 NICER telescope mounted on theIntegrated Truss Structure of theInternational Space Station | |
| Mission type | Neutron starastrophysics |
|---|---|
| Operator | NASA / GSFC / MIT |
| Website | https://heasarc.gsfc.nasa.gov/docs/nicer/ |
| Mission duration | 18 months (planned) 8 years, 8 months and 8 days (in progress) |
| Spacecraft properties | |
| Launch mass | 372 kg (820 lb)[1] |
| Start of mission | |
| Launch date | 3 June 2017, 21:07:38UTC[2] |
| Rocket | Falcon 9 Full Thrust,B1035.1 |
| Launch site | Kennedy Space Center,LC-39A |
| Contractor | SpaceX |
| Orbital parameters | |
| Reference system | Geocentric orbit |
| Regime | Low Earth orbit |
| Perigee altitude | 402 km (250 mi) |
| Apogee altitude | 407 km (253 mi) |
| Inclination | 51.64° |
| Period | 92.66 minutes |
| Instruments | |
| X-ray Timing Instrument (XTI) | |
 NICER * SEXTANT mission patch Explorer program | |
TheNeutron Star Interior Composition Explorer (NICER) is aNASA telescope on theInternational Space Station, designed and dedicated to the study of the extraordinary gravitational, electromagnetic, and nuclear physics environments embodied byneutron stars, exploring the exotic states of matter where density and pressure are higher than inatomic nuclei. As part of NASA'sExplorer program,NICER enabled rotation-resolvedspectroscopy of the thermal and non-thermal emissions of neutron stars in thesoft X-ray (0.2–12keV) band with unprecedented sensitivity, probing interior structure, the origins of dynamic phenomena, and the mechanisms that underlie the most powerful cosmic particle accelerators known.[3]NICER achieved these goals by deploying, following the launch, and activation ofX-ray timing and spectroscopy instruments.NICER was selected by NASA to proceed to formulation phase in April 2013.[4]
NICER-SEXTANT uses the same instrument to test X-ray timing for positioning and navigation,[5] and MXS is a test of X-ray timing communication.[6] In January 2018, X-ray navigation was demonstrated using NICER on ISS.[7]
In May 2023, NICER's thermal shields developed a leak that allowed stray light to enter the telescope. A repair kit containing specialized patches was delivered to the station by theCygnus NG-21 resupply mission in August 2024,[8] and were applied byNick Hague in a January 16, 2025spacewalk.[9]
The NICER team suspended science observations on June 17, 2025 due to an issue with the motor used to point the telescope.[10]
By May 2015, NICER was on track for a 2016 launch, having passed itscritical design review (CDR) and resolved an issue with the power being supplied by the ISS.[11] Following the loss ofSpaceX CRS-7 in June 2015, which delayed future missions by several months, NICER was finally launched on 3 June 2017,[2] with theSpaceX CRS-11 ISS resupply mission aboard aFalcon 9 v1.2 launch vehicle.[12]
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. AGlobal Positioning System (GPS) receiver enables accurate timing and positioning measurements. X-ray photons can be time-tagged with a precision of less than 300 ns.[13] In August 2022 a fast X-ray follow-up observation program was started with theMAXI instrument named "OHMAN (On-orbit Hookup of MAXI and NICER)" to detect sudden bursts in X-ray phenomena.[14]
During each ISS orbit, NICER will observe two to four targets. Gimbaling and astar 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.[15]
An enhancement to theNICER mission, theStation Explorer for X-ray Timing and Navigation Technology (SEXTANT), will act as a technology demonstrator forX-ray pulsar-based navigation (XNAV) techniques that may one day be used for deep-space navigation.[16]
 | This section needs to beupdated. Please help update this article to reflect recent events or newly available information.(February 2020) |
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.[6] As of February 2019[update] the XCOM test is scheduled for spring 2019.[17] XCOM (inc MXS) was delivered to the ISS in May 2019.[18] Once the test was complete XCOM and the STP-H6 payload malfunctioned in September 2021. It was removed in November 2021 and disposed of onCygnus NG-16.[19]
In May 2018, NICER discovered anX-ray pulsar in the fastest stellar orbit yet discovered.[20] The pulsar and its companion star were found to orbit each other every 38 minutes.[20]
On 21 August 2019 (UTC; 20 August in the U.S.), NICER spotted the brightest X-ray burst so far observed.[21] It came from the neutron starSAX J1808.4−3658 about 11,000 light-years from Earth in theconstellationSagittarius.
Astronomers using NICER found evidence that a neutron star from alow-mass X-ray binary inNGC 6624 is spinning at 716Hz (times per second), or 42,960revolutions per minute, the same velocity as the fastest known spinning neutron starPSR J1748−2446ad and the only one in such a binary system.[22][23]
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This article incorporates text from this source, which is in thepublic domain. This article incorporates text from this source, which is in thepublic domain.Previously scheduled for a December 2016 launch on SpaceX CRS-12, NICER will now fly to the International Space Station with two other payloads on SpaceX Commercial Resupply Services (CRS)-11, in the Dragon vehicle's unpressurized Trunk.
This article incorporates text from this source, which is in thepublic domain.Each photon detected by NICER is time-tagged with an absolute precision of much better than 300 nanoseconds
This article incorporates text from this source, which is in thepublic domain. This article incorporates text from this source, which is in thepublic domain. This article incorporates text from this source, which is in thepublic domain.
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