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Gravitational physics, planetary science and exploration with laser
retroreflectors
Manuele Martini
Laboratori Nazionali di Frascati (LNF) dell’INFN, Frascati (Rome), Italy
For the SCF_Lab Team
http://www.lnf.infn.it/esperimenti/etrusco
CCRs Array on Moon
Manuele Martini
Apollo 11
Apollo 15Re-discoveredLunokhod 1
(Luna 17 lander)
Apollo 14
Apollo MoonLIGHT
t
Short Pulse to Moon Wide Pulse to Earth Pulse to Moon Pulses to Earth
t3 t2 t1time time
t3
t1
t2t
1 unresolved widened pulseback to Earth due to multi-CCR and lunar librations
3 separatedpulses back to Earth
1st gen. Lunar Laser Ranging
2nd gen. Lunar Laser Ranging
3
LLRRA21/MoonLIGHT
Manuele Martini
INNERCONFORMAL
THERMAL SHIELD(Au-Ag coated)
SUN/DUSTSHADE
SUN/DUST SHADE
• Mass ~ 1.7 kg• Size ~ 150mm (r) x 300mm (h)• Sophisticated thermal design (sun heat shade,
2 internal heat shields), tight optical specs
LLR tests of General Relativity
Manuele Martini
Science measurement / Precision test of violation of General Relativity Time scale
Apollo/Lunokhod few cm accuracy*
3 MoonLIGHTs 1 mm 0.1 mm
Parameterized Post-Newtonian (PPN) β Few years |β-1|<1.1×10-4 10-5 10-6
Weak Equivalence Principle (WEP) Few years |Δa/a|<1.4×10-13 10-14 10-15
Strong Equivalence Principle (SEP) Few years |η|<4.4×10-4 3×10-5 3×10-6
Time Variation of the Gravitational Constant ~5 years |Ġ/G|<9×10-13yr-1 5×10-14 5×10-15
Inverse Square Law (ISL) ~10 years |α|<3×10-11 10-12 10-13
Geodetic Precession Few years |Kgp|<6.4×10-3 6.4×10-4 6.4×10-5
* J. G. Williams, S. G. Turyshev,and D. H. Boggs, PRL 93, 261101 (2004)
LNF measurement of the Geodetic Precession with Apollo/Lunokhod, including new APOLLO station, with Planetary Ephemeris Program (PEP) by CfA: <1% accuracy
N. laser returns to make a “standard” ~2-cm LLR range:- MoonLIGHT single, large reflector: ~1- Apollo/Lunokhod multi-reflector array: thousands
INRRI
Manuele Martini
‘Petit Poucet’ rover:arm, CCR, camera …
Crater or canyon or iced sea?
1064nm
VIS
Planet/asteroid/icy-rocky moonrover at EoL
Cartoon not to scale
rockor
iceberg
NIR
Planet/asteroid/icy-rocky moon
camera
Laser altimeter
Laserranging
INstrument for landing-Roving laser ranging/altimetry Retroreflector InvestigationsPassive 25 gr, 60 mm×20 mm, no pointing
Future prospects
Manuele Martini
• Characterization in space conditions of MoonLIGHT and INRRI.• Improve the precision of Lunar Laser Ranging for better tests of
General Relativity.• Before the end of the decade, robotic mission on the lunar
surface will deploy new scientific payloads, which include MoonLIGHT-type laser retroreflectors and INRRI payloads.