Repairing the NICER Telescope on the International Space Station: Solving the Light Leakage Issue

2024-04-20 07:15:12

This image, taken on June 8, 2018, shows NICER (Neutron Star Interior Composition Explorer) on the International Space Station, where it studies neutron stars and other X-ray sources. NICER is about the size of a washing machine. The sunshades of its X-ray concentrators appear as an array of circular features. Credit: NASA

This time-lapse video, obtained on June 8, 2018, shows the precise choreography of NASA’s Neutron Star Interior Composition Explorer (NICER) as it probes pulsars and other X-ray sources from its on-board station

International Space Station

The International Space Station (ISS) is a large spacecraft in orbit around the Earth that serves as a research laboratory and spaceport for international collaboration in space exploration. It was launched in 1998 and has been continuously occupied by rotating crews of astronauts and cosmonauts from around the world since 2000. The ISS is a joint project of five space agencies: NASA (USA), Roscosmos (Russia), JAXA (Japan), ESA (Europe), and CSA (Canada). It orbits the Earth at an altitude of approximately 400 kilometers (250 miles), and provides a unique platform for scientific research, technological development, and human space exploration.

” data-gt-translate-attributes=”({” attribute=”” tabindex=”0″ role=”link”>International Space Station. NICER observes and monitors many sources every day, from the closest star to the Sun, Proxima Centauri, to X-ray sources in other galaxies. The motion in the film, which represents just over one 90-minute orbit, is sped up 100 times. Credit: NASA

The design and contributions of NICER

NICER is located near the station’s starboard inner solar panels. From this pole, it peers into the X-ray sky, collecting data on many cosmic phenomena, such as regular pulses from dense stellar remnants called neutron stars and “light echoes” from expanding black holes. Observing these objects helps answer questions about their nature and behavior and increases our understanding of matter and gravity. In 2017, NICER also demonstrated the use of pulsating neutron stars in our galaxy to serve as navigation beacons for future deep space exploration through a program called SEXTANT (Station Explorer for X-ray Timing and Navigation Technology).

The telescope has 56 aluminum X-ray concentrators. Each concentrator has a set of nested mirrors, designed to bounce X-rays into a detector. In front of the hub is a thin filter, called a thermal shield, which blocks the sunlight. At the top of the hub is a hollow round piece of carbon composite, called a sunshade, with six sections that resemble a sliced ​​pie. The canopy is designed to keep the concentrations cool in the sunlight and protect the delicate thermal shields. After the light leak developed, the images revealed some small areas of damage to some of the shields, though it’s still unclear what caused them.

The International Space Station appears in this photo taken by the Expedition 56 crew of the Soyuz spacecraft after it lifted off on October 4, 2018. NICER is the small white box that sits above the station’s main truss at the far right, near the inner solar panel. Credit: NASA/Roscosmos

Challenges in the NICER service

“We didn’t design NICER for mission service. It was installed robotically, and we operate it from the ground,” said Keith Gendreau, NICER’s principal investigator at Goddard. “The possibility of repair was an exciting challenge. We considered both solutions for spacewalking and robotic solutions, and debated how to install patches using what already exists in the telescope and space station toolkits.”

After many months of consideration, space walking was chosen as the way forward. The Hubble Space Telescope and NASA’s Solar Maximum Mission, as well as the AMS (Alpha Magnetic Spectrometer, also on the station) are the only scientific observatories repaired by astronauts in orbit.

Remedial strategy and future steps

NICER’s solution is simple. Five pie-shaped wedges will go into the sunshades over the areas with the most damage and lock into place. The patches are designed to utilize an existing piece of astronaut gear, called a T-handle tool.

“While we’ve worked hard to ensure the patches are mechanically simple, most repair operations in space are very complicated,” said Steve Kenyon, NICER’s mechanical lead at Goddard. “We conducted tests to confirm that the repair work would be both an effective fix for the NICER light leak and completely safe for the astronauts on the spacewalk and the space station.”

The repairs are now scheduled to launch to the space station aboard Northrop Grumman’s 21st Commercial Supply Services mission later this year. Astronauts will complete their installation during a spacewalk, along with other tasks.

Collaborative efforts and scientific impact

NICER is an Astrophysics of Opportunity mission under NASA’s Explorers Program that provides frequent flight opportunities for world-class scientific investigations from space using innovative, efficient and effective management approaches in the heliophysical and astrophysical sciences. NASA’s Space Technology Mission Directorate supports the SEXTANT component of the mission, and demonstrates Pulsar based spacecraft navigation.

NICER also automatically cooperates with

JAXA

Formed in 2003, the Japan Aerospace Exploration Agency (JAXA) was born through the merger of three institutions, namely the Institute of Space and Astronautical Science (ISAS), the National Aerospace Laboratory of Japan (NAL) and the National Space Development Agency of Japan (NASDA). JAXA performs various activities related to aerospace, from basic research in the aerospace field to development and utilization and is responsible for research, technology development, and launch of satellites into orbit, and is involved in advanced missions such as asteroid exploration and possible human exploration of the Moon.

” data-gt-translate-attributes=”({” attribute=”” tabindex=”0″ role=”link”>JAXAThe (Japan Aerospace Exploration Agency) MAXI (All-Sky X-ray Image Monitor) experiment to quickly observe stars and other objects that flare up unexpectedly, advancing scientific understanding of our dynamic universe.