Hinode (SOLAR-B) - Overview

Contents

Introduction

Hinode is using three instruments together to unravel basic information about the Sun. Hinode's Mission: To Measure Solar Magnetic Fields.

Hinode's Overall Goals

• to understand how energy generated by magnetic-field changes in the lower solar atmosphere (photosphere) is transmitted to the upper solar atmosphere (corona),
• to understand how that energy influences the dynamics and structure of that upper atmosphere, and
• to determine how the energy transfer and atmospheric dynamics affects the interplanetary-space environment.

The satellite weighs approximately 700 kg (dry) with some 170 kg of thruster gas for maintaining a polar, sun-synchronous orbit for more than two years. Two solar panels will provide 1000 watts of power.

Hinode is using three instruments (see below) together to help scientists unravel some still unanswered questions about the Sun.
(for specifics, see the NASA Science Library)

Some of the basic questions Hinode seeks to address include:

1. How is energy from magnetic fields near the solar surface (photosphere) transmitted into the corona?

   Scientists have studied the Sun for over 100 years, and although we have learned a lot about the major changes that take place on its surface and upper atmosphere, we still don't have enough information about how various forms of energy move from place to place. One of the most important forms of stored energy is in the magnetic fields which can be concentrated and tangled up. When this energy is released, it can heat local gases to 100s of thousands of degrees or more. Scientists want to know exactly how this stored energy is released, and in what forms it makes its way into the solar corona.

2. How does this energy cause changes in the structure and interactions that take place in the corona?

   The release of magnetic energy is a complex process that involves changing one magnetic field shape into another, like taffy being pulled. Scientists want to know how magnetic fields change their shape in an explosive way to create solar flares, and how these changes alter the solar atmosphere and corona.

3. How do these changes affect the environment of interplanetary space?

   Earth and the planets in our solar system orbit the Sun inside the Sun's outer atmosphere. During solar eclipses we see the brightest part of this atmosphere - the corona. As it moves farther from the sun, this expanding atmosphere becomes more dilute and we call it the solar wind. The entire atmosphere extends beyond the orbit of Pluto and we call it the heliosphere. Scientists want to know how magnetic changes near the surface of the Sun affect the heliosphere. Because Earth interacts with the solar wind and heliosphere, and severe changes in this dilute atmosphere can cause satellite outages and electrical power blackouts, scientists want to know exactly how all of its various parts work together as a system.

Images from Hinode. For a high-resolution (150 dpi) PDF poster explaining Hinode (produced for the Chabot Science Center).  For the back-side of the poster.

Three Major Instruments

To do the necessary research in answering these questions, an international team of dozens of scientists have developed the Hinode satellite and equipped it with three major instruments:

1. Solar Optical Telescope (SOT) – is composed of two main parts: an optical telescope assembly, which holds the mirrors and other optics of the instrument and a focal plane package, which uses polarizing optics to measure magnetic fields in the solar photosphere. The Solar Optical Telescope will obtain measurements of the magnetic field with a spatial resolution of 0.2 arcseconds and will become the first telescope in space to measure the Sun's three-dimensional magnetic field vector.  (More information on the Solar Telescope.)
    
2. Extreme Ultraviolet Imaging Spectrometer – Built by a consortium led by the UK's Mullard Space Science Laboratory (MSSL), the Extreme Ultraviolet Imaging Spectrometer (EIS) has a total length of 3 meters. EIS will obtain high-cadence, monochromatic images of the transition region and corona of the Sun.
    
3. Solar X-Ray Telescope – The High Energy Astrophysics Division of the Smithsonian Astrophysical Observatory is building the Solar X-ray Telescope (SXT) for Solar-B. Similar to the X-ray telescope of Yohkoh, the new SXT will have significant improvements in spatial resolution and temperature response. The focal length of the telescope will be 2.7 meters and when combined with imaging electronics, will yield a resolution of 1.0 arcsec.

Solar Optical and softX-Ray Telescope are joint Japan-US instruments.
EIS is a joint Japan-UK-US instrument.

These instruments will study the detailed way in which magnetic fields and solar gases behave during solar flares.

Click link below right for more information on Hinode (SOLAR-B) »