MESSENGER Goes to Mercury with NIST Calibrated Instrument

Aug 15, 2004

The first spacecraft intended to orbit Mercury was launched on Aug. 3, 2004, carrying an instrument for mapping the composition of the planet's crust that was calibrated with a novel procedure at the National Institute of Standards and Technology (NIST). The procedure, using NIST-produced, high-energy gamma rays, enabled the device to be prepared for the same intense radiation levels typically produced in outer space.

Mercury is a rocky planet like the Earth but smaller, denser and with an older surface. Scientists believe that by studying Mercury they can develop a better understanding of how the Earth formed, evolved and interacts with the Sun.

Scheduled to orbit Mercury in 2011, the National Aeronautics and Space Administration's (NASA) MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft carries seven scientific instruments, including a detector that will measure gamma rays emitted by Mercury's crust as it is bombarded by cosmic rays. The bombardment releases neutrons, which react with the elements in the crust; analysis of the resulting gamma rays will help identify the elements. The detector's efficiency (the fraction of incoming gamma rays detected) needed to be calibrated based on the gamma-ray energy for 37 different orientation angles associated with the orbits around the planet. Typical gamma ray sources, such as those used for medical treatments, emit at lower energy levels than those needed for the calibration.

NIST scientists, in collaboration with the mission's prime contractor, the Johns Hopkins University Applied Physics Laboratory, solved the calibration problem by using a high-intensity neutron beam to irradiate targets made of sodium chloride and chromium. The targets captured neutrons and emitted gamma rays, which were measured by MESSENGER's gamma-ray detector. These gamma rays spanned the energy range that will be measured in the planetary assay. According to Johns Hopkins' Edgar A. Rhodes -- lead scientist for the MESSENGER instrument --the calibration procedure "will likely set a new standard for space-flight gamma-ray spectrometers."

Source: NIST

Explore further: Dawn spirals closer to Ceres, returns a new view

Related Stories

Recommended for you

Dawn spirals closer to Ceres, returns a new view

10 hours ago

A new view of Ceres, taken by NASA's Dawn spacecraft on May 23, shows finer detail is becoming visible on the dwarf planet. The spacecraft snapped the image at a distance of 3,200 miles (5,100 kilometers) ...

NASA telescopes set limits on space-time quantum 'foam'

16 hours ago

A team of scientists has used X-ray and gamma-ray observations of some of the most distant objects in the universe to better understand the nature of space and time. Their results set limits on the quantum ...

Shining message about the end of the Dark Ages

18 hours ago

An international team, including researchers from the Centre for Astronomy of Heidelberg University (ZAH), has discovered three "cosmic Methusalems" from the earliest years of the universe. These unusual stars are about 13 ...

The kinematics of merging galaxies

19 hours ago

The unprecedented sensitivity of space telescopes has powered a revolution over the past decade in our understanding of galaxies in the young universe during its first billion years of existence. These primitive ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.