scholarly journals Astrometry in Local Reference Frames for Deep Space Navigation

1988 ◽  
Vol 129 ◽  
pp. 333-334
Author(s):  
R. N. Treuhaft
Keyword(s):  
Reference Frames ◽  
Local Network ◽  
Single Source ◽  
Deep Space ◽  
Space Navigation ◽  
Source Method ◽  
Long Baseline ◽  
Sample Covariance ◽  
Local Reference ◽  
Navigation Accuracy

Future deep space missions will benefit from submilliarcsecond angular navigation accuracy (< 25 km projected distance at Neptune). Conventional Very Long Baseline Interferometry (VLBI) measurement strategies entail observations of a radio source (RS) and spacecraft pair. To increase the 3–5 milliarcsecond accuracies currently attainable, instrumental improvements could be coupled with either of two methods: 1) Use improved calibration measurements with the single RS as the spacecraft reference, or 2) use a reference frame established by a local network of RS's near the spacecraft to reduce the contribution of sky-dependent error sources. The demanding baseline vector (earth orientation) and tropospheric calibrations needed to realize submilliarcsecond accuracy with the single-source strategy would not be necessary with the multi-source strategy. The two strategies are compared via a sample covariance analysis. In this analysis, the single-source method yields 1.5 milliarcseconds for the navigation accuracy, while the multi-source method yields 0.5 milliarcseconds.

scholarly journals Determination of UT1 and Polar Motion by the Deep Space Network Using Very Long Baseline Interferometry

1979 ◽  
Vol 82 ◽  
pp. 199-209 ◽  
Author(s):  
J. L. Fanselow ◽  
J. B. Thomas ◽  
E. J. Cohen ◽  
P. F. MacDoran ◽  
W. G. Melbourne ◽  
...  
Keyword(s):  
Polar Motion ◽  
Very Long Baseline Interferometry ◽  
Deep Space ◽  
Deep Space Network ◽  
Accuracy Requirement ◽  
Space Network ◽  
Long Baseline ◽  
Navigation Accuracy ◽  
Better Than

The Deep Space Network (DSN) [operated by JPL under contract to the National Aeronautics and Space Administration] is implementing a Very Long Baseline Interferometry (VLBI) capability at DSS 63 (Spain), DSS 14 (California, USA), and DSS 43 (Australia) to support the navigation requirements of planetary space missions. The early development work for this system has already demonstrated the capability of measuring UT1 with a formal accuracy as low as 0.6 msec with only 6 hours of data. Further, a radio astrometric catalog of approximately 45 sources whose positions are known to better than has been constructed. In addition to these measurements, this paper describes the characteristics and anticipated performance of the complete VLBI system being implemented within the DSN for operational use in mid-1979. In particular, one of the capabilities of this system will be the measurement of UT1 and polar motion at weekly intervals. Although the navigation accuracy requirement is only 50 cm for the Voyager mission, this system should be capable of delivering UT1 and polar motion determinations with decimeter accuracy if it is operated at maximum performance. An additional requirement of this operational system is that it have the capability of providing these results within 24 hours of the actual observations.

The Application Research of Phase Referencing Imaging in Deep Space Navigation

2014 ◽  
Vol 926-930 ◽  
pp. 3568-3572
Author(s):  
Huan Zhou ◽  
Hai Tao Li
Keyword(s):  
Measurement Errors ◽  
Space Exploration ◽  
Radio Interferometry ◽  
Application Research ◽  
Deep Space ◽  
Space Navigation ◽  
Deep Space Exploration ◽  
Spacecraft Navigation ◽  
Navigation Accuracy

Aimed at the higher requirements for spacecraft navigation accuracy and shortcomings of traditional radio interferometry methods, this paper analyzes the advantages of phase referencing imaging used in deep space navigation, and then gives an introduction of its application in several missions. Finally, combined with the ground stations configuration and facilities in China, the feasibility of carrying out such experiments is discussed, as well as the possible measurement errors. The conclusion is that China has the ability to do phase referencing imaging experiments, and the available precision is about 4 nanorad (nrad). It’s hopeful to apply this technique into Chinese future deep space exploration.

scholarly journals The Definition and Stability of Local Inertial Reference Frames

1990 ◽  
Vol 141 ◽  
pp. 253-260
Author(s):  
R. N. Treuhaft ◽  
S. T. Lowe
Keyword(s):  
Reference Frame ◽  
Reference Frames ◽  
Broad Class ◽  
Radio Sources ◽  
Local Frame ◽  
Long Baseline ◽  
Angular Deflection ◽  
Limiting Error ◽  
Local Reference ◽  
Single Epoch

Inertial reference frames spanning approximately 10°-30° square on the sky and capable of locating objects to few-hundred microarcsecond accuracies are useful for a broad class of astrometric measurements. Deep space tracking and general relativistic angular deflection experiments are examples of astrometric measurements which can profitably reference the positions and/or motions of objects to a field of radio sources in a local frame. A method for defining local inertial reference frames has been developed based on Very Long Baseline Interferometry (VLBI) measurements of extragalactic radio sources. By observing the radio emission from the object to be located in the frame, as well as that from about five radio sources which define the frame, dominant systematic astrometric errors can be minimized through parameter estimation. The entire reference frame measurement is of the order of 30 minutes including all the sources in a frame. The limiting error for single-epoch position determination in a local frame is the unknown structure of both target and reference objects. Structure can cause systematic milliarcsecond-level errors. The limiting error for epoch-to-epoch differential position measurements is tropospheric fluctuations, assuming that the radio source structures do not change from one epoch to the next. Preliminary results of an epoch-to-epoch measurement of relativistic gravitational deflection by Jupiter, in which the total deflection was about 600 microarcseconds, suggest that the local reference frame is stable at the 240-microarcsecond level over twelve days. Data have been taken at longer time intervals to determine the annual stability of the frames. At the time of preparation of these proceedings, those data have not yet been analyzed.

scholarly journals Some Considerations in the Use of Very-Long-Baseline-Interferometry to Establish Reference Coordinate Systems for Geodynamics

1980 ◽  
Vol 56 ◽  
pp. 205-216
Author(s):  
Douglas S. Robertson
Keyword(s):  
Reference Frames ◽  
Geodetic Survey ◽  
Limiting Factors ◽  
Radio Sources ◽  
National Geodetic Survey ◽  
Terrestrial Reference Frames ◽  
Long Baseline ◽  
Lithospheric Plates ◽  
Long Time ◽  
The Stability

AbstractPresent knowledge of the number, distribution, proper motion and structures of extragalactic radio sources indicates that there should be no problem in defining a celestial reference frame with stabilities of a few milliseconds of arc over time spans of the order of a decade. One of the limiting factors appears to be the structure of the sources. By measuring and monitoring these structures, the stability could probably be improved by as much as one or two orders of magnitude. Even without this improvement, a network of properly distributed fixed observatories making regular interferometric observations of these radio sources could be used to define a terrestrial coordinate system that could be maintained at the few centimeter level over indefinitely long time periods. Such a stable terrestrial reference system would be useful for a host of modern geodetic and geodynamic applications, including, in particular, studies of the time varying deformations and relative motions of lithospheric plates. The National Geodetic Survey has already begun work on a three station base network of permanent observatories under project POLARIS as a first step toward implementing the new celestial and terrestrial reference frames. It is hoped that others will join in the effort and make the new reference frames a reality by the middle of this decade.

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