As you surely know, the Gravity Probe B experiment will check, very precisely, tiny changes in the direction of spin of four gyroscopes contained in an Earth satellite orbiting at 400-mile altitude directly over the poles, comparing their values to those predicted by General Relativity. During the 50-week science phase of the GP-B mission and the 7-week instrument calibration phase, which lasted from August 2004 – September 2005, it collected over a terabyte of experimental data. The data analysis phase currently underway will culminate, by next year, an amazing work spanning more than four decades. The GP-B Stanford site is just impressive, containing everything you’ll ever one to know about the experiment, from an introductory General Relativity Q&A or a series of beautiful litographs explaining the experiment to relevant scientific papers and directions to build your own GP-B spacecraft.
Thus, there’s really no point in duplicating that well-organized and excellently presented information here, my point being instead recommending the whole site to the few of you that didn’t knew it, and drawing the attention of everyone to a recent addition: an entertaining public lecture by the mission’s principal investigator and instigator, Francis Everitt. Targeting a non-specialist audience sitting in the aisles, Everitt covers the following ground:
- Testing Einstein
- The invention of many new technologies
- Collaboration between university departments
- Highly successful student involvement in a long-running space program
- A remarkable range of spin-offs, some of which made possible other NASA missions, including IRAS, COBE, WMAP, and the Spitzer telescope
- Collaboration between NASA, academia, and industry
- The challenge of managing a flight program with a very highly integrated payload and spacecraft
Or, if you don’t feel like going to the movies, read Everitt himself explaining this amazing journey in a recent interview.