, as it wastes precious fuel. If there is no restriction on the amount of fuel used, they can stay up a lot longer than a normal satellite could.

Post reply on HN