Testing Gravity with Lunar Laser Ranging DoE Site Visit James Battat August 21, 2006.
-
Upload
andra-freeman -
Category
Documents
-
view
216 -
download
0
Transcript of Testing Gravity with Lunar Laser Ranging DoE Site Visit James Battat August 21, 2006.
![Page 1: Testing Gravity with Lunar Laser Ranging DoE Site Visit James Battat August 21, 2006.](https://reader030.fdocuments.in/reader030/viewer/2022032612/56649ef35503460f94c04f91/html5/thumbnails/1.jpg)
Testing Gravity with Lunar Laser Ranging
DoE Site Visit
James Battat
August 21, 2006
![Page 2: Testing Gravity with Lunar Laser Ranging DoE Site Visit James Battat August 21, 2006.](https://reader030.fdocuments.in/reader030/viewer/2022032612/56649ef35503460f94c04f91/html5/thumbnails/2.jpg)
Testing Gravity with Lunar Laser Ranging
New Mexico, near White Sands. Note SDSS
3.5 m
![Page 3: Testing Gravity with Lunar Laser Ranging DoE Site Visit James Battat August 21, 2006.](https://reader030.fdocuments.in/reader030/viewer/2022032612/56649ef35503460f94c04f91/html5/thumbnails/3.jpg)
APOLLO
UCSD:Tom Murphy - PIEric MichelsenAdam Orin
Harvard:Christopher StubbsJames Battat
U. Washington:Eric AdelbergerErik SwansonC. D. HoyleLarry Carey
JPL:Jim WilliamsJean DickeySlava Turyshev
Lincoln Lab:Brian AullBernie KosickiBob Reich
Northwest Analysis:Ken Nordtvedt
Mapping the lunar orbit to 1 millimeter
APD detectors
Ephemeris
![Page 4: Testing Gravity with Lunar Laser Ranging DoE Site Visit James Battat August 21, 2006.](https://reader030.fdocuments.in/reader030/viewer/2022032612/56649ef35503460f94c04f91/html5/thumbnails/4.jpg)
Why Push Gravity Tests Further?
• Order of magnitude in constraints
• Dark energy, w
• Scalar field modifications to GR– Predict non-GR effects
• Brane-world cosmology– Gravitons leaking into bulk modify gravity at
large scales
![Page 5: Testing Gravity with Lunar Laser Ranging DoE Site Visit James Battat August 21, 2006.](https://reader030.fdocuments.in/reader030/viewer/2022032612/56649ef35503460f94c04f91/html5/thumbnails/5.jpg)
LLR is a Powerful Test of Gravity
With one millimeter range precision:
• Weak EP a/a 10-14
• Strong EP 3×10-5
• Gravitomagnetism 10-4
• dG/dt 10-13•G/year• Geodetic precession 3×10-4
• Long range forces 10-11 × the strength of gravity
* In each case, LLR currently provides the best limit.
![Page 6: Testing Gravity with Lunar Laser Ranging DoE Site Visit James Battat August 21, 2006.](https://reader030.fdocuments.in/reader030/viewer/2022032612/56649ef35503460f94c04f91/html5/thumbnails/6.jpg)
LLR is a Powerful Test of Gravity
With one millimeter range precision:
• Weak EP a/a 10-14
• Strong EP 3×10-5
• Gravitomagnetism 10-4
• dG/dt 10-13•G/year• Geodetic precession 3×10-4
• Long range forces 10-11 × the strength of gravity
* In each case, LLR currently provides the best limit.
![Page 7: Testing Gravity with Lunar Laser Ranging DoE Site Visit James Battat August 21, 2006.](https://reader030.fdocuments.in/reader030/viewer/2022032612/56649ef35503460f94c04f91/html5/thumbnails/7.jpg)
Nordtvedt Effect
Nordtvedt, Phys Rev, 169, 1014, 1968
Nordtvedt, Phys Rev, 169, 1017, 1968
Nordtvedt, Phys Rev, 170, 1186, 1968
Synodic period = 29.35 days
r = 13 cos(D) meters
![Page 8: Testing Gravity with Lunar Laser Ranging DoE Site Visit James Battat August 21, 2006.](https://reader030.fdocuments.in/reader030/viewer/2022032612/56649ef35503460f94c04f91/html5/thumbnails/8.jpg)
Avalanche Photodiode Array
= 30m
-Courtesy of MIT Lincoln Lab
3.5 meter telescope
Good seeing
APOLLO: Reaching 1 mm
![Page 9: Testing Gravity with Lunar Laser Ranging DoE Site Visit James Battat August 21, 2006.](https://reader030.fdocuments.in/reader030/viewer/2022032612/56649ef35503460f94c04f91/html5/thumbnails/9.jpg)
Laser Ranging Apparatus: Transmit
2.3 Watt NdYAG laser2.3 Watt NdYAG laser20 Hz, 20 Hz, = 530 nm = 530 nm < 100 ps pulse width< 100 ps pulse width110 mJ per pulse110 mJ per pulse
APD arrayAPD array
START
3.5m primary3.5m primary
LASER
Corner cubeCorner cube
![Page 10: Testing Gravity with Lunar Laser Ranging DoE Site Visit James Battat August 21, 2006.](https://reader030.fdocuments.in/reader030/viewer/2022032612/56649ef35503460f94c04f91/html5/thumbnails/10.jpg)
Laser Ranging Apparatus: Receive
2.3 Watt NdYAG laser2.3 Watt NdYAG laser20 Hz, 20 Hz, = 530 nm = 530 nm < 100 ps pulse width< 100 ps pulse width110 mJ per pulse110 mJ per pulse
APD arrayAPD array
STOP
3.5m primary3.5m primary
LASER
![Page 11: Testing Gravity with Lunar Laser Ranging DoE Site Visit James Battat August 21, 2006.](https://reader030.fdocuments.in/reader030/viewer/2022032612/56649ef35503460f94c04f91/html5/thumbnails/11.jpg)
25 km
4 km
~1017 attenuation
MOON
![Page 12: Testing Gravity with Lunar Laser Ranging DoE Site Visit James Battat August 21, 2006.](https://reader030.fdocuments.in/reader030/viewer/2022032612/56649ef35503460f94c04f91/html5/thumbnails/12.jpg)
Interpretation Requires Sophisticated Modeling
Measure telescope-to-reflector distanceWant center-to-center separationThrough the atmosphereNeed precise ephemeris information – JPL collaboration
![Page 13: Testing Gravity with Lunar Laser Ranging DoE Site Visit James Battat August 21, 2006.](https://reader030.fdocuments.in/reader030/viewer/2022032612/56649ef35503460f94c04f91/html5/thumbnails/13.jpg)
MLRS: The Old Way
28 photons in 42 minutes
![Page 14: Testing Gravity with Lunar Laser Ranging DoE Site Visit James Battat August 21, 2006.](https://reader030.fdocuments.in/reader030/viewer/2022032612/56649ef35503460f94c04f91/html5/thumbnails/14.jpg)
Enter APOLLO
1,500 photons in 13 minutes
1 mm statistical uncertainty
![Page 15: Testing Gravity with Lunar Laser Ranging DoE Site Visit James Battat August 21, 2006.](https://reader030.fdocuments.in/reader030/viewer/2022032612/56649ef35503460f94c04f91/html5/thumbnails/15.jpg)
Current Status
Millimeter precision dataReturns from all 3 Apollo arraysRemote operations
• Enter campaign mode (October)1-2 hours every 2-3 nights
• Improve site coordinates
• New constraints on gravitational params
![Page 16: Testing Gravity with Lunar Laser Ranging DoE Site Visit James Battat August 21, 2006.](https://reader030.fdocuments.in/reader030/viewer/2022032612/56649ef35503460f94c04f91/html5/thumbnails/16.jpg)
The End
![Page 17: Testing Gravity with Lunar Laser Ranging DoE Site Visit James Battat August 21, 2006.](https://reader030.fdocuments.in/reader030/viewer/2022032612/56649ef35503460f94c04f91/html5/thumbnails/17.jpg)
THE END
![Page 18: Testing Gravity with Lunar Laser Ranging DoE Site Visit James Battat August 21, 2006.](https://reader030.fdocuments.in/reader030/viewer/2022032612/56649ef35503460f94c04f91/html5/thumbnails/18.jpg)
EXTRA SLIDES
![Page 19: Testing Gravity with Lunar Laser Ranging DoE Site Visit James Battat August 21, 2006.](https://reader030.fdocuments.in/reader030/viewer/2022032612/56649ef35503460f94c04f91/html5/thumbnails/19.jpg)
APOLLO: Reaching 1 mm
• Large-aperture, good seeing– Figure of merit goes like (D/)2
• Incorporate modern technology– Detectors, precision timing, laser
• Re-couple data collection to analysis/science
![Page 20: Testing Gravity with Lunar Laser Ranging DoE Site Visit James Battat August 21, 2006.](https://reader030.fdocuments.in/reader030/viewer/2022032612/56649ef35503460f94c04f91/html5/thumbnails/20.jpg)
LLR Targets
![Page 21: Testing Gravity with Lunar Laser Ranging DoE Site Visit James Battat August 21, 2006.](https://reader030.fdocuments.in/reader030/viewer/2022032612/56649ef35503460f94c04f91/html5/thumbnails/21.jpg)
Gravitational Self-Energy + SEP
Object mSE/m
1 kg sphere, 6” diam 5 x 10-27
Moon 0.2 x 10-10
Earth 5 x 10-10
![Page 22: Testing Gravity with Lunar Laser Ranging DoE Site Visit James Battat August 21, 2006.](https://reader030.fdocuments.in/reader030/viewer/2022032612/56649ef35503460f94c04f91/html5/thumbnails/22.jpg)
APOLLO Random Error BudgetExpected Statistical Error RMS Error (ps) One-way Error (mm)
Laser Pulse (95 ps FWHM) 40 6
APD Jitter 50 7
TDC Jitter 15 2.2
50 MHz Freq. Reference 7 1
APOLLO System Total 66 10
Lunar Retroreflector Array 80–230 12–35
Total Error per Photon 105–240 16–37
![Page 23: Testing Gravity with Lunar Laser Ranging DoE Site Visit James Battat August 21, 2006.](https://reader030.fdocuments.in/reader030/viewer/2022032612/56649ef35503460f94c04f91/html5/thumbnails/23.jpg)
Nordtvedt, Class. Quantum Grav., 15, 3363, 1998
Lunar Phase Coverage
• EP violation has a null at Quarter moon and maxima at Full and New Moons
• Same data, uniform coverage gives tighter
No measurements at max signal
![Page 24: Testing Gravity with Lunar Laser Ranging DoE Site Visit James Battat August 21, 2006.](https://reader030.fdocuments.in/reader030/viewer/2022032612/56649ef35503460f94c04f91/html5/thumbnails/24.jpg)
Current PPN Constraints
1
0.998 10.999 1.001 1.002
1.002
1.001
0.999
0.998
Lunar Laser Ranging
Mercury Perihelion Shift
Mars Radar Ranging
VLBI & combined planetary data
Spacecraft range & Doppler
Basic phenomenology:
measures curvature ofSpacetime
measures nonlinearity of gravity
= (2.1 § 2.3) x 10-5
= (1.2 § 1.1) x 10-4
= (4.4 § 4.5) x 10-4
![Page 25: Testing Gravity with Lunar Laser Ranging DoE Site Visit James Battat August 21, 2006.](https://reader030.fdocuments.in/reader030/viewer/2022032612/56649ef35503460f94c04f91/html5/thumbnails/25.jpg)
Solar System Parameters• Separation
– Moon-Earth 0.38 million km– Sun-Earth 150 million km
• Mass– Sun 2 x 10^30 kg– Earth 6.0 x 10^24 kg– Moon 0.073 x 10^24 kg
• Radius– Sun 695,000 km– Earth 6380 km– Moon 1740 km
• Gravitational Constant6.67 x 10^-11 m^3 kg^-1 s^-2
![Page 26: Testing Gravity with Lunar Laser Ranging DoE Site Visit James Battat August 21, 2006.](https://reader030.fdocuments.in/reader030/viewer/2022032612/56649ef35503460f94c04f91/html5/thumbnails/26.jpg)
Testing Gravity with Lunar Laser Ranging
![Page 27: Testing Gravity with Lunar Laser Ranging DoE Site Visit James Battat August 21, 2006.](https://reader030.fdocuments.in/reader030/viewer/2022032612/56649ef35503460f94c04f91/html5/thumbnails/27.jpg)
Historical Accuracy of LLR Data
30 cm
0 cm
1970 present
![Page 28: Testing Gravity with Lunar Laser Ranging DoE Site Visit James Battat August 21, 2006.](https://reader030.fdocuments.in/reader030/viewer/2022032612/56649ef35503460f94c04f91/html5/thumbnails/28.jpg)
Laser Ranging Apparatus
2.3 Watt NdYAG laser2.3 Watt NdYAG laser20 Hz, 20 Hz, = 530 nm = 530 nm < 100 ps pulse width< 100 ps pulse width110 mJ per pulse110 mJ per pulse
APD arrayAPD array START
3.5m primary3.5m primary
LASER
Corner cubeCorner cube
![Page 29: Testing Gravity with Lunar Laser Ranging DoE Site Visit James Battat August 21, 2006.](https://reader030.fdocuments.in/reader030/viewer/2022032612/56649ef35503460f94c04f91/html5/thumbnails/29.jpg)
2.3 Watt NdYAG laser2.3 Watt NdYAG laser20 Hz, 20 Hz, = 530 nm = 530 nm < 100 ps pulse width< 100 ps pulse width110 mJ per pulse110 mJ per pulse
APD arrayAPD array
3.5m primary3.5m primary
Laser Ranging Apparatus
LASER
STOP