Satellite orbit analyses for geodetic purposes.
Statistical model for determining satellite tracking station positions and longitudinal variations of the gravitational field
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Statistical model for determining satellite tracking station positions and longitudinal variations of the gravitational field
Voyager's flyby of Neptune in August of 1989 was the most distant planetary encounter ever achieved. Round trip light travel time was more than eight hours, exceeding view periods at two of the three tracking station sites. Consequently, the majority of radiometric tracking was accomplished by transmitting the uplink from one station, and receiving the downlink at a different station. This procedure defines three-way data. Dependence on three-way data for orbit determination is one distinguishing element of Voyager's successful encounter with Neptune. This paper addresses the performance of three-way range and Doppler data supporting pre-encounter orbit determination and post-encounter orbit reconstruction. Also, calibrations which reduce systematic errors inherent to three-way data are described and analyzed.
As one of the tracking systems used for the altimeter missions (such as TOPEX/Poseidon, Envisat, Jason-1/-2/-3, CryoSat-2, Saral/AltiKa, Sentinel-3A/-3B, HY-2A/C/D, Jason-CS/Sentinel-6A, SWOT), the position of the DORIS tracking stations provides a fundamental reference for the estimation of the precise orbits and so, by extension is fundamental for the quality of the altimeter data analysis and derived products. Due to the time evolution of the DORIS ground network, stations included in ITRF2020 may have been decommissioned and stations that were added to the tracking network after 2021.0 are, by definition, not part of ITRF2020. Therefore, to satisfy operational requirements for precise orbit determination and routine delivery of geodetic products, the International DORIS Service maintains the DORIS terrestrial reference frame for Precise Orbit Determination (DPOD) solutions. Since 2016, the DPOD products are computed by the IDS Combination Center (CC) as a DORIS cumulative position and linear velocity solution aligned to the latest available ITRF and using the latest IDS weekly combined series. Mid-2023, the IDS CC started the computation of the second version of the DPOD2020 based on the IDS 20 weekly solutions from 1993.0 to 2023.0. With that new solution, the IDS CC will include Post Seismic Deformation (PSD) corrections for some DORIS sites such as Socorro Island. These DPOD PSD corrections are determined from the analysis of DORIS coordinate time series only. The second version will also include optional annual and semi-annual station corrections. The presentation will describe the analysis used for extracting the PSD and seasonal DORIS station corrections, compare such corrections to those derived for ITRF2020, and evaluate the impact these new corrections have on station positioning and satellite POD.
The international activities of the NASA space program were studied with emphasis on the development and maintenance of tracking stations in Australia. The history and administration of the tracking organization and the manning policies for the stations are discussed, and factors affecting station operation are appraised. A field study of the Australian tracking network is included.
Tracking stations engineering and operations, and communications engineering, research, and development for Deep Space Network
Evaluation of potential locations for Airborne Range and Orbit Determination ground stations
Earth-based radio tracking data types are considered, which involve simultaneous or nearly simultaneous spacecraft tracking from widely separated tracking stations. These data types are conventional tracking instrumentation analogs of the very long baseline interferometry (VLBI) of radio astronomy-hence the name quasi-VLBI. A preliminary analysis of quasi-VLBI is presented using simplified tracking data models. The results of accuracy analyses are presented for a representative mission, Viking 1975. The results indicate that, contingent on projected tracking system accuracy, quasi-VLBI can be expected to significantly improve navigation performance over that expected from conventional tracking data types.
TIGRAS is client-side software, which provides tracking-station equipment planning, allocation, and scheduling services to the DSMS (Deep Space Mission System). TIGRAS provides functions for schedulers to coordinate the DSN (Deep Space Network) antenna usage time and to resolve the resource usage conflicts among tracking passes, antenna calibrations, maintenance, and system testing activities. TIGRAS provides a fully integrated multi-pane graphical user interface for all scheduling operations. This is a great improvement over the legacy VAX VMS command line user interface. TIGRAS has the capability to handle all DSN resource scheduling aspects from long-range to real time. TIGRAS assists NASA mission operations for DSN tracking of station equipment resource request processes from long-range load forecasts (ten years or longer), to midrange, short-range, and real-time (less than one week) emergency tracking plan changes. TIGRAS can be operated by NASA mission operations worldwide to make schedule requests for the DSN station equipment.
This paper details the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) Flight Dynamics Facility (FDF) tracking data certification effort of the Lunar Reconnaissance Orbiter (LRO) Space Communications Network (SCN) complement of tracking stations consisting of the NASA White Sands 1 antenna (WS1), and the commercial provider Universal Space Network (USN) antennas at South Point, Hawaii; Dongara Australia; Weilheim, Germany; and Kiruna, Sweden. Certification assessment required the cooperation and coordination of parties not under the control of either the LRO project or ground stations as uplinks on cooperating spacecraft were necessary. The LRO range-tracking requirement of 10m 1 sigma could be satisfactorily demonstrated using any typical spacecraft capable of range tracking. Though typical Low Earth Orbiting (LEO) or Geosynchronous Earth Orbiting (GEO) spacecraft may be adequate for range certification, their measurement dynamics and noise would be unacceptable for proper Doppler certification of 1-3mm/sec 1 sigma. As LRO will orbit the Moon, it was imperative that a suitable target spacecraft be utilized which can closely mimic the expected lunar orbital Doppler dynamics of +/-1.6km/sec and +/-1.5m/sq sec to +/-0.15m/sq sec, is in view of the ground stations, supports coherent S-Band Doppler tracking measurements, and can be modeled by the FDF. In order to meet the LRO metric tracking data specifications, the SCN ground stations employed previously uncertified numerically controlled tracking receivers. Initial certification testing revealed certain characteristics of the units that required resolution before being granted certification.
Digital computer program for IBM 7094 computer to generate spacecraft tracking station calculations
Geodetic information is presented for NASA tracking stations and observation stations in the NASA geodetic satellites program. A geodetic data sheet is provided for each station, giving the position of the station and describing briefly how it was established. Geodetic positions and geocentric coordinates of these stations are tabulated on local or major geodetic datums, and on selected world geodetic systems when available information permits.
Commercial operators are now proposing to install thousands of High Density Fixed Services (HDFS) microwave transmitters in large urban centers, such as Los Angeles. These transmitters will share the same frequencies in the Ka band (32 GHz and 37 - 38 GHz) as some Space Research Service (SRS) receiving Earth stations. To face this challenge, Resolution 126 (WRC-97) has requested the International Telecommunications Union-Radiocommunications (ITU-R) to conduct, as a matter of urgency and in time for WRC-99, appropriate studies to determine sharing criteria between stations in the fixed service and stations in other services. The three DSN tracking stations worldwide utilize this frequency band and may become vulnerable to interference from the planned deployments of HDFS transmitters. These HDFS transmitters operate at a relatively strong signal power (up to -60 dBW/Hz). Thus, they will seriously interfere with the sensitive DSN receivers. It has become imperative to accurately predict the impact of HDFS transmitters on NASA's DSN receivers in the Ka band.
When astronauts landed on the moon on July 20, 1969, the Eagle lander carried a small, unconventional television camera affixed to the inside of the door. It had one mission. Once astronauts opened the door and activated the camera, it would begin shooting live images of the historic event, transmitting the raw footage by way of an antenna to Earth below. There, engineers at three tracking stations would tape the original signals onto one-inch telemetry tapes fpr backup and then also convert the raw feed into a conventional format compatible with American broadcast standards.
Geodetic error effects on time dependence of satellite tracking data as received by surface tracking station
The trajectory of the Ulysses spacecraft carries it over the South polar region of the Sun in mid-1994, albeit at a great distance from the Sun itself. During this time the South Solar latitude of Ulysses' orbit reaches a maximum value of 80.2 degrees, and the geocentric declination reaches a magnitude of over 75 degrees. As a result, a number of unique and interesting events occur, not the least of which being that Ulysses never sets over the Canberra tracking station of the DSN for more than two months. A less obvious aspect of the Sun-spacecraft-Earth geometry during this time is the return of solar-induced nutation to the spin-stabilized Ulysses spacecraft, and the consequent use of active nutation control. Both of these events have significant implications for theory and practice of Ulysses' orbit determination during this period, which is the subject of the proposed paper.
The directory documents geodetic information for NASA tracking stations and observation stations in the NASA Geodetic Satellites Program, including stations participating in the National Geodetic Satellite Program. Station positions of these facilities are given on local or preferred major datums, and on the Modified Mercury Datum 1968. A geodetic data sheet is provided for each station, giving the position of the station and describing briefly how it was established. Geodetic positions and geocentric coordinates of these stations are tabulated on local or major geodetic datums, and on selected world geodetic systems when available information permits.
A technique is described by which laser measurements may be used in an explicit definition of geodetic parameters at the one-meter level of resolution. Observations made by a tracking station at the Goddard Space Flight Center of the Beacon Explorer C satellite are analyzed with this technique to yield highly precise measures of perturbations in the satellite's inclination, including the effect of earth and ocean tides and variations in the station's latitude due to polar motion. The tracking configuration is described, and the basic technique is outlined (analysis of six-hour observations with a weighted least squares orbit determination method). Techniques for analyzing orbital errors and inclination perturbations are described, and it is shown that quarter-day spans of laser data can be employed to monitor the inclination of the satellite to the order of 0.01 arcseconds precision over a period of 17 months.
The higher accuracy and extended coverage of the SEASAT-A altimeter allows for the determinations of a highly refined geoid, of open ocean currents and circulations, of ocean subsurface topography, and of earth surface topography. The radar altimeter on SEASAT-A is also considered as a tracking station in orbit for range and range rate tracking work.