[X] My Assistant

[deglr6328]

Gravity probe B is effectively dead, after having exhausted its superfluid liquid He and taking data for ~ 1 year. Current temperature now likely exceeds 10K and rising (beyond the superconducting critical temp of niobium) with drag-free orbit mode around the quartz gyros switched off. Data analysis begins now and is expected to be complete in one year.

[deglr6328]

It's so over. The relevant quote from the assessment:

"Theories that can be expressed in Post-Newtonian (PN) formalism in the weak-field limit are sharply constrained by spacecraft laser ranging, VLBI observations of light bending, lunar laser ranging and radio pulsar timing. In PN formalism, geodetic precession is proportional to 1 + 2γ and frame dragging to 1 + γ + ¼ α1. Taken together, these observations constrain γ to a precision of about 1 part in 10^5 and α1 by about 1 part in 10^4. These are about 2 orders of magnitude below the limits that might be achieved by GP-B in the team’s optimistic projection of what they can do. Hence, in the most optimistic case, they would fail by 2 orders of magnitude to improve the current constraints on these alternate theories."


I would be very surprised to see funding continue and they're right to cut them off. A pathetic end really for such a storied project. Everitt seems grossly in denial in this NPR piece http://www.npr.org/templates/story/story.p...toryId=91007322 .