An SLR system and GNSS receiver are currently located at the 10,000 foot summit of Mt. Haleakala on the island of Maui, Hawaii. The Haleakala Observatory is situated on property held by the University of Hawaii, Institute for Astronomy. The facility has a long time series of SLR and GNSS measurements. Various location and system issues make this site less than ideal for co-locating a VLBI antenna. SGP is evaluating the use of a network of high performance GNSS receivers on both Haleakala and Kokee Part to perform precise site tie measurements between the two islands.
NASA installed the TLRS-4 at the summit of the Haleakala volcano in Maui, Hawaii in September 2006. Since the start of routine operations in November 2006, upgrades to the laser and to the timing system have greatly simplified operations and improved data quality. TLRS-4 is currently in its twelfth year of continuous operation at Haleakala Observatories. TLRS-4 is located on property held by the University of Hawaii Institute for Astronomy and staffed by University of Hawaii personnel. The Haleakala site is excellent for SLR, providing clear sky 80% of the time.
Prior to the installation of TLRS-4, the LURE (LUnar Ranging Experiment) observatory conducted both Lunar Laser Ranging (LLR) and SLR operations. Built in 1974 in support of the Apollo Program, LURE was modified to support SLR with the launch LAGEOS in 1976. Both activities continued until 1990, when support for lunar ranging was dropped. LURE was closed in 2004 to make room for new construction.
The National Geodetic Survey posted the results of their local tie survey at the NSGN Haleakala site on Maui, Hawaii. Vectors were measured between the SLR and GNSS station and ground marks to support the International Terrestrial Reference Frame and NGS's Foundation CORS program.
A winter storm damaged commercial power transmission lines to the observatories on Haleakala, Hawaii, USA on February 10, 2019. Commercial power to TLRS-4 at Haleakala has been restored.
A winter storm damaged commercial power transmission lines to the observatories on Haleakala, Hawaii, USA. Since February 10, TLRS-4 has been without power.
The local electric power company estimates repair to take a minimum of 4 weeks and as long as 8 weeks. The team is exploring ways to power the site with a backup generator or by connecting to a nearby observatory that has backup power.
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