Half a croissant, on a plate, with a sign in front of it saying '50c'
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Scavenger satellite

eats space junk for fuel
  (+17, -5)(+17, -5)
(+17, -5)
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This satellite will approach a piece of space debris; use a solar furnace to break it down to small pellets that feeds a mass driver for propulsion. It will then calculate the trajectory to the next victim of junk. This will reduce the orbital trash into smaller parts.
the great unknown, Jun 06 2006

mass driver http://en.wikipedia.org/wiki/Mass_driver
the wiki entry [the great unknown, Jun 06 2006]

(?) solar furnance http://www.xenotech...ch.com/solfurn1.htm
bulid your own w/flat lens [the great unknown, Jun 06 2006]

Space Debris http://en.wikipedia.org/wiki/Space_Debris
Wikipaedia entry on 'Space Debris' with links to a number of interesting documents on the subject. [DrBob, Jun 08 2006]

My very similar idea. Scavenger_20II_20Space_20Program
Too close to call. [WcW, Mar 05 2008]


       What's a solar furnace?
Jinbish, Jun 06 2006

       On the edge of magic, but a nice concept for a cleaner robot.
normzone, Jun 06 2006

       I wonder if you could forgo the furnace and modify a baseball pitching machine to take the collected junk and fire it away at a vector calculated to either achieve escape orbit or re-entry for the space junk. (or a vector calculated to thru and thru the FOX satellite)   

       A saw may also be required to cut junk into pieces for complicated manuevering.
Zimmy, Jun 06 2006

       A solar furnace may look like a satellite dish with a mirrored surface.Or it could just be a magnifying lens. it will face the sun & focus the light & heat to one spot. it should be enought to melt most debris. If melted in 0g, it will be a ball. the mass driver works like a pitching machine, using magnetic forces. the furnace is used to cut the junk into baseball (or any) size chunks. If it makes a vector so it can reach another piece o'junk, the pellets/chunks may/may not burn/escape
the great unknown, Jun 06 2006

       I like the Scavenger satellite, but what happens when it meets its sister ship ? - bun hovers temptingly waiting to see quality of answer.....
xenzag, Jun 06 2006

       There was an idea here, once, that I can't find now. And either in the heart of the idea, or in an anno, there was the concept of homeless persons living in orbit, sweeping the lanes for discarded/lost satellite trash, and turning it in for credit at the local recycling center.   

       I liked it for the picture it made in my story-addled mind, but I don't know if it's still around.
normzone, Jun 07 2006

       [xenzag], This scavenger satellite is not called "The Highlander" for no reason.
methinksnot, Jun 07 2006

       We still need functioning satellites up there, you know. To paraphrase Moe: "That thing better not have carried the Spice channel"
methinksnot, Jun 07 2006

       Great idea! Mostly.   

       //If melted in 0g, it will be a ball// That depends on its surface tension and purity. I wouldn't depend on it staying in place, either, as outgassing could send it jetting away.   

       Which thought inspires me to suggest several changes: Add a grabber arm to catch the debris--this will simplify maneuvering. Then use the arm to move the debris in front of the onboard cameras and examine its shape and composition via telemetry. Then use the arm to hold the debris in position in the firing chamber. Using lasers, slowly vaporize the debris.   

       The vapor puffs are the reaction mass, usable in two ways. If the lasers are aimed and pulsed, they make pits which act as rocket motors for the vapor, which blasts out from the heat of the lasers. Simultaneously, an electric charge applied to the vapor makes it reaction mass in an ion engine. Vaporized material will be blown out of orbit by solar wind, after a while, and will not be as great a danger as having chunks thrown from a mass driver.   

       If something is too big to fit in the firing chamber, a laser could be used to cut it up. An extremely large object could possibly be pushed from orbit, if enough reaction mass is available to slow it and then to get the satellite back up to speed.   

       The satellite is controlled from the ground. There is a project currently operating to identify and track space debris. The information from that could be used to plot courses for the satellite and for its exhaust. Autonomy is not easy.   

       To get back to the original plan, it is possible to use the mass driver without long-term danger to other spacecraft. If the satellite is inserted in a low orbit, all mass intercepted and launched could be thrown backwards, so to speak. The reaction would drive the satellite into a higher orbit to hunt more debris. The thrown mass would be moving below orbital velocity, and fall into the atmosphere. Anything below ten miles per second could then be used for the exhaust velocity.
baconbrain, Jun 08 2006

       What if this scavenger wound up falling to earth? THERE WOULD BE NO WAY TO STOP IT!!!
bungston, Jun 08 2006

       Just introduce it to the Halfbakery. That's pretty much stopped me from getting anything done.
baconbrain, Jun 08 2006

       The vast majority of space junk is made up of small items such as flecks of paint that are the debris from explosions. The amount of energy that you are likely to get from feeding them into your furnace would be miniscule.
DrBob, Jun 08 2006

       //The vast majority of space junk is made up of small items such as flecks of paint....// I thought the majority of space was made of "dark matter" - could it not burn that?
xenzag, Jun 08 2006

       Thanks, B-brain. I always invisioned arms to handle the debris. the solar furnance can supply a focused beam of light to use like a laser. I like the idea of heating the junk to a vapor & using that for propulsion or even thrusters. It could be conrtolled from the ground, I aways thought it will calulate its own tranjectory & confrim it with the ground base. between that & it's database, it will leave active satellites & the precious Spice channel alone. Since it's aiming for it's next "prey", the pellets/etc. may either burn on reentry or stay in space. I'm not sure about tossing big chunks back to earth. That would be like throwing away it's own food.
the great unknown, Jun 08 2006

       Alright - since we're doing this, there is a similar preheated idea in John Varley's "Golden Globes". Read up on "snarks".
normzone, Jun 08 2006

       What did the snarks look like? I can remember a description in a science fiction story of self-replicating scavenger satellites that were cylindrical.
nomocrow, Jan 26 2007

       Here's a bun. [tgu] and [baconbrain] can split it between them.
wagster, Jan 26 2007

       What if you used magnets? If you slowly approached an object and upon imminent (but controlled and very, very slow, relatively) impact apply a weak electromagnet thus grasping the object. The satellite then turns towards earth and activates a very powerful electromagnet to fire it back into the atmosphere. Of course the hunter satellite would have to use a little thrust to counteract the falling satellite's force (Newton's Laws and such...) and thus would require refueling or its own destruction. Nonetheless, it is an interesting notion.
DavidT, Jan 27 2007

       Solid material is expensive to place in orbit. When we finally get around to major space construction any solid matter could be useful if kept in orbit. The problem is all that loose crap buzzing around at speeds faster than bullets is dangerous. What is needed is something to consolidate it into a junk satellite that can be mined for future use and have it firmly located so it can be avoided. Something like a super vacuum cleaner permanantly in orbit.
JSand, Jan 27 2007

       [As I recall, the snarks were idealized in a childrens cartoon as somewhat dragonfly-like, but the actual tech may have been a bit more clunky. I will look it up and get back here eventually.
normzone, Jan 27 2007

       I have always loved the idea of satellites zipping around space grazing on debris like a herd of cattle, or maybe nibbling at the debris like rodents. Either way, there is certainly no shortage of junk out in space providing all kinds of methods for disposal, avoidance, and utilization. It's a wide open field for commercialization.   

       I don't believe you could do a significant amount of demolition or attain much fuel through heating the debris alone. The closer you are to the sun the more energy you get without massive (expensive) solar reflectors, but you would encounter less debris that hasn't already melted.   

       You don't necessarily want smaller pieces of flying debris either. This makes it harder to detect. It would be really neat to create an artificial asteroid junkyard where debris could be broken down through the force of collision and later harvested for fuel or parts for scavenger satellites.
evildork, Nov 20 2007

       If I'm reading the idea right, the fuel would be solar power for the mass driver, the particulated junk would just be the reaction mass.

Also any trajectory could be achieved (such as to the next piece of junk) and still dispose of the just collected bits by sending the driven particles on different courses. Just a very simple example, but one projected away from the earth on a very sharp elliptical orbit that enters the atmosphere on return, and one sent directly towards the planet, would result in no net velocity change, and still dispose of both particles. Slightly different variations would allow for any course while eliminating all particles.
MechE, Nov 20 2007

       Hate to wreck the dreams of nascent rocket scientists, but sometimes it has to be done. The first problem is “approaching” the space junk in the first place.   

       When bringing two orbiting objects together, in this case, a space vacuum cleaner and a piece of space junk, you need to keep the speed these things travel in mind. They're not just up there lazily floating around in zero gravity with the Blue Danube Waltz playing in the background like in the movie 2001. These bodies overcome the pull of the Earth's gravity by flying very fast, 17,000 miles per hour at least. Imagine flying in an airliner at only 600 miles per hour and reaching out the window to "catch" a bird for instance. There's going to be a lot of impact to deal with even at those relatively low speeds but when you start getting up into orbital velocities, catching an empty vodka bottle tossed out of an old Soviet space station is going to raise issues of shattering of the debris and the vehicle trying to catch the debris thus causing more debris. In short, taking one big problem and breaking it into thousands of little problems. The force of the impact will be determined by the difference between the speed of the space vacuume and the garbage it's picking up. At these velocities, a 10% difference in the relative speeds of scavenger satellite and junk could mean an impact of thousands of miles per hour. And that's if they're traveling in the exact same direction which would be pretty hard to achieve.   

       It can be done, but you’re also talking about a lot of energy to catch this orbiting junk. If you’re going to try to approach it slowly, the energy used to put this junk into orbit will have to be matched by the energy used to put something to catch it in the same orbit. One catch-all roving satellite fueled by burning what it catches as it goes along isn’t going to get enough energy to match trajectories and velocities that took the burning of fuel in tanks the size of multi-story office buildings to achieve.   

       I’ll give you a mercy bun though just for suffering through my merciless beating.
doctorremulac3, Nov 20 2007

       Thanks doc. I understand that there's a lot of physics, number crunching and energy calulation to see if something like this works, but I guess that's why it's called the HALF-bakery. I can imagine the guys at NASA back in the '60s biting fingernails over this same math while prepaing space docking "There travelling thousands of miles per hour! It's like catching a bird in an airplane!"
the great unknown, Mar 04 2008

       I think this is as viable as my suggestion for a scavenger space program and seemlingly pointless.
WcW, Mar 05 2008

       A different thought train of intuition here in the form of thought poetry, but ....   

       Kind of like burning black ants with a magnifying glass; But metal ants would melt, not explode; hmmm, metal ants in microgravity would melt into into a perfect moltent ball bearing; although, not sure how long it would take to melt and evaporate a metal ant with a parabolic mirror as there is a huge database of different metal ants and alphas to choose from; albeit, space junk is probably mostly lightweight aluminum-titanium which is very reflective, but will melt under hot enough conditions   

       P@focus = d(h*w)/dt @focus = n*(Q/A)*dA {% incident sunlight focused by mirror} = Qabsorbed + Qreflected {space junk heat budget} ...   

       E {energy of space junk} = Eo + (Qabsorbed - Qradiated)*dt > or = (E/mol)*Nmoles {energy required for space junk evaporation}   

       Although, I would guess that "Qabsorbed" is dependent on the temperature of the space junk and would fall to zero as temperature equilibrium is reached with the incident focused radiation .... meaning that the evaporation temperature of the alloys would need to be less than the average photonic temperature of the sunlight.   

       Conclusion: This would work on some kinds of space junk, but not all kinds of space junk. Now to work out how to capture the gasified space junk and focus the momentum behind the craft .... perhaps the space junk could somehow be collected and funelled into the glass tip of carbon-fiber rocket tubes before aiming the mirror directly at the sun and gasifying it.
quantum_flux, Mar 06 2008


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