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Tiny Particle Blows Hole In European Satellite's Solar Panel (go.com)

Posted by BeauHD on from the technical-difficulties dept.

An anonymous reader quotes a report from ABC News: A tiny piece of debris has punched a gaping hole in the solar panel of one of Europe's Earth observation satellites, causing visible damage but not enough to affect its routine operations, the European Space Agency said Wednesday. The unknown particle just a few millimeters big slammed into the back of a solar panel on Copernicus Sentinel-1A on Aug. 23. Using on-board cameras, engineers have determined that the hole is about 40 centimeters (16 inches) in diameter. The European Space Agency said the loss of power caused by the strike is "relatively small" -- less than 5 percent of the wing's usual output. The likelihood of such a strike is calculated at between 1:35 and 1:130 during the satellite's five-year lifetime, said Holger Krag, who heads the agency's space debris office. While the particle probably had a mass of less than 1 gram (0.04 ounces), scientists calculated that it was traveling at up to 40,000 kilometers an hour (24,856 mph) when it hit Sentinel-1A. Space.com has posted a video about the incident, showing images taken before and after the impact.

29 of 225 comments (clear)

  1. At last! by hcs_$reboot · · Score: 3, Funny

    Someone found that screw we lost in space!

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    Slashdot, fix the reply notifications... You won't get away with it...
  2. Unit conversion not needed by sjbe · · Score: 5, Funny

    Using on-board cameras, engineers have determined that the hole is about 40 centimeters (16 inches) in diameter.

    That's 0.00198838 furlongs for those too lazy to do the conversion.

    I think slashdot readers are fine with having just the metric units. Anyone who couldn't do the conversion in their head if they cared probably isn't reading slashdot.

    1. Re:Unit conversion not needed by Anonymous Coward · · Score: 2, Insightful

      Even then, I doubt that there are many people who do not have a feeling for how big 40 cm is, even in countries where inches and feet are still in use.

    2. Re:Unit conversion not needed by jabuzz · · Score: 4, Insightful

      If you are going to do a unit conversion then learn about significant digits. So 0.0020 furlongs is the actual conversion for people that actually know about units and measurement.

    3. Re:Unit conversion not needed by burtosis · · Score: 2

      I prefer my units in beard seconds you insensitive clod!

    4. Re:Unit conversion not needed by arth1 · · Score: 3, Insightful

      While most are probably fine as you say. Nothing was lost by including the information and if it helped a few it was helpful.

      Yes, something was lost by the conversion - the uncertainty factor changed.

      40 cm in this context where the hole hasn't been accurately measured is an estimate, not a fixed value. If translating to inches, 16 inches implies a much higher precision than what's implied by 40 cm.
      "14-18 inches" would be a much better conversion.

    5. Re:Unit conversion not needed by Grishnakh · · Score: 2

      This is an old argument. The thing you're missing is that unit conversion simply isn't important to most people who aren't scientists or engineers. Think about Suzy Homemaker or HR Manager Bob: why would they ever need to convert between inches, yards, or miles? Or better yet, why would they ever need to do a unit conversion involving temperature? Very few people in society ever use the Ideal Gas Law outside of Chemistry 101, and the people who do don't use Fahrenheit, or Celcius, they use Kelvins. In short, the people who care about unit conversions are already using the SI system when they do such work, and those same people have zero trouble converting between English and metric as necessary. For everyone else, they simply don't care, and it doesn't affect their daily lives.

    6. Re:Unit conversion not needed by david_thornley · · Score: 2

      The meter was originally as stated, the size to make it ten thousand kilometers from the equator to the North Pole through Lyons. After that measurement was determined, the meter became the distance between two scratches on a bar. Eventually, it and the second were determined by the speed of light in a vacuum and a very particular way of generating EM radiation.

      The liter was originally supposed to be one cubic decimeter, and the kilogram was supposed to be the mass of a liter of water. They missed, and the liter is no longer exactly a cubic decimeter (although it is a kilogram of water). The kilogram is, last I checked, the only basic unit defined as an artifact, specifically a piece of metal massing (by definition) a kilogram. There's been talk of finding a reproducible way of determining it, but it has to be a practicable measurement that has at least as good accuracy as what we've got now.

      One advantage of the metric system is that almost every country uses it, most in everyday use. The US is weird in that it normally uses certain units defined in relation to the metric system: for example, the legal definition of an inch in the US is 25.4mm. Another is that there's not more than one unit with the same name. A ton can be 2000 or 2240 pounds (a megagram is about 2204 tons, and is often referred to as a ton). There are different miles, the most commonly used ones being the statute and nautical miles. Then there's the obvious advantage that the calculations are a lot easier. Even though I know how many inches are in a statute mile, 63360 is not an easy number to do mental calculations with.

      I don't see humanity changing from the metric system ever. There's no replacement system that would be significantly better.

      --
      "When you have eliminated the unacceptable, whatever is left, however improbable, must be the truthiness" - Holmes
  3. It's absolutely amazing by wkwilley2 · · Score: 2

    how much kinetic energy a spec of dust has when it's travelling over 11k m/s.

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    Have you ever fallen asleep at the keybhanusdiog?
    1. Re:It's absolutely amazing by OneSmartFellow · · Score: 4, Informative

      The answer 61K joules doesn't tell you much unless you are really familiar with energy.
      So, let's look at another similar energy values to help us understand how much energy the solar panel experienced (for lack of a better word).
      This https://en.wikipedia.org/wiki/... bullet (when fired) has a muzzle energy value of about half that amount. This is basically the size of round fired from a .50 Calibre machine gun. That gun is so large, that it is difficult for one person to carry it, and is normally fired from an anchored position (a mount). This is a common ship-board defense weapon against small craft.

    2. Re:It's absolutely amazing by Salgak1 · · Score: 3, Informative

      Considering that 3800 joules is the force applied by a 7.62x39 rifle bullet (i.e an AK-47 round), this is the equivalent of about 8 rounds hitting simultaneously in an area likely under a square millimeter. . .

    3. Re:It's absolutely amazing by saider · · Score: 2

      Considering that 3800 joules is the force

      Not force, energy.

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      Remember, You are unique...just like everyone else.
  4. Re:40cm? by Mathinker · · Score: 2

    Sorry, Michael, I guess we Earth dwellers just don't have the technology your Martian foster parents had... </humor_attempt>

    Actually, it's not a hole, just an "affected area" (from URL http://www.esa.int/Our_Activit...)...

    The pictures of the affected area show a diameter of roughly 40 cm created on the solar array structure, confirming an impact from the back side, as suggested by the satellite’s attitude rate readings.”

  5. Re:40cm? by Anonymous Coward · · Score: 3, Informative

    Kinetic energy = 1/2 of mass times speed squared.
    At 11 km/s, even a mote of dust kicks more than one part of human anatomy.

  6. more and more and more by Anonymous Coward · · Score: 5, Insightful

    that space debris has created more space debris that will create more space debris that ...

  7. Re:40cm? by willy_me · · Score: 3, Insightful

    Everyone knows that the projectile has a large amount of energy. The question is how much of the energy was transferred to the solar panels. When a projectile blows through a thin object, most of the energy remains with the projectile.

  8. Re:40cm? by Salgak1 · · Score: 3, Informative

    One half mass of the particle times the square of the velocity applies everywhere. So, given the value of 1 gram, and 40K kph, we get just a bit under 62 kilojoules. While the mass was likely less than a gram, the velocity is the primary issue.

    The initial impact area is over maybe a square millimeter at best. Given the kinetic impact of relatively common events, this is roughly 8 rifle bullets. So a 40 cm area is entirely expected. While the actual hole is small (as expected, it punched through) cracks would run through a small group of solar cells, rendering the affected cells useless due to transmitted shock. . .

  9. Why the heck by advocate_one · · Score: 5, Insightful

    does it need a flash video (of all things) to show a before and after image of the panel?

    --
    Donald 'Duck' Dunn: We had a band powerful enough to turn goat piss into gasoline.
    1. Re:Why the heck by Big+Hairy+Ian · · Score: 2

      Why does ANYTHING need a Flash video????

      It's the only way to combat Ming The Merciless

      --

      Build a Man a Fire, and He'll Be Warm for a Day. Set a Man on Fire, and He'll Be Warm for the Rest of His Life.

    2. Re:Why the heck by Stinky+Cheese+Man · · Score: 4, Informative

      Article and non-flash photos here at ESA web site: http://www.esa.int/Our_Activit...

  10. Ban all tiny particles! by Anonymous Coward · · Score: 2, Funny

    Build a wall and make the depths of space pay for it!

    !!! TRUMP 2016 !!!

  11. Re:Exponential debris spread by g3rr!t · · Score: 2

    Mod parent up!
    So, a 1-5 mm piece of debris caused a hole 40cm, i.e. 400mm wide - probably creating hundreds or thousands of pieces of new debris. Since the satellite is in the crowded low earth orbit (apogee 693km), perhaps the chance of it hitting a piece of its own solar panel in the future is probably now higher than "1:35 and 1:130", though those bits would not be traveling quite as (relatively) fast as the original impact.

    Apparently this exponential debris effect is called the Kessler_syndrome

  12. Energy of 3x 50 cal bullets by Anonymous Coward · · Score: 2, Informative

    that is about 60000J of energy, 3 times as much as 50 cal round at 20000J

  13. Re:40cm? by Big+Hairy+Ian · · Score: 2

    Both objects were likely traveling in excess of 16000mph (approx 9 times the speed of a bullet). We only know which direction the impactee was traveling. As for the impactor we do not know it's mass and have only vague information as to it's volume (We know it's less than 6cm wide because otherwise it would be trackable by radar). So please explain why what is effectively a pane of glass struck by an object of unknown proportions should have suffered less damage!

    --

    Build a Man a Fire, and He'll Be Warm for a Day. Set a Man on Fire, and He'll Be Warm for the Rest of His Life.

  14. Particle? by Luthair · · Score: 2

    Aren't particles microscopic, something that can be measured in millimetres doesn't seem like it ought to be described as a particle...

    1. Re:Particle? by The+Grim+Reefer · · Score: 5, Informative

      Aren't particles microscopic, something that can be measured in millimetres doesn't seem like it ought to be described as a particle...

      In physics, yes. But they were using the general definition, which does seem somewhat out of place in this case, but is correct. This is similar to talking about a particle of dust getting into a camera lens.

  15. Re:40cm? by v1 · · Score: 5, Informative

    The question is how much of the energy was transferred to the solar panels.

    When the density of the particle is high relative to the hardness of the target, there's a very high chance for penetration and low energy transfer.

    But when the projectile density is relatively low compared to the target hardness, the projectle is usually deformed and stops inside the target. Or as in this case, is completely atomized, causing nearly perfect energy transfer. (approaching 100%)

    So being able to ignore energy loss in the transfer make the math and modeling pretty easy. You just imagine an explosion at the point of contact, with about double the energy of the projectile. (since explosions are omnidirectional, wasting 50% of their energy in the other direction on impact, and in this case, 100% of the energy is transferred into the target)

    And at orbital and escape velocities, delta-V is so high that even a very low M yields a lot of joules.

    Final thing to consider, these panels aren't terribly sturdy. They're made to be extremely light, store compactly, and self-deploy/assemble in space, making them overall pretty delicate. This isn't built anything like the solar panel on your roof. It's more like the model car in your dad's display cabinet. Shoot that thing with an airsoft gun and see what happens.

    --
    I work for the Department of Redundancy Department.
  16. Re:That could have been some astronaut's head by abies · · Score: 2

    https://www.quora.com/Spoiler-...
    "Testing for NASA's helmets included dropping an 8 lb steel ball from 6 feet."

    As for the micrometeoroid - let's assume it is 1g, travelling at 40000 km/h. This is 11111m/s. This means around 61kJ
    For comparison, 5.56 bullet is around 4g and travels below 1000m/s. We are talking about less than 2kJ
    Steel ball will reach around 4.5m/s at point of impact, which gives 36J (not kJ)

    Fracture process is complicated and depends on many factors, but from what I understand it depends more on kinetic energy (as given above) as opposed to momentum (where steel ball still loses to micrometeoroid, but wins with bullet).

    From above, micrometeoroid seems to be many time more dangerous than point blank shot from m4 rifle. I would obliterate the helmet from what I can understand. It wouldn't neccesarily go much futher (like 10 astronauts in row) due to destruction of meteroid itself.

    What is bit surprising is that 11.1km/s is considerably larger than escape velocity in near Earth orbit (7.something km/s). This would suggest it was of external origin, rather than part of orbiting debris?

  17. Re: 40cm? by jareth-0205 · · Score: 2

    its cold up there

    Since the damaged object was a solar panel, I suspect it might have been exposed to, y'know, the sun? In which case it would not be very cold.

    Yes yes very clever. There is this thing called "shade" that means the temperature is all over the shop during normal operation. Solar panels in space have to survive between -100 & 125 Celsius.