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13th International Laser Ranging
Workshop
"Toward Millimeter Accuracy"
Submitted
Abstracts
Target Design, Signatures, and Biases (G. Appleby and V. Vasiliev)
| Title | Primary Author |
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| Laser Retroreflector Array (LARA) for IRS Mission | Kattimuthu Elango |
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Kattimuthu Elango M.Pitchaimani, P.Soma, and S.K.Shivakumar Indian Space Research Organization (ISRO) is supporting multiple satellites currently for remote sensing applications through its ground stations within and outside the country. ISRO has also plans to launch in the near future advanced remote sensing missions like Cartosat, Oceansat, Metsat, etc., which require ground imagery resolutions of the order of 2.5 m. It is not possible to meet this stringent requirement with the present orbit determination using RF tracking. In view of this, a high level task team was set up for advanced tracking systems to improve the orbit accuracy and Satellite Laser Ranging was one of the recommendations by the task team since SLR is the most accurate technique available for observing the orbits of the artificial satellites. Also, ISRO has initiated space geodetic activity which is a nascent field in India and to pursue this, advanced tracking techniques such as SLR, GPS, PRARE, DORIS, VLBI are required. ISRO is already operating PRARE and GPS stations and addition of SLR will complement data for space geodesy and geo-dynamic studies. ISRO, having a long experience in SLR operation for more than a decade, is an added advantage for this program. Hence, to enable laser ranging to a satellie, laser retro reflectors are to be fitted with the earth facing side of the satellite.This paper presents the design and analysis of the Laser Retroreflector Array (LARA) for future IRS mission. The maximum energy reaching the spacecraft as well the ground receiver, cut off angles, LARA onboard location and other relevant analysis are also brought out. Oral presentation; received August 6, 2002 |
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| Velocity Aberration | David Arnold |
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94 Pierce Road This paper computes the velocity aberration for a solid, two-dimensional retroreflector moving at velocity v with respect to a stationary laser transmitter. The basic approach is the same as in the paper “Effect of motion of the optical medium in optical location”, V.P. Vasiliev, V.A. Grishmanovskii, L.F. Pliev, and T.P. Startsev, 1992. However, the equations are set up differently and give a different answer. The relativistic equations for the addition of velocities are used to compute the velocity of the rays parallel and anti-parallel to the velocity v. The expression obtained for the velocity aberration angle is 2v/c with a small second order term that can be neglected. The index of refraction cancels. Oral presentation; received August 16, 2002; revised August 22, 2002 |
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| Retroreflector Array Transfer Functions | David Arnold |
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94 Pierce Road This paper presents some cross section and range correction matrices for satellites such as LAGEOS, TOPEX, and WESTPAC. Diffraction patterns for individual cube corners are also shown. The effects of polarization, and dihedral angle offset are studied. Basic principles of retroreflector array design are discussed for maximizing cross section and minimizing variations in cross section and range correction. Tables of range correction as a function of signal strength for LAGEOS and for target calibration measurements are presented for a particular set of system parameters and detection algorithms. Oral presentation; received August 16, 2002; revised August 22, 2002 |
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| Difference of LAGEOS satellite response from raw data analysis of the collocation experiment between the Grasse Satellite and Lunar Laser Ranging stations | Joëlle Nicolas |
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Observatoire de la Côte d'Azur/CERGA Jean-François Mangin, Gilles Metris, and François
Barlier We performed a collocation experiment at the Grasse observatory (France) between three independent laser ranging instruments: a Satellite Laser Ranging (SLR), a Lunar Laser Ranging (LLR) station, and the French Transportable Laser Ranging Station (FTLRS). The normal point analysis of the common passes on LAGEOS-1 and -2 satellites showed a systematic difference of 13 mm between the SLR and the LLR station results. To explain this bias, from the raw data and a geometrical analysis, we computed the difference of the LAGEOS satellite ranges due to instrumental differences. So, we show that it effectively exists a dependence between the laser ranging station and the satellite signature, at the level of 3 mm between the two considered stations. Moreover, we have to add a center edge effect of 9 mm for the LLR return photo-detector. Thus, we are able to explain a difference of 12 mm between the two considered stations. We also propose to adopt a LAGEOS center of mass correction value depending on the kind of laser ranging station, dependency especially coming from the difference between a single and a multi photoelectron detection modes. We found that this difference can reach a few millimeters from the one usually used for the laser ranging data analysis. Oral presentation; received August 20, 2002 |
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| Design of a laser retro-reflector for the first satellite ranging mission in S. Korea on an elliptical orbit | Seungbum Kim |
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Satellite Technology Research Center/Korea Advanced Inst. Science
and Technology Kwang-sun Ryu STSAT (Science and Technology Satellite)–5 is the fifth of Korean micro-satellite, which has the laser ranging mission for the first time in Korea. STSATs, formerly known as KITSAT or KAISTSAT, are a series of cost-effective micro-satellites, developed and operated since 1992 by Satellite Technology Research Center (SATREC), Korea Advanced Inst. Science and Technology (KAIST). The primary objective of the STSAT program is to test novel technologies and payloads at low cost (~10 million US$) and a short development period (~ three years). STSATs 1-3 were launched in 1992, 1993 and 1999 and STSAT-4 is due for launch in 2003. They have performed successfully, particularly in mapping the Earth’s surface at 13m resolution. STSAT5, scheduled for launch in 2005, has the following specifications: total weight of ~ 100 kg; dimension of ~ 600 ´ 500 ´ 800 mm; sun-synchronous elliptical orbit at 300 – 1600 km. One of its primary mission goals is to verify the performance of the first Korean launcher through precise orbit determination. The verification scenario consists of GPS (global positioning system) and SLR (satellite laser ranging) positioning. In this context, we are developing the laser retro-reflector (LRR) by integrating the experiences of ground laser ranging and laser optics in Korea and, possibly, by collaborating with international partners. The work scope includes also the analysis of SLR data and the determination of the precise position on the elliptical orbit. For this we will utilize our experiences of processing SLR and satellite altimeter data. Finally we will present a brief overview of space program in Korea. Oral presentation; received August 22, 2002 |
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| Recovery of target response function for centre-of-mass corrections of spherical satellites | Toshimichi Otsubo |
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Communications Research Laboratory Graham M Appleby Accurate center-of-mass corrections for geodetic spherical satellites are expected to contribute to accurate determination of the scale of the earth, i.e., the scale of terrestrial reference frame and the geocentric gravitational constant GM. We devised a new method to recover the response function of geodetic satellites. Post-fit residual histograms of single photon data were used to overcome ambiguities in the treatment of far-field diffraction effects. Given the response functions, the center-of-mass corrections for LAGEOS, AJISAI and ETALON satellites were derived for various types of laser ranging systems. Among them, the single-photon ranging provides the strongest result because we can produce one unique center-of-mass correction that is always applicable without additional corrections. Oral presentation; received August 22, 2002 |
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| Reflector arrangement on H2A-LRE satellite | Toshimichi Otsubo |
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Communications Research Laboratory Hiroo Kunimori Keisuke Yoshihara and Hidekazu Hashimoto We designed the arrangement of cube corner reflectors carried on the Japanese H2A-LRE satellite. 126 reflectors (6 reflectors x 21 sets) are distributed on the surface of the quasi-spherical satellite whose diameter is 50 cm. Half of the reflectors are made of fused silica (optical index = 1.46) whereas the other half are made of BK7 (optical index = 1.52). The optical responses of the two materials are not very different at the beginning but the BK7 is expected to degrade in a short time. We modeled the optical behaviour both before and after the BK7 reflectors spoil. The center-of-mass correction is reduced by about five mm after the degradation, for all types of laser ranging systems. For users whose interrest is in one-cm precision, a center-of-mass correction of 210 mm can be uniformly applied. Oral presentation; received August 22, 2002 |
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| LAGEOS-2 spin rate and orientation | Robert Sherwood |
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NERC Space Geodesy Facility Roger Wood Toshimichi Otsubo Presented by: Roger Wood The Herstmonceux photometer system (which allows brightness measurements to be made simultaneously with laser ranging) has been upgraded to provide 1ms time resolution. Precise timing of solar glints from the front faces of the corner-cube reflectors on LAGEOS-2 over a two-year period has yielded a detailed record of the slowing of the satellite's rotation and enabled an accurate determination of the precessional behaviour of the spin axis. Oral paper; received August 23, 2002 |
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| International experiment in space for investigation of a novel-type laser retroreflector | Vladimir Vasiliev |
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IPIE N. Parkhomenko, V, Shargorodsky V. Glotov, N. Sokolov On board of the METEOR-3M(1) spacecraft launched on December 10, 2001, a novel-type laser retroreflector (RR) is installed. The spherical RR uses the principle of an optical Luneberg lens, and has the advantage of minimum target error introduced in ranging measurements. The basic goal of the experiment is to determine the return signal level in real environment conditions. After the METEOR-3M(1) launching, problems arose with the GPS/GLONASS equipment on board of this satellite, and to provide the necessary precision of orbit determination for the NASA SAGE-III equipment operation, it has been decided to use the international SLR network. Based on measurement results obtained at the SLR-station near Moscow, estimations have been made of the spherical RR cross-section. The main center responsible for precision orbit determination (POD) was MCC (Russia). POD was made also by Honeywell Technology solutions, Inc (HTSI). The MCC and HTSI results have practically equal accuracy, and are satisfactory for the SAGE-III mission purpose. Results are presented of comparison between METEOR-3M(1) orbit parameters obtained from laser measurements and regular RF measurements. The obtained results may be basis for development and engineering of a full-scale ball-lens RR-satellite providing an extremely small target error, which is important for geophysics, geodynamics, and some other scientific areas. Oral paper; received August 23, 2002 |
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| Development and on-orbit performance of moderate-cost spherical retroreflector arrays for the Starshine program | Robert Kessel |
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Naval Research Laboratory William Braun, Mark Davis, Amey Peltzer, Anne Reed, Ilene Sokolsky,
John Vasquez, Paul Wright The Starshine program provided a successful test of a laser ranging array designed for a spherical satellite and built from standard commercially-available retroreflectors. The basic result from the on-going satellite laser ranging observations is that such a moderate-cost array has satisfactory on-orbit performance for altitudes below 470 km and has also demonstrated to date at least a year long lifetime. The array contains thirty-one 1 cm retroreflectors arranged for low variability in laser radar cross section for all illumination directions. The number and diameter of the retroreflectors resulted from parametric design studies to minimize both number retroreflectors in the array and the effects of velocity aberration. The experimental verification of the design is based on the observed raw data point density as determined from the field-generated normal points. Oral paper; received September 04, 2002 |
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| The Atmospheric Neutral Density Experiment: a Mission Overview | Andrew Nicholas |
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Naval Research Laboratory, Code 7607 S.E. Thonnard, G.C. Gilbreath The Atmospheric Neutral Density Experiment (ANDE) is a mission proposed by the Naval Research Laboratory to monitor the thermospheric neutral density at an altitude of 400km. The primary mission objective is to provide total neutral density along the orbit for improved orbit determination of resident space objects. The mission serves as a test platform for a new space to ground optical communications system, the Modulating Retror-reflector Array in Space (MODRAS). The mission consists of two spherical spacecraft fitted with retro-reflectors for satellite laser ranging (SLR). One spacecraft is completely passive, the other carries three active instruments; a miniature Wind And Temperature Spectrometer (WATS) to measure atmospheric composition, cross-track winds and neutral temperature; a Global Positioning Sensor (GPS); and a Thermal Monitoring System (TMS) to monitor the temperature of the sphere. A design requirement of the active satellite is to telemeter the data to the ground without external protrusions from the spherical spacecraft (i.e. an antenna). The active satellite will be fitted with the MODRAS system, which is a science enabling technology for the ANDE mission. The MORDAS system consists of a set of modulating retro-reflectors coupled with an electronics package, that will telemeter data to the ground by modulating and reflecting the SLR laser interrogation beam. This paper presents a mission overview and emphasis will be placed on the design, optical layout, performance, ground station, and science capabilities of the mission. Oral paper; received September 05, 2002 |
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Last Updated:
September 5, 2002
