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Gravity Probe B

Testing Einstein's Universe



As we near the end of 2004, the GP-B spacecraft has been in orbit for just under eight months and collecting science data for almost four months. It remains in fine health, and all subsystems are continuing to perform well. The spacecraft is beginning to experience brief periods of being eclipsed from sunlight by the Earth during each orbit, signaling that its recent full-sun season is waning. It is flying drag-free around gyro #3, maintaining a constant roll rate of 0.7742 rpm (77.5 seconds per revolution.) The temperature inside the Dewar is holding steady at just under 1.82 kelvin. Recent measurements indicate that approximately half of the superfluid has now been expended from the Dewar. All four gyros are digitally suspended in science mode. We are now approximately 40% of the way through the science phase of the mission. The data collection process is continuing to proceed smoothly, and the quality of the data remains excellent.


Looking back, 2004 has been a year of monumental triumph for GP-B. The year began with a re-work of the Experiment Control Unit (ECU), and its subsequent reinstallation into the space vehicle.

At the beginning of April, as the space vehicle was being readied for launch, the official GP-B pre-launch press conference was held at NASA headquarters in Washington DC. (You can view a streaming video of this press conference, which includes many technical details about the GP-B science experiment and technology, on NASA's Kennedy Space Center ELV Web page.)

Three weeks following the press conference, at 9:57 am PST on 20 April 2004, a Boeing Delta II rocket carried the GP-B spacecraft, embodying over 40 years of dogged persistence in science and engineering, into a perfect orbit. That emotionally overwhelming day, culminating with the extraordinary live video of the spacecraft separating from the second stage booster meant, as GP-B Program Manager Gaylord Green put it, "that 10,000 things went right." The GP-B launch will long be remembered--not only by GP-B Principal Investigator, Francis Everitt, and the GP-B team, but also by thousands of people who have been associated with GP-B in one way or another over the years and countless others who have been following it.

The launch was the “end of the beginning” for GP-B. The ensuing 4-month IOC period demonstrated the exceptional preparedness and dedication of the GP-B team, from dealing with anomalies in orbit to spinning up the four gyros last August, which following the launch, was the second greatest milestone in the program.

Now, four months into the 10-month science phase of the mission, our whole GP-B team can reflect back on the past year with an enormous sense of pride and accomplishment. And, as we look forward to the coming year, we are keenly aware of our continued responsibility to see this once-in-a-lifetime experiment through to its final conclusion.


This is the last of our scheduled Weekly Highlights for 2004. Stanford University--and most of our GP-B staff--is officially on holiday for the next two weeks. However, our Mission Operations Center (MOC) will continue to operate around the clock. Should an unexpected critical event occur during this period, we will post a special update. Otherwise, we will resume these regular updates on 7 January 2005.


We conclude our weekly highlights for 2004 with a GP-B twist on the poem, “The Night Before Christmas,” composed by GP-B/Lockheed Martin Poet Laureate, David Spencer. (A jargon/names/acronym glossary follows the poem.)

T’was the night before Christmas, when all through the MOC
Not a creature was stirring, not even the clock
The pass plans were done by the console with care
Waiting for TDRS or GN so fair

The ARB was all nestled all snug in their beds
While visions of science danced in their heads
And Francis in his kerchief and Brad in his cap
We’d all settled in for a two-week lapse

When on RTWorks there arose such a color
I sprang from my chair to see what was the matter
Away to the console I flew like a flash
Popped open the screen and my face went all ash

The lights on the screens of the SGI stations
Gave the luster of satin to all variations,
When what to my wondering eyes should appear
But a red limit change, my heart grew in fear

With a number of limits going out of their way
I knew in a moment I‘d need help on this day
More rapid than eagles I picked up the phone
And dialed and dialed the ARB at their homes

Now Benzce, now Mester, and Muhlfelder too
On Gaylord! On Surzyn and Shestople too!
To the top of the stairs, to the top of the MOC
Now dash away, dash away, dash, do not walk!

As old PPCRs before the wild ARB fly
When met with an obstacle, mount to the sky
So up to the MOC the ARB they did fly
With thoughts of a safemode, and no reason why

And then in a twinkling I heard on the stairs
The prancing and pawing at the lock with no care
As I drew up my head and was turning around
In came the ARB with almost no sound

They were dressed in their jammies, from their heads to their toes
And their hair was all tousled, that’s how it goes
A bundle of papers were held tight in their hands
And they looked very nerdy, without any tans.

Their eyes didn’t twinkle, their faces were gray
Their cheeks were all saggy, no dimples I say
Their mouths were drawn tight like a nice Christmas bow
And the hair on their chins had started to grow

A folder of plans they held tight in their arms
Was it answers I needed to fix the alarms?
No coffee was made; I’d drunk it all up
They were groggy at best, I said, “Wassup?”

They walked by me quickly, just like an elf
And I laughed when I saw them, in spite of myself
With that look on their faces and a nod of their heads
Soon gave me to know I had nothing to dread

They spoke not a word, but went straight to their work.
And filled out the forms, then turned with a jerk
They gave me THE PLAN, the guy who was there
And giving a nod, they said “Have a care”

The problem was solved; in my heart I was glad
That the ARB all came in, it wasn’t so bad
And I heard them exclaim, ere they drove out of sight
This could’ve waited until morning’s light!


Glossary of Jargon, Names & Acronyms Used in the Poem


Mission Operations Center


NASA Tracking & Data Relay Satellite


NASA’s satellite telemetry Ground Network


GP-B Anomaly Review Board


Francis Everitt, GP-B Principal Investigator


Brad Parkinson, GP-B Co-PI


Computerized spacecraft status report


Silicon Graphics Inc. computer workstation


Bill Bencze, Deputy Program Mgr. & ARB coordinator


John Mester, Mission Director & ARB member


Barry Muhlfelder, Deputy Program Mgr. & ARB member


Gaylord Green, Program Manager


Joe Surzyn, Lockheed Martin ARB coordinator


Paul Shestopl, Mission Director & ARB member


Telemetry] Pass Plan Change Request


If you're going to be in Los Angeles anytime before 30 May 2005, and if you’re interested in Einstein’s life and work, the Einstein Exhibition at the Skirball Cultural Center (just north of the Getty Museum on Interstate 405) is the most comprehensive presentation ever mounted on the life and theories of Albert Einstein (1879-1955). It explores his legacy not only as a scientific genius who re-configured our concepts of space and time, but also as a complex man engaged in the social and political issues of his era. It examines the phenomenon of his fame and his enduring status as a global icon whose likeness has become virtually synonymous with genius.

In this exhibit, you can examine Einstein's report card, inspect his FBI file, and enjoy his family photographs, love letters, and diary entries. Exhibition highlights include scientific manuscripts and original correspondence—including original handwritten pages from the 1912 manuscripts of the special theory of relativity and his 1939 letter to President Roosevelt about nuclear power—and a wealth of other documents from the Albert Einstein Archives at the Hebrew University of Jerusalem.

In addition to these displays of Einstein memorabilia, the exhibit also features a number of interactive components that help provide an understanding of Einstein's revolutionary theories. Furthermore, several “explainers,” identified by their red aprons, are on hand to discuss various aspects of the exhibit and to explain and demonstrate difficult concepts, such as time dilation and warped spacetime. At the end of the exhibit, you’ll find one of GP-B’s gyro rotors on display.

The Einstein exhibition was jointly organized by the American Museum of Natural History (AMNH), the Hebrew University of Jerusalem, and the Skirball Cultural Center. It was designed by the AMNH under the supervision of Dr. Michael Shara, curator of the exhibit and chairman of the museum’s Astrophysics Department. It opened in November 2002 at the AMNH in New York and then traveled to Chicago and Boston, spending about 8 months in each location. It will remain at its final U.S. stop at the Skirball Center in Los Angeles through 29 May 2005, after which time it will move permanently to the Hebrew University in Jerusalem.

Information about the Einstein exhibition is available on the Skirball Center Web site. If you can’t make it to Los Angeles, you can visit the AMNH’s virtual Einstein exhibit on the Web.

Drawings & photos: GP-B Public Affiars Coordinator, Bob Kahn, created the composite photo of the GP-B spacecraft in orbit using a scale model of the spacecraft, a NASA photo of the Earth, and Adobe Photoshop, The photos of the ECU and fairing are courtesy of Lockheed Martin Corporation. The launch photo is courtesty of the Boeing Corporation. The photo of the spacecraft separation was extracted from separation video, taken by a camera on-board the second stage booster rocket. The photos of activity in the GP-B Mission Operations Center (MOC) were taken by GP-B Public Affairs Coordinator, Bob Kahn. The photos from the Einstein Exhibit are courtesy of the Skirball Cultural Center. Click on the thumbnails to view these images at full size.

Please Note: Until further notice, we intend to continue posting these GP-B highlights on a weekly basis. Also, from time to time, we may post special reports and special updates, as warranted by mission events.

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