GP-B Post-Flight Analysis—Final Report - Gravity Probe B - Stanford ...

In November, 2004 there was a large solar mass ejection accompanied by class X and M solar flares, which lastedfor several days. This event was promptly picked up by the GP-B PM. Figure 13-25 shows the increased flux onboth the horizontal and the vertical detector during this event.Figure 13-25. Proton Monitor Data from November 2004Figure 13-26 is a zoomed-out view of Figure 13-25. It is interesting to note that the maximum flux over the SAAwas slightly smaller during the times corresponding to the two peaks in Figure 13-25. At first, this might seemunusual, but Katherine Harine from NASA’s Marshal Space Flight Center explains this phenomenon, “After asolar event, the trapped proton flux should actually drop a bit. The slight atmospheric heave due to solar energywill increase the loss mechanism of protons more than the number of protons created by the event. Typicallyduring a solar event the proton flux will increase at the Earth’s magnetic poles due to the absence ofgeomagnetic shielding, but may decrease slightly at lower latitudes due to the atmospheric heave lossmechanism mentioned above.”Figure 13-26. Zoomed out view of Figure 13-25372 March 2007 Chapter 13 — Other Payload Subsystems Analyses