4 ms·

Can somebody just put one of these in space already? We're seeing a post every week refuting the previous week's posts. http://i.imgur.com/W6CyRnB.gif http://i

by Zikes 10y ago

Can somebody just put one of these in space already? We're seeing a post every week refuting the previous week's posts. http://i.imgur.com/W6CyRnB.gif http://i.imgur.com/W6CyRnB.gif

superkuh 10y ago
That'd just add more uncontrolled variables. What they need to do is stop assuming they can disassociate effects from a superposition with a trend fitted by eye.
- stale2002 10y ago
  Not really. You put it in space, turn on the engine, and see if it STAYS in space. If it crashes to earth after a year, then it clearly doesn't work. If it steadily starts to escape earth's orbit, then it DOES work.
  - cjensen 10y ago
    The forces they are claiming are not sufficient to stay in space. Also, some sources of error would provide actual boosts in orbit without being useful as spacecraft engines.
    - taneq 10y ago
      Wouldn't an 'actual boost in orbit' be useful in and of itself?
      - monocasa 10y ago
        Not if it's as inefficient as is claimed.
  - walrus01 10y ago
    A little bit more complicated than that, the very tiny thrust of the 60W to 80W units reported so far is not enough to keep a medium sized LEO satellite from deorbiting due to atmospheric drag. Now if you were to put it in a MEO orbit where the atmospheric effects would have negligible impact on perigee and periapsis over even a 1000 year time period, and then turn on the "thruster" 24x7 while aimed in a prograde direction, you could observe if the satellite gradually gained a few km apogee over the period of measurement. If it works you would see a gain of dozens of km apogee over a several month time scale.
  - powera 10y ago
    Hah. Not even the people who think it does work think it works that well.
  - superkuh 10y ago
    Nope. In space there would be even more thermal effects (due to varying amounts of sunlight). Then there's also photon pressure, uncontrolled outgassing, the variable ram pressure of the upper atmosphere due to it's changing height with the EUV output of the sun. As of right now the claimed effect is smaller than the thermal effects even in the lab. You put it in space and it'd be impossible to untangle the tiny real effect, if it exists, from all the other forces superimposed upon it that are much larger and literally impossible to predict the time variation of.
saycheese 10y ago
EmDrive: China claims success with this 'reactionless' engine for space travel https://news.ycombinator.com/item?id=13249730 https://news.ycombinator.com/item?id=13249730
Pfhreak 10y ago
Someone is: http://www.popularmechanics.com/science/energy/a22678/em-drive-cannae-cubesat-reactionless/ http://www.popularmechanics.com/science/energy/a22678/em-dri...

by Zikes 10y ago

Can somebody just put one of these in space already? We're seeing a post every week refuting the previous week's posts. http://i.imgur.com/W6CyRnB.gif http://i.imgur.com/W6CyRnB.gif

superkuh 10y ago

That'd just add more uncontrolled variables. What they need to do is stop assuming they can disassociate effects from a superposition with a trend fitted by eye.

stale2002 10y ago
Not really. You put it in space, turn on the engine, and see if it STAYS in space. If it crashes to earth after a year, then it clearly doesn't work. If it steadily starts to escape earth's orbit, then it DOES work.
- cjensen 10y ago
  The forces they are claiming are not sufficient to stay in space. Also, some sources of error would provide actual boosts in orbit without being useful as spacecraft engines.
  - taneq 10y ago
    Wouldn't an 'actual boost in orbit' be useful in and of itself?
    - monocasa 10y ago
      Not if it's as inefficient as is claimed.
- walrus01 10y ago
  A little bit more complicated than that, the very tiny thrust of the 60W to 80W units reported so far is not enough to keep a medium sized LEO satellite from deorbiting due to atmospheric drag. Now if you were to put it in a MEO orbit where the atmospheric effects would have negligible impact on perigee and periapsis over even a 1000 year time period, and then turn on the "thruster" 24x7 while aimed in a prograde direction, you could observe if the satellite gradually gained a few km apogee over the period of measurement. If it works you would see a gain of dozens of km apogee over a several month time scale.
- powera 10y ago
  Hah. Not even the people who think it does work think it works that well.
- superkuh 10y ago
  Nope. In space there would be even more thermal effects (due to varying amounts of sunlight). Then there's also photon pressure, uncontrolled outgassing, the variable ram pressure of the upper atmosphere due to it's changing height with the EUV output of the sun. As of right now the claimed effect is smaller than the thermal effects even in the lab. You put it in space and it'd be impossible to untangle the tiny real effect, if it exists, from all the other forces superimposed upon it that are much larger and literally impossible to predict the time variation of.

saycheese 10y ago

EmDrive: China claims success with this 'reactionless' engine for space travel https://news.ycombinator.com/item?id=13249730 https://news.ycombinator.com/item?id=13249730

Pfhreak 10y ago

Someone is: http://www.popularmechanics.com/science/energy/a22678/em-drive-cannae-cubesat-reactionless/ http://www.popularmechanics.com/science/energy/a22678/em-dri...