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

• In November 2005, the entire GP-B team was awarded a NASA Group Achievement Award “Forexceptional dedication and highly innovative scientific and engineering accomplishments leading to thesuccessful execution and completion of the Gravity Probe B Science Mission.”3.2 Extraordinary Technology of GP-BThis sub-section describes the extraordinary technologies, redundancy, and unique technological innovationsthat enabled the GP-B experiment to come to fruition.3.2.1 An Overview of GP-B TechnologyTo test Einstein's theory of general relativity, Gravity Probe B must measure two minuscule angles withspinning gyroscopes, floating in space. While the concept of Gravity Probe B is relatively simple in design, thetechnology required to build it is some of the most sophisticated in the world. Scientists from StanfordUniversity, NASA's Marshall Space Flight Center, and Lockheed Martin Space Systems have drawn from adiverse array of physical sciences, and have invented much of the technology that made the mission possible. Infact, much of the technology did not even exist when the experiment was first suggested in late 1959 - early1960.3.2.1.1 World’s Most Perfect GyroscopesTo measure the minuscule angles predicted by Einstein’s theory, 6,614.4 milliarcseconds (6.6 areseconds) peryear and 40.9 milliarcseconds per year, Gravity Probe B needed to build a near-perfect gyroscope—one whosespin axis would not drift away from its starting point by more than one hundred-billionth of a degree each hourthat it was spinning. This was an especially stiff challenge, given that the spin axes of all gyroscopes tend to driftslightly while they are spinning. Even the spin axis drift in the most sophisticated Earth-based gyroscopes,found in missiles and jet airplanes, is seven orders of magnitude greater than GP-B could allow.Figure 3-1. Gravity Probe B gyroscope rotor, with quartz housing halves.Gravity Probe B — Post Flight Analysis • Final Report March 2007 69