Neutron Star Interior Composition Explorer

The Neutron star Interior Composition Explorer (NICER) is a NASA Explorers program Mission of Opportunity dedicated to the study of the extraordinary gravitational, electromagnetic, and nuclear physics environments embodied by neutron stars, exploring the exotic states of matter where density and pressure are higher than in atomic nuclei. 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. NICER will achieve these goals by deploying, following launch, an X-ray timing and spectroscopy instrument as an attached payload aboard the International Space Station (ISS). NICER was selected by NASA to proceed to formulation phase in April 2013. The Neutron star Interior Composition Explorer (NICER) is a NASA Explorers program Mission of Opportunity dedicated to the study of the extraordinary gravitational, electromagnetic, and nuclear physics environments embodied by neutron stars, exploring the exotic states of matter where density and pressure are higher than in atomic nuclei. 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. NICER will achieve these goals by deploying, following launch, an X-ray timing and spectroscopy instrument as an attached payload aboard the International Space Station (ISS). NICER was selected by NASA to proceed to formulation phase in April 2013. NICER-SEXTANT uses the same instrument to test X-ray timing for positioning and navigation, and MXS is a test of X-ray timing communication. In January 2018, X-ray navigation was demonstrated using NICER on ISS. By May 2015, NICER was on track for a 2016 launch, having passed its critical design review and resolved an issue with the power being supplied by the ISS. Following the CRS-7 loss in June 2015, which delayed future missions by several months, NICER was finally launched on 3 June 2017, with the SpaceX CRS-11 ISS resupply mission aboard a Falcon 9 v1.2 rocket. NICER's primary science instrument, called the X-ray Timing Instrument (XTI), is an array of 56 X-ray photon detectors. These detectors record the energies of the collected photons as well as with their time of arrival. A GPS receiver enables accurate timing and positioning measurements. During each ISS orbit, NICER will observe two to four targets. Gimbaling and a star tracker allow NICER to track specific targets while collecting science data. In order to achieve its science objectives, NICER will take over 15 million seconds of exposures over an 18-month period. An enhancement to the NICER mission, the Station Explorer for X-ray Timing and Navigation Technology (SEXTANT), will act as a technology demonstrator for X-ray pulsar-based navigation (XNAV) techniques that may one day be used for deep-space navigation. As part of NICER testing, a rapid-modulation X-ray device was developed called Modulated X-ray Source (MXS), which is being used to create an X-ray communication system (XCOM) demonstration. If approved and installed on the ISS, XCOM will transmit data encoded into X-ray bursts to the NICER platform, which may lead to the development of technologies that allow for gigabit bandwidth communication throughout the Solar System. As of February 2019 the XCOM test is scheduled for spring 2019. In May 2018, NICER discovered a X-ray pulsar in the fastest stellar orbit yet discovered. The pulsar and its companion star were found to orbit each other every 38 minutes.  This article incorporates public domain material from websites or documents of the National Aeronautics and Space Administration.