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: Image: Striking lightning from space

add to favorites email to friend print save as pdf

Related Stories

Astronomical pranks of April fools' past

Apr 01, 2013

The first day of April is always a traditional time for pranks and puns, and astronomers and scientists aren't above an April Fools' Day shenanigan or two. Hey, I gotta admit, as a freelance science journalist, ...

Recommended for you

Image: Striking lightning from space

17 minutes ago

Lightning illuminates the area it strikes on Earth but the flash can be seen from space, too. This image was taken from 400 km above Earth in 2012 by an astronaut on the International Space Station travelling ...

Are asteroids the future of planetary science?

17 minutes ago

I don't think I ever learned one of those little rhymes – My Very Educated Mother Just Served Us Nine Pizzas – to memorize the order of the planets, but if I had, it would've painted for me a minimalist ...

Asteroid flying past Earth today has mini-moon

53 minutes ago

Wonderful news! Asteroid 2004 BL86, which passed closest to Earth today at a distance of 750,000 miles (1.2 million km), has a companion moon. Scientists working with NASA's 230-foot-wide (70-meter) Deep ...

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.