The Misasa Deep Space Station ("MDSS"), located in Nagano Prefecture is a facility that communicates with deep-space (at a distance of more than two million kilometers from Earth) spacecrafts launched by JAXA and overseas space agencies. Facilities and functions have been added to MDSS to improve its reliability and operability. Integration testing was also started to verify these functions. We asked YUCHI Koji, who coordinates all such testing, for further details.

“We have been developing a redundant system at MDSS since 2021. A redundant system is one that does not suffer from failures that occur in parts of MDSS prone to failures or where failures could cause major disruptions to a spacecraft mission. The manufacturers involved completed installation in May 2023, and JAXA has been conducting integration tests since June 2023 to verify whether the added equipment and functions are consistent with the overall system.”

One such test was conducted on July 19, 2023 to receive data from the Mercury Planetary Orbiter (MPO).

“MPO is an ESA (European Space Agency) spacecraft designed to explore Mercury. MPO communicates with antennas at MDSS and other stations in addition to ESA's own antennas to exchange a variety of information while navigating through space. The radio frequencies used for this communication are the X-band (8 GHz band) and the Ka-band (32 GHz band). We sought to receive both X-band and Ka-band signals simultaneously in this test, and JAXA's antenna successfully did so for the first time.”

The X-band and Ka-band frequencies are also used by the Hayabusa2 Asteroid Explorer and the Martian Moons eXploration (MMX) spacecraft currently under development. The ability to receive signals on both frequencies at the same time will thus be very important for future deep space exploration.

“lThe Ka-band is a frequency that allows spacecraft to transmit about 2.5 times more data than the X-band, and the ability to receive two types of radio waves simultaneously will enable speedy exchanges of such as detailed observation data and high-resolution images etc., leading to more fruitful spacecraft missions.”

Finally, when asked about his enthusiasm regarding the future development and maintenance of the redundant system, Yuchi replied, “Once the integration tests are done, we will enter a trial operation phase that simulates actual spacecraft operations, including the operational system. Many things will come up during the tests, and we will deal with them one by one.”