Citation
Abstract
During the Mars Pathfinder mission, there was a 30-second period in which the 8.4-GHz (X-band) communications link to Earth was lost during the atmospheric entry phase. An analysis of the Mars Pathfinder reconstructed flight profile using aero-thermodynamic tools provided estimates of the electron densities in the stagnation and wake regions of the spacecraft. For the wake region, where the low-gain antenna used to communicate with Earth was located, the electron-density estimates exceeded the critical X-band electron density during the first 20 seconds of the 30-second blackout period. High Doppler dynamics and low signal-to-noise ratio may have contributed to the blackout during the last 10 seconds. Thus, at least part of the Mars Pathfinder communications blackout during entry was possibly due to the sheath of charged particles generated by heating incurred by the shock. The upcoming Mars Exploration Rover (MER) missions, MER-A and MER-B, scheduled for 2003 launches, are not expected to experience communication blackouts due to charged particles during their entry phases into the Martian atmosphere in 2004. The estimated peak electron densities expected for MER lie about three orders of magnitude below the critical X-band electron density required for blackout.
Keywords
Details
- Volume
- 42-150
- Published
- August 15, 2002
- Pages
- 1–23
- File Size
- 232.0 KB