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NuSTAR

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NuSTAR
COSPAR ID2012-031A Edit this at Wikidata
SATCAT no.38358Edit this on Wikidata
Websitewww.nustar.caltech.edu
Start of mission
Launch date13 June 2012, 16:00:37 (2012-06-13UTC16:00:37) UTC[1]

NuSTAR (the Nuclear Spectroscopic Telescope Array) is a space-based X-ray telescope that uses a Wolter telescope to focus high energy X-rays from astrophysical sources, especially for nuclear spectroscopy, and operates in the range of 5 to 80 keV.[3] It is the eleventh mission of the NASA Small Explorer satellite program (SMEX-11) and the first space-based direct-imaging X-ray telescope at energies beyond those of the Chandra X-ray Observatory and XMM-Newton. It was successfully launched on 13 June 2012, having previously been delayed from 21 March due to software issues with the launch vehicle.[4][5]

Its primary scientific goals are to conduct a deep survey for black holes a billion times more massive than the sun, understand how particles are accelerated to within a fraction of a percent below the speed of light in active galaxies, and understand how the elements are created in the explosions of massive stars by imaging the remains, which are called supernova remnants.

History

NuSTAR's predecessor, the High Energy Focusing Telescope (HEFT), was a balloon-borne version that carried telescopes and detectors constructed using similar technologies. In February 2003, NASA issued an Explorer Program Announcement of Opportunity. In response, NuSTAR was submitted to NASA in May, as one of 36 mission proposals vying to be the tenth and eleventh Small Explorer missions.[6] In November, NASA selected NuSTAR and four other proposals for a five-month implementation feasibility study.

In January 2005, NASA selected NuSTAR for flight pending a one-year feasibility study.[7] The program was cancelled in February 2006 as a result of cuts to science in NASA's 2007 budget. On 21 September 2007 it was announced that the program had been restarted, with an expected launch in August 2011, though this was later delayed to June 2012.[5][8][9][10]

The principal investigator is Fiona Harrison of the California Institute of Technology (Caltech). Other major partners include the Jet Propulsion Laboratory (JPL), University of California at Berkeley, Danish Technical University (DTU), Columbia University, Goddard Space Flight Center, Stanford University, University of California, Santa Cruz, Sonoma State University, Lawrence Livermore National Laboratory, and the Italian Space Agency (ASI). NuSTAR's major industrial partners include Orbital Sciences Corporation and ATK Space Systems-Goleta.

Launch

NASA contracted with Orbital Sciences Corporation to launch NuSTAR (mass 772 pounds (350 kg)[11]) on a Pegasus XL rocket for 21 March 2012.[5] It had earlier been planned for 15 August 2011, 3 February 2012, 16 March 2012, and 14 March 2012.[12] After a launch meeting on 15 March 2012, the launch was pushed further back to allow time to review flight software used by the launch vehicle's flight computer.[13] The launch was conducted successfully at 16:00:37 UTC on 13 June 2012[1] about 117 nautical miles south of Kwajalein Atoll.[14] The Pegasus rocket was dropped from the L-1011 'Stargazer' aircraft.[11][15]

Deployment and commissioning

On 22 June 2012 it was confirmed that the 10 m mast was fully deployed. Its 56 cube shaped elements were assembled one by one.[16]

Optics

NuSTAR employs two grazing incidence focusing optics each of which consists of 133 concentric shells. The particular innovation enabling NuSTAR is that the optics are coated with depth-graded multilayers (alternating atomically thin layers of a high-density and low-density material); with NuSTAR's choice of Pt/SiC and W/Si multilayers, this enables reflectivity up to 79 keV (the platinum K-edge energy).[17][18]

The optics are produced, at Goddard Space Flight Center, by heating thin (210 µm) sheets of flexible glass in an oven so that they slump over precision-polished cylindrical quartz mandrels of the appropriate radius. The coatings are applied by a group at the Danish Technical University.

The shells are then assembled, at the Nevis Laboratories of Columbia University, using graphite spacers machined to constrain the glass to the conical shape, and held together by epoxy. There are 4680 mirror segments in total (the 65 inner shells each comprise six segments and the 65 outer shells twelve; there are upper and lower segments to each shell, and there are two telescopes); there are five spacers per segment. Since the epoxy takes 24 hours to cure, one shell is assembled per day – it takes four months to build up one optic.

The expected point spread function for the flight mirrors is 43 arc-seconds, giving a spot size of about two millimeters at the focal plane; this is unprecedentedly good resolution for focusing hard-X-ray optics, though up to two orders of magnitude worse than the best resolution achieved at longer wavelengths by Chandra.

The optics have a 10.15-metre focal length, and so are held at the end of a long deployable mast; a laser metrology system is used to determine the exact relative positions of the optics and the focal plane at all times, so that each detected photon can be mapped back to the correct point on the sky even if the optics and the focal plane move relative to one another during an exposure.

See also

References

  1. ^ a b "Mission Status Center". Spaceflight Now. Retrieved 13 June 2012.
  2. ^ "Nuclear Spectroscopic Telescope Array, or NuSTAR" (PDF). June, 2012. Retrieved 16 June 2012. {{cite web}}: Check date values in: |date= (help)
  3. ^ About NuSTAR: The Nuclear Spectroscopic Telescope Array
  4. ^ Launch of NASA's NuSTAR Mission Postponed
  5. ^ a b c "NASA Selects Explorer Mission Proposals for Feasibility Studies (03-353)" (Press release).
  6. ^ "NASA Selects Explorer Mission Proposals for Feasibility Studies (03-353)" (Press release). Dwayne Brown, NASA. 4 November 2003. Retrieved 20 July 2011.
  7. ^ "NASA Selects Small Explorer Mission (05-026)" (Press release). Dolores Beasley/Gretchen Cook-Anderson, NASA. 26 January 2005. Retrieved 20 July 2011.
  8. ^ "NASA Restarts Telescope Mission to Detect Black Holes (07-198)" (Press release). Grey Hautaluoma, NASA. 21 September 2007. Retrieved 20 July 2011.
  9. ^ "NASA Restarts Telescope Mission to Detect Black Holes". NASA/JPL. 21 September 2007. Retrieved 20 July 2011.
  10. ^ Staff writers (21 September 2007). "NASA Plans Black Hole Finder". SPACE.com. Retrieved 20 July 2011.
  11. ^ a b "NuSTAR".
  12. ^ Nelson, Jon (4 September 2009). "NASA Approves X-ray Space Mission". NASA/JPL. Retrieved 20 July 2011.
  13. ^ Clavin, Whitney; Perrotto, Trent J; Diller, George (16 March 2012). "Launch of NASA's NuSTAR Mission Postponed". NASA.gov. Retrieved 31 May 2012.
  14. ^ "NASA Selects Orbital's Pegasus Rocket to Launch NuSTAR Space Science Satellite". Orbital. 18 February 2009. Retrieved 20 July 2011.
  15. ^ Clara Moskowitz (13 June 2012). "NASA blasts NuSTAR telescope into orbit to hunt black holes". MSNBC. Retrieved 15 June 2012.
  16. ^ "NuSTAR Successfully Deploys Huge Mast". 22 June 2012.
  17. ^ "NuSTAR optics".
  18. ^ Hailey, Charles (2010). "The Nuclear Spectroscopic Telescope Array (NuSTAR): optics overview and current status". SPIE Proceedings. 7732.
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