LUNACUBE Lunar Retroreflector

9th ILEWG International Conference on Exploration and Utilisation of the

S. Dell’Agnello1, G. O. Delle Monache1,A. Donati2, A. Tortora2, V. Zolesi2, M.D. Graziano3, V. De Cosmo3 and R. Vittori4

1INFN-LNF, Via E. Fermi 40 - 00044 Frascati – Italy 2Kayser Italia S.r.l., Via di Popogna 501 -57128 Livorno – Italy 3Agenzia Spaziale Italiana – Viale Liegi 26 – 00198 Rome – Italy 4Italian Air Force, Viale dell’Università 20, Rome – Italy

24-Oct-2007 9th ILEWG International Conference on Exploration and Utilisation of the Moon Scientific Requirements

ƒStudy of the Earth from the Moon Æ LLR for geodetic measurements

ƒObservation of the Universe from the Moon Æ Robotic version of : high-accuracy tests of General Relativity and of Brane-World Theories; Gravitational Redshift measurement, if combined with an active precision clock (as an additional payload). A manned version of MoonLIGHT (i.e., with astronaut deployment) has been submitted to NASA by a US-Italy team, whose PI is D.G. Currie (Univ. of Maryland at College Park, MD, USA). R. Vittori is active in both the manned and robotic proposals to address pros and cons of the two types of deployments.

ƒScience of the Moon Æ Study of lunar

Transversal payload common to the three scientific studies

24-Oct-2007 9th ILEWG International Conference on Exploration and Utilisation of the Moon NASA RTD proposal vs. ASI concept study

• NASA call Suitcase science to the Moon: submitted manned version, “MoonLIGHT-M” (Oct. 2006) – Passive experiment only – Italian work at zero cost to NASA – Work on manned deployment by R. Vittori – US hardware to be tested at LNF • ASI study: robotic version, “MoonLIGHT-R” – MoonLIGHT-R is one of highest priority and lightest P/L – Can be combined with Optical clock (G. Tino et al, this ASI study) to measure the Gravitational Redshift • accuracy 4000 times better than GP-A and 400 times better than expected results of ACES on ISS !! • LNF will do thermal and laser ranging tests on NASA CCRs and has already performed P/L design + climatic simulations

24-Oct-2007 9th ILEWG International Conference on Exploration and Utilisation of the Moon Lunar Laser Ranging (LLR)

•Started in 1969 by Currie et al •Currie is the MoonLIGHT PI

APOLLO 11, 14,15 4 retroreflectors currently in operation on lunar : 3 from Apollo11, 14,15 and 1 Russian lunakhod

24-Oct-2007 9th ILEWG International Conference on Exploration and Utilisation of the Moon State-of-the-art

Currently:

•Matrix of small retroreflectors (RR, 38 mm diameter) covering, each, ~ 0.15m2 surface (Apollo mission). •Lean against the (thermal excursion -140 ÷ +127 K) Æ Displacement of the order of (0.5 ÷ 1) mm •Optical components and mechanical supports not adequate to high-precision measurements •Grouped elements Æ Impossibility to establish which element is responsible for the pulse return on Earth

Residual uncertainty (~ 1 cm)

24-Oct-2007 9th ILEWG International Conference on Exploration and Utilisation of the Moon Corner Cube Retroreflectors (CCR) of “new generation”

•Single elements of 100 mm diameter

•Dissemination on a large portion of the Moon surface (~100m x 100m) Æ No overlapping in the distribution of each retroreflector

•Anchorage to the isothermal lunar rock under the regolith through a support characterized by very low thermal expansion coefficient.

New “generation” Æ The baseline goal is a Current 0.1 mm accuracy, i.e. a RR RR factor 100 improvement.

Sent Pulse Return pulses

24-Oct-2007 9th ILEWG International Conference on Exploration and Utilisation of the Moon Payload LUNACUBE (I)

P/L LUNACUBE = retroreflector (RR) element + case + anchorage support to the soil

Retroreflector element: Two options: 1. RR in fused silica similar to the current Apollo RR. Intrinsically reliable

2. “Hollow” RR composed of three orthogonal surfaces. New approach requiring further laboratory analysis (e. g. thermal stress…)

24-Oct-2007 9th ILEWG International Conference on Exploration and Utilisation of the Moon Payload LUNACUBE (II)

Case of the RR element + anchorage support:

Multi-layer insulations

•Case Æ Multi-layer insulating materials •Support Æ anchored to the isothermal lunar rock. Materials with very low thermal coefficient (e. g. Kevlar or Ca fiber)

24-Oct-2007 9th ILEWG International Conference on Exploration and Utilisation of the Moon Technical Budgets

LUNACUBE is one of the lightest P/Ls and is based on totally passive RR elements:

9RR in fused silica ´ P/L mass ~ 1000 gr 9Hollow RR ´ P/L mass ~ 550 gr

24-Oct-2007 9th ILEWG International Conference on Exploration and Utilisation of the Moon Synergies with other P/L

LUNACUBE + CLOCK ´ improvement in the measure of the GRS of a factor ~ 4000

Possible scenario: Earth OAC Clock P/L under the regolith (in order to limit the thermal excursions) and LUNACUBE P/L

l

a

c coupled to the clock. i t

p k

n O i The measurements shall be performed through l comparison with a clock on ground.

An optical link shall allow the data exchange. RR Regolith OAC

Isothermal rock Moon

24-Oct-2007 9th ILEWG International Conference on Exploration and Utilisation of the Moon Why high-accuracy GR tests?

• Main theoretical goal: quantum theory of Gravity and Unification of the 4 interactions. GR is a classic theory !

• New theories.. – Brane world: “The accelerated Universe and the Moon” (Dvali et al)

24-Oct-2007 9th ILEWG International Conference on Exploration and Utilisation of the Moon