Up to this point I have left out the effects of sunlight on ROMIT simply because I thought it was neglible. The other day a read a book about scientific mistakes and found one (a trip to Mars) in which NASAs subcontractor had forgotten that units should be in the SI (metric) system.

Consequently all course corrections were about 5 times more than necessary, and eventually the craft burned up in the marsian athmosphere.

The reason for the corrections was the effect of sunlight on the asymmetrical body of the spacecraft.

That made me think about the effect of sunlight on ROMIT. It will be travelling in sunlight for 1 to 3 months (maybe more), and will thus receive a sunlight pressure per mass unit (accelleration) equal to:

(1.36 kW/m2) /(3*10E8)/10 kg = 4.53*10E-7 m/s2. (ROMIT is assumed to weight 10 kg at this stage).

This means that the deviation after 1000 seconds will be 25 centimeters or after one month 3043 km, which is more than the width of the Moon.

So in the future, the sunlight pressure will be included.

BTW, this calculation assumed that the radiation is absorbed. Most of it is reflected, so that may double the deviation.

Tor Foss Mortensen
Trajectory Tool Programmer