NASA is planning to repair NICER (Neutron star Interior Composition Explorer), an X-ray telescope on the International Space Station, during a spacewalk later this year. It will be the fourth science observatory in orbit serviced by astronauts. In May 2023, scientists discovered that NICER had devel...
Sounds like the parts for the repair will launch on the Cygnus for NG-21, which will fly on a Falcon instead of Antares since the new Antares 300 isn’t ready yet.