5 ms·

Seems like the previously leaked 1.2 ± 0.1 mN/kW is true. I look forward to seeing it tested in space to finally see if its real or not.

by aeleos 9y ago

valarauca1 9y ago
China claims their testing a mock up as one of the experiments being conducted on the Tiangong-2
simonh 9y ago
That's such a tiny thrust it might be quite difficult to measure in space. Orbits are complicated, what with complex gravitational variability of the Earth (mountain ranges, continental shelves, the fact it's not a sphere), the influence of the moon and sun, interaction with the magnetic field, solar winds, and down in low earth orbit even the last vestiges of the atmosphere.
- Sanddancer 9y ago
  Those forces are actually pretty well behaved and can be readily measured and accounted for. Also, light sails have a order of magnitude less power, and the Pioneer Anomaly [1] was smaller yet. Space is probably the best place to test something like this. [1] https://en.wikipedia.org/wiki/Pioneer_anomaly https://en.wikipedia.org/wiki/Pioneer_anomaly
  - simonh 9y ago
    The Pioneer Anomaly was only detectable over several decades and a journey to the furthest reaches of the solar system. I'd expect a useful propulsion system to produce effects quite a bit more detectable than that. This effect is about 1/25 the power efficiency of the lowest power ion thrusters. Output at this level over a very long period might be useful at the interplanetary level and maybe at geostationary altitudes, but the low earth orbit environment is actualy highly variable and unpredictable at this scale of effect.
    - consp 9y ago
      Wouldn't variations in atmospheric drag negate any possibility of detecting the actual thrust component in leo? The trusts are small, as is the device, but any variation would be extremely hard to detect and measure. Please correct me if my line of thinking is wrong though, I'm not an aerospace engineer.
- tzs 9y ago
  Couldn't many of those effects be accounted for by having a non-operating unit in the same orbit as the test unit, and looking for differences in the motion of the two?
  - simonh 9y ago
    Yes, all I'm saying is the orbital experiment would have to be well designed. It's not necessarily trivial.

Seems like the previously leaked 1.2 ± 0.1 mN/kW is true. I look forward to seeing it tested in space to finally see if its real or not.

by aeleos 9y ago

Seems like the previously leaked 1.2 ± 0.1 mN/kW is true. I look forward to seeing it tested in space to finally see if its real or not.

valarauca1 9y ago

China claims their testing a mock up as one of the experiments being conducted on the Tiangong-2

simonh 9y ago

That's such a tiny thrust it might be quite difficult to measure in space. Orbits are complicated, what with complex gravitational variability of the Earth (mountain ranges, continental shelves, the fact it's not a sphere), the influence of the moon and sun, interaction with the magnetic field, solar winds, and down in low earth orbit even the last vestiges of the atmosphere.

Sanddancer 9y ago
Those forces are actually pretty well behaved and can be readily measured and accounted for. Also, light sails have a order of magnitude less power, and the Pioneer Anomaly [1] was smaller yet. Space is probably the best place to test something like this. [1] https://en.wikipedia.org/wiki/Pioneer_anomaly https://en.wikipedia.org/wiki/Pioneer_anomaly
- simonh 9y ago
  The Pioneer Anomaly was only detectable over several decades and a journey to the furthest reaches of the solar system. I'd expect a useful propulsion system to produce effects quite a bit more detectable than that. This effect is about 1/25 the power efficiency of the lowest power ion thrusters. Output at this level over a very long period might be useful at the interplanetary level and maybe at geostationary altitudes, but the low earth orbit environment is actualy highly variable and unpredictable at this scale of effect.
  - consp 9y ago
    Wouldn't variations in atmospheric drag negate any possibility of detecting the actual thrust component in leo? The trusts are small, as is the device, but any variation would be extremely hard to detect and measure. Please correct me if my line of thinking is wrong though, I'm not an aerospace engineer.
tzs 9y ago
Couldn't many of those effects be accounted for by having a non-operating unit in the same orbit as the test unit, and looking for differences in the motion of the two?
- simonh 9y ago
  Yes, all I'm saying is the orbital experiment would have to be well designed. It's not necessarily trivial.