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America's mystery X-37B space drone lands after two years in orbit

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it is unlikely that it carries any weapons... cough... cough...

it is unlikely that it carries any weapons.

Depends what are you trying to hit.

An ion drive accelerated kinetic can be as small as you wish. The size of a cubesat. If you are not in a hurry to hit the target and the target is another satellite you can send it off on a nice long journey to slingshot around the moon and whack whatever you want with 10km/s. Bonus points for doing the orbital mechanics so that it hits the target head on adding its orbital velocity to its escape velocity.

The energy released by whacking something with 15kg at 18km/s collision velocity is roughly equivalent to a kiloton of TNT. No satellite will be able to maneuver out of the path, it will be too late by the time they see it.

20-30kg kinetic with terminal velocity around 40km/s gets you into atomic weapons range. For that you will need to send it on a rather long excursion but if you want let's say an asteroid incident above the North Korean launch facilities...

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Re: it is unlikely that it carries any weapons... cough... cough...

No need for a space plane for a cubesat. They can be launched along with almost anything. Impact energy has to come from somewhere even with an ion drive which also has to get its energy from somewhere. Smaller objects have less area for solar panels and an atom bomb's worth of energy would take a very long time to accumulate. Course corrections would have to be planned long in advance as well.

A pellet gun would probably suffice to destroy a satellite if it could be aimed precisely enough.

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Re: it is unlikely that it carries any weapons... cough... cough...

Salyut-3 space station and its successors had a modified Rikhter R-23 aircraft cannon mounted for 'testing' purposes. At four feet 10 inches long it's a comfortable fit for the American bird.

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Re: it is unlikely that it carries any weapons... cough... cough...

"a modified Rikhter R-23 aircraft cannon"

Recoil's a bitch in microgravity.

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Re: it is unlikely that it carries any weapons... cough... cough...

"The energy released by whacking something with 15kg at 18km/s collision velocity is roughly equivalent to a kiloton of TNT."

Actually, Google says 1 kiloton is 4TJ, and I think the KE of 15kg at 18000m/s is about a thousandth of that. This makes sense, because it was several hundred tons of chemical energy that put the payload up there in the first place, so it is reasonable that it would have a ton or so equivalent of KE once it is up there.

But you don't need the ion gun. Just let a small lump of payload hang out of the side of your satellite and "encounter" the target on a non-glancing trajectory. The relative velocity will provide plenty of destructive power and you can blame it on space-junk.

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FAIL

Re: it is unlikely that it carries any weapons... cough... cough...

A pellet gun would probably suffice to destroy a satellite if it could be aimed precisely enough.

In the vacuum of space? I think not!

(a "pellet gun", aka an air rifle or air pistol, usually relies on a a spring to rapidly compress the air in a chamber behind the pellet. That in turn pushes the pellet out under pressure. The principle isn't really much beyond a pea shooter or blowpipe. No air means no force pushing the pellet).

</pedant>

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Re: it is unlikely that it carries any weapons... cough... cough...

<pedant mode>

There are three types of air guns (pistols and rifles work in the same way, however the air rifle is incorrectly named as the barrel of an air rifle isn't rifled)

1) Spring-piston

Cocking the gun causes the pump piston to move backwards and compress the spring until its rear engages the sear. The act of pulling the trigger disengages the sear, allows the spring to decompress and release the elastic potential energy stored within it, and pushes the piston forward thereby compressing the air in the pump cylinder. Because the pump outlet (located to the front of the pump) is directly behind the pellet sitting in the chamber, once the air pressure has risen enough to overcome any static friction and/or barrel restriction holding back the pellet, the pellet is propelled forward by an expanding column of pressurized air. This version will not work in a vacuum

2) Pneumatic

Pneumatic air guns uses internally stored compressed air as the source of energy to propel the projectile. Single-stroke and multi-stroke guns utilize an on-board pump to pressurize air in an internal reservoir. Pre-charged pneumatic guns' reservoirs are filled using either a high-pressure hand pump or by decanting air from a diving cylinder. This version may work in a vacuum as can be an external source of air.

3) CO2

Originally called CG guns (compressed gas guns),[10] air guns utilizing prefilled removable gas cylinders as power source have now become known as CO2 guns due to the ubiquitous commercial use of bottled carbon dioxide gas. Most CO2 guns use a disposable cylinder called a "Powerlet", that is often purchased with 12 grams (0.42 oz) of pressurized CO2 gas, although some, usually more expensive models, use larger refillable CO2 reservoirs like those typically used with paintball markers.

This version will work in a vacuum

</pedant mode>

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Re: it is unlikely that it carries any weapons... cough... cough...

relevent? https://what-if.xkcd.com/21/

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This post has been deleted by its author

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Re: it is unlikely that it carries any weapons... cough... cough...

"and I think the KE of 15kg at 18000m/s is about a thousandth of that."

Agreed [ 0.5*15*(18000^2) = 2.4e9 J]

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Agreed [ 0.5*15*(18000^2) = 2.4e9 J]

One of the reasons why the comments section of this site is so lovely : The Express commenters would have noticed the correlation of the landing with the 10th anniversary of Madeline McCann vanishing. In the Mail, you'd probably get people arguing about how many migrants you'd fit in the payload bay.

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Re: it is unlikely that it carries any weapons... cough... cough...

Thank you, a much better explanation than I would have written, and well deserving of a thumb up.

I must, however, query one of your statements:

however the air rifle is incorrectly named as the barrel of an air rifle isn't rifled

My current (ageing) air rifle (Air Arms TX200, FWIW) certainly does have a rifled barrel. As does my previous rifle (Weihrauch HW 77K), and several owned by my father (including rifles from Anschütz, BSA, Gamo and Parker-Hale).

In fact, I don't think I've ever seen an air rifle without a rifled barrel.

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Stop

Re: it is unlikely that it carries any weapons... cough... cough...

"the air rifle is incorrectly named as the barrel of an air rifle isn't rifled"

Bollocks. I looked down the barrel of mine, using my remaining good eye, and you can see the rifling. A quick internet search confirms this.

http://www.pyramydair.com/blog/2006/08/different-types-of-rifling/

Here's a picture.

http://www.airgundevelopment.com/images/rifling/DSC05929.JPG

Maybe BB guns aren't rifled? There's no point if the projectile is spherical. Air rifles fire pellets. Here's picture with the rifling marks.

http://www.photosbykev.com/wordpress/wp-content/gallery/various/_mg_9948.jpg

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Joke

Re: it is unlikely that it carries any weapons... cough... cough...

"I looked down the barrel of mine, using my remaining good eye,"

Did no one warn you not to do that again after the first time?

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Anonymous Coward

Re: it is unlikely that it carries any weapons... cough... cough...

In defence of Voland, not all the energy would come from the ion drive. They mentioned slingshot so the 'weapon' will have taken a good amount of kinetic energy from the celestial body chosen for the gravity assist.

Topical for the moment is Cassini - the majority of it's delta-v came from two Venus flybys, 1 Earth flyby and a final assist from Jupiter on it's way to Saturn. It added a lot of speed.

The planets don't mind so it's about the closest you can get to "energy for free"

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Re: it is unlikely that it carries any weapons... cough... cough...

"There's no point if the projectile is spherical."

The British Army would disagree

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Facepalm

Re: it is unlikely that it carries any weapons... cough... cough...

Aladdin, of course, you're quite right. I withdraw the comment about spherical projectiles. A shot ball from a smooth bore gun will behave a bit like a knuckleball in baseball, it will move all over the place as it tumbles. Thanks for the correction!

https://youtu.be/e3uzXOuYUcM

Or in football:-

https://youtu.be/00fcef8z0z0

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Re: it is unlikely that it carries any weapons... cough... cough...

It's quite alright, I now have the urge to spend the rest of my day watching Sharpe.

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Re: it is unlikely that it carries any weapons... cough... cough...

@Ochib

Rifling through my rifles....

My 1930's vintage BSA Light Pattern 'A' series springer air rifle has a rifled barrel - http://www.network54.com/Forum/670443

My Webley Tempest air pistol even has a rifled barrel.

I'm pretty sure my Air Arms S400 MPR PCP 10m competition air rifle has a rifled barrel

Otherwise I agree on what you say may, or may not, work in a vacuum.

When going in to pendant mode it pays to check you know everything about what your talking about :-)

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Re: it is unlikely that it carries any weapons... cough... cough...

Sometimes pendant mode is like an albatross hanging from your neck.

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Happy

Re: it is unlikely that it carries any weapons... cough... cough...

Upvote from me - I look but don't see! Made me laugh :-)

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Re: it is unlikely that it carries any weapons... cough... cough...

Of course an Air Rifle has a rifled barrel, the term "rifle" literally means "rifled barrel". This distinguishing them from smoothbore muskets which weren't rifled because rifling was expensive once upon a time. The British Army still has musketry (referring to smoothbore barrels) in some job titles with regards to shooting amusingly, apparently nobody wants to be the killjoy to break half a millennia's worth of tradition.

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Boffin

Re: it is unlikely that it carries any weapons... cough... cough...

A pellet gun would probably suffice to destroy a satellite

Or the old standby - a handful of lead shot or gravel. Nice even spread, reduces the chance of missing.

Also increases the chance of hitting something else but hey, collateral damage is a thing y'know.

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Re: it is unlikely that it carries any weapons... cough... cough...

A shot ball from a smooth bore gun will behave a bit like a knuckleball in baseball, it will move all over the place as it tumbles.

Which is why the accurate range was no more than about 50 yards. And, even then, a good amount of luck was involved.

Or, for the British Army, the ability to fire 3 rounds a minute - which meant more bits of fast-moving lead moving in the direction of the enemy. Especially if they are advancing in column (a-la French Guards).

Add a few rifemen in the mix to take out the officers and file-closers and things get considerably less eventful for the scum[1] of the line.

[1] Wellington reffered to the rank and file as "the scum of the earth".. which he then postfixed with "but they are *my* scum of the earth".

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Re: Agreed [ 0.5*15*(18000^2) = 2.4e9 J]

One of the reasons why the comments section of this site is so lovely : The Express commenters would have noticed the correlation of the landing with the 10th anniversary of Madeline McCann vanishing. In the Mail, you'd probably get people arguing about how many migrants you'd fit in the payload bay.

Almost any speculation about what this aircraft does is on that level anyway. Ion canons are almost as ridiculous. There's sensible reasons why it's for looking at things rather than breaking things but even then the U2 is still a thing largely untroubled in most of the world.

Signals could be a thing; could be a comms relay (supporting deployments providing coverage in a way that's manoeuvrable and tunable).

Military satellite test bed makes sense too - and frankly that's what the US military says it does. Though honestly I'd say a military look-down satellite where you can upgrade it whenever you feel like and put it where you need it is a hell of a thing.

It's barely even worth speculating without at least an indication of where it's operating. If one knew that one could start narrowing it down.

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Headmaster

Re: it is unlikely that it carries any weapons... cough... cough...

Maybe BB guns aren't rifled? There's no point if the projectile is spherical.

Sure there is. Early muzzle-loaded rifles fired spherical lead balls much more accurately than non-rifled muskets.

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Re: Agreed [ 0.5*15*(18000^2) = 2.4e9 J]

"It's barely even worth speculating without at least an indication of where it's operating. If one knew that one could start narrowing it down."

Take your pick. It's orbiting and can manouver. A carefully designed initial orbit plus the right amount of fuel can conceivably bring it over any given location on Earth a couple of times in two years.

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Re: Agreed [ 0.5*15*(18000^2) = 2.4e9 J]

A cross-range capability means it can get up to all sorts of sneaky stuff.

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Re: it is unlikely that it carries any weapons... cough... cough...

BB guns fire steel ball bearings, hence no rifling whereas air rifles typically fire a shaped lead projectile where the skirt can engage the rifling

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Thumb Up

Re: it is unlikely that it carries any weapons... cough... cough...

unhand me greybeard loon!

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Re: Agreed [ 0.5*15*(18000^2) = 2.4e9 J]

"The Express commentators would have ..."

"In the Mail ..."

Whereas my first thought was "So If I wanted to get some OSB sheets in there, they'd have go though the hatch diagonally" Hmmm?.

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Re: it is unlikely that it carries any weapons... cough... cough...

" weren't rifled because rifling was expensive "

There were two other reasons why muskets were retained past their sell by date.

Training for a musketeer was quicker and simpler.

The tactics of the day emphasized relatively short range mass fire. A bludgeon, not the scalpel of rifle fire.

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Re: it is unlikely that it carries any weapons... cough... cough...

"Recoil's a bitch in microgravity."

if only it were possible to know exactly what your weapon's recoil pulse would be ahead of time, and fire a calibrated reaction thruster in opposition exactly when firing. Or ejecting a heavier mass at lower speed the opposite direction.....:)

sadly the "hart part" is the aiming calculation. Shoot "forward" and the round goes "up" as the round slings out to higher orbit. shoot "back" and it drops. and all sorts of other nastiness depending on cannon orientation. All predictable and calculable, if one makes sure they got all the variables and can accurately measure that orientation and integrate it with nav. No midcourse correction option on dumb slugs and it takes a decent amount of computer to handle the details of aiming

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Alien

One man working alone...

to save us from the alien threat.

Has anyone seen Duke Nukem lately?

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Re: One man working alone...

Has anyone seen Duke Nukem lately?

Yeah - he's currently the US Ambassador to the Peace Corps..

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Unhappy

More surveillance

Yep, that's what we need.

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Does this qualify as the longest space mission where the craft in question has returned to Earth in a useable condition?

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I'm trying to recall if the Space Shuttle returned any satellites that had been up a while. I don't think so but could be wrong.

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Space Shuttle returned any satellites

The shuttles did a LOT of "classified missions". The US military had a big input on the design.

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Alien

Long flight

I think this does qualify as the longest *reusable spacecraft* mission to return to earth. The longest shuttle mission was 17 days. There have been payloads which have been in orbit longer. And there is certainly the space station (not a moon, BTW). As far as a spacecraft that can be sent up again, I think this just set the bar.

This may even be an overall "flight" record for all things that leave terra firma and have the capability to repeat the task.

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Unhappy

returned to Earth in a useable condition?

Google Long Duration Exposure Facility.

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Re: Space Shuttle returned any satellites

@Mage,

The shuttles did a LOT of "classified missions". The US military had a big input on the design.

Dunno why that was down voted; the DoD certainly did have a big hand in the Shuttle's design and did indeed make use of it to launch some payloads.

There's some suggestions that the reason that the Shuttle's wings were quite large was to give it good cross range performance, ie. to be able to launch into a polar trajectory, do a partial orbit, and come back down in California. The cross range performance meant that it could catch back up with the planet that would have rotated underneath it, and it would re-enter out over the Pacific and needed to glide back East to reach CA.

The theory was that in this less than 1 polar orbit it could snaffle a Ruski spy satellite without them spotting this happening...

They never did it; it's a bit obvious what's going on when you see which way it goes at launch (North or East?), and it's too hard to conceal the launch of one of the loudest machines on or off the planet. People tend to notice something that loud...

That alone cast doubts on the whole hypothesis, but it was the early 70s when the Shuttle was specified and all sorts of crazy cold war shit was still going on. Such an idea could easily have made it through several design reviews before it was dropped as 'too hard', but too late to rework the design.

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Shuttle and Satellites

The Shuttle could bring back a satellite. There were a couple of missions were the Shuttle repaired a satellite. On one I believe they actually put the satellite in its bay. So a satellite grab as an engineering problem has been solved; as a potential political problem....

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Re: Long flight

Except that this shuttle is the payload rather than the vehicle and being able to launch the same payload twice is hardly rocket science.

The launch vehicle is a distinctly non-reusable rocket. There are no re-usable spacecraft and existing propulsion technology provides no means to build any such.

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Re: Long flight

"There are no re-usable spacecraft and existing propulsion technology provides no means to build any such."

X-37B weighs about 5 Tonnes. Falcon 9 has a capacity of around 10 Tonnes to LEO and has demonstrated first stage re-use. That leaves you 5 Tonnes of fuel and equipment on the second stage to de-orbit, re-enter and get it back to the ground intact. It's not so far from reality as to be at least plausible.

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the real question

The point of this vehicle - and the shuttle - is not about what it can put into orbit, but about what it can bring back.

They have spent a LOT of money giving themselves the ability to land space things from inclined orbit.

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Possible surveillance

Unlike a satellite it can more easily change orbit. It comes back to get refuelled.

One application is possibly to spot the location of UPLINKS of two-way data, especially ones that use privately rented transponders rather than regular ISP ground-stations.

Anyway not just optical surveillance, which can certainly count albatrosses people. Likely all kinds of RF. UHF stuff that is less than 1 km on the ground can easily be monitored from low earth orbit. Check out what a "ham" needs to chat to a "ham" on ISS.

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Re: Possible surveillance

"Check out what a "ham" needs to chat to a "ham" on ISS."

Not much, as it turns out. I picked up a signal from the ISS with a super cheap handheld radio.

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Devil

@Mark 85

does this count?

https://en.wikipedia.org/wiki/Long_Duration_Exposure_Facility

not "satellite" but an orbiting lab that was designed to be brought back.

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