12/02/2022
NASA Delivers First Flight Hardware to ESA for Lunar Pathfinder
NASA delivered the first flight hardware for the Lunar Pathfinder mission to ESA (European Space Agency), which formally accepted the instrument on Nov. 4. NASA's Goddard Space Flight Center in Greenbelt, Maryland, developed the instrument, a laser retroreflector array, which will test new navigation techniques for lunar missions.
NASA and ESA plan to launch Lunar Pathfinder via a future Commercial Lunar Payload Services delivery. In addition to testing navigation capabilities, Lunar Pathfinder will operate as a commercial communications relay satellite and provide communications services for exploration missions on the lunar surface.
The Lunar Pathfinder mission is led by Surrey Satellite Technology Ltd (SSTL), and ESA arranged for the mission to provide communications services to NASA. NASA Space Geodesy Project Manager Stephen Merkowitz, along with teams from ESA and SSTL, completed inspections when the laser retroreflector array arrived at SSTL's facility in Guildford, U.K., where it will be installed in the satellite.
NASA's laser retroreflector array arriving for inspection and approval (Credit: Surrey Satellite Technology Ltd.)
Read more on nasa.gov
09/14/2022
Gimbal and Telescope Assembly (GTA) #1 installed in the SGSLR shelter in late June 2022
The Gimbal with Mass Simulator was removed from the GGAO SGSLR facility in June 2022 and shipped back to Cobham. After the Factory Acceptance Test at Cobham in Lansdale, the Gimbal and Telescope Assembly (GTA) #1 was shipped to GGAO and installed in the SGSLR shelter in late June 2022. Preparations for the Site Acceptance Testing (SAT) were begun shortly after installation.
GTA#1 in the SGSLR dome at GGAO.
Ny-Ålesund SGSLR dome hydraulic pump successfully replaced
09/14/2022
The Ny-Ålesund SGSLR dome hydraulic pump was successfully replaced in August 2022 by Baader Planetarium as warranty work. The original pump was replaced with one that has a larger motor and does not require a heating element. Continued testing post-installation indicates that this replacement pump is working well.
Shortest day in modern times
08/12/2022
As noted in social media and the press (for example, here), the Earth recently experienced its shortest day in modern history. The length of day (LOD) of June 29, 2022 was recorded with 1.59 ms shorter than a standard 24-hour day (86,400 SI seconds). While this is a record in the era of atomic clocks (since the 1960s), it is nothing out of the extraordinary. LOD fluctuates over time and there were local minima in recent years as well. What is surprising is the fact that the Earth was speeding up a bit. In general terms, the Earth is slowing down mostly due to tidal friction caused by the moon: tidal bulges slow down the rotation of the Earth. For that, leap seconds are inserted to account for the slowed rotation. The currently observed increased rotational speed may be attributed to different geophysical phenomena, by themselves or in combination, including post-glacial rebound effects following the melting of ice masses particularly in the polar regions (including both recent ice mass loss as well as the long-term loss since the Pleistocene), climatological impacts on global hydrology due to recent consecutive La Nina events and changes in the parameters of the Earth's Chandler wobble (see articles here and here). On geological time scales (millions of years), however, the Earth has seen much shorter days (minutes to hours). Also, pre-atomic clock era LOD derivations using telescopic data from lunar occultations of stars point at around 2 ms shorter days in the 1870s, though with a much larger uncertainty. Hence, June 29, 2022 was not the shortest day ever in the history of the Earth but the shortest day in recent modern times. Monitoring these changes in the Earth's rotation is a critical function of the NASA Space Geodesy Project and its international partners as the changes are often unpredictable and provide key information about the geophysical changes affecting the Earth system (solid Earth, hydrosphere and atmosphere) and support precise positioning, satellite navigation, and the definition and maintenance of the Terrestrial Reference Frame.
The time history of LOD from space geodesy measurements since 1975 are available from the IERS here.
The twelfth session of the United Nations Committee of Experts on Global Geospatial Information Management (UN-GGIM) was held August, 3-5 2022
08/02/2022
The twelfth session of the United Nations Committee of Experts on Global Geospatial Information Management (UN-GGIM) was held August, 3-5 2022 at the United Nations Headquarters in New York. The session brought together senior officials and executives from national geospatial information and statistical authorities within Member States, and international geospatial experts from across the globe. Several NASA personnel from the Space Geodesy Program participated in support of the UN-GGIM Subcommittee on Geodesy. Dr. Karen St. Germain, the Earth Science Division Director at NASA Headquarters, presented "the critical role that geodesy and the global observatories play in Earth observation" during the Forum on Global Geodetic Reference Frame for Sustainable Development. The recording of Dr. St. Germain's presentation is available here.
