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

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.

THANKS FOR YOUR ATTENTION

Manuele Martini

Manuele.Martini@lnf.infn.it