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back to article NASA boffins: Space 'scope JUST missed dead Cold War spy sat

NASA has released rare details of a near miss between a delicate space telescope and a disused Cold War spy satellite. Julie McEnery, project scientist for NASA's Fermi Gamma-ray Space Telescope, was alerted to the threat when she received an automatic warning generated by the space agency’s Robotic Conjunction Assessment Risk …

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So, how are all those programmes to remove debris from orbit going?

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You mean the DYSON programme?

De-orbit

Your

Satellite

Over

Nothing important

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In other overblown hysteria

I was travelling to work this morning when I recieved an automated signal from the TRAFFIC (will think of contrived acronym later) light which suggested that 30tons of truck would be intercepting my orbit off the sliproad which would have resulted in a massive collision.

Fortunately my car was equipped with a kinetic energy to heat transferal system intended to reduce my orbital velocity into the parking space at the end of the mission/commute

The decision was taken to initiate a BRAKE (acronym to follow) manouver and the truck passed ahead of me missing by mere meters (a gnats hair on a canadian scale)

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Mushroom

Re: In other overblown hysteria

I was taking a dump this morning when I received an automated signal from the TOILET (True Ocular Interdiction Lateral Electromatic Transmogrifier) which suggested that approximately 1 pound of semi-solid human waste would be intercepting the orbit of your face, which would have resulted in a massive, but hilarious, collision.

Fortunately, my conscience is equipped with a chemical inhibition actuation system intended to reduce the chances of me caring about the impending collision.

The decision was taken to initiate an endorphin release, and the sound of the impact was successfully accompanied by the sound me me going "ahhhhhhh" in quiet, excretory bliss.

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Boffin

Re: In other overblown hysteria

"The decision was taken to initiate an endorphin release, and the sound of the impact was successfully accompanied by the sound me me going "ahhhhhhh" in quiet, excretory bliss."

Carefully executed and no back splash then?

Of course the suggestion of an 'endorphin release' might indicate that there was some wide area downward splatter with collaterals being collected by 'the bowl' requiring extension of the manipulator arm equipped with tool 342 of a set of 678.

AKA 'Bog Brush'.

... Or you vacated the scene of the crime with a smug smile and left someone else to 'tidy up' afterwards.

"Fortunately, my conscience is equipped with a chemical inhibition actuation system intended to reduce the chances of me caring about the impending collision."

Uhm... No. Inhibition is not the correct term. Your farts smell real good to you.

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RE: Re: In other overblown hysteria

...which suggested that approximately 1 pound of semi-solid human waste would be intercepting the orbit of your face which suggests that you have had an encounter with one of your manglers.

I am so glad I don't work for your company!!

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Panic.

"Realising the two craft were travelling at almost perpendicular orbits and were predicted to come within 700 feet (213m) of each other, the equivalent of an interstellar hair’s breadth, McEnery immediately began to panic."

That's always the best course of action! Some people are just good at thinking on their feet, thanks to their quick reactions and ability to instantly size up a situation.

I feel secure.

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Alien

Re: Panic.

KEEP CALM AND KEEP FIRING THRUSTERS!

Yours truthfully,

Cmdr Koenig.

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Coat

I felt like I'd lost 20 pounds

You probably did.

Mine's the one that comes with spare trousers

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Happy

Bit surprised this satellite could re-fold its panels and antennae.

AFAIK most them unfurl as a one shot deal. Lots of pyrotechnics and springs.

I think the take away from this story is meant to be.

CARA is a very cost effective way to stop very expensive bits of hardware (mostly NASA's but possibly others) from getting destroyed by lumps of dead space crap.

Something the US Legislature might like to keep in mind come the annual funding round.

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The programmes which sould grab a piece of orbiting junk and them pull it into a firely death are probably the most realistic if expensive. The one that uses lasers to shift stuff is proper sci-fi.

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A small thing caught my attention...

A bit of nit-picking, really.

At the end of the third paragraph, you wrote: "...more than enough to obliterate both spacecrafts."

The plural of spacecraft is spacecraft.

Aside from that, it was an interesting article.

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Anonymous Coward

Solar sail? Ion drive?

For this sort of manoeuvre, where you only have to change your trajectory by a small amount and you have plenty of time to do it, is there any practical alternative to "highly flammable fluids"?

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Happy

Re: Solar sail? Ion drive?

Get out and push...

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Re: Solar sail? Ion drive?

1st warning: 29th March

2nd, more critical warning: 30th March

Burn date: 3rd April, 12:00

Original estimated collision date/time: 3rd April, 13:00 (? the article doesn't explicitly mention, but the text leads me to this conclusion)

The delta-vee available from a solar sail or ion drive is tiny - the wiki guesses as <1N (for what I assume is an absolutely mahoosive sail). Fermi has a mass of around 4,300kg, so a mono-Newton force isn't going to achieve much in the timescales we're talking about - particularly with the uncertainties of working out which direction to apply the thrust.

Solar sail obviously has the problem of mostly only being able to apply force in one direction only, and you need to have a solar sail ready to deploy.

Ion drives are similarly limited in thrust - up til now they've been measuring thrust in mN, although there's some experimental jobbies with 80+N of thrust using a pulsed engine and a whacking great big power supply.

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Re: Solar sail? Ion drive?

The other problem with solar sails in LEO is that the atmospheric drag from the sail would probably do more than you hoped to get from sunlight. Nope; for now orbital corrections are likely to use thrusters. Ion drives are ok, and most new comms sats use them, but you are talking about at least a kilowatt of power, which is more than a lot of LEO sats have, and you are talking about it being fired up for maybe hours at a time.

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Re: Solar sail? Ion drive?

How about a bottle rocket?

Just mount a pressurised canister of fluid (since water would likely freeze in orbit you might want to use ammonia or LN2 or some such) on the thing, with a valve you can crack to let some of the liquid out. Good old Sir Isaac takes care of the rest - no flammable liquids or barely-controlled explosions involved.

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Re: Solar sail? Ion drive?

What's wrong with trusty

http://en.wikipedia.org/wiki/Monopropellant_rocket

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Boffin

Re: Solar sail? Ion drive?

@ Steven Roper: Hi Steve, Similar ideas have been proposed before but the problem is that your adding another form of debris into the orbit, when you burn a monopropellant or similar you should (hopefully) end up with nothing larger then molecule size and it should all be in gas or plasma states (which tend to disperse becoming even less of a hazard). This means that its unlikely to cause damage to something running through it.

However, Liquids tend to cling together (their are clips on you tube of astronauts "drinking" tea with chopsticks) which means you have a much larger target which at orbital velocities will do a lot of damage. Best earth example I can think of is that if you jump off a high bridge (Sydney Harbour Bridge, Forth Bridge, etc) hitting the water is akin to landing on concrete (and you get very similar injuries, and well death!). So even though your hitting a liquid if you hit it fast enough you arent going to notice that it wasnt solid. The damage will still be extensive...

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Boffin

Re: Solar sail? Ion drive?

Assuming you mean the technology is trusty, not Wiki From the link given:

http://en.wikipedia.org/wiki/Monopropellant_rocket

"LMP-103S has low toxicity due to the methanol (common rubbing alcohol)."

Er, yeah, methanol... low toxicity, NOT. Propanol, perhaps?

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Anonymous Coward

Re: Solar sail? Ion drive?

Methanol, while toxic (g/kg LD50) when ingested, is easy to handle and does not have long term smal scale exposure effects.

Hydrazine, the common monopropellant on that page, is highly toxic(mg/kg LD50) as something lying around. It can have long term toxic effects.

While doing shots of either is likely to kill you rapidly, one of the two is fairly easy to handle in fuel sized quantities, the other is a dangerous pain in the ass, as the "things which burn by themselves" category of chemicals tends to be.

TL;DR The Wikipedia (not fucking "wiki", thats the software is runs on) article, which is probably pulling the term straight from the sourced article, is completely correct in calling methanol "low toxicity" in the context of monopropellant fuels. Also simple hydrocarbons are better propellants as far as I know.

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Anonymous Coward

Cosmos 1805

Gosh, that's old. Those crafty Sovs, we were still fighting Napoleon ...

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Devil

Re: Cosmos 1805

They always were a bit bolshy.

Hands up if anyone remembers the flap about Kosmos 954 coming down for a visit with a nuclear pile still sticking in its backside....

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Coat

Meanwhile on an alien craft that's just passing by...

"Hey that planet looks interesting, lets go in for a closer loo..."

[Boom]

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Let's launch a neodymium magnet satellite built with thrusters which are designed to guide it (and anything stuck to it) into the atmosphere in 2 years time.

Bagsy it lands in my back garden so I can claim the scrap

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Anonymous Coward

"It’s a difficult business forecasting what will happen to objects in orbit"

You what?

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Look at this: http://heavens-above.com/IssHeight.aspx

Decay in LEO is clearly far from regular.

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Units.

> ...objects which are more than 4 inches (10cm) wide

What less than a football but more than a tennis ball?

We need a meaningful unit!

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Re: Units.

Coconut?

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Re: Units.

Canteloupe?

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Re: Units.

Politician's brain?

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Re: Units.

Vicious rumor that such a thing exists

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M7S
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Re: Units.

Coconut is good. Then we could assign units of thrust measured in swallows.

(I'm waiting.....)

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Facepalm

Re: Units.

> Politician's brain?

That isn't a measure, it is a synonym for "Nothingness"...

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@M7S Re: Units.

European or African ?

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Anonymous Coward

Nasa spots problem only Nasa could see and then solves problem then tells us how clever they were

Thanks Nasa

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Sooo do you feel the same about Science?

A lot of Scientific effects are due to subtle causes. Avoidance of those effects often involves equally subtle changes.

If it wasn't done, I'll bet that a collision would have impressed you...

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Re: Sooo do you feel the same about Science?

Maybe when the Soviets peer review the event....

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Realising the two craft were travelling at almost perpendicular orbits and were predicted to come within 700 feet (213m) of each other, the equivalent of an interstellar hair’s breadth, McEnery immediately began to panic.

Umm, why?

On nearly every road on this planet, large chunks of metal with a mass of several tons come within 3 feet (1m) of each other at a closing speed that can be in excess of a hundred miles an hour, and it happens ALL THE TIME!

In my book, even in orbit, 200+ metres is a clean miss.

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FAIL

OK lets try this

The speed of the satellites relative to each other was over 24,000 km/h. In 1 second at that speed you travel 6.67km! So to cover that 200m which you say is an easy miss, that takes all of 30milliseconds. You cant blink that fast.

Now considering that predicting a trajectory where the slightest perturbation might mean that in the course of 1 second you are now 6.67km from where you were supposed to be, do you really consider 200m to be close...

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Iglethal puts the case very well, but to add my two bits I'll couch my comparison in car terms:

Suppose your large chunks of metal with a mass of several tons travelling at relative velocities of over a hundred miles an hour, were coming within 3 millimetres of each other? You wouldn't feel that was a bit of a close shave? That's the car equivalent of these satellites passing within 200 m of each other at orbital velocities.

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Re: OK lets try this

Nice! I was about to get out my calculator (do I use this opportunity to admit that I still own a slide rule) and do the same calcs but you beat me to it.

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Good call! Yes, some people have little to no idea of scale.

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Bagsy it lands in my back garden so I can claim the scrap

You welcome to the irradiated dust hole that was once you back garden but I think the Health and Safety Council may have something to say about the standard of cleanliness required that your liable for by the way, in the aftermath of the devastation.

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Anonymous Coward

Where are the Space (Dump)Truckers when you need them...

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Boffin

Looking at the ion drive and solar sail options

Are not quite as dumb as people think.

The collision takes place at both a point and a time in space.

Speedup (or slow down) the satellite just a little over the remaining 3 days and the miss would be as good as a mile.

4300Kg. IIRC sunlight can do 1x 10^-9N and lets say an ion drive at 10x 10^-3N. I'd guess you could have a 10 sq m PV array you could use as a sail (the other is folded up) so maybe 10 nN giving 2.3 x 10^-12 m/s-2 using distance traveled as S= 1/2 x acceleration x time^2 (about 260 k secs squared) gives a shift along track of about 77mm. OTOH the ion drive gives a position shift of 78604m.

If you have an ion drive on board able to run for the 3 days needed.

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Re: Looking at the ion drive and solar sail options

See the recent article in this website about using ground-based lasers to help de-orbit space junk. Perhaps one could use the same system to nudge satellites out of the way of an impending collision. As you say, it takes just a small nudge a few days in advance to do the trick.

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Laser beam?

Couldn't you have the makings of a laser powered drive on-board and direct a beam up from Earth to power it should it be needed?

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Devil

Thanks for the pointers, NASA!!

I'll have to review all this when I put my atomic death ray into orbit.....

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[Broadcast Eclear, sent 1367530650.0]

xGSV Slightly Perturbed

oBOFH Reg Readers

A bottom-clenching moment for all involved, I'm sure. Jolly good show chaps, well done.

Also https://www.youtube.com/watch?v=hthl28SEGfk

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