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Space

Big Hopes for Tiny Satellites 152

Posted by michael
from the size-matters dept.
shelflife writes: "ST5, according to NASA, will usher in a new era of small, smart spacecraft. Why send a human into space when you can send a computer? And why send something almost as heavy as a UNIVAC if a laptop will do? Compact nanosatellites will have everything you'd want in a full-size, luxury satellite. They will have the attitudinal and navigational capabilities needed to maintain proper orbits, and they will be capable of complex, high-bandwidth communications functions."
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Big Hopes for Tiny Satellites

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  • by isdnip (49656) on Tuesday September 25, 2001 @10:39PM (#2350962)
    This isn't entirely new. There were "microsats" flown in the 1980s, some sponsored by the Amateur Satellite Corp. (AMSAT), and some university sats like Webersat (from Utah).

    With today's smaller and more powerful chips, of course, it's a lot easier to do more in a small package.
    • by jensend (71114) on Tuesday September 25, 2001 @11:10PM (#2351074)
      Well, the microsats sent out from my home state were fairly well one-purpose, one-use machines (amateur radio for webersat, rotation/attitude manipulation with tracking for the JAWSAT)- see here [weber.edu] for an optimistic description. See here [asu.edu] for other previous microsats. NASA's microsats, according to their page, "carry a wide range of spacecraft services including guidance, navigation and control, attitude control, propulsion, high bandwidth and complex communication functions," some of which are diagrammed on that page [nasa.gov] and its successor. With the previous story and the other ways in which NASA has exceeded expectations on almost all of their craft in mind, I think this is an idea whose time has come.
  • ...this is the planet-wide network of Mac cubes? I recall some loon wanted to do that.
  • Why not? (Score:5, Funny)

    by dghcasp (459766) on Tuesday September 25, 2001 @10:41PM (#2350970)
    Why send a human into space when you can send a computer

    That would have made Apollo 11 a really boring movie: write(nasafd,"houston, we have a problem",31)

    • First of all, it was Apollo 13, not 11, and it wasn't only a movie, it actually happened. Show some respect.
    • It's Apollo 13.
    • It's not a matter of one or the other. You send spacecraft to do dull, routine stuff (like handle communications relays) or exploration that is too dangerous or far-away for people. However, robots only do what they're engineered to do, witness the Deep Space 1 probe that totally missed photographing the one asteroid because it couldn't get the camera gain set right. You send people, usually after the robots, to look at things and do on-site decision making. Only a human can say "hmm, that looks wierd, I wonder what will happen if...."
  • Something that NASA with all its budget cuts will need to do in order to get some satalities for studies... now if there can be also a way to cut down on costs for transport that'd be great also!

    Maybe there will be a Pluto-Kupier Express project -- I sure hope so; I'd like to see Pluto's CH4 frost... otherwise think of all the little things we can do with these buggers!
  • can MicroSOFT be far behind?

    Maybe that's why my Win98 machine is so flaky sometimes. Microsoft has been building solar flare disturbance simulators into the Windows kernel since 3.1...
  • Why send a human into space when you can send a computer?
    Because a computer simply wouldn't get the same sense of pride and satisfaction out of planting the American Flag on the surface of Mars.
    • more likely it would just have pride and satisfaction from planting the flag of our computer overlords.......... I've been told I have said too much...... logging off now....
  • by Bruce Perens (3872) <bruce@perens.com> on Tuesday September 25, 2001 @10:51PM (#2351006) Homepage Journal
    There are some significant challenges in building "smart satellites".

    Solar radiation is an extremely serious problem for any computer in space. To be rad-hard, chips need to be made of silicon on sapphire, which means a $1 embedded processor suddenly costs twenty thousand dollars. This is not material cost, it's because the economies of scale in production of terrestrial processors are what drives the cost down. Nobody can afford sapphire RAM banks, and thus memories get a flipped bit per orbit, in general. The only way they keep working is that there is a "washing" process that scans memory and does ECC correction continuously. Shielding is simply too heavy to be practical (send up a lead-clad satellite, and your rocket becomes 10 times as large to boost the weight).

    Because it's available in sapphire and is flight-proven, the microprocessor of choice for controlling satellites is the 1802. Remember the RCA Cosmac Elf? Most of you weren't born when that was a popular hobby computer

    I was surprised to find that the Phase 3D satellite [amsat.org] boots up with no ROM. Hardware loads RAM directly from a radio modem. They couldn't afford a ROM they could trust.

    Heat is a problem, too. Heat sinks don't work so well without an atmosphere to carry away heat. You have to pipe heat around with heat-pipes filled with a phase-change gas, and then radiate the heat away.Bruce

    • Isn't heat electromagnetic radiation of a particular frequency band? Shouldn't it radiate? Isn't it cold enough in space that the heat would be useful in maintaining a constant, even temperature within the satellite (kinda like a crystal oven on a radio station's transmitter)?

      I remember the COSMAC Elf, and I've got the well-worn mid 70s copies of Radio-Electronics and (the original)Popular Electronics to prove it. Unfortunately I didn't have the spare cash for one at the time.

      • You have to get the heat to somewhere that you can radiate it. Also, it's sometimes 300F on one side, and -100F on the other side of the satellite, so you pipe heat around just to gain a degree of temperature stability.

        Thanks

        Bruce

      • Actually heat is not just a form of electromagnetic radiation. Heat is the measure of the energy of the atoms/molecules of a substance (gas/liquid/solid/plasma et. al.). This energy produces (through some mechanism I'm unsure of) electromagnetic radiation in the infrared frequency range, and if the energy is high enough in the visible range. Heat transfer occurs through three means in this order of efficiency: Conduction, convection, and radiation. In Earth's atmosphere with cooling fins you are not actually relying on radiation, but rather convection. In space you only have radiation to rely on without a much more complicated heat removal system.
    • I found a good reference on how ECC works here [oreilly.com].

      Bruce

      Comment added here to get by the slashcode postcomment compression filter.

    • by Christopher Thomas (11717) on Wednesday September 26, 2001 @12:04AM (#2351224)
      By coincidence, I happen to both be a grad student studying IC architecture and living about 20 feet from someone working on rad-hard space electronics.

      It turns out that the situation isn't quite as grim as the scenario you've painted.

      Solar radiation is an extremely serious problem for any computer in space. To be rad-hard, chips need to be made of silicon on sapphire, which means a $1 embedded processor suddenly costs twenty thousand dollars.

      Silicon-on-insulator chips are used because they aren't vulnerable to latch-up (triggering of parasitic SCR structures formed by the many regions of doped silicon in conventional chips). However, there are other approaches to dealing with latch-up.

      A common approach is to just add enough substrate contacts and apply design rules conservatively enough to ensure that latch-up currents won't be immediately destructive, and to power-cycle the chip either on a regular schedule, or when you see a huge current spike, or both. Powering down the chip turns off the SCR, and when you power up, everything's fine again.

      On the flip side of this equation, SiOI is slowly becoming more common. There was a Slashdot article about IBM rolling out a SiOI process a while back; while plain silicon is still cheaper, I doubt you'd be looking at a factor of 10,000 price difference. The main problem with spacecraft electronics is that any custom chips will be fabbed in very low quantities, so you don't get the economics of devoting a wafer run to them. This is true whether they're rad-hard or not.

      Nobody can afford sapphire RAM banks, and thus memories get a flipped bit per orbit, in general. The only way they keep working is that there is a "washing" process that scans memory and does ECC correction continuously.

      You get noise events affecting the processor's activities too. You can get around this either by running two processors back-to-back with HA hardware to compare outputs, or by living with occasional errors and resetting the chip every so often. An expensive solution isn't necessarily needed :).

      Also, using SiOI doesn't save you from these noise events. It's only useful for latch-up. An ionizing event could still cause conduction through gate oxide or do any of a number of other fun things that cause errors.

      Because it's available in sapphire and is flight-proven, the microprocessor of choice for controlling satellites is the 1802.

      Actually, rad-hard 386 chips have been standard for many applications for quite a while now.

      Heat is a problem, too. Heat sinks don't work so well without an atmosphere to carry away heat. You have to pipe heat around with heat-pipes filled with a phase-change gas, and then radiate the heat away

      Heat is indeed a problem, but you can get away with using the spacecraft structure as a passive heat sink if your electronics are low-power enough. This is a common trick, because you're on a limited power budget and want low-power electronics anyways. That way you only have to worry about craft-wide climate control (well, that and instruments that require very stable temperatures).

      It's an interesting field, in any event.
      • by Bruce Perens (3872) <bruce@perens.com> on Wednesday September 26, 2001 @12:55AM (#2351335) Homepage Journal
        Wow, someone who knows first-hand. Of course most of what I know of this comes from AMSAT, and while I have a few friends who work on the birds, I never have. AMSAT are the people who have been making microsats, and on the other hand they're the ones with the low budgets and sometimes a technological lag (although they lead a surprising amount of the time).

        What about latch-up and RAM? Use dynamic RAM and power it down between refresh cycles?

        Rad-hard '386? Is it a static version? I was aware that Harris did a fully static '286. AMSAT flew an ARM, and that probably has the most MIPS per mA, but due to the problems with P3D I don't think they've gotten much chance to test it.

        Bruce

        • by Anonymous Coward
          Some devices experience SEL (Single event latch-up) and some don't. You can make measurements to determine which ones do and fly only those that don't. Or you can put a latch-up monitor (detects current spikes and resets) on board. Powering down during the refresh cycle would be ludicrous because refreshes happen so frequently. Powering down between uses would work though. Most utilization profiles have a large time of no use with short utilization spikes.

          I believe that SEi (now Maxwell) produces a rad-hard 486 also.

        • Wow, someone who knows first-hand.

          Actually only second-hand :). Ask my father for first-hand details.

          I'm afraid I don't know the answer to either of your other questions.
    • How hard can it be to guard from bit rot with cheap, conventional silicon?

      You could do this with three (or more) identical systems running in parallel. If one of them loses sync with the other, he could halt the system, reload his state from the others (which are still in consesus) and then resume. I know I'm over simplifying this, but we're already using such hardware redundancy schemes on Earth.
    • Because it's available in sapphire and is flight-proven, the microprocessor of choice for controlling satellites is the 1802.

      Probably the only reason they still make them. Interesting term the set index register instruction has in assember though.
    • by Anonymous Coward
      Actually you don't need to shield the whole thing - just the parts that are sensitive to radiation. There are a lot of studies of radiations on the commerical grade FPGA (surprise !!).

      As for ROM vs RAM, wouldn't a Mask ROM be more reliable than RAM ? I would assume you mean 6T or 8T SRAM not those 1T DRAM cells.
    • by Anonymous Coward
      Bruce,

      I would like to add that it is quite possible to fly commercial processors in space. It merely requires good system engineering. Space radiation is merely another source of faults. A number of techniques can be used to get much better performance out of the commercial processor than the rad-hard processor while keeping it free from errors and up in terms of availability.

      For instance the Iridium constellation uses Power PC 603s. In side by side comparisons, most of the time, the commercial processor is the better choice.

      Besides performance and price, schedule is the big concern for using rad-hard parts. Most rad-hard processors that are being developed now (Rad-hard Pentium by Sandia, Rad-750 by BAE Systems, etc.) are way behind schedule and their performance by the time their designs are finished will be too far behind what is current to be useful.
  • We've burned up a lot of space junk in the upper reaches of our atmosphere, and it always strikes me as a big waste, albeit for the time being, perhaps an unavoidable one. But these little satellites, according to the article, don't have much transmission power. Perhaps that'd offer some insentive to get them to survive re-entry, bringing the data back home the old-fashioned way.
  • by thinmac (98095) on Tuesday September 25, 2001 @10:56PM (#2351021) Homepage
    Why send humans? Because there's more to life than just knowing new things. We're an expansive race, and for better or for worse (in my opinion for better) we need to grow. Robots, while they can give us a lot of information, are no substitute for actually being there and experiencing it for ourselves.
  • by gusnz (455113) on Tuesday September 25, 2001 @11:01PM (#2351044) Homepage
    With the growing amount of space detritus, another good point in favour of smaller satellites is less statistical risk of a collision.

    This would go both ways -- less risk of debris colliding with satellites, and less risk of a rogue satellite colliding with something else. The odds are minimal anyway, but it can't hurt that much.
    • Yes, but it's far easier to see and track something the size of a Volkwagen than it is to see and track something the size of a basketball.
      • According to this page [esoc.esa.de], ground based stations can track things down to 10 cm (about 4 inches). Admittedly they would be harder to see by an astronaut, but they typically aren't responsible for spotting the things visually. So long as people on the ground keep track of the satellites, it shouldn't be a problem.
      • Yes, but it's far easier to see and track something the size of a Volkwagen than it is to see and track something the size of a basketball.

        Radar Cross Section isn't simply a function of size though. If you can make a UAV with the same RCS as a B52 it should be possible to make a nanosat which can easily be tracked from Earth.
  • by Autonomous Crowhard (205058) on Tuesday September 25, 2001 @11:03PM (#2351050)
    While the article talked about beach balls, Univac, birthday cakes, Broncos, bowling balls, Coke cans, and Callista Flockhart.. It was completely devoid of any information we have not seen before.

    It's called Brilliant Pebbles, guys. Sheesh!

    OK, they mentioned funding is a consideration in the development.

    A complete fluff piece.

  • So -that's- why I never see "Pigs In Space" anymore. Damn. I loved that sketch.
  • Space Junk Threat? (Score:5, Insightful)

    by Jucius Maximus (229128) <zyrbmf5j4x@sn k m a i l.com> on Tuesday September 25, 2001 @11:19PM (#2351103) Homepage Journal
    Would smaller satellites be more or less vulnerable to being hit by flecks of space junk [space.com] in comparison to their larger counterparts?

    Larger satellites tend to be plagued by little dints and holes in their solar sails because of these flecks of paint and whatnot. Smaller satellites would be harder to hit (because there's less volume up there in the first place,) HOWEVER the greater density of the devices could make a single unfortunate hit rather catastrophic because it could knock a whole bunch of things out at once.

    It's like of like an ultra-powerful shuttlecraft compared to a borg cube. Small centralisation versus big generalisation. Comments anyone?

    • well, I thought that if you have many of these little ones, then they in fact become space junk themselves. if all is controlled well, then no prob, one goes off, or gets killed via space junk itself, then it adds to it, etc etc.
    • Ya, less chance of being hit by space junk... but if it does get hit, it's garunteed to be a catastophic failure... With the big satellites, at least there is a chance it can survive a collision, but with these smaller sats, I doubt anything would work after an impact with even a 5 mm peice of space junk at orbital speeds...
    • How about a manned spacecraft colliding with one of these mini-sats? How small are we talking about? Baseball size? In any case, smaller (read: cheaper) satellites mean MORE sattelites, and that means the volume of space junk increases exponentially, thus the sharply increased risk of collision.
  • by wfmcwalter (124904) on Tuesday September 25, 2001 @11:21PM (#2351112) Homepage
    There's lots of advantages for a satellite being small (and thus having a low mass):

    • Lower launch cost.
      Rocket cost proceeds geometrically as payload size increases only linearly, so big satellites are much more expensive to launch than are smaller ones. Build a satellite small enough, then there's a real chance it can be put into orbit by an ambitious amateur rocket.
    • Cheaper makes for cheaper still
      If a satellite is cheaper (by which I mean total cost = system cost + launch cost) then you're more able to throw it away and replace it. The more inclined you are to throw it away, the less you worry about its maintaining an orbit - in the extreme case you don't build in any altitude maintainance and only gyroscopic attitute maintainance - then you don't need orbital control jets (and fuel, and all the associated systems) - so your satellite becomes cheaper and cheaper yet. So the satellite size reduces and reduces until its stopped by another parameter (e.g. mass of electronics, transponders etc.) which doesn't shrink in this way.
    • Smaller is simpler is more reliable
      As we said, smaller satellites don't need as much (or any) orbital maintainance equipment. That's one of the parts of a satellite that's most likely to fail (and thus leave the satellite useless because its pointing the wrong way). If you can get the platform + payload cost down far enough, it'll be cheaper (and more reliable) to launch 10 cheap sats than one delux biggie.
    • It's much cheaper to scale up on the ground
      Sure, making a small satellite makes for poorer signal strength, but ground-based equipment (dishes, antennae, amps etc.) scale with a much flatter geometric curve than do the same improvements in orbit (when you've spent all that money shoving them up the gravity well). If the VLA can detect "a cellphone at Saturn", a bigger dish here can detect a cokecan in LEO.
    The current satellite design philosphy is largely to engineer from a reliability-first perspective, which is guaranteed to produce an expensive solution. If satellites were built by consumer-technology companies (Sony, Philips, Dell, VolksWagen) they'd be cost-engineered first (without reliability being at such a premium) - and our solar system would soon have another planet with a ring round it :)
    • What? I think you need to put your geometric scales back where you found them because I don't think you're using them correctly. Making smaller sats doesn't lower the launch cost of the rocket. A majority of the rocket exists just to get the rest of the rocket up to a point where the payload can be delivered. making the payload smaller just means you wasted alot more money getting it into orbit. Putting a bunch of small mini-payloads doesn't reduce the cost anymore because you need to include the mass and bulk of the delivery system for each mini-sat. Where the fuck do you come up with smaller sats not needing orbital maintainance equipment? All birds need attitude controls at the very least to point them the right way. The concept of disposable birds is ludicrous. Even if it costs ten bucks to build it costs thousands of dollars to get in the air. Nobody in their right mind would design a bird and send it up if they didn't plan on getting their money's worth out of it. And the dumb comment about building a transceiver bigger than VLA to manage mini-sats nearly made me piss myself. Increasing the size of the ground base tranceiver adds way too much to the cost of launching any sat. why should you have to pour the millions of dollars in maintainance of a VLA sized unit to talk to a sat that costs a fraction of a percent of the ground station?
      • Question: is your sig a refence of the Get Up Kids or straight back from Pee Wee?
      • I believe the benefits of small sats is that you can put several of them on a single launch vehicle, and reduce the launch costs that way. Of course you need a launch system capable of carrying a number of smaller payloads - which there aren't very many of right now.

        As far as I know the best for doing that are not US built which is why Surrey Space [sstl.co.uk] over in England are making a killing right now in the nanosat category.

        Jedidiah
        • Surrey's technologies are still pretty experimental and rely in some pretty difficult formation flying. Nanosats don't carry much in the way of tranceiving equipment and if you read the datasheets they carry uncooled CMOS cameras and basically are good for inspecing other spacecraft they're in formation with. Other formation flying ideas are lots of small birds with one or two tranceivers each that fly in formation and can output at least 10 watts PEP. You could have one sat with an uplink receiver that beams data to the rest of the birds in formation and they downlink different pieces of the signal on their tranceivers. Basically breaking a single comsat into a bunch of small pieces so if one component fails you could deorbit it hopefully and replace it by pushing another bird into the formation or having a backup fill its place. Nobody's really done this yet because formation flying in orbit is still a complex procedure and until recently birds weren't smart enough to navigate themselves. Also keep in mind that Surrey's sats are still all experimental and are using equipment that hasn't been recognized as spaceworthy quite yet. Trying to sell someone a satellite that has a 10% chance of working after a good sized solar storm won't be too effective. I think it is sort of interesting and cool they're powering their birds with StrongARMs.
        • I believe the benefits of small sats is that you can put several of them on a single launch vehicle, and reduce the launch costs that way. Of course you need a launch system capable of carrying a number of smaller payloads - which there aren't very many of right now.
          Only must good if you want them all in the same orbit. Otherwise a good chunk of your payload will be rocket motors to alter the orbit. Also this isn't going to work without some kind of attitude control on them, even if it's simply using compressed gas.
      • Why should you have to pour the millions of dollars in maintainance of a VLA sized unit to talk to a sat that costs a fraction of a percent of the ground station?

        Because the ground station is reusable?

        Regardless, if you can narrow your signal to a specific enough frequency, you could pick it up with an accurate amature ham set.

        All this talk about more transmission power being better...drives me nuts. If people can limit their transmissions to extremely specific frequency ranges (or use timed broad-spectrum pulses [uwb.org])
  • by AnimeFreak (223792)
    What OS would you run if you went into space? :)
  • http://www.apple.com/scitech/stories/skycorp/
    Small, off the shelf components...good future. I've already got my computer in a little space suit, looking forward to the day it will orbit this spinning hunk of rock and smelly stuff.
  • by r2q2 (50527)
    Why make small satellites when you can use solar powererd airplanes. Cheaper and easier to upgrade.
  • Lets hurl a dozen VAX, Punch Card readers, and an IBM 701 out there. We can even hurl the ancient operators when they get cranky about retraining to answer phones at a helpdesk and say "You have a problem with MS Word.. umm.. I am gonna page teh Unix admin at home"

    ??!?!?

    --cgeek--
  • by Bowie J. Poag (16898) on Wednesday September 26, 2001 @12:02AM (#2351220) Homepage


    While it seems like a "cool" idea on the outside, it probably isn't. There are at least two problems I can think of, off the top of my head, as to why microsatellites would be a Bad Idea (tm) ...

    First and foremost, tracking. Suppose your microsatellite fulfills its useful lifespan, and dies, like so many other satellites....Without any means to communicate, the object is too small (and its irregular orbit too unpredictable) to be reliably tracked from the ground. Your microsatellite now becomes a big danger to other spacecraft, and other satellites, as it joins the ranks of tens of thousands of other pieces of other untrackable space junk.

    Secondly, suppose you to manage to get a microsatellite up into orbit. You're an amateur, of course, which means you arent really aware of the orbital paths of other satellites. It might just be a matter of time before your little science fair project interrupts communication to half a continent due to the radio noise it gives off from a poor design meant to maximize for space, and not function.

    I think we'd be wise to leave space for the professionals and be content with ground-based communications like shortwave packet and slow-scan TV.

    Cheers,
    • We could always establish a spacegoing equivalent of the FAA: some administrative agency whose laws and regulations govern space travel. Any electronic equipment that wants to go up, must be first approved by the National Spacecraft Testing Labs. NSTL, what a flashy acronym! Too bad it's already used...
      • But these are not amateur sats.
        The ST5 nanosatellites will be "full service", meaning they will carry a wide range of spacecraft services including guidance, navigation and control, attitude control, propulsion, high bandwidth and complex communication functions.
        This is what NASA is trying to develop - a new generation of smart sats, with an exciting set of new technologies [nasa.gov]
  • but are they wireless?

    If not, I know a GREAT technology that's readily available.
  • Space - Patriotism (Score:3, Insightful)

    by ZaBu911 (520503) <zackster AT gmail DOT com> on Wednesday September 26, 2001 @12:17AM (#2351256) Homepage
    I know a few of us have long dreamed of the stars. The riches beyond our grasp. Sure, we can find a few more facts with a computer, but we can never have the same satisfaction as we would have had if we sent a person.

    I'd like to [mis?]quote a line from the movie Contact: "This is so beautiful...words cannot describe...they should have sent a poet."

    Ponder that for a while. And no CmdrTaco, the poem-producing engine you wrote doesn't count!
    • And these tiny microsats are our forebears. They are letting us do the research that will someday make it cost-effective to send people into space on a large scale.

      I should like to think that machines (such as these sats) will someday be our companions up there, the spaceborne equivalent of the civil infrastructure of water lines, power grids, streets and highways that we all take for granted.
      • They are letting us do the research that will someday make it cost-effective to send people into space on a large scale.

        I fail to see how microsats make it easier to get out of this gravity well. And what gives you the idea that NASA really wants lots of people in space? All they ever needed to do was make it reasonably inexpensive to reach orbit. No small task, to be sure, but they've had 50 years and umpteen billions of dollars to do it with. The rest of us would have taken care of the rest. Everything, absolutely everything else they did should have been secondary to that. But instead, they have spent many times more putting a flag on the moon than they have on, say, scramjets and laser boosts and other potentially very cheap means of getting to orbit. Yes, the stuff they've done is certainly very impressive, but how useful is it to know the components of lunar regolith when nobody has set foot there for over 30 years and there are no such plans in the forseeable future? Or that there are planets in other star systems light-years away when we can barely go 60 miles straight up? It's all wonderful, fascinating knowledge and, with the way NASA's been going, completely and totally useless.
  • by cluening (6626)
    They will have the attitudinal and navigational capabilities needed to maintain proper orbits, and they will be capable of complex, high-bandwidth communications functions."

    ...And they are a lot harder to dodge when in the space shuttle, ISS, or other such things. What a great idea! :)

    Of course, I am sure somebody in charget has thought of that already...
    • Re:And... (Score:5, Interesting)

      by Xeger (20906) <`ten.regex.rekcart' `ta' `todhsals'> on Wednesday September 26, 2001 @01:29AM (#2351398) Homepage
      Now there's an amusing thought: astronauts waking in the middle of the ship's night to the clunking of dozens of microsats on the hull. Like a hailstorm in an automobile. *thump thump clunk thump* "What's that noise?" "Aww, just a couple GPS birds. Nothing to worry about."

      In actuality, it's pretty hard to hit anything in orbit. There's a whole lot of space out there, and not a very large volume of space junk. And, at least for spacecraft which are still in the middle of their useful mission lives, the orbit of everything up there is calculated. I'm sure there is even a repository or tracking agency for random space debris. Collision avoidance has got to be largely a planning matter (adjusting the Shuttle's flight plan so its orbit never intersects with known random space crap).

      I wonder...does the Shuttle even have a search radar operating, to watch the space around it for navigational hazards? I've never heard of such a thing...
      • The thing that drives down the cost of equipment earthside is volume. Why not design a mini-satellite platform that accepts custum modules. This platform would contain as part of its design all the attitudinal and orbital controls. As part of that design, include a simple system that would respond to a signal by moving the satellite away from the source. Thereby, the shuttle or other manned or higher priority craft would just need to transmit the signal as a warning and all the hords of mini-satellite would move to the side.

      • As a Point of referance, I was watching up here in Canada on the TLC (The Learning Channel), that quite regularly the shuttle missions will have to re-direct course, or rotate the ship for component/people safety when approching space debris. According to the show, any object larger than say a computer mouse is currently being tracked.
  • micro satilites (Score:1, Interesting)

    by Anonymous Coward
    Hmm I suppose they could make them football sized & launch them into space with a giant cannon.

    Hey, I'm serious.
  • What about rain fade? What about wild feeds?? I'm sticking with my big ugly dish!
  • Formation Flying (Score:3, Interesting)

    by Betelgeuse (35904) on Wednesday September 26, 2001 @12:53AM (#2351334) Homepage
    They talk in this article about flying a bunch of small telescopes in formation as a surrugate to HST. This is _rediculously_ complicated. I have been at conferences where they talk about plans for the Terrestrial Planet Finder: a giant telescope array that will be space-based and fly in formation (slated, very optimistically, to fly in 2020). Just keeping the _distances_ accurate is hard enough, much less keeping all the instruments in the same plane. At least for Astronomical applications, these minis aren't going to replace the bigger guys any time soon.
  • Clear mouse (Score:5, Insightful)

    by Graymalkin (13732) on Wednesday September 26, 2001 @01:08AM (#2351355)
    Microsats would be cooler if there were cheaper ways of getting them into orbit. Even if you get the bird's weight down to as little as possible you still need a deployment module. Then you've got this thousands of pounds of rocket to get a little bird into orbit. Your launch cost will still be in the order of a thousand dollars a kilogram if not more (especially if your rocket is wasting all of its power getting a tiny 100kg bird into orbit). Nearly all of the work being done at Marshall SFC has to do with the reduction of cost with any and all ground launches including getting birds in the air for alot less than they currently cost. They changed their site around or I'd put some useful links from there like the magnetic linear accelerator. It looks like a fucking brochure now. Maybe if a couple of us donate ten bucks to them they'll put some useful information back there. One can only dream I suppose.
    • I think the point is the bollowing:
      But if you're looking to launch a handful of satellites that are each the size of a bowling ball or a desktop computer monitor, you're likely to be able to squeeze them onto a flight that's already arranged with some other primary purpose, such as servicing the International Space Station, Hirschbein said. "Little tiny critters are a lot easier to tack on."
      These guys are meant to fly in swarms, or packs. I think the most interesting part of this is the "ability to configure a set of nanosats as a single craft" - flexible distributed processing among craft, not just small autonomous craft.
      • Formation flying with birds is still a very difficult thing to arrange. you'd also want something a little bit bigger than a 5-10kg nanosat as a functional unit of a swarm. Lets say you want to replace a comsat with a formation of small birds each with one or two transponders. You're not going to use a 10kg nanosat that can barely push a watt of PEP over the transponder. You need something a little bigger than can give you more power. With some nanosat designs you end up with sharply diminishing returns as the size decreases. Like the article says these really small sats might be best suited as ROVs controlled by the IIS crew that could at the very least just give them an eye in the sky of sorts. I mean look at when Mir was hit by the meteoroid which caused all their problems. They didn't know exactly how damaged Mir was until the shuttle went up and could get an external view. Now lets say they had a couple nanosats with cameras and maybe a little epoxy gun or something. They might have been able to more easily repair parts of the station. until we can stick little nuclear power supplies or 80% efficient solar panels on nanosats they aren't going to be flying in a communication array formation replacing comsats, they just haven't the power. Maybe we could just have one big sat that powers the formation by beaming nanosats power using microwaves.
    • Or, you combine rides. Stanford University is working on a standardized "cubesat", 4" on a side. A standard dispenser holds 3 of them. The dispensors are mounted as secondary payloads on rockets (or LOTS of them as primary payloads). I believe that their estimated cost to orbit is $50k for one cubesat.
  • Compact nanosatellites will have everything you'd want in a full-size, luxury satellite

    Excellent! So they'll have a bar and mini-fridge and in room service. None of those second rate MacroSat's for me.. I'm going for the luxury model.
  • Satellite Page (Score:1, Informative)

    by Anonymous Coward
    Here's a really cool satellite engineering page that lists a bunch of small satellites - micro, nano, and pico. Also check out the humor section down towards the bottom. There are plenty of points that are applicable across many disciplines.

    http://www.ee.surrey.ac.uk/SSC/SSHP/

    AW
  • {paranoia}
    Millions of satellites, smaller and vastly more powerful satellites.
    How long before satellites, with increasingly sophisticated cameras, DSP, raw CPU power, and cross-referencing data amongst satellite clusters, get so powerful that they can:
    1) Read the fine print of newspapers on the surface
    2) Accurately recognise faces where the satellite's elevation from the subject is less than 80 degrees, and
    3) Read infra-red signatures through building roofs, sufficient to discern number of people inside and their movements?
    {/paranoia}
  • They will have the attitudinal and navigational capabilities needed to maintain proper orbits...

    ... and avoid the millions of other tiny satellites that are launched under the same program? Got a plan for that one?

    O' course, I'm picturing the future when they become miniaturized to a few ounces and cheap enough so that everyone can afford one. Maybe they'll be the bugs on the space shuttle's windshield.

  • by kingdon (220100) on Wednesday September 26, 2001 @02:38AM (#2351474) Homepage

    The page says that the satellite is the size of a birthday cake, and also that it is "42 centimeters (17 inches) across . . . weighs about 21.5 kilograms (47 pounds)". I don't know about you, but on my last birthday I didn't get a cake that big ;-).

    More seriously, this is cool stuff. My favorite item from the list of new technologies [nasa.gov] is the "electrically tunable coating that can change its properties from absorbing heat when the spacecraft is cool to reflecting or emitting heat when the spacecraft is in the sun by applying electrical power". When you look at conventional ways of managing heat on a spacecraft (such as large and heavy radiators on the Space Station), this is pretty exciting.

  • do you call it a ST5Cat Cluster or a Beowulf Cluster?
  • small is nice (Score:4, Interesting)

    by vittal (52825) on Wednesday September 26, 2001 @05:09AM (#2351651) Homepage
    somewhat off topic, but this sort of idea has been around for a long time, have a read of rodney brook's paper "Fast, Cheap and Out of Control: A Robot Invasion of the Solar System [mit.edu]" [www.ai.mit.edu] (Journal of the British Interplanetary Society, October 1989).
    similar ideas, but with robots. v

  • "Due to a computer glitch at NASA, there will be a hailstorm over Oslo tonight."

    Mvh:
    - Knut S.
  • Why send a human into space when you can send a computer?

    To press Ctrl-Alt-Del of course.

  • rodney barnes would be impressed - but do they get all the gold shiny foil stuff? (he always mentioned that in the talk I saw him present on nasa stuff)
  • by crumley (12964)
    There is another nanosatellite program that's going to fly soon called ION-F [usu.edu]. This is a group of 3 10 kg nanosats that fly in formation that are supposed to launch in 2002. They'll be used to studdy the ionosphere.
  • Why send a human into space when you can send a computer?

    Because he is a senator?
  • Under related stories was this link [newsfactor.com] to a story about using satellites to spy on the secret camp for Survivor 3! While there are no pictures to see, it's nice to see that we're finally using satellites for something important.

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