Hinode (satellite)

Lore & Background

Hinode was launched on the final flight of the M-V rocket from Uchinoura Space Center, Japan, on 22 September 2006 at 21:36 UTC. Its initial orbit had a perigee height of 280 km and apogee height of 686 km, with an inclination of 98.3 degrees, after which it maneuvered to a quasi-circular Sun-synchronous orbit over the day/night terminator, enabling near-continuous observation of the Sun. On 28 October 2006, the probe's instruments captured their first images.

The mission carries three main instruments. The Solar Optical Telescope (SOT) is a 0.5-meter Gregorian optical telescope with an angular resolution of about 0.2 arcsecond, featuring a Focal Plane Package built by Lockheed Martin that includes a Broadband Filter Imager, Narrowband Filter Imager, and Spectropolarimeter. The X-Ray Telescope (XRT) is a modified Wolter I design using grazing incidence optics to image the solar corona's hottest components (0.5 to 10 million K), designed by the Smithsonian Astrophysical Observatory. The Extreme-Ultraviolet Imaging Spectrometer (EIS) obtains spatially resolved spectra in two wavelength bands (17.0–21.2 nm and 24.6–29.2 nm) to identify processes involved in heating the solar corona.

Reader's Guide

Hinode represents a significant advancement in solar physics, providing a factor of five improvement in spatial resolution over previous space-based solar telescopes like the MDI instrument on SOHO. Its coordinated set of optical, EUV, and X-ray instruments allows simultaneous observation of the Sun's photosphere, chromosphere, and corona, enabling scientists to study the mechanisms that power the solar atmosphere and drive solar eruptions. The mission's data are downloaded to the Norwegian Svalsat station on Svalbard and transmitted via fiber-optic network to users in North America, Europe, and Japan. Originally planned as a three-year mission, Hinode's operations have been extended and, as of March 2024, are planned to continue until 2033, underscoring its enduring value for understanding solar magnetic fields and coronal heating.

Did You Know?

• The EUV Imaging Spectrometer (EIS) was built by a consortium led by the Mullard Space Science Laboratory in the UK.
• Data from Hinode are downloaded to the Svalsat station in Svalbard, Norway.

Mission Purpose & Scientific Ambitions

Hinode, originally designated Solar-B, was conceived as a three-year Japanese solar observatory tasked with unraveling the complex relationship between the Sun's magnetic field and its outer atmosphere. As the successor to the Yohkoh (Solar-A) mission, it was designed to deploy a coordinated suite of optical, extreme ultraviolet, and x-ray instruments that work in concert to probe how magnetic energy is stored, released, and transformed within the solar corona. The overarching scientific goal was to build a deeper mechanistic understanding of what powers the solar atmosphere and what triggers the violent eruptions it produces. Although the mission was initially scoped for three years, its operational success has been remarkable: as of March 2024, the spacecraft's operations are still planned to continue through 2033, far exceeding its original design life. This extended longevity has allowed the international science community to accumulate a vast and unprecedented dataset on solar magnetic phenomena, making Hinode one of the most productive solar observatories ever to reach orbit.

A Triad of Cutting-Edge Instruments

The spacecraft carries three principal instruments, each targeting a different wavelength regime to build a complete picture of solar physics. The Solar Optical Telescope is a half-meter Gregorian design delivering roughly 0.2 arcsecond angular resolution across a 400-by-400 arcsecond field, a fivefold improvement over earlier space-based solar telescopes such as SOHO's MDI. At its focal plane, the Focal Plane Package houses a Broadband Filter Imager for photospheric and chromospheric imaging, a Narrowband Filter Imager for magnetogram and dopplergram production, and a Spectropolarimeter that generates the most sensitive vector magnetograph maps of the photosphere achieved to date. The X-ray Telescope, a modified Wolter I grazing-incidence design, images the corona's hottest plasma between 0.5 and 10 million kelvin with one-arcsecond pixel resolution across a 34-arcminute field. The Extreme-Ultraviolet Imaging Spectrometer captures spatially resolved spectra in two bands spanning 17.0 to 21.2 and 24.6 to 29.2 nanometers, probing emission from temperatures as low as 50,000 kelvin up to 20 million kelvin to identify the physical processes responsible for coronal heating.

A Three-Nation Engineering Partnership

Hinode is a prime example of deep multinational aerospace collaboration. The mission is led by Japan's Aerospace Exploration Agency, but critical instrument components were developed across the Atlantic. NASA contributed the Focal Plane Package, the X-ray Telescope, and a component of the Extreme-Ultraviolet Imaging Spectrometer, while also sharing operational responsibilities for science planning and instrument command generation. The EIS itself was built by a consortium led by the Mullard Space Science Laboratory in the United Kingdom. The X-ray Telescope was designed and constructed by the Smithsonian Astrophysical Observatory, part of the Harvard-Smithsonian Center for Astrophysics, with the camera developed jointly by the National Astronomical Observatory of Japan and JAXA. The Focal Plane Package originated at the Lockheed Martin Solar and Astrophysics Laboratory in Palo Alto, California. This distribution of engineering expertise across three nations meant that no single agency bore the full technical risk, and the resulting instrument suite benefits from the distinct strengths each partner brought to the table.

From Uchinoura to Svalbard: Launch and Data Flow

Hinode reached space on the very last flight of Japan's M-V launch vehicle, lifting off from Uchinoura Space Center on 22 September 2006 at 21:36 UTC. Its initial elliptical orbit had a perigee of 280 kilometers and an apogee of 686 kilometers at a 98.3-degree inclination. The satellite then performed a series of maneuvers to settle into a quasi-circular Sun-synchronous orbit positioned over the day-night terminator, a geometry that grants it near-continuous visibility of the solar disk. Just over a month after launch, on 28 October 2006, the onboard instruments recorded their first images. On the ground, the data downlink chain is equally remarkable: signals are received at the Svalsat terrestrial station, a few kilometers west of Longyearbyen in the Svalbard archipelago, operated by Kongsberg. From there, Telenor carries the data via a fibre-optic backbone to Harstad on mainland Norway, and onward to science users in North America, Europe, and Japan.