The Wikipedia article NASA Solar Technology Application Readiness says:
The ions are accelerated through two fine grids with roughly a 1300 V difference between them for 2.3 kW operation, with a thrust of 20-92 mN, a specific impulse of 1950-3100 N·s/kg and a total impulse capability of 2.65 x106 Ns.
and the Wikipedia article subsection Dawn (spacecraft); Propulsion system says:
The Dawn spacecraft was propelled by three xenon ion thrusters derived from NSTAR technology used by the Deep Space 1 spacecraft, using one at a time. They have a specific impulse of 3,100 s and produce a thrust of 90 mN.
Both numerical values are about 3,000.
But Isp in seconds is obtained by dividing Isp in N·s/kg (which has units of velocity) by Earth's standard gravity of 9.80665 m/s^2, so one of those numbers is off by roughly a factor of 10.
- Which one is wrong, or are they both wrong?
- If so, then what's the right number?