NASA's Gravity Probe B mission on TV

Robh (Rob) · #1 08-06-2009, 04:23 PM

Hi all,

For anyone interested in NASA's attempt to confirm two more effects predicted by Einstein's general theory of relativity, watch Catalyst on Thursday 8pm abc1.
The Gravity Probe B physic's experiment is an attempt to establish the geodetic effect and frame dragging.

For more info on the mission, see ...
http://einstein.stanford.edu/MISSION/mission1.html

Regards, Rob

xelasnave · #2 10-06-2009, 12:16 PM

Quote:

Originally Posted by Robh

Hi all,

For anyone interested in NASA's attempt to confirm two more effects predicted by Einstein's general theory of relativity, watch Catalyst on Thursday 8pm abc1.
The Gravity Probe B physic's experiment is an attempt to establish the geodetic effect and frame dragging.

For more info on the mission, see ...
http://einstein.stanford.edu/MISSION/mission1.html

Regards, Rob

Yes I noted that Rob I hope I can be near a TV and catch it...
IF particles flow along the space time grid line and the aspect of frame dragging is demonstrated I feel this suggests that this experiment does better than the MM experiment and in effect finds what they set out to find... and I bet no one has a clue what I am driving at.. but thats normal

alex

sjastro · #3 10-06-2009, 03:19 PM

Quote:

Originally Posted by xelasnave

Yes I noted that Rob I hope I can be near a TV and catch it...
IF particles flow along the space time grid line and the aspect of frame dragging is demonstrated I feel this suggests that this experiment does better than the MM experiment and in effect finds what they set out to find... and I bet no one has a clue what I am driving at.. but thats normal

alex

It has absolutely nothing to do the MM experiment.

The MM experiment was devised to find if light required a medium for propogation like sound waves requiring air.

The Probe B experiment is devised to find

(a) The geodesic effect where the "start" and "end" points of the satellite orbit are determined. If the points coincide space-time is flat, if not there is curvature.

The experiment is based on how mathematicians calculate curvature by loop integrating a surface.

(b) Frame dragging where an object in orbit can drag space-time with it.

Regards

Steven

leinad (Dan) · #4 11-06-2009, 11:19 PM

In case anyone missed it; you can watch it here:
http://www.abc.net.au/catalyst/stories/2594259.htm

h0ughy (David) · #5 11-06-2009, 11:28 PM

was good to watch - another theory proven

mswhin63 (Malcolm) · #6 12-06-2009, 01:52 AM

Great story, Prior to my interest in science and astronomy I always thought the theory was proven. I wonder how many other thought that.

Good result.

Robh (Rob) · #7 12-06-2009, 10:31 AM

The program was very interesting from both a historical and experimental viewpoint. The GP-B was designed to confirm two key predictions of Einstein's general theory of relativity, now some 90 year's old. It wasn't until recently that the technology became available to actually carry out the experiment. The 1.5 inch gyroscopic spheres used, if blown to the size of the Earth would have no peaks higher than 2.4 metres. They are the roundest objects ever made.

Stanford University Professor Francis Everitt spent 40 years of his life getting this project to reality. What struck me was the continual struggle by Everitt to keep the project going, as funding was cancelled 7 times. The Gravity Probe B was finally placed in orbit around the Earth in 2004. A lot of initial calibration was necessary. The geodesic effect was confirmed but frame dragging needed more data. NASA funding evaporated in 2008 but the project was kept going by a Saudi Arab to get results for frame dragging.

From my understanding, the proof for the geodesic effect was strong but the evidence for frame dragging is still to be generally agreed upon by the scientific community.

Regards, Rob

Quark (Trevor) · #8 12-06-2009, 01:08 PM

Another top program by Catalyst, God bless the ABC.

What a truly amazing story, in the first place to find a way to prove GTR and to then have the tenacity and drive to follow through with it, even as ever higher hurdles kept being thrown in the way.
Inspirational stuff indeed.

Cheers
Trevor

erick (Eric) · #9 12-06-2009, 01:29 PM

So glad I stumbled over this edition of Catalyst.

The website is great:-

"Following is a list of some of the extraordinary accomplishments achieved by GP-B during the 17 months of its flight mission.

Over the course of the 17.3-month mission, we communicated with the spacecraft over 4,000 times, and the Mission Planning team successfully transmitted over 106,000 commands to the spacecraft.
GP-B is the first spacecraft ever to achieve nine degrees of freedom in control. The spacecraft itself maintained three degrees of freedom in attitude control (pitch, yaw, and roll), plus three degrees of freedom in translational drag-free control (front-to-back, side-to-side, and up-down). In addition, the Gyro Suspension System (GSS) for each gyro maintained three degrees of freedom in controlling the location of its spherical rotor within the gyro housing.
The GP-B gyros, which performed extraordinarily well in orbit, have been listed in the Guinness Database of World Records as being the roundest objects ever manufactured.
The spin-down rates of all four gyros were considerably better than expected. GP-B’s conservative requirement was a characteristic spin-down period (time required to slow down to ~37% of its initial speed) of 2,300 years. Measurements during IOC showed that the average characteristic spin-down period of the GP-B gyros was approximately 15,000 years—well beyond the requirement.
The magnetic field surrounding the gyros and SQUIDs (Super-conducting QUantum Interference Device) was reduced to 10-7 gauss, less than one millionth of the Earth’s magnetic field—the lowest ever achieved in space.
The gyro readout measurements from the SQUID magnetometers had unprecedented precision, detecting fields to 10-13 gauss, less than one trillionth of the strength of Earth’s magnetic field.
The gyro suspension system operated magnificently. It had to be able to operate both on the ground for testing purposes prior to launch, as well as in space. This meant that the suspension system had to operate over 11 orders of magnitude—an enormous dynamic control range—and its performance throughout the mission was outstanding.
The science telescope on board the spacecraft tracked the guide star, IM Pegasi (HR 8703), to superb accuracy, and it also collected a year’s worth of brightness data on that star. The brightness data we collected on IM Pegasi represents the most continuous data ever collected on any star in the universe."

xelasnave · #10 15-06-2009, 05:03 PM

I am so excited to see the posts on this matter. Up until now I did not think anyone gave a dam about this mission and the work and advances it has chalenged humans to meet.
Steven thanks for your input /// I see a similarity between the both experiments..er experiment and mission... but I can accept what I see may be a vission I alone enjoy...unfortunately I was on the boat no tv or radio but I have followqed this mission for some time...it is my belief that spacve has physical properties thatr the gravity b probe mission will bear out...and I know what the physics is about however it sees little relationship between the theory bewhind frame dragging and the physical reality that the presumed observations will bring and the concept of an aether... I will look at your post in detail to consider all your wonderful knowledge in these matters... So much effort goes into these experiments yet so often they get no recognition or comment..it was so good that they made a movie about this and maybe more folk will think about the most important thing there is ....gravity..

alex