LIST OF ABSTRACTS

Session 5: "New and Upgrade Stations, Extended Facilities"

Engineering process of SLR for LEO orbiters

M.Abele, J.Balodis, M.Caunite, I.Janpaule, A.Rubans, G.Silabriedis, A.Zarinsjh
University of Latvia
E-mail: janis.balodis@lu.lv

The ground based satellite tracking system has been developed at the Institute of Geodesy and Geoinformation (GGI), University of Latvia in cooperation with a Riga municipality surveying company named Rigas GeoMetrs SIA. The SLR hardware and software is designed in GGI by integrating advanced industrially produced components. The experience gained by the SLR personnell in Riga has been applied. There is an alt/alt original small size telescope mount, EKSPLA diode pumped 17 mJ laser used with a repetition rate 50Hz and a 35 psec pulse width. A032-ET event timer and the Quartzlock (UK) GPS steered time service applied. Hamamatsu PMT used. SLR is placed on the roof of 150 years old 5 storey University building. The joint system of both the GNSS network and SLR will be applied for LEO satellite positioning, The system consists of a EUPOS-RIGA GNSS RTK five reference station network developed by Rigas GeoMetrs SIA and a satellite laser ranging system developed by GGI. The JAVAD GNSS chock ring antennas calibrated in Garbsen, Germany. The heights of antennas were determined by levelling to the 1-2 order levelling benchmarks. The analyses centre's server at the GGI and the GNSS receivers connected via optical cables. The signal from each receiver is received in GGI with a latency of 1-2 msec. The Geo++ network solution software GNSMART is used. EUPOS-RIGA is operational more than one year and its RTCM correction data is widely used by land surveyors. SLR construction is completed. However, fint adjustment of optical system and collection of engineering data still in process.

Ukrainian SLR network

Olga Bolotina
Main Astronomical Observatory of the National Academy of Sciences of Ukraine
E-mail: olga@mao.kiev.ua

Poster:
The structure of Ukrainian SLR network is described in the article. Technical description and current activities for each of the station are presented. Perspectives and plans for future of the Ukrainian SLR network are outlined.

Current status of SLR Simeiz-1873

Dmytrotsa A.I., Artemov I.V., Neyachenko D.I.
SRI Crimean Astrophysical Observatory, Ukraine
E-mail: dmytrotsa@gmail.com

Poster:
Despite that the question on the new laser is not solved yet, modernisation of existing one in the purpose of stability and power increase has been done. Works on optimisation of software and processing GPS data are continued.

Herstmonceux - towards kHz ranging and multi-technique status

Philip Gibbs, Graham Appleby, David Benham, Christopher Potter, Robert Sherwood, Toby Shoobridge, Vicki Smith and Matthew Wilkinson
NERC Space Geodesy Facility, UK
E-mail: pgib@nerc.ac.uk

The Space Geodesy Facility at Herstmonceux UK has been developing a kHz ranging capability in parallel with the long-running 10 Hz system. It also manages two IGS systems, one of which is taking part in the EUREF and IGS realtime projects, from mid 2006 an absolute gravimeter, plus an emerging LIDAR programme to run simultaneously with laser ranging.
In this paper we primarily detail some of the highs and lows of the drive towards full kHz operational capability, including the ability to rapidly switch between the 10Hz and 2kHz laser systems, the former remaining important for projects such as transponder and time-transfer work. We also outline the extended nature of the site by briefly discussing in particular the status of the operational gravity measurements, the use of GPS solutions to monitor site stability and progress with the LIDAR.

First SLR Operation in Korea using TROS, Chinese Transportable Ranging Observation System

Hyung-Chul Lim, Guo Tangyong, Wang Peiyuan, Hyeon-Seok Jeon, Yoon-Kyung Seo, Jong-Uk Park, Zou Tong
Korea Astronomy and Space Science Institute
E-mail : hclim@kasi.re.kr

The memorandum of agreement (MoA) between Institute of Seismology, China Earthquake Administration (ISCEA) and Korea Astronomy and Space Science Institute (KASI) was concluded for a productive collaboration in the field of space geodesy in June 2008, which specially includes a collaborative operation of TROS in Korea. TROS was moved to Korea in August 2008 on the basis of MoA and it will be operated for 12 months in KASI headquarter in Daejeon. The all-electronic part of TROS is integrated in one FPGA board, including event timer, GPS locked clock, range gate generator, servo system, software and so on. Additionally, it is capable of KHz ranging and ISCEA succeeded in obtaining laser ranging data using KHz laser system in the beginning of this year. Now TROS is operated by using a laser system with several Hz repetition rate because the new KHz laser system is not stable. KASI and ISCEA want to contribute to the international laser ranging societies by a collaborative operation of TROS.

Actuality and futurity of San Juan 7406 SLR Station

W Liu, Y Han, E Actis, E.Alonso, R. Podesta, A.A. Gonzalez, A.M.Pacheco, L Zhao, C Liu, Z Yin
National Astronomical Observatories of Chinese Academy of Sciences
E-mail: wdliu@bao.ac.cn

Poster:
San Juan 7406 SLR station is operated by National Astronomical Observatories of Chinese Academy of Sciences and Félix Aguilar Observatory of San Juan University of Argentina. The SLR station began to operate in the end of February of 2006. Due to the colleagues of the SLR team work hard and San Juan has a lot of clear nights, 7406 station obtained excellent results in the past two years and more. Our SLR team has established a upgrade plan on the SLR system. We hope that the SLR system can implement daylight tracking and KHz operating, also improve the precision of observations. According to the suggestion of ILRS, we will soon install a GPS receiver collocated with the SLR system.

About Current Status of Katzively SLR Station

Andriy A. Makeyev
Crimean Laser Observatory, Ukraine
E-mail: makeyev_a.a@mail.ru

Poster:
Over the last few years on SLR station Katzively-1893 some changes occurred. In late 2005 our station got a new laser made in "Polus" research institute (250 ps, 2-10 Hz, 100 mJ). Introduction of user-friendly interactive time-table in 2006 allowed observers to schedule the passes for the whole night in the evening and quickly switch from one satellite to another in case of necessity. At the beginning of 2008 old photomultiplier Hamamatsu H6279 was replaced with more sensitive H6780. Due to these upgrades our station significantly increased satellite ranging data quantity and crossed ILRS quantity baseline for LEO and high satellite passes. After installation of CCD camera on main guide of the telescope in 2007 our system became more eyesafe though there left optical paths with open laser radiation yet. In spring 2008 we installed simplified program packages for ephemeris preparation and for processing of ranging results so nowadays most of our observers can send normal points to data centers as soon as there would be a little break between passes. It has essentially reduced the data delivery latency. Though most of our measuring equipment made more than 20 years ago (except for SR-620 which is 10 years old) personnel of our station makes efforts to improve quality of SLR data performing maintenance repairs and adjustments of our devices in order to meet international guidelines.

Saturable Absorber Laser Upgrade

T. Oldham, H. Donovan, M. Blount, J. Horvath, O. Brogdon, D. McCollums
NASA SLR/HTSI, USA
E-mail: Thomas.Oldham@Honeywell.com

Since 1983, the current network of NASA Satellite Laser Ranging (SLR) stations used an Nd: YAG oscillator cavity in an active-passive configuration to generate 150-200 psec (2mj) 1064nm pulses for satellite ranging. This cavity (active-passive) used a liquid (chlorobenzene) dye cell as the passive saturable absorber. The dye consisted of Exciton (Kodak-9740) Q-Switch I dye and monochlorobenzene as a solvent. The dye mixture would degrade during use and would require daily maintenance. Chlorobenzene is a hazardous substance that requires special handling equipment and procedures.
The dye cell was replaced with a Cr4+:YAG crystal used as a saturable absorber in an active-passive mode-locked Nd:YAG laser. The new absorber requires little or no daily maintenance and the improved stability and laser performance is equal to or better than the dye cell. Pulse widths of 150psec were easily obtained and output energy variations of less than 10% shot to shot.

Status and Progress of ARGO

Jong Uk Park¹, Hyung-Chul Lim¹, Yoon-Kyung Seo¹, Young-Su Kim¹, Jang-Hyun Park¹, Young Su Son² and Yong Ki Kim³
1. Korea Astronomy and Space Science Institute
2. Korea Institute of Machinery and Materials
3. Kongju National University, Korea
E-mail : jupark@kasi.re.kr

Over the last few years, Korea Astronomy and Space Science Institute had prepared for introducing the SLR system in Korea. Even though we spent a lot of time to overcome the many barriers just same as other projects, we could finally start the ARGO project to make the series of SLR from this year. ARGO, new SLR systems of Korea, stands for the Accurate Ranging system for Geodetic Observation and this was the name of ship on which Jason and Argonauts voyaged to retrieve the Golden Fleece in Greek mythology. The goal of ARGO project is to make two SLR systems, one is a 40 centimeter mobile SLR system and another one is an 1 meter fixed SLR system, and to start the operation from the year 2011 and 2013 respectively.
The participants of ARGO project are involved in five working groups related with the components of SLR system, for example Electro-Optics, to work more specifically. Due to their efforts including the visiting to several SLR sites in abroad, we could determined the more detailed requirements and scheduling for ARGO system. In this paper, we will give the current status and future plan of ARGO project with the context of requirements and scheduling of ARGO.

FTLRS : Past and currents missions, upgrade for future

M. Pierron¹, F. Pierron¹, M. Furia¹, J.M. Torre¹, P. Bonnefond¹, P. Exertier¹, E. Samain¹
and Laser Staff¹ R. Coleman², C. Watson² , P. Tregoning³, J. Zhang³
1 Observatoire de la Cote d'Azur, France
2 University of Tasmania, Hobart, Australia
3 The Australian National University, Canberra, Australia
E-mail: monique.pierron@obs-azur.fr

Poster:
In this poster, we present recent and current missions as well technological upgrades for future projects ( T2L2..)
- Tasmania campaign (November 2007-April 2008) in collaboration with Australian colleagues ( R.Coleman, C.Watson, P.Tregoning, J.Zhang), the detailed set of data acquired with statistics and first results.
- Current Corsica campaign for Jason1/Jason2 Calval activities to inter-calibrate radar altimeters on the the spacecrafts
- Recent installation during last spring of Dassaut Event Timer on this mobile system to add the capability of accurate time stamp at the picosecond level. This very important upgrade has been achieved to imply Ftlrs in Time Transfer experiment on T2L2/Jason2 in future months with a very quick identification of triplets by the Grasse Center of mission in July some days after the launch of Jason2.

MeO : THE NEW French Lunar Laser Ranging station

Etienne Samain¹, Abdel Abchiche², Dominique Albanese¹, Nicolas Geyskens², Gilles Buchholtz², Aurélien Drean¹, Julien Dufour¹, Jérôme Eysseric³, Pierre Exertier¹, Francis Pierron¹, Monique Pierron¹, Grégoire Martinot Lagarde¹, Jocelyn Paris¹, Jean- Marie Torre¹, Hervé Viot¹,
1 OCA, 2130 route de l'observatoire, 06460 Caussols, France
2 OHP
3 INSU DT
Observatoire de la Cote d'Azur, France
E-mail: Francis.Pierron@obs-azur.fr

Since the beginning of the year 2004 a new organization focused on the Lunar Laser Ranging (LLR) and the mobile laser stations has been set up at OCA. In 2005 the LLR station was stopped in order to realize some important modifications. The LLR station is now renamed MeO for Metrology and Optics. Data acquisitions on low Earth altitude satellites, that were performed until now by the SLR station, will be done by MeO.
Since 2005, many developments was done:
          Telescope : high speed motorisation, high accuracy pointing
          Dome : new guiding device
          Building : offices, focus laboratory
          Optics : optical benches for experimental research, optical path
          Operational telemetry : lasers, high speed laser commutation, photo-detection
          Software.

First echoes in the new configuration scheme on both low and high altitude satellite has been obtained in July 2008.

The upgrading of the Borowiec SLR station

S. Schillak, J. Bartoszak, P. Michalek
Space Research Centre, Polish Academy of Sciences, Astrogeodynamic Observatory,Borowiec, Poland
E-mail : sch@cbk.poznan.pl

The presentation shows the results of the modernization of the Borowiec SLR station (7811) in 2007 and 2008. The several parts of the SLR system was modernize for improving the quality and efficiency of tracking. The part of these tasks was installation of a new transmitting telescope with remote control of divergence of the laser beam and modernization of the laser building, especially operator's and laser rooms with a new air-condition system. The most important task was installation of a new MicroChannel Plate PhotoMultiplier Tube (MCP-PMT) HAMAMATSU with 30% Quantum Efficiency (QE). The paper presents first results of calibrations and satellite observations with new MCP-PMT. We observe the better efficiency of the satellite tracking but little lower single shot RMS. The next task was re-cover of the main and secondary mirrors and installation of the new mirrors and their regulation systems in Coude path. Additionally in receiving part were installed the new interference and neutral filters, remote control of the space filter and camera CCD for control of the output laser beam position by the main mirror. The main changes in the electronic part include installation of a new gating system with 1 ns accuracy for stop channel of the time interval counter and MCP-PMT photocathode. The software changes include modernization of a real time control system. The installation of an indoor calibration target and installation of the event timer will be next tasks in 2008 and 2009.

Upgrading Plan of the Chinese SLR Network

Yang Fumin¹, Wu Bin¹, Zhang Zhongping¹, Guo Tangyong²
1 Shanghai Astronomical Observatory, Chinese Academy of Sciences, China
2 Institute of Seismology, China Earthquake Administration, Wuhan, China
E-mail: yangfm@shao.ac.cn

Under the support of the second of stage the national project "Crustal Movement Observation Network of China", the Chinese SLR stations will be upgraded to better performance in two years. The main improvements will be as follows: First, all stations will change to kHz ranging (except Kunming station, due to common transmit/receiving optics). The second, all stations will start routine daylight track.
In addition, the Chinese Academy of Sciences has decided to build a powerful SLR station at the Urumqi Astronomical station, National Astronomical Observatories of China. The new station will have 1-meter telescope and kHz laser ranging system. The site has very good weather and high sea level (2000m) and important location. There are VLBI and GPS systems at the station already, so the station will be a multi-technique collocation site.
The upgrading proposal for the San Juan SLR system is under consideration by the Ministry of Science and Technology of China.

Progress of Changchun SLR

You ZHAO, Cunbo FAN, Xinwei HAN, Gang ZHAO, Ziang ZHANG, Xue DONG
Changchun Observatory/NAOC, CAS, China
E-mail: youzhao@cho.ac.cn

The paper presents the summary and progress of Changchun SLR during the past years. It includes some special satellites observation, such as ETS-8, GIOVE-B, and Beidou; the time transfer and comparison experiment cooperated with shanghai observatory; the maintenance and improvement of the system; the design and development of any frequency fire rate control system; the basic process and application of SLR data.