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Space Topics: MESSENGER

MESSENGER's Science Instruments

Diagram of MESSENGER's science instruments
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MESSENGER's science instruments
Credit: NASA / JHUAPL

MESSENGER carries seven science instruments, which will work together to perform the first complete reconnaissance of Mercury’s geochemistry, geophysics, geologic history, atmosphere, magnetosphere, and plasma environment.

Mercury Dual Imaging System (MDIS) consists of two cameras, one wide-angle for color imaging, and one narrow-angle for high-resolution monochrome imaging. The cameras are on a platform that can pivot independently of the position of the spacecraft, in order to allow the spacecraft to maintain its sunshade pointed at the Sun.  The wide-angle camera has 12 filters covering wavelengths of light from 395 to 1,040 nanometers (ultraviolet through visible to near-infrared light).  The narrow-angle camera will obtain images with resolutions as small as 18 meters per pixel.

Gamma-Ray and Neutron Spectrometer (GRNS) will map the elemental makeup of Mercury's crust.  This instrument must be kept at a frigid -183 degrees Celsius (-298 degrees Fahrenheit) in an environment where the Sun is as much as 11 times brighter than it is at Earth.  GRNS will be able to map the abundances of hydrogen, magnesium, silicon, oxygen, iron, titanium, sodium, and calcium.

X-Ray Spectrometer (XRS) will also map elemental abundances in crustal materials by observing how they fluoresce when solar X-rays hit them.  XRS has one detector pointed at the Sun to measure the flux of X-rays reaching Mercury, and three detectors pointed at Mercury to watch the response.  XRS is sensitive to magnesium, aluminum, silicon, sulfur, calcium, titanium, and iron.

The Earth and Moon as seen by MESSENGER
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Earth and the Moon as seen by MESSENGER
This image was cropped from the MESSENGER Dual Imaging System (MDIS) full frame of the Earth and Moon captured on May 11, 2005. MESSENGER was about 29.6 million kilometers (18.4 million miles) from Earth at the time that the photo was taken, approaching its August 2 flyby.Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

Magnetometer (MAG) will map the detailed structure and dynamics of Mercury's magnetic field and search for regions of magnetized crustal rocks.  Because the electronics within MESSENGER also generate magnetic fields, the MAG detector is separated from the body of the spacecraft on a 3.6-meter (12-foot) boom.

Mercury Laser Altimeter (MLA) will map Mercury’s topography by transmitting pulses of laser light off the planet and measuring the delay until the echo is returned.  Pulses are broadcast 8 times per second.  MLA can operate only for a small segment of each orbit, when the spacecraft is within 1,000 kilometers (620 miles) of the surface of Mercury.

Mercury Atmospheric and Surface Composition Spectrometer (MASCS) is two instruments in one.  The Ultraviolet Visible Spectrometer (UVVS) will stare across the edge of the Mercurian disk, studying the composition and structure of the exosphere (low-density atmosphere).  The Visible-Infrared Spectrograph (VIRS) will capture detailed spectral information of points across the Mercurian surface, studying the detailed composition and abundance of iron- and titanium-bearing minerals common in Mercury’s basaltic rocks.

Energetic Particle and Plasma Spectrometer (EPPS) will measure the makeup and characteristics of charged particles within and around Mercury's magnetospher