This week, members of the NuSTAR Science Operations Center (SOC) team successfully performed an update to the payload’s flight software to try to extend the life of NuSTAR's two metrology lasers. The metrology lasers are used to track the slight relative motion of the optics and focal plane benches, allowing the analysis software to correct for blurring caused by tiny amounts of flexing in the 10-m long mast. Over time, the metrology lasers have declined in intensity as they have aged. The NuSTAR instrument team acted to extend the laser lifetime in 2020 by reducing the duty cycle (the fraction of a second that the laser is “on”) by a factor of roughly 25. This slowed the decay of the laser signal over the last five years. Early in 2026, the team determined that an additional reduction in the duty cycle by a factor of 4 was required to further extend the laser lifetime. This flight software patch was first extensively tested on the “engineering module” test unit at Caltech, and updates to the ground processing software delivered in advance of the change. The patch was successfully uploaded to the spacecraft on Thursday, September 24, 2026. Science data were received an hour later, and the SOC team confirmed that the instrument and all of the ground processing software were performing as expected with zero impact to the science data products. The SOC will continue monitoring the laser performance and determine if any additional actions are required. NuSTAR users should note that any data taken during or after September 24, 2026 will require NuSTARDAS v2.1.6 for analysis. This is available in HEASoft v6.37 and later. 

Author: Brian Grefenstette, NuSTAR Instrument Scientist (Caltech)