• Volume 114, Issue 6

      December 2005,   pages  573-841

    • Preface

      N Bhandari

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    • International partnership in lunar missions - Inaugural address by His Excellency Dr A P J Abdul Kalam President of India

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    • Lunar science: An overview

      Stuart Ross Taylor

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      Before spacecraft exploration, facts about the Moon were restricted to information about the lunar orbit, angular momentum and density. Speculations about composition and origin were unconstrained. Naked eye and telescope observations revealed two major terrains, the old heavily cratered highlands and the younger mostly circular, lightly cratered maria. The lunar highlands were thought to be composed of granite or covered with volcanic ash-flows. The maria were thought to be sediments, or were full of dust, and possibly only a few million years old. A few perceptive observers such as Ralph Baldwin (Baldwin 1949) concluded that the maria were filled with volcanic lavas, but the absence of terrestrial-type central volcanoes like Hawaii was a puzzle.

      The large circular craters were particularly difficult to interpret. Some thought, even after the Apollo flights, that they were some analogue to terrestrial caldera (e.g., Green 1971), formed by explosive volcanic activity and that the central peaks were volcanoes. The fact that the craters were mostly circular was difficult to accommodate if they were due to meteorite impact, as meteorites would hit the Moon at all angles. The rilles were taken by many as definitive evidence that there was or had been, running water on the lunar surface. Others such as Carl Sagan thought that organic compounds were likely present (see Taylor 1975, p. 111, note 139).

    • Origin of the Earth—Moon system

      E M Galimov A M Krivtsov

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    • Capture of interplanetary bodies in geocentric orbits and early lunar evolution

      Malapaka Shivakumar N Bhandari

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      During the accretion of planets such as Earth, which are formed by collisional accretion of plan-etesimals, the probability of capture of interplanetary bodies in planetocentric orbits is calculated following the approach of Hills (1973) and the n-body simulation, using simplectic integration method. The simulation, taking an input mass equal to about 50% of the present mass of the inner planets, distributed over a large number of planetoids, starting at 4 M y after the formation of solar system, yielded four inner planets within a period of 30 M y. None of these seed bodies, out of which the planets formed, remained at this time and almost 40% mass was transferred beyond 100 AU. Based on these calculations, we conclude that ∼ 1.4 times the mass of the present inner planets was needed to accumulate them. The probability of capture of planetoids in geocentric orbits is found to be negligible. The result emphasizes the computational difficulty in ’probability of capture’ of planetesimals around the Earth before the giant impact. This conclusion, however, is in contradiction to the recent observations of asteroids being frequently captured in transient orbits around the Earth, even when the current population of such interplanetary bodies is smaller by several orders of magnitude compared to the planetary accumulation era.

    • Determination of lunar surface ages from crater frequency—size distribution

      B S Shylaja

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      Crater size-frequency distribution is one of the powerful techniques to estimate the ages of planetary surfaces, especially from remote sensing studies. This has been applied to images of the Moon obtained from Clementine mission in 1994. Simple techniques of measurement of the diameter of the craters (in pixels) are used and converted into linear dimensions. Among the several maria studied, the results of Mare Humorum and the central region of Mare Imbrium are reported. The results are compared with age estimates from other sources.

    • Low energy trajectories for the Moon-to-Earth space flight

      V V Ivashkin

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      The Moon-to-Earth low energy trajectories of ‘detour’ type are found and studied within the frame of the Moon-Earth-Sun-particle system. These trajectories use a passive flight to the Earth from an initial elliptic selenocentric orbit with a high aposelenium. The Earth perturbation increases the particle selenocentric energy from a negative value first to zero and then to a positive one and therefore leads to a passive escape of the particle motion from the Moon attraction near the translunar libration pointL2. This results in the particle flight to a distance of about 1.5 million km from the Earth where the Sun gravitation decreases the particle orbit perigee distance to a small value that leads to the particle approaching the Earth vicinity in about 100 days of the flight. A set of the Moon-to-Earth ‘detour’ trajectories is defined numerically. Characteristics of these trajectories are presented. The ‘detour’ trajectories give essential economy of energy (about 150 m/s in Delta V) relative to the usual ones.

    • An analysis of near-circular lunar mapping orbits

      R V Ramanan V Adimurthy

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      Numerical investigations have been carried out to analyse the evolution of lunar circular orbits and the influence of the higher order harmonics of the lunar gravity field. The aim is to select the appropriate near-circular orbit characteristics, which extend orbit life through passive orbit maintenance. The spherical harmonic terms that make major contributions to the orbital behaviour are identified through many case studies. It is found that for low circular orbits, the 7th and the 9th zonal harmonics have predominant effect in the case of orbits for which the evolution is stable and the life is longer, and also in the case of orbits for which the evolution is unstable and a crash takes place in a short duration. By analysing the contribution of the harmonic terms to the orbit behaviour, the appropriate near-circular orbit characteristics are identified.

    • Microwave brightness temperature imaging and dielectric properties of lunar soil

      Wu Ji Li Dihui Zhang Xiaohui Jiang Jingshan A T Altyntsev B I Lubyshev

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      Among many scientific objectives of lunar exploration, investigations on lunar soil become attractive due to the existence of He3 and ilmenite in the lunar soil and their possible utilization as nuclear fuel for power generation. Although the composition of the lunar surface soil can be determined by optical and γ/X-ray spectrometers, etc., the evaluation of the total reserves of He3 and ilmenite within the regolith and in the lunar interior are still not available. In this paper, we give a rough analysis of the microwave brightness temperature images of the lunar disc observed using the NRAO 12 meter Telescope and Siberian Solar Radio Telescope. We also present the results of the microwave dielectric properties of terrestrial analogues of lunar soil and, discuss some basic relations between the microwave brightness temperature and lunar soil properties.

    • Energy conversion evolution at lunar polar sites

      James D Burke

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      Lunar polar environments have many advantages from the standpoint of energy supply to robotic and human surface bases. Sunlight is nearly continuous and always horizontal at peaks of perpetual light, while waste heat rejection is aided by the existence of cold, permanently shadowed regions nearby. In this paper a possible evolution of lunar polar energy systems will be described, beginning with small robotic photovoltaic landers and continuing into the development of increasingly powerful and diverse energy installations to provide not only electric power but also piped-in sunlight, air conditioning and high-temperature process heat.

    • Escape of atmospheric gases from the Moon

      Da Dao-an Yang Ya-tian

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      The escape rate of atmospheric molecules on the Moon is calculated. Based on the assumption that the rates of emission and escape of gases attain equilibrium, the ratio of molecular number densities during day and night, n0d/n0n, can be explained. The plausible emission rate of helium and radioactive elements present in the Moon has also been calculated.

    • The Clementine mission —A 10-year perspective

      Trevor C Sorensen Paul D Spudis

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      Clementine was a technology demonstration mission jointly sponsored by the Department of Defense (DOD) and NASA that was launched on January 25th, 1994. Its principal objective was to use the Moon, a near-Earth asteroid, and the spacecraft’s Interstage Adapter as targets to demonstrate lightweight sensor performance and several innovative spacecraft systems and technologies. The design, development, and operation of the Clementine spacecraft and ground system was performed by the Naval Research Laboratory. For over two months Clementine mapped the Moon, producing the first multispectral global digital map of the Moon, the first global topographic map, and contributing several other important scientific discoveries, including the possibility of ice at the lunar South Pole. New experiments or schedule modifications were made with minimal constraints, maximizing science return, thus creating a new paradigm for mission operations. Clementine was the first mission known to conduct an in-flight autonomous operations experiment. After leaving the Moon, Clementine suffered an onboard failure that caused cancellation of the asteroid rendezvous. Despite this setback, NASA and the DOD applied the lessons learned from the Clementine mission to later missions. Clementine set the standard against which new small spacecraft missions are commonly measured. More than any other mission, Clementine has the most influence (scientifically, technically, and operationally) on the lunar missions being planned for the next decade.

    • Advances in lunar science from the Clementine mission: A decadal perspective

      Mark Robinson Miriam Riner

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      The Clementine spacecraft orbited the Moon and acquired science data for 10 weeks in the Spring of 1994. During this time it collected global 11-band multispectral images and near global altimetry. Select areas of the Moon were imaged at 25 m/pixel in visible light and 60 m/pixel in thermal wavelengths. From these datasets a new paradigm for the evolution of the lunar crust emerged. The Moon is no longer viewed as a two-terrane planet, the Apollo samples were found not to represent the lunar crust as a whole, and the complexity of lunar crustal stratigraphy was further revealed. More than ten years later the Clementine datasets continue to significantly advance lunar science and will continue to do so as new measurements are returned from planned missions such as Chandrayaan, SELENE, and Lunar Reconnaissance Orbiter. This paper highlights the scientific research conducted over the last decade using Clementine data and summarizes the influence of Clementine on our understanding of the Moon.

    • SMART-1 after lunar capture: First results and perspectives

      B H Foing G D Racca A Marini E Evrard L Stagnaro M Almeida D Koschny D Frew J Zender D Heather M Grande J Huovelin H U Keller A Nathues J L Josset A Malkki W Schmidt G Noci R Birkl L Iess Z Sodnik P McManamon

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      SMART-1 is a technology demonstration mission for deep space solar electrical propulsion and technologies for the future.SMART-1 is Europe ’s first lunar mission and will contribute to developing an international program of lunar exploration.The spacecraft was launched on 27th September 2003,as an auxiliary passenger to GTO on Ariane 5,to reach the Moon after a 15-month cruise, with lunar capture on 15th November 2004,just a week before the International Lunar Conference in Udaipur.SMART-1 carries seven experiments,including three remote sensing instruments used during the mission ’s nominal six months and one year extension in lunar science orbit.These instruments will contribute to key planetary scienti fic questions,related to theories of lunar origin and evolution,the global and local crustal composition,the search for cold traps at the lunar poles and the mapping of potential lunar resources.

    • Chandrayaan-1: Science goals

      N Bhandari

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      The primary objectives of the Chandrayaan-1 mission are simultaneous chemical,mineralogical and topographic mapping of the lunar surface at high spatial resolution.These data should enable us to understand compositional variation of major elements,which in turn,should lead to a better understanding of the stratigraphic relationships between various litho units occurring on the lunar surface.The major element distribution will be determined using an X-ray fluorescence spectrometer (LEX),sensitive in the energy range of 1 –10 keV where Mg,Al,Si,Ca and Fe give their K 𝛼 lines.A solar X-ray monitor (SXM)to measure the energy spectrum of solar X-rays,which are responsible for the fluorescent X-rays,is included.Radioactive elements like Th will be measured by its 238.6 keV line using a low energy gamma-ray spectrometer (HEX)operating in the 20 –250 keV region.The mineral composition will be determined by a hyper-spectral imaging spectrometer (HySI)sensitive in the 400 –920 nm range.The wavelength range is further extended to 2600 nm where some spectral features of the abundant lunar minerals and water occur,by using a near-infrared spectrometer (SIR-2),similar to that used on the Smart-1 mission,in collaboration with ESA.A terrain mapping camera (TMC)in the panchromatic band will provide a three-dimensional map of the lunar surface with a spatial resolution of about 5 m.Aided by a laser altimeter (LLRI) to determine the altitude of the lunar craft,to correct for spatial coverage by various instruments, TMC should enable us to prepare an elevation map with an accuracy of about 10 m.

      Four additional instruments under international collaboration are being considered.These are: a Miniature Imaging Radar Instrument (mini-SAR),Sub Atomic Re flecting Analyser (SARA), the Moon Mineral Mapper (M3)and a Radiation Monitor (RADOM).Apart from these scientific payloads,certain technology experiments have been proposed,which may include an impactor which will be released to land on the Moon during the mission.

      Salient features of the mission are described here.The ensemble of instruments onboard Chandrayaan-1 should enable us to accomplish the science goals de fined for this mission.

    • Launch strategy for Indian lunar mission and precision injection to the Moon using genetic algorithm

      V Adimurthy R V Ramanan S R Tandon C Ravikumar

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      The Indian lunar mission Chandrayaan-1 will have a mass of 523 kg in a 100 km circular polar orbit around the Moon. The main factors that dictate the design of the Indian Moon mission are to use the present capability of launch vehicles and to achieve the scientific objectives in the minimum development time and cost. The detailed mission planning involves trade-off studies in payload optimization and the transfer trajectory determination that accomplishes these requirements. Recent studies indicate that for an optimal use of the existing launch vehicle and space-craft systems, highly elliptical inclined orbits are preferable. This indeed is true for the Indian Moon mission Chandrayaan-1. The proposed launch scenario of the Indian Moon mission program and capabilities of this mission are described in this paper, highlighting the design challenges and innovations. Further, to reach the target accurately, appropriate initial transfer trajectory characteristics must be chosen. A numerical search for the initial conditions combined with numerical integration produces the near accurate solution for this problem. The design of such transfer trajectories is discussed in this paper.

    • Terrain mapping camera for Chandrayaan-1

      A S Kiran Kumar A Roy Chowdhury

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      The Terrain Mapping Camera (TMC) on India’s first satellite for lunar exploration, Chandrayaan-1, is for generating high-resolution 3-dimensional maps of the Moon. With this instrument, a complete topographic map of the Moon with 5 m spatial resolution and 10-bit quantization will be available for scientific studies. The TMC will image within the panchromatic spectral band of 0.4 to 0.9 Μm with a stereo view in the fore, nadir and aft directions of the spacecraft movement and have a B/H ratio of 1. The swath coverage will be 20 km. The camera is configured for imaging in the push broom-mode with three linear detectors in the image plane. The camera will have four gain settings to cover the varying illumination conditions of the Moon. Additionally, a provision of imaging with reduced resolution, for improving Signal-to-Noise Ratio (SNR) in polar regions, which have poor illumination conditions throughout, has been made. SNR of better than 100 is expected in the ±60° latitude region for mature mare soil, which is one of the darkest regions on the lunar surface. This paper presents a brief description of the TMC instrument.

    • Hyper-Spectral Imager in visible and near-infrared band for lunar compositional mapping

      A S Kiran Kumar A Roy Chowdhury

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      India’s first lunar mission, Chandrayaan-1, will have a Hyper-Spectral Imager in the visible and near-infrared spectral bands along with other instruments. The instrument will enable mineralogical mapping of the Moon’s crust in a large number of spectral channels. The planned Hyper-Spectral Imager will be the first instrument to map the lunar surface with the capability of resolving the spectral region, 0.4 to 0.92 Μm, in 64 continuous bands with a resolution of better than 15 nm and a spatial resolution of 80 m. Spectral separation will be done using a wedge filter and the image will be mapped onto an area detector. The detector output will be processed in the front-end processor to generate the 64-band data with 12-bit quantization. This paper gives a description of the Hyper-Spectral Imager instrument.

    • Lunar ranging instrument for Chandrayaan-1

      J A Kamalakar K V S Bhaskar A S Laxmi Prasad R Ranjith K A Lohar R Venketeswaran T K Alex

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      Lunar Laser Ranging Instrument (LLRI) proposed for the first Indian lunar mission Chandrayaan-1 is aimed to study the topography of the Moon’s surface and its gravitational field by precisely measuring the altitude from a polar orbit around the Moon. Altimetry data close to the poles of the Moon would also be available from the instrument, which was not covered by earlier missions. This instrument supplements the terrain mapping camera and hyperspectral imager payloads on Chandrayaan-1. The instrument consists of a diode pumped Nd:YAG pulsed laser transmitter having 10 nsec pulse width and a receiver system. The receiver system features 17 cm diameter Ritchey—Chrétien collecting optics, Si Avalanche Photo Detector (APD), preamplifiers, constant fraction discriminators, time-of-flight measurement unit and spacecraft interface. Altimeter resolution of better than 5 m is targeted. The received signal strength of LLRI depends on laser pulse backscatter from the Moon’s surface. Moon’s surface being a poor reflector, the choice of receiver size and its type and the selection of detector play an important role in getting a good signal-to-noise ratio and in turn achieving the target resolution. At the same time, the spacecraft puts a limitation on payload size and weight. This paper discusses the proposed LLRI system for Chandrayaan-1 and signal-to-noise ratio estimation.

    • High energy X-γ ray spectrometer on the Chandrayaan-1 mission to the Moon

      J N Goswami D Banerjee N Bhandari M Shanmugam Y B Acharya D V Subhedar M R Sharma C N Umapathy P Sreekumar M Sudhakar L Abraham P C Agrawal

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      The Chandrayaan-1 mission to the Moon scheduled for launch in late 2007 will include a high energy X-ray spectrometer (HEX) for detection of naturally occurring emissions from the lunar surface due to radioactive decay of the238U and232Th series nuclides in the energy region 20–250 keV. The primary science objective is to study the transport of volatiles on the lunar surface by detection of the 46.5 keV line from radioactive210Pb, a decay product of the gaseous222Rn, both of which are members of the238U decay series. Mapping of U and Th concentration over the lunar surface, particularly in the polar and U-Th rich regions will also be attempted through detection of prominent lines from the U and Th decay series in the above energy range. The low signal strengths of these emissions require a detector with high sensitivity and good energy resolution. Pixelated Cadmium-Zinc-Telluride (CZT) array detectors having these characteristics will be used in this experiment. Here we describe the science considerations that led to this experiment, anticipated flux and background (lunar continuum), the choice of detectors, the proposed payload configuration and plans for its realization

    • Imaging and power generation strategies for chandrayaan-1

      Ananth Krishna N S Gopinath N S Hegde N K Malik

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      The Chandrayaan-1 mission proposes to put a 550 kg lunarcraft into Geostationary Transfer Orbit (GTO) using the Polar Satellite Launch Vehicle (PSLV) which will subsequently be transferred into a 100 km circular lunar polar orbit for imaging purposes. In this paper, we describe certain aspects of mission strategies which will allow optimum power generation and imaging of the lunar surface.

      The lunar orbit considered is circular and polar and therefore nearly perpendicular to the ecliptic plane. Unlike an Earth orbiting remote sensing satellite, the orbit plane of lunar orbiter is inertially fixed as a consequence of the very small oblateness of the Moon. The Earth rotates around the Sun once a year, resulting in an apparent motion of Sun around this orbit in a year. Two extreme situations can be identified concerning the solar illumination of the lunar orbit, noon/midnight orbit, where the Sun vector is parallel to the spacecraft orbit plane and dawn/dusk orbit, where the Sun vector is perpendicular to the spacecraft orbit plane. This scenario directly affects the solar panel configuration. In case the solar panels are not canted, during the noon/midnight orbit, 100% power is generated, whereas during the dawn/dusk orbit, zero power is generated. Hence for optimum power generation, canting of the panels is essential. Detailed analysis was carried out to fix optimum canting and also determine a strategy to maintain optimum power generation throughout the year. The analysis led to the strategy of 180‡ yaw rotation at noon/midnight orbits and flipping the solar panel by 180‡ at dawn/dusk orbits. This also resulted in the negative pitch face of the lunarcraft to be an anti-sun panel, which is very useful for thermal design, and further to meet cooling requirements of the spectrometers.

      In principle the Moon’s surface can be imaged in 28 days, because the orbit chosen and the payload swath provide adequate overlap. However, in reality it is not possible to complete the imaging in 28 days due to various mission constraints like maximum duration of imaging allowed keeping in view the SSR sizing and payloads data input rate, time required for downlinking the payload data, data compression requirements and visibility of the lunarcraft for the Bangalore DSN. In each cycle, all the latitudes are swept. Due to the constraints mentioned, only 60‡ latitude arc coverage is possible in each orbit. As Bangalore DSN is the only station, half of the orbits in a day are not available. The longitudinal gaps because of non-visibility are covered in the next cycle by Bangalore DSN. Hence, in the firstprime imaging season, only 25% of the prime imaging zones are covered, and an additional threeprime imaging seasons are required for a full coverage of the Moon in two years. Strategy is also planned to cover X-ray payload coverage considering swath and orbit shift.

    • Low energy neutral atom imaging on the Moon with the SARA instrument aboard Chandrayaan-1 mission

      Anil Bhardwaj Stas Barabash Yoshifumi Futaana Yoichi Kazama Kazushi Asamura David McCann R Sridharan Mats Holmstrom Peter Wurz Rickard Lundin

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      This paper reports on the Sub-keV Atom Reflecting Analyzer (SARA) experiment that will be flown on the first Indian lunar mission Chandrayaan-1. The SARA is a low energy neutral atom (LENA) imaging mass spectrometer, which will perform remote sensing of the lunar surface via detection of neutral atoms in the energy range from 10 eV to 3 keV from a 100km polar orbit. In this report we present the basic design of the SARA experiment and discuss various scientific issues that will be addressed. The SARA instrument consists of three major subsystems: a LENA sensor (CENA), a solar wind monitor (SWIM), and a digital processing unit (DPU). SARA will be used to image the solar wind-surface interaction to study primarily the surface composition and surface magnetic anomalies and associated mini-magnetospheres. Studies of lunar exosphere sources and space weathering on the Moon will also be attempted. SARA is the first LENA imaging mass spectrometer of its kind to be flown on a space mission. A replica of SARA is planned to fly to Mercury onboard the BepiColombo mission.

    • Lunar-A mission: Outline and current status

      H Mizutani A Fujimura S Tanaka H Shiraishi T Nakjima

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      The scientific objective of the Lunar-A,Japanese Penetrator Mission,is to explore the lunar interior by seismic and heat-flow experiments.Two penetrators containing two seismometers (horizontal and vertical components)and heat-flow probes will be deployed from a spacecraft onto the lunar surface,one on the near-side and the other on the far-side of the moon.The data obtained by the penetrators will be transmitted to the earth station via the Lunar-A mother spacecraft orbiting at an altitude of about 200 km.

      The spacecraft of a cylindrical shape,2.2 m in maximum diameter and 1.7 m in height,is designed to be spin-stabilized.The spacecraft will be inserted into an elliptic lunar orbit,after about a half- year cruise during which complex manoeuvering is made using the lunar-solar gravity assist.After lunar orbit insertion,two penetrators will be separated from the spacecraft near perilune,one by one,and will be landed on the lunar surface.

      The final impact velocity of the penetrator will be about 285 m/sec;it will encounter a shock of about 8000 G at impact on the lunar surface.According to numerous experimental impact tests using model penetrators and a lunar-regolith analog target,each penetrator is predicted to penetrate to a depth between l and 3 m,depending on the hardness and/or particle-size distribution of the lunar regolith.The penetration depth is important for ensuring the temperature stability of the instruments in the penetrator and heat flow measurements.According to the results of the Apollo heat flow experiment,an insulating regolith blanket of only 30 cm is sufficient to dampen out about 280 K lunar surface temperature fluctuation to > 3K variation.

      The seismic observations are expected to provide key data on the size of the lunar core,as well as data on deep lunar mantle structure.The heat flow measurements at two penetrator-landing sites will also provide important data on the thermal structure and bulk concentrations of heat- generating elements in the Moon.These data will provide much stronger geophysical constraints on the origin and evolution of the Moon than has been obtained so far.

      Currently,the Lunar-A system is being reviewed and a more robust system for communication between the penetrators and spacecraft is being implemented according to the lessons learned from Beagle-2 and DS-2 failures.More impact tests for penetrators onto a lunar regolith analogue target will be undertaken before its launch.

    • SELENE project status

      Konishi Hisahiro Manabu Kato Susumu Sasaki Yoshisada Takizawa Hitoshi Mizutani

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      SELENE (Selenological and Engineering Explorer) project started as a joint mission of the former ISAS (Institute of Space and Astronautical Science) and the former NASDA (National Space Development Agency: the two organizations were merged into JAXA in 2002) of Japan in 1998. The launch target is rescheduled for 2006 due to delay of completion of launch vehicle, H-IIA. The SELENE project is now under a sustained design phase. The flight model components were manufactured, and the interface tests between the bus-system and the mission instruments were completed by the end of March 2004. The functional checks and calibration for the flight model components are being carried out at present. From the beginning of 2005, the final assembly tests will start.

    • Japanese lunar robotics exploration by co-operation with lander and rover

      Takashi Kubota Yasuharu Kunii Yoji Kuroda

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      Unmanned mobile robots for surface exploration of the Moon or planets have been extensively studied and developed. A lunar rover is expected to travel safely in a wide area and explore in detail. Japanese lunar robotics exploration is under study to conduct an unmanned geological survey in the vicinity of central peaks of impact craters for investigation of the sub-surface materials. This will give us the key information to study the lunar inner structure and understand the Moon’s origin and evolution as well as to investigate the evolution of magma ocean and later igneous processes. To carry out the geological exploration in the central peak, lander and rover co-operative exploration is proposed. The working group has been conducting feasibility study of advance technologies. This paper addresses an overview of lunar exploration with lander and rover and also enumerates future technologies to be established.

      The rover R&D group has developed an innovative science micro rover with a new mobility system and a lightweight manipulator. The design and implementation of a science rover for the near future lunar missions requiring long traverses and scientific observations are described and some experimental results are presented.

    • Scientific objectives and the payloads of Chang’E-1 lunar satellite

      Sun Huixian Dai Shuwu Yang Jianfeng Wu Ji Jiang Jingshan

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      China plans to implement its first lunar exploration mission Chang ’E-1 by 2007.The mission objectives are


      To achieve the above mission goals,five types of scientific instruments are selected as payloads of the lunar craft.These include stereo camera and spectrometer imager,laser altimeter,microwave radiometer,gamma and X-ray spectrometers and space environment monitor system.In order to collect,process,store and transmit the scientific data of various payloads a special payload data management system is also included.In this paper the goals of Chang ’E-1 and its payloads are described.

    • Space operation system for Chang’E program and its capability evaluation

      Yu Zhi-jian Lu Li-chang Liu Yung-chun Dong Guang-liang

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      Space operation for China’s first lunar exploration program, Chang’E will be provided by the S-band aerospace Telemetry, Tracking and Command (TT&C) network designed for China’s manned space program. This is undoubtedly a great challenge to the ground TT&C system. The largest antennas of China’s S-band aerospace TT&C network has an aperture of only 12 m. A series of technical measures have been taken into the designing of the spacecraft-ground TT&C system to ensure that such antennas can communicate with Chang’E-1 lunar probe 400,000 km away. These include installation of high-gain directional antennae and medium-gain omni-directional antennae for the probe, adding channel encoding to the downlink channel, using both high and low data rates for information transmission and upgrade and design of ground equipment terminals. Among them, the omni-directional antenna will operate in the earth-ground transfer orbit phase and the directional antenna will operate in the lunar orbit phase. These measures satisfy the spacecraft-ground link and program design requirements.

      To provide accurate navigation for the probe during its Earth-Moon flight and initial lunar orbiting flight, China’s VLBI system designed for astronomical observations, will also be used besides the ranging and range rate measurement capabilities of the S-band TT&C network. The purpose is to provide 100 m accuracy in position determination during lunar orbit. This paper describes the system design, technical challenges, solutions and capability evaluation of space operation for Chang’E-1.

    • Luna-Glob project in the context of the past and present lunar exploration in Russia

      E M Galimov

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      The Russian Luna-Glob project has been conceived with a view to understand the origin of the Earth-Moon system. The objectives and main features of the Luna-Glob mission, which will mainly study the internal structure of the Moon by seismic instruments, are described in the context of the past and current program of lunar exploration in Russia.

    • Analysis of optimal strategies for soft landing on the Moon from lunar parking orbits

      R V Ramanan Madan Lal

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      Optimal trajectory design of a probe for soft landing on the Moon from a lunar parking orbit by minimizing the fuel required is obtained. The problem is formulated as an optimal control problem with the thrust direction being the control variable. Using the maximum principle of Pontryagin, the control variable is expressed as a function of co-state variables and the problem is converted into a two-point boundary value problem. The two-point boundary value problem is solved using an optimization technique, i.e., controlled random search. The strategies such as


      are analyzed and an optimal strategy that achieves the goals is suggested. Also, appropriate design parameters are selected using this analysis

    • Telerobotic exploration and development of the Moon

      B L Cooper B Sharpe D Schrunk M Thangavelu

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      There has been a debate for the last thirty years about the relative merits of human versus robotic systems and we argue here that both are essential components for successful lunar exploration and development. We examine the role of robots in the next phases of exploration and human development of the Moon. The historical use of robots and humans in exploration is discussed, including Apollo-era exploration, International Space Station, and deep-water petroleum exploration. The technological challenges of lunar operations are addressed in the context of how robotic systems can be designed for robust and flexible operations. System design recommendations are given based on the lessons learned from terrestrial and space robotics.

    • Subject Index

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    • Author Index

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    • Acknowledgements

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