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Session Overview
Session
P08: Future of geodesy from space - posters
Time:
Monday, 20/Mar/2017:
6:00pm - 7:00pm

Session Chair: Roger Haagmans
Session Chair: Adrian Jäggi

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Presentations

ESA's Studies of Next Generation Gravity Mission Concepts

Luca Massotti1, Christian Siemes1, Olivier Carraz1, Roger Haagmans2, Pierluigi Silvestrin2

1RHEA for ESA - European Space Agency, The Netherlands; 2ESA - European Space Agency, The Netherlands

The presentation addresses the preparatory studies of future ESA mission concepts devoted to improve our understanding of the Earth’s mass transport phenomena causing temporal variations in the gravity field, at different temporal and spatial scales, due to ice mass changes of ice sheets and glaciers, continental water cycles, ocean masses dynamics and solid-earth deformations.

The ESA initiatives started in 2003 with a study on observation techniques for solid Earth missions and continued through several studies focussing on the satellite system, technology development for propulsion and distance metrology, preferred mission concepts, the attitude and orbit control system, as well as the optimization of the satellite constellation. These activities received precious inputs from the in-flight lessons learnt from the GOCE and GRACE missions. More recently, several studies related to new sensor concepts based on cold atom interferometry were initiated, mainly focussing on technology development for different instrument configurations (GOCE-like and GRACE-like).

The latest results concerning the preferred satellite architectures and constellations, payload design and estimated science performance will be presented as well as remaining open issues for future concepts.


Cold Atom Interferometers Used in Space (CAIUS) for Measuring the Earth’s Gravity Field

Olivier Carraz1, Luca Massotti1, Christian Siemes1, Roger Haagmans2, Linda Mondin2, Pierluigi Silvestrin2

1RHEA for ESA - European Space Agency, The Netherlands; 2ESA - European Space Agency, The Netherlands

In the past decades, it has been shown that atomic quantum sensors are a newly emerging technology that can be used for measuring the Earth’s gravity field. Whereas classical accelerometers typically suffer from high noise at low frequencies, Cold Atom Interferometers are highly accurate over the entire frequency range.

There are two ways of making use of that technology: one is a gravity gradiometer concept, which relies on a high common mode rejection that relaxes the drag free control compare to GOCE mission; and the other one is in a low-low satellite-to-satellite ranging concept to correct the spectrally colored noise of the electrostatic accelerometers in the lower frequencies. We will present for both concepts the expected improvement in measurement accuracy and for the gravity gradiometer concept the expected improvement of Earth gravity field models, taking into account the different type of measurements (e.g. single vs. 3 axis, integration time, etc.) and different mission parameters such as attitude control, altitude of the satellite, time duration of the mission, etc.


GNSS-SLR Co-Location On-Board GNSS Satellites: Possible Contribution to the Realization of Terrestrial Reference Frames

Sara Bruni1, Susanna Zerbini1, Zuheir Altamimi2, Paul Rebischung2, Maddalena Errico1, Efisio Santi1

1DIFA Department of Physics and Astronomy, University of Bologna, Italy; 2IGN, LAREG, Univ Paris Diderot, Sorbonne Paris Cité, Paris, France

The International Terrestrial Reference Frame (ITRF) is computed on the basis of the data provided by four space geodetic techniques (GNSS, SLR, VLBI and DORIS). Their independent ground networks are currently connected by terrestrial ties measured at those ITRF sites where instruments of at least two different techniques are co-located. As a possible alternative or complementary approach, the geodetic community has been long discussing the possibility of exploiting the technique co-location in space, relying on spacecrafts equipped with positioning payloads of different techniques. In principle, space ties could overcome two major limitations of terrestrial ties, namely their poor spatial distribution and infrequent updates. On the other hand, the efficiency of their performance shall be carefully addressed under actual operative conditions. This study assesses the potential of the GNSS-SLR ties on-board GNSS satellites for the realization of homogeneous Terrestrial Reference Frames. For this purpose, the data collected by the whole SLR network and about 100 GNSS stations during the period 2011-2014 were analyzed and combined. Both long-term and quasi-instantaneous reference frames were computed, in order to verify whether the selected space ties could transfer the origin and scale information from the SLR to the GNSS network.The study was complemented by a series of simulations investigating the impact of possible future improvements in tracking performances. This analysis revealed that, at present, the GNSS-SLR co-location on-board GNSS satellites is not sufficient to realize a homogeneous technique combination. In addition, the achieved results highlighted that a deep understanding of the mechanisms driving the sensitivity of each geodetic technique to the reference frame parameters is fundamental in order to fully exploit the co-location in space.



 
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