Monday, April 16, 2007

Dragging Delayed

So my first experience with physics research was with the Gravity Probe B project, where I worked part-time for my first few years in college. GPB is a satellite mission, 40 years in the making, designed to measure frame-dragging -- a fairly subtle prediction of Einstein's General Theory of Relativity. GPB also amounted to a full-employment program for physics undergrads - at any rate, they allowed me to play around with physics experiments without a lot of pressure to churn out hard results. It was pretty cool introduction to physics research, but ultimately not the sort of project I was really interested in, so I eventually moved on to other stuff.

After going to grad school I realized that many astrophysicists actually held a rather dim view of GPB for a lot of different reasons. Dan Holz has an excellent post that explains the science behind the project, and some of the discontent.

Anyway, after 40 years of planning they finally launched the sucker in 2004 and were planning to unveil their Big Result this past weekend when suddenly ... they decided they needed more time to finish the exam. I guess what's a few more months of waiting after 40 years.

4 comments:

Anonymous said...

I cannot even pretend that I understand Einstein's Curved Space-Time deformation that explains the planets movements around the Sun, but I enjoy reading about it none the less. I browsed through all your links Thanks!!

Eugene said...

Speaking as a former spacecraft engineer, GPB is really quite a piece of work engineering-wise. Sad thing is that they are really 40 years too late....

Tim said...

Anon- glad you enjoyed it!

Hi Eugene! Yeah, it is a pretty cool satellite. When I was working there I knew a guy who knew a guy who had dropped one of those $1M super-smooth gyroscopes. Sometimes I'm reminded of that when I've had a bad day...

Eugene said...

Yeah, I've destroyed satellite equipment (a high energy proton sensor) to the tune of about $150000 (80k pounds at that time), not counting the weeks of lost manpower time to make a replacement and *retest* it (which adds up the cost).

And it was really "I", because I was in overall charge of that piece of equuipment, and we put the whole thing into vibration testing without properly encasing it in stiffening gel. I remember that day, when I heard "weird" clinging when the test was running, and checking the pre/post vibration spectra and saw an extra
harmonic....

Cosmology, on the other hand, is soooo less stress inducing.

Ouch.