The Neutron star Interior Composition ExploreR Mission

The Neutron star Interior Composition Explorer (NICER) is an International Space Station (ISS) payload devoted to the study of neutron stars through soft X-ray timing. Neutron stars are unique environments in which all four fundamental forces of nature are simultaneously important. They squeeze more than 1.4 solar masses into a city-size volume, giving rise to the highest stable densities known anywhere. The nature of matter under these conditions is a decades-old unsolved problem, one most directly addressed with measurements of the masses and, especially, radii of neutron stars to high precision (i.e., better than 10 percent uncertainty). With few such constraints forthcoming from observations, theory has advanced a host of models to describe the physics governing neutron star interiors; these models can be tested with astrophysical observations.

NICER will enable rotation-resolved spectroscopy of the thermal and non-thermal emissions of neutron stars in the soft (0.2-12 keV) X-ray band with unprecedented sensitivity, probing interior structure, the origins of dynamic phenomena, and the mechanisms that underlie the most powerful cosmic particle accelerators known. The NICER mission achieves these goals by deploying an X-ray timing and spectroscopy instrument on the International Space Station (ISS).

By answering a long-standing astrophysics question - How big is a neutron star? - NICER will confront nuclear physics theory with unique measurements, exploring the exotic states of matter within neutron stars through rotation-resolved X-ray spectroscopy. The capabilities that NICER brings to this investigation are unique: simultaneous fast timing and spectroscopy, with low background and high throughput. NICER will also provide continuity in X-ray-timing astrophysics more broadly, post-Rossi X-ray Timing Explorer, through a Guest Observer program. Finally, in addition to its science goals, NICER will enable the first space demonstration of pulsar-based navigation of spacecraft, through the Station Explorer for X-ray Timing and Navigation Technology (SEXTANT) enhancement to the mission, funded by the NASA Space Technology Mission Directorate's Game-Changing Development program.

NICER's X-ray Timing Instrument (XTI) represents an innovative configuration of high-heritage components. The heart of the instrument is an aligned collection of 56 X-ray "concentrator" optics (XRC) and silicon drift detector (SDD) pairs. Each XRC collects X-rays over a large geometric area from a roughly 30 arcmin2 region of the sky and focuses them onto a small SDD. The SDD detects individual photons, recording their energies with good (few percent) spectral resolution and their detection times to an unprecedented 100 nanoseconds RMS relative to Universal Time. Together, this assemblage provides a high signal-to-noise-ratio photon-counting capability within the 0.2-12 keV X-ray band, perfectly matched to the typical spectra of neutron stars as well as a broad collection of other astrophysical sources.

From NICER's ISS platform, a star-tracker-based pointing system allows the XTI to point to and track celestial targets over nearly a full hemisphere. The pointing system design accommodates the ISS vibration and contamination environments, and enables (together with NICER's GPS-based absolute timing) high-precision pulsar light-curve measurements through ultra-deep exposures spanning the 18-month mission lifetime. Anticipated launch of NICER is in early 2017.

Simulated NICER count rates and spectra can be derived using the WebPIMMS and WebSPEC tools.

A 12-slide overview of NICER science is available here.

More NICER documentation and publications.

If you would like to receive email about NICER developments, please subscribe to the NICER-announce email list.

For those interested in general astronomy/astrophysics information please go to the Education and Public Outreach site.

Targets of Opportunity (ToOs) Capability with NICER
NICER is capable of following up on Targets of Opportunity (ToO) within 4 hours upon receipt of request by either:

Keith Gendreau (keith.c.gendreau@nasa.gov) or Zaven Arzoumanian (zaven.arzoumanian@nasa.gov)

Once operations commence, the NICER team will also monitor the Gamma-ray Coordination Network (GCN)/Transient Astronomy Network (TAN).

The possibility of quicker responses than 4 hours to ToOs is currently being investigated.

Artist concept of NICER

Latest News
  • Current NICER launch date: June 1, 2017 (23 May 2017)
    NICER is currently scheduled for launch to the ISS on SpaceX-11, which is now scheduled for launch on June 1 at 5:55 pm eastern time from the Kennedy Space Center. Backup dates are June 3 (5:04 PM EDT) and 4 (4:44 PM EDT).
  • News Feature: SpaceX Dragon to Deliver Research - including NICER - to the Space Station (22 May 2017)
    SpaceX is scheduled to launch its Dragon spacecraft for its 11th commercial resupply mission to the International Space Station on June 1 from Kennedy Space Center's historic pad 39A. Dragon will lift into orbit atop the Falcon 9 rocket carrying crew supplies, equipment and scientific research, including the NICER payload, to crew members living aboard the station. Once affixed to the exterior of the space station, NICER will study the physics of neutron stars, providing new insight into their nature and behavior.
  • NICER launch date update: June 1, 2017 (02 May 2017)
    NICER is currently scheduled for launch to the ISS on SpaceX-11, which is now scheduled for launch on June 1 at 5:55 pm eastern time from the Kennedy Space Center.
  • NICER expected launch date: May 14, 2017 (21 March 2017)
    NICER is currently scheduled for launch to the ISS on May 14, 2017 from the Kennedy Space Center.
  • NICER, the New NASA Mission Studying Neutron Stars, Is On Track for Launch (09 Jun 2016)
    On June 8th, NICER arrived at Kennedy Space Center. The launch for NICER onboard a SpaceX Dragon cargo spacecraft is currently set for February 2017. NICER will deploy as an external attached payload on the ISS ExPRESS Logistics Carrier 2.