Problems and priorities in Exploration of the Moon

N.BhandariBasic Sciences Research Institute,

Ahmedabad, India

With special Reference to

CHANDRAYAAN-1

Problems: Origin and early evolution

ORIGIN Giant Impact Hypothesis explains

• chemical similarity with Earth’s mantle, • iron deficiency, low density (3.34g/cc vs

5.52g/cc),• isotopic similarity: Oxygen(16:17:18) and Cr

(52:53) isotopic ratios But does not explain

• Absence of K isotopic fractionation,siderophiles elemental ratios Fe:Mn:Cr

EarthM = 1.0

MoonM ≈0.01

impactorMass = 0.1

Alternative Hypotheses

• Formation of small “Moons” at LagrangianPoints (L4 and L5) :

Belbruno and Gott, 2005

• Capture of “Moonlets” in geocentric orbits during accretion of the earth

• Formation of Moon in Enstatite chondritebelt and subsequent capture?

Early Evolution

• Primary differentiation (Extent: global or whole moon )

• Core ? Size(300 km??), composition• Basin formation (Late heavy

bombardment, role of tellurian moons)• Volcanism (duration: recent?)

Other Problems

• Transport of volatiles: Polar deposits: water, organics, hydrogen

• Transient Lunar Phenomena (LTP): degassing from Moon’s interior, magnetic anomalies, cometary impacts

• Bulk composition: radioactive (U,Th,K) content, Heat flow

ThoriumPotassium

Upcoming Missions for lunar exploration• Lunar A: 2006: Lunar core, heat flow

• Selene (2006),Chandrayaan-1: (2007-8) and Chang’e (2007) have many objectives in common and some payloads are similar

• Lunar Reconnaissance Orbiter (2008): high resolution mapping, gravity field

Can these missions throw some light on some of these problems?

Chandrayaan-1:Lunar Polar orbiter

Objectives: Mineralogical, Chemical and Photogeologic Mapping

Configuration : 100 km circular, polar orbiter

Observation Period : 2 years

CHANDRAYAAN-I

Mission Configuration

Rocket : Polar Satellite Launch Vehicle (PSLV)

Scientific Objectives of Chandrayaan-1CHANDRAYAAN-I

1. Mg, Al, Si and possibly Ca, Ti and Fe mapping by X-Ray Fluorescence

2. Mapping of radioactive elements such as Th to identify radioactive hot spots by low energy gamma ray spectrometer. Water ?

3. To determine the distribution of 210Pb and identify sites with enhanced concentration to see how gases and volatiles escape from the moon and get re-deposited on colder surfaces using 222Rn as a tracer.

4. To determine the mineral distribution by imaging spectroscopy.

5. 3D mapping and DEM with stereo camera and laser altimeter

Global Topographic, Chemical & Mineral mapping at high resolution

~ - 1700C~ +120 0C

SUN222Rn

Diffusion from rock & soil Seismic activity

Use radon as a tracer

238U

226Ra 1622yα

222Rn 3.8dα

218Po 3.05mα

214Pb 23.8m

214Bi 19.7m

214Po 1.6x10-4sα

210Pb 22.3y paint

210Bi 5.01d210Po 138dα

206Pb

CHANDRAYAAN-I

Transport of Volatiles

Chandrayaan – 1 A Polar Orbiter for Global Imaging, Mineralogical & Chemical

Mapping with high spatial & spectral resolutionBase line Indian Payloads

☯ Terrain Mapping Camera (TMC)

☯Hyperspectral Imager (HySi) (0.4-0.95µm)☯ Laser Ranging (LLRI)

☯ Low energy γ- ray spectrometer (HEX) (20-250KeV)

☯ Low energy X-ray spectrometer (LEX) (1-10KeV)

International Collaboration:*Fluorescence X-ray spectrometer (1-10keV) RAL-CIX * Near Infra-red spectrometer (0.9-2.6 microns) SIR * Synthetic Aperture Radar 2.5GHz (Mini SAR) * Moon Mineral Mapper (0.9-3.0 microns) M3 * Radiation Monitor (RADOM)* Neutral Atom Analyser (SARA)Under Consideration

Chandrayaan-I

TMC

Terrain Mapping Camera Kiran Kumar (SAC)

Hyperspectral Imager Kiran Kumar (SAC)

High Energy X-ray Spectrometer(PRL)

X-ray Fluorescence Spectrometer(RAL)

CHANDRAYAAN-I

Lunar Laser Ranging Instrument

T.Alex (LEOS)

CIXS

Payloads

Payload Configuration Range Resolution Objective

Hyper Spectral Imager (HySI)

Wedge filter pixelated imager

0.4-0.92 µm

Spatial - 80mSpectral-15nm64 channels

Mineralogical mapping

Terrain Mapping Camera (TMC)

Three stereo cameras with pixelated imagers

Panchromatic (40 Km swath)

Spatial - 5mVertical - 5m

To prepare a high resolution Atlas of the whole moon

Laser ranging(LLRI)

Pulsed Nd-YAG laser 1064 nm Vertical -10 m or better

Gravity model and topography

Low energy X-ray spectrometer(LEX)

RAL-CIX (SCXD) detector >14 sq. cm area

0.5-10 keV 20 km Elemental mapping Mg, Al, Si, Ca, Fe, Ti

High energy X-ray spectrometer(HEX)

CdZnTe detector 100 sq. cm. area

20-250 keV

40 km 210Pb, Radon degassing, U, Th

Solar X-ray Monitor (SXM)

Si-Pin Diode2 or 3 detectors viewing orthogonally

2-10 keV-

Solar X-ray flux monitoring

CHANDRAYAAN-I

Payload Configuration

Chandrayaan-I ConfigurationChandrayaan-I

CHANDRAYAAN-I

CHANDRAYAN-1

SIR-2

HySI

CIXS

MINI-SAR

SWIM

LLRI

HEX

IMPACT PROBERADOM

LENA

TMC

MMM

28 kg?Impactor

>10 kg>10 WInt’l Payloads

0.6 kg3 WSXM

18 kg20WHEX

5.5 kg 15-25W LEX(CIX)

10 kg8WLLRI

8 kg20WTMC

3 kg15WHySI

MassPowerPayloads

Total 91-101 W 51.5 - 56 kgSolar Power capacity : 670 wattsLunar craft maintenance : 158 wattsPayload : 91-101 wattsImaging (Sunlit/Eclipse) : 234 – 276 wattsPSLV lunar orbit (100 km) capacity : 540 kgLunar craft dry mass : 440 kgOrbit maintenance for 2 years : : 46 kgPayloads : 51.5 - 56 kg

CHANDRAYAAN-I

Power & Mass Budget

Sun

Moon at Launch

ETOGTO

Lunar Transfer Trajectory

Lunar Insertion Manoeuvre

Mid Course Correction

Trans Lunar Injection

Initial Orbit ~ 1000 km

Final Orbit 100 km Polar

To achieve 100 x 100 km Lunar Polar Orbit.

PSLV to inject 1050 kg in GTO of 240 x 36000 km.

Lunar Orbital mass of 523 kg with 2 year life time Scientific payload 55 kg.

Indian Lunar MissionChandrayaan-I

Prime Sites for detailed study

Mare Ingneii(33.7° S 163.5° E)

Mare Marginis(13.3° N 86.1° E)

Peary (North Pole)(88.6° N 33° E)

73 kilometers

Sites for Chemical Analysis

Existence of water-ice on permanently shadowed regions on the lunar poles indicated by Clementine and Lunar Prospector can be confirmed by measuring gamma-ray signal in low-energy region.

Tsiolkovsky21.2° S 231.1°

185 km

Reiner Gamma7.5°N 59°

Mare Fecunditatis(7.8° S 308.7°)

Pre-nectarian Ingenii basin, located on the moon's southern far-side and Fecunditatis on the near-side have younger basalts, swirls and have a relatively thin filling. Rn-222/Po-210 anomaly has been found at the edges of Mare Fecunditatis.

Mare Marginis, associated with swirls, represents a low-lying region on the highlands where mare lavas were just able to reach the surface.

Lunar Transient Phenomena (LTP) have been observed at many sites but their causes are not known. Swirls are associated with magnetic anomalies, degassing events, or cometary impacts. Measurements of radioactivity (Pb-210, Rn-222) may be helpful in assessing the importance of degassing2.

Shackleton (South Pole)(89.6° S 110° E)

Plato51.6°N 9.4° W

Schiller51.9° S 39°

180 km

Davy Catena11.0°S 7.0°W

Sites for Gamma-ray Spectrometry

Mendel 48.8° S 109.4°

138 km

Coulomb54.7° N 114.6°89 km

Alphonsus13.7° S 3.2° W

108 km

Freundlich25° 189°

85 km

MASCONS have been found in large basins with and without lava filling. A comparison of the mineralogical and elemental nature of basins will enable us to understand the internal structure of the crust.

There are some craters and crater chains formed by cometary impacts such as Davy Catena. Their chemical & mineral composition would indicate the nature of the impactor.

Sites for Visible & IR Spectroscopy

Tycho43.4° S 11.1°

102 km

Young-rayed craters have fresh, deep material exposed. Their study will be useful for determining mineralogical and chemical composition, least affected by space weathering.

Giordano Bruno35.9° N 257.2°

22 km

Aristarchus23.7°N 47.4°

Proclus16.1°N 46.8°E

References[1] Pieters et al. (2001) JGR, 106, 28001 [2] Bhandari et al. (2003) ILEWG 5 Proceedings, 33

Galileo and Clementine missions have indicated that some areas in South Pole-Aitken Basin have excavated deep crust or upper mantle material. We propose to study Olivine Hill, Bhabha and Bose craters to look for signatures of lower crust, upper mantle materials and other peculiarities.

55.1° S 164.564 km

53.5° S 168.6°91 km

Olivine Hill57° S 160°

(Pieters et al., 2001)

Central hills of complex craters contain material from great depths (upto 30 km). Their mineralogy, chemical composition and structural disposition should enable us to understand compositional variation with depth in the crust.

Search for Water-ice

Acknowledgement

The images have been taken by various missions to Moon & presently available on the web.

Hertzsprung2.6° N 129.2

591 km

Langrenus8.9° S 60.9° W

132 km

Copernicus 9.7° N 20° W93 km

The photon flux in 50-150 keV range which is mainly due to radioactive elements and cosmic ray interactions from the Moon varies for different terrain types, being maximum for KREEP and decreasing for basalts and highlands. Minimum flux is expected for water-ice

Gerasimovich22.9° S 122.6°

THANK YOU