Gravity Probe B scores an end-of-year ‘F’, but scores an ‘A’ in the exam!

Back in May 2008 a New Scientist article outlined a NASA Review that almost meant the end for Gravity Probe B, a project conceived in the 1960s to measure how the Earth warps the fabric of nearby space-time, and if it did indeed do so.

Imagine space-time as a large piece of fabric. If you imagine a ball placed on that fabric, this can be thought of as the geodetic effect – the fabric bending around the ball.

Now, consider the ball as being slightly-sticky. If you spin that ball, the fabric will be “dragged” along with the ball, this twisting of the space-time can be considered “Frame-Dragging“.

Einstein theorized that because our Sun warps the space-time surrounding it, the objects around it travel in a curved line (a circle). It is this theory that explains why Earth orbits the Sun. This distortion was first measured in 1919 by Sir Arthur Eddington (and his collaborators) during a total solar eclipse as they noted the position of stars passing near the Sun, but no one has ever measured this effect for the Earth.

Enter Gravity Probe B.

GP-B had two goals:

  1. Demonstrate that Earth has the hypothesized geodetic effect: The warping of Space & Time around a gravitational body; and
  2. Demonstrate the amount of Frame-Dragging caused by the Earth: The amount a spinning object pulls space and time with it as it rotates

Gravity probe B’s total cost was around US$750 million and was another project that almost never was because of dwindling funding for scientific investigation. Back in 2008, 15 experts commissioned by NASA doubted further analysis of the GP-B results would produce any significant new information, and as such they recommended that Gravity Probe B receive no additional funding after September 2008.

Despite this, GP-B secured alternative funding from King Abdulaziz City of Science and Technology. Thanks to that funding, the Stanford-based analysis group and NASA announced on May 4, 2011 that the data from GP-B confirmed the two predictions of Albert Einstein’s general theory of relativity.

NASA’s Gravity Probe B (GP-B) mission has confirmed two key predictions derived from Albert Einstein’s general theory of relativity, which the spacecraft was designed to test. The experiment, launched in 2004, used four ultra-precise gyroscopes to measure the hypothesized geodetic effect, the warping of space and time around a gravitational body, and frame-dragging, the amount a spinning object pulls space and time with it as it rotates. GP-B determined both effects with unprecedented precision by pointing at a single star, IM Pegasi, while in a polar orbit around Earth.
NASA’s GP-B Mission Page

It may not seem like much up front, but this concludes one of the longest-running projects operated by NASA, and as a result of decades of research has led to many technological marvels.

GP-B awesome array of groundbreaking technologies were applied to NASA’s Cosmic Background Explorer mission, which accurately determined the universe’s background radiation – The measurement that is the underpinning of the big-bang theory, and led to the Nobel Prize for NASA physicist John Mather.

Additionally, Gravity Probe B has led to advancements in Control Technologies:

  • Aerodynamic Drag
  • Magnetic Fields
  • Thermal Variations
  • and GPS Technologies allowing planes to land unaided.

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