Perseverence Is Paying Off for a Test of Relativity in Space
By GUY GUGLIOTTA
STANFORD, Calif. — For 46 years, Francis Everitt, a Stanford
has promoted the often perilous fortunes of Gravity Probe B,
perhaps the most exotic, “Star Trek”-ish experiment ever
undertaken in space. Finally, with emergency financial help from
a pair of unusual sources, success is at hand.
Conceived in the late 1950s, financed by $750 million from NASA and
launched into orbit in 2004, the Gravity Probe B spacecraft has
sought to prove two tenets of Einstein’s theory of general
relativity. The first, called the geodetic effect, holds that a
large celestial body like Earth will
warp time the way a rubber sheet stretches when a bowling ball
is placed on it. The second, known as frame-dragging, occurs
when the rotation of a large body “twists” nearby space and
time; turn the resting bowling ball, and the rubber sheet
To measure these phenomena, Dr. Everitt and his Stanford team
equipped Gravity Probe B with a special telescope attached to
several gyroscopes. They pointed the telescope at a “guide
star,” IM Pegasi, and then spun up the gyros with their axes
also fixed on the guide star. If Einstein was right, the gyros
would drift slightly over time to follow the space-time
The Stanford team collected 11 ˝ months’ worth of transmissions
from Gravity Probe B, but tiny unforeseen drift in the gyros
fouled the results. Dr. Everitt had to ask NASA for extra time
and money so his 11-member team could figure out how to scrub
Four painstaking years later, the team has confirmed the
geodetic effect and put a credible frame-dragging result within
reach. Nevertheless, NASA was forced to stop financing the
project last May. This 11th-hour catastrophe might have been
terminal, but Dr. Everitt, long known for his tenacity as well
as his charm, had nursed Gravity Probe B through several
near-death experiences over the years.
To persevere into 2008, he had already won a $500,000
contribution from Richard
Fairbank, the founder and chief executive of Capital
One Financial and the youngest son of his old mentor, the
Stanford physicist William Fairbank. Richard Fairbank stipulated
that Stanford and NASA each match his contribution, and they
But by mid-2008, that $1.5 million was running out. That is when
Dr. Everitt turned to Turki al-Saud, vice president for research
institutes at the King Abdulaziz City for Science and Technology
in Saudi Arabia and a member of the Saudi royal family. Dr.
Saud, who has a doctorate in aeronautics and astronautics from
Stanford, arranged a $2.7 million grant. The work goes on.
“I didn’t imagine I would ever visit Riyadh,” Dr. Everitt said.
“We will need more money, but $2.7 million by itself is really
helpful. We now have a clear end in sight.”
The Gravity Probe B experiment was conceived at the dawn of the
Space Age by the Stanford physicist Leonard Schiff and George E.
Pugh of the Defense Department. Dr. Schiff brought William
Fairbank into the project in 1959, and in 1962 Dr. Fairbank
induced the British-born Dr. Everitt to come for a visit. Now
74, Dr. Everitt has directed Gravity Probe B ever since.
While the experiment itself was relatively straightforward, the
engineering demands were unprecedented. The theoretical
distortion in space-time for the geodetic effect was 6,614.4
milliarcseconds per year; for frame-dragging it was only 14
milliarcseconds per year. A milliarcsecond is about one
four-millionth of a degree of arc.
To make measurements that fine using an object as large as
Earth, the spacecraft’s gyros had to be virtually friction-free
and unaffected by heat, magnetic fields or unpredictable
movements. The pristine environment of space made the attempt
But success was not guaranteed. Arcane, often unprecedented
technologies were needed. The four fused-quartz,
Ping-Pong-ball-size gyroscopes, coated with the metal niobium,
were the most perfectly spherical objects ever created by
humans. A coffin-size lead “bag” shielded the gyros from Earth’s
A large thermos-like container called a dewar contained 645
gallons of liquid helium to be cooled to within two degrees of
absolute zero. The helium held the niobium coating at
superconducting temperatures, so the metal could track the
deviations in the gyros’ spin axis.
By the time the 21-foot-long, 3-ton spacecraft was launched on
April 20, 2004, Gravity Probe B had become a very expensive tool
designed to prove something that many scientists over the years
had come to accept as already proved by theoretical physics and
some previous experiments.
That argument has no heft with Dr. Everitt. “We are doing a
measurement with a massive object, and this is valid,” Dr.
Everitt said. “This is what the general theory of relativity
says, and this is the experiment.”
The mission, however, did not go according to plan. The niobium
coating on the gyros and their housings was slightly uneven,
causing tiny unpredictable electrical torques that made the
gyros drift. The mission ended in 2005, but since then the
Stanford team has been mapping niobium anomalies on each gyro,
finding the patterns of distortion and subtracting the noise
from the data.
NASA had budgeted money for a year’s worth of post-flight data
analysis, but Dr. Everitt needed a lot more time, and NASA
financed the project through 2007. That, it seemed, would be the
Richard Fairbank, whom Dr. Everitt had known since he was a
child, thought differently. “Nearly 50 years ago, my father had
talked with me about the integrity of a bold quest and never
giving up,” Mr. Fairbank said. “I just felt that the project was
on the 1-yard line.”
The financing brought about by his contribution took the project
into 2008, but in May, Gravity Probe B went before NASA’s senior
review, where an independent committee of scientists rates
continuing agency projects to determine financing priorities.
“We ended up dead last,” Dr. Everitt said.
That month, however, Dr. Saud visited Stanford and spoke briefly
with Dr. Everitt. Saudi Arabia, which has built 12 small
satellites, “was interested in forming partnerships” for future
space missions, Dr. Saud said in a telephone interview, and has
since done so with Stanford and NASA. Dr. Everitt met with Dr.
Saud in London in July, and Gravity Probe B received $2.7
The team has forged ahead. In August, graduate students made a
breakthrough in data analysis to bring the frame-dragging
deviation within 15 percent of the predicted result. Dr. Everitt
hopes to get it within 3 percent by mid-2010. The geodetic
effect is currently within 1 percent of the predicted result and
is expected to go even lower.
“They fly the mission and have what seems like an insurmountable
problem,” said Michael Salamon, program scientist for the
Physics of the Cosmos Program at NASA and a staunch supporter of
the project despite the senior review decision. “Then they do
this. It’s spectacular, frankly, and when it’s done we are going
to have a press announcement.”