Chandra X-ray Center Manager's Report
Reporting period: October 2020 November 2021
The Chandra X-ray Observatory has carried out more than 22 years of highly successful and productive science operations. Chandra is unique in its capability for producing the sub-arcsecond X-ray images that are essential to accomplish the science goals of many key X-ray and multi-wavelength investigations in current astrophysical research. The Project is looking forward to many more years of scientific productivity. In recognition of Chandras important role in high-energy astrophysics, NASA chose to continue the mission and extend the contract to operate Chandra. In August 2021, NASA extended science observing under the contract through September 2024, with the potential for further extension of observing through September 2027.
Dr. Edward Mattison was appointed CXC Manager in February 2021. He succeeds Dr. Roger Brissenden, who transitioned to a senior advisory role within the CXC and Smithsonian Institution. Dr. Mattison had been CXC Deputy Manager since 1997. Prior to his work on the Chandra mission, Dr. Mattison carried out research at SAO on hydrogen maser frequency standards, including as a member of the 1976 Gravity Probe-A team that used a rocket-borne maser to test Einstein’s theory of general relativity.
Dr. Brissenden has been with the Chandra program (initially called AXAF) since 1990, and served as CXC Manager since 1993. In addition to his original charge of overseeing the establishment of the AXAF Science Center, he took on the development and implementation of the Operations Control Center when NASA assigned that role to the Smithsonian Astrophysical Observatory in the mid-1990’s, and also served as one of the original Chandra Flight Directors. He has taken on many other significant managerial and advisory roles, including as Associate Director of the High Energy Astrophysics Division of the Center for Astrophysics | Harvard and Smithsonian (CfA), Deputy Director of the CfA, and more recently, Acting Under Secretary for Science & Research for the Smithsonian Institution. He has served on many high-level committees for the Smithsonian, NASA and other agencies. We will miss him, but are fortunate to have continued access to his wisdom and advice.
Dr. Mark Weber has assumed the role of CXC Deputy Manager. Dr. Weber is a solar astrophysicist who was the U.S. Project Scientist for the X-ray Telescope (XRT) instrument on the Hinode mission and has since been the SAO manager of the XRT and Transiting Exoplanet Survey Satellite (TESS) programs.
Since March 2020, Chandra science and mission operations have been challenged by the Coronavirus pandemic. Our primary goals are ensuring the health of our staff and maintaining the continued normal operation of Chandra. CXC staff have successfully adapted to the telework environment, conducting normal spacecraft operations, responding to anomalies, processing and distributing data, administering the project, communicating with the public and supporting the scientific community, all largely remotely.
The High Resolution Camera (HRC) has returned to full service following a hardware anomaly in August 2020. After careful analysis, planning and review, staff swapped the HRC’s control electronics to its redundant circuits. (Chandra is equipped with duplicate sets of electronics and hardware for many functions.) Following thorough checkout, HRC resumed normal science observations in November 2020.
In August 2021 the Low Energy Transmission Grating (LETG) failed to insert properly into the telescope’s optical axis. Operations staff halted science observing and quickly established that no hardware or software had failed. The LETG was retracted and science observing, without gratings, was resumed three days later with a loss of 122.5 ks of observing time. A thorough engineering analysis, including Fourier analysis of data from the LETG’s stepper motor, showed that the anomaly was due to the temperature dependence of a capacitor in the motor drive circuit that had caused the LETG to travel marginally faster than normal. In October the flight team loaded revised parameters into the spacecraft’s database to take account of changing temperatures, and the use of both gratings during science observations was resumed.
The Observatory continues to operate extremely well overall, but with a number of incremental changes in performance. The gradual accumulation of molecular contamination on the UV filter that protects the ACIS detector, reduces ACIS’s sensitivity to low-energy X-rays (but does not affect the HRC). Overall spacecraft heating due to the slow degradation of Chandra’s multi-layer thermal insulation requires extra effort in scheduling observations, but has not significantly affected Chandra’s observing efficiency.
In response to the December 2020 call for proposals for Cycle 23 observations, scientists worldwide submitted 517 proposals, including 418 proposals for observing and 99 for archive and theory research. Observing proposals requested 81.2 Ms of telescope time, for an oversubscription factor of 4.2. In June the Chandra Director’s Office conducted the annual peer review of proposals remotely. The review approved 132 observing proposals and 22 archive and theory proposals, for a total of 19.3 Ms of observing time.
The CXC held a workshop, Chandra Data Science: Novel Methods in Computing and Statistics for X-ray Astronomy, during August 2021. The workshop, which was conducted remotely, featured 19 invited speakers.
The Chandra Press Office has been active in issuing image releases, science press releases and other communications of Chandra research results. A complete listing is available. Information about the Chandra Observatory and the Chandra X-ray Center can be found at cxc.harvard.edu.