date: 2022-08-21T09:32:53Z pdf:unmappedUnicodeCharsPerPage: 0 pdf:PDFVersion: 1.7 pdf:docinfo:title: Towards NGGM: Laser Tracking Instrument for the Next Generation of Gravity Missions xmp:CreatorTool: LaTeX with hyperref Keywords: NGGM; GRACE; GRACE Follow-On; laser interferometry; Earth gravity access_permission:modify_annotations: true access_permission:can_print_degraded: true subject: The precise tracking of distance variations between two satellites in low Earth orbit can provide key data for the understanding of the Earth?s system, specifically on seasonal and sub-seasonal water cycles and their impact on water levels. Measured distance variations, caused by local variations in gravitational field, serve as inputs to complex gravity models with which the movement of water on the globe can be identified. Satellite missions GOCE (2009?2013) and GRACE (2002?2017) delivered a significant improvement to our understanding of spatial and temporal gravity variations. Since 2018, GRACE Follow-On has been providing data continuity and features for the first time through the use of a laser interferometer as the technology demonstrator, in addition to a microwave ranging system as the main instrument. The laser interferometer provides an orders-of-magnitude lower measurement noise, and thereby could enable a significant improvement in the measurement of geoids if combined with suitable improvements in auxiliary instrumentation and Earth system modelling. In order to exploit the improved ranging performance, the ESA is investigating the design of a ?Next Generation Gravity Mission?, consisting of two pairs of satellites with laser interferometers, improved accelerometers and improved platform performance. In this paper, we present the current design of the laser interferometer developed by us, the development status of the individual instrument units and the options available. dc:creator: Kolja Nicklaus, Kai Voss, Anne Feiri, Marina Kaufer, Christian Dahl, Mark Herding, Bailey Allen Curzadd, Andreas Baatzsch, Johanna Flock, Markus Weller, Vitali Müller, Gerhard Heinzel, Malte Misfeldt and Juan Jose Esteban Delgado dcterms:created: 2022-08-21T09:01:11Z Last-Modified: 2022-08-21T09:32:53Z dcterms:modified: 2022-08-21T09:32:53Z dc:format: application/pdf; version=1.7 title: Towards NGGM: Laser Tracking Instrument for the Next Generation of Gravity Missions Last-Save-Date: 2022-08-21T09:32:53Z pdf:docinfo:creator_tool: LaTeX with hyperref access_permission:fill_in_form: true pdf:docinfo:keywords: NGGM; GRACE; GRACE Follow-On; laser interferometry; Earth gravity pdf:docinfo:modified: 2022-08-21T09:32:53Z meta:save-date: 2022-08-21T09:32:53Z pdf:encrypted: false dc:title: Towards NGGM: Laser Tracking Instrument for the Next Generation of Gravity Missions modified: 2022-08-21T09:32:53Z cp:subject: The precise tracking of distance variations between two satellites in low Earth orbit can provide key data for the understanding of the Earth?s system, specifically on seasonal and sub-seasonal water cycles and their impact on water levels. Measured distance variations, caused by local variations in gravitational field, serve as inputs to complex gravity models with which the movement of water on the globe can be identified. Satellite missions GOCE (2009?2013) and GRACE (2002?2017) delivered a significant improvement to our understanding of spatial and temporal gravity variations. Since 2018, GRACE Follow-On has been providing data continuity and features for the first time through the use of a laser interferometer as the technology demonstrator, in addition to a microwave ranging system as the main instrument. The laser interferometer provides an orders-of-magnitude lower measurement noise, and thereby could enable a significant improvement in the measurement of geoids if combined with suitable improvements in auxiliary instrumentation and Earth system modelling. In order to exploit the improved ranging performance, the ESA is investigating the design of a ?Next Generation Gravity Mission?, consisting of two pairs of satellites with laser interferometers, improved accelerometers and improved platform performance. In this paper, we present the current design of the laser interferometer developed by us, the development status of the individual instrument units and the options available. pdf:docinfo:subject: The precise tracking of distance variations between two satellites in low Earth orbit can provide key data for the understanding of the Earth?s system, specifically on seasonal and sub-seasonal water cycles and their impact on water levels. Measured distance variations, caused by local variations in gravitational field, serve as inputs to complex gravity models with which the movement of water on the globe can be identified. Satellite missions GOCE (2009?2013) and GRACE (2002?2017) delivered a significant improvement to our understanding of spatial and temporal gravity variations. Since 2018, GRACE Follow-On has been providing data continuity and features for the first time through the use of a laser interferometer as the technology demonstrator, in addition to a microwave ranging system as the main instrument. The laser interferometer provides an orders-of-magnitude lower measurement noise, and thereby could enable a significant improvement in the measurement of geoids if combined with suitable improvements in auxiliary instrumentation and Earth system modelling. In order to exploit the improved ranging performance, the ESA is investigating the design of a ?Next Generation Gravity Mission?, consisting of two pairs of satellites with laser interferometers, improved accelerometers and improved platform performance. In this paper, we present the current design of the laser interferometer developed by us, the development status of the individual instrument units and the options available. Content-Type: application/pdf pdf:docinfo:creator: Kolja Nicklaus, Kai Voss, Anne Feiri, Marina Kaufer, Christian Dahl, Mark Herding, Bailey Allen Curzadd, Andreas Baatzsch, Johanna Flock, Markus Weller, Vitali Müller, Gerhard Heinzel, Malte Misfeldt and Juan Jose Esteban Delgado X-Parsed-By: org.apache.tika.parser.DefaultParser creator: Kolja Nicklaus, Kai Voss, Anne Feiri, Marina Kaufer, Christian Dahl, Mark Herding, Bailey Allen Curzadd, Andreas Baatzsch, Johanna Flock, Markus Weller, Vitali Müller, Gerhard Heinzel, Malte Misfeldt and Juan Jose Esteban Delgado meta:author: Kolja Nicklaus, Kai Voss, Anne Feiri, Marina Kaufer, Christian Dahl, Mark Herding, Bailey Allen Curzadd, Andreas Baatzsch, Johanna Flock, Markus Weller, Vitali Müller, Gerhard Heinzel, Malte Misfeldt and Juan Jose Esteban Delgado dc:subject: NGGM; GRACE; GRACE Follow-On; laser interferometry; Earth gravity meta:creation-date: 2022-08-21T09:01:11Z created: 2022-08-21T09:01:11Z access_permission:extract_for_accessibility: true access_permission:assemble_document: true xmpTPg:NPages: 17 Creation-Date: 2022-08-21T09:01:11Z pdf:charsPerPage: 3840 access_permission:extract_content: true access_permission:can_print: true meta:keyword: NGGM; GRACE; GRACE Follow-On; laser interferometry; Earth gravity Author: Kolja Nicklaus, Kai Voss, Anne Feiri, Marina Kaufer, Christian Dahl, Mark Herding, Bailey Allen Curzadd, Andreas Baatzsch, Johanna Flock, Markus Weller, Vitali Müller, Gerhard Heinzel, Malte Misfeldt and Juan Jose Esteban Delgado producer: pdfTeX-1.40.21 access_permission:can_modify: true pdf:docinfo:producer: pdfTeX-1.40.21 pdf:docinfo:created: 2022-08-21T09:01:11Z