Analysis Methods of Environmental Induced Anomalies of Spacecraft

Mathematics – Logic

Scientific paper

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

Scientific paper

Thirty years after the first evidence of in-flight electrostatic discharges on synchronous spacecraft, they are still a threat. Analysis of anomalies will be always necessary for improving design guidelines and standards. A Ground Control Center dedicated to a Space System is monitoring for the nominal configuration of the spacecraft. An alarm or warning is triggered when the spacecraft gets out of its nominal working state. How to know what happens in flight? An electrostatic discharge is never observed itself but only its permanent consequences. Telemetry data is never designed for detecting unforeseen events, it is only defined for command purpose and good-health diagnosis. Probes are exceptionally implemented on commercial spacecraft to determine the state of environment at the location of the spacecraft at the time of the anomaly. The first step is the elimination of non-environmental causes: electromagnetic interference problem, equipment failure, corona discharge inside a high-voltage powered box, or man-made spurious command. Heavy ions or micrometeoroids are environmental causes with consequences that look like electrostatic discharges, so involving charging needs detailed and exhaustive analysis. The spacecraft-charging anomaly is at the end of a long chain of causes and consequences. Some regions of space have a radiation and particle content able to build up absolute and differential potentials at the surface or inside the spacecraft up to exceeding the breakdown voltage. Charges are released that induce electromagnetic fields in coupling current and voltage transients to cables. The pulses penetrate boxes and propagate along printed circuit board tracks, reaching active devices, upsetting logical devices, saturating amplifiers, or fusing lanes inside integrated circuits. Spacecraft event understanding is the conclusion of three convergent ways of analysis: environmental data, vacuum charging tests, electromagnetic immunity tests. When there is no borne particle detectors, we rely on Space Weather plots issued by the Space Environment Center of Boulder, CO, USA. It is only informative since measurements are not made at the same location of the orbit as the spacecraft of concern. A proton analyzer provides proton flux data from solar flares in three spectral bands: E>10 MeV, E>50 MeV, and E>100 MeV. Electron fluxes are plotted for two bands: E>600 keV and E>2 MeV. The geomagnetic field at GOES location and the planetary K-indices are also given. The photoemission from illuminated parts of the spacecraft prevents charging but large negative potentials can build up on shadowed parts. The sun direction is known from the spacecraft attitude in the geocentric axes, the sun seasonal inclination, and the local time. Bulk and surface resistivity, secondary emission yield to electrons and ions, photoemission efficiency responsible for charging characteristics are documented during the spacecraft development. Testing flight-representative items in a vacuum chamber under electron beams allows forecasting of in-flight potentials and assessment of the discharge risk. During the tests we identify the electromagnetic pulses to reproduce them in normal laboratory ambience testing the electromagnetic immunity of equipment.

No associations

LandOfFree

Say what you really think

Search LandOfFree.com for scientists and scientific papers. Rate them and share your experience with other people.

Rating

Analysis Methods of Environmental Induced Anomalies of Spacecraft does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Analysis Methods of Environmental Induced Anomalies of Spacecraft, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Analysis Methods of Environmental Induced Anomalies of Spacecraft will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFWR-SCP-O-1331544

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.