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United States Air ForceDelta II 7920-10CSpace Launch Complex 2W, Vandenberg SFB, CA, USA
Gravity Probe B
Launched
April 20, 2004
Summary
Gravity Probe B launched on an United States Air Force Delta II 7920-10C from Space Launch Complex 2W, Vandenberg SFB, CA, USA on April 20, 2004. It was United States Air Force's 1,060th launch, 3rd this year and humanity's 4,653rd orbital launch attempt. It was the 13th Delta II 7920-10C flight and the 1st this year. The payload was bound for low Earth orbit (LEO). Gravity Probe B, one of 2 catalogued objects, reached a 648 × 653 km orbit inclined 90.0°. 2 objects from this launch are catalogued, one of them a payload.
- Watch
- No webcast on record.
- Vehicle
- Delta II 7920-10C · United States Air Force
- Booster
- No booster details on record.
- Mission
- Astrophysics · Low Earth Orbit (LEO)
- Milestone
- 13th Delta II 7920-10C flight · 1st this yearUnited States Air Force's 1,060th launch3rd this yearhumanity's 4,653rd orbital launch attempt14th orbital launch attempt this year
Flight preview
Orbit: as tracked
Gravity Probe B · NORAD 28230 · 2004-014 · Space-Track · tracking 1 of 2 objects
Show the numbers for orbit elements
- Object
- GP-B
- Object ID
- 2004-014A
- Epoch
- 2004-04-20 22:49:10 UTC
- Mean motion
- 14.75633025 rev/day
- Eccentricity
- 0.0003208
- Inclination
- 90.008°
- Ascending node
- 163.1266°
- Arg. of perigee
- 92.2116°
- Mean anomaly
- 267.9419°
- Element set
- 999
- Rev at epoch
- 3
- B*
- 0.027742
Perigee, apogee and period are Kepler figures from the catalogued mean elements, not a propagated state. Published orbit: LEO. Ascent drawn from padside's representative profile.
Catalogued objects
2 catalogued: 1 payload, 1 rocket stage; 1 still in orbit
- Gravity Probe B · NORAD 28230 · in orbit
Delta 304 · re-entered May 27, 2004
Data from J. McDowell, planet4589.org
About this launch
Gravity Probe B (GP-B) was a satellite-based experiment to test two unverified predictions of general relativity: the geodetic effect and frame-dragging. This was to be accomplished by measuring, very precisely, tiny changes in the direction of spin of four gyroscopes contained in an Earth-orbiting satellite at 650 km (400 mi) altitude, crossing directly over the poles.
Pad
Space Launch Complex 2W, Vandenberg SFB, CA, USA
71st launch from Space Launch Complex 2W, 1st this year · 617th from Vandenberg SFB, CA, USA
99 launches from this pad · 919 from Vandenberg SFB, CA, USA
463 days after the previous launch from this pad
Questions
When did Gravity Probe B launch?
Gravity Probe B launched on April 20, 2004. The time is known to the hour, not the minute.
Where can I watch Gravity Probe B?
No webcast is on record for this launch.
What rocket launched Gravity Probe B?
Delta II 7920-10C, flown by United States Air Force. Delta II 7920-10C spec sheet
Where did Gravity Probe B launch from?
Space Launch Complex 2W, Vandenberg SFB, CA, USA.
What orbit did Gravity Probe B reach?
Gravity Probe B, one of 2 catalogued objects, reached a 648 × 653 km orbit inclined 90.0°.
How many satellites did Gravity Probe B launch?
1 payload from this launch is catalogued, still in orbit (Data from J. McDowell, planet4589.org).