A Spacecraft That Goes to Find Retired Satellites

Japanese space-sustainability company Astroscale has unveiled plans for a 2027 mission that would be the world's first to inspect multiple defunct satellites in different orbits within a single flight. Named In-situ Space Situational Awareness-Japan 1 (ISSA-J1), the mission will conduct close-up inspections of two retired Japanese satellites using a single spacecraft.

Weighing approximately 650 kg, ISSA-J1 will be equipped with multiple thrusters and precision imaging systems to perform rendezvous and proximity operations, gather detailed visual data on target satellites, and help determine the causes of their failures.

Why This Mission Matters

Assessing the condition of defunct satellites from the ground has significant limitations. "On-orbit inspection provides critical insight into the condition of satellites that cannot be obtained from the ground," said Nobu Okada, managing director of Astroscale Japan. "By inspecting multiple objects in different orbits in a single mission, ISSA-J1 will help demonstrate new capabilities that support satellite operators in understanding spacecraft condition and preparing for future servicing."

Beyond inspection, this technology lays the groundwork for a broader in-orbit servicing industry—including repairs, refueling, and controlled deorbiting. With thousands of inactive satellites and debris fragments currently orbiting Earth, the ability to systematically assess and manage them has become a critical challenge for space traffic safety.

The Two Target Satellites

ISSA-J1's first target is the Advanced Land Observing Satellite (ALOS), launched in 2006. Bus-sized and weighing approximately 4,000 kg, it lost power in 2011 but remains in a near-polar orbit at an average altitude of 691 km.

The second target is the Advanced Earth Observing Satellite-II (ADEOS-II), launched in 2002. Slightly lighter at around 3,700 kg, it orbits at a higher altitude of approximately 806 km. Its mission ended in less than a year due to a solar panel failure.

ISSA-J1 will begin observations of ALOS from a distance before gradually closing in, then transition to a new orbit to repeat the process with ADEOS-II—demonstrating a repeatable cycle of approach, inspection, departure, and orbital transition.

Building on ADRAS-J's Success

ISSA-J1 builds on the success of Astroscale's earlier Active Debris Removal by Astroscale-Japan (ADRAS-J) mission, which captured detailed close-up footage of a spent rocket stage in orbit. The new mission was selected by Japan's Ministry of Education, Culture, Sports, Science and Technology under its Small and Business Innovation Research program, as part of efforts to advance Japan's space situational awareness and in-orbit servicing capabilities.