Hisaki, also known as the Spectroscopic Planet Observatory for Recognition of Interaction of Atmosphere (SPRINT-A) was a Japanese ultraviolet astronomy satellite operated by the

Japan Aerospace Exploration Agency The is the Japanese national Aeronautics, air and space agency. Through the merger of three previously independent organizations, JAXA was formed on 1 October 2003. JAXA is responsible for research, technology development and launch of satell ...

(JAXA). The first mission of the Small Scientific Satellite program, it was launched in September 2013 on the maiden flight of the

Epsilon Epsilon (, ; uppercase , lowercase or ; ) is the fifth letter of the Greek alphabet, corresponding phonetically to a mid front unrounded vowel or . In the system of Greek numerals it also has the value five. It was derived from the Phoenic ...

rocket. It was used for

extreme ultraviolet Extreme ultraviolet radiation (EUV or XUV) or high-energy ultraviolet radiation is electromagnetic radiation in the part of the electromagnetic spectrum spanning wavelengths shorter than the hydrogen Lyman-alpha line from 121 nm down to ...

observations of the Solar System planets. Hisaki was decommissioned by deactivation on 8 December 2023.

Launch and naming

Hisaki was launched with an

rocket, which was its first flight. The four-stage Epsilon rocket flew from the Mu rocket launch complex at the Uchinoura Space Center. The launch occurred at 05:00 UTC on 14 September 2013, following a scrubbed launch attempt on 27 August 2013. Following its successful insertion into orbit and deployment of its solar arrays, the satellite was renamed ''Hisaki'', having been designated SPRINT-A until that point. Hisaki was named after a cape used by local fishermen to pray for safe travels in the eastern part of

Kimotsuki, Kagoshima 270px, Kimotsuki Town Hall 270px, Kimotsuki River 270px, '' Yabusame'' in Kimitsuki is a town in Kimotsuki District. , the town had an estimated population of 13,766 in 7503 households, and a population density of 45 persons per km2. The tot ...

near the Uchinoura Space Center, but has the additional meaning of "beyond the Sun". An old name for the mission was EXCEED (Extreme Ultraviolet Spectroscope for Exospheric Dynamics).

Observations

Hisaki carries an

spectrometer A spectrometer () is a scientific instrument used to separate and measure Spectrum, spectral components of a physical phenomenon. Spectrometer is a broad term often used to describe instruments that measure a continuous variable of a phenomeno ...

, which is used to study the composition of the

atmosphere An atmosphere () is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosph ...

s and the behavior of the

magnetosphere In astronomy and planetary science, a magnetosphere is a region of space surrounding an astronomical object in which charged particles are affected by that object's magnetic field. It is created by a celestial body with an active interior Dynamo ...

s of the planets of the Solar System. Designed for a one-year mission, Hisaki was operated in a

low Earth orbit A low Earth orbit (LEO) is an geocentric orbit, orbit around Earth with a orbital period, period of 128 minutes or less (making at least 11.25 orbits per day) and an orbital eccentricity, eccentricity less than 0.25. Most of the artificial object ...

with a

perigee An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. The line of apsides (also called apse line, or major axis of the orbit) is the line connecting the two extreme values. Apsides perta ...

of , an

apogee An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. The line of apsides (also called apse line, or major axis of the orbit) is the line connecting the two extreme values. Apsides perta ...

of , 31 degrees of

inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Eart ...

and a period of 106 minutes. In 2016, Hisaki recorded dust storms on Mars altering the upper atmosphere. In October 2020, it performed joint observation with the BepiColombo probe which performed a flyby of Venus en route to Mercury. In 2023, Hisaki performed joint observations with ''Juno'' orbiter. It was decommissioned on 8 December 2023 due to accuracy issues.

References

{{2013space Spacecraft launched in 2013 2013 in Japan Satellites of Japan Extreme ultraviolet telescopes Satellites orbiting Earth Spacecraft decommissioned in 2023