HORIBA Jobin Yvon Grating Helps NASA Discover Icy Mountains on Pluto

27. August 2015

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/ Southwest Research Institute

On July 14, 2015, the NEW HORIZONS probe flew over and sent pictures of the planet Pluto, and its satellite Charon, revealing information about their geology, their surface and atmosphere. Pictures of mountains show this geological activity occurred less than 100 million years ago. Areas of carbon monoxide ice, methane, nitrogen were detected. The Pluto's atmosphere consists mainly of nitrogen. However, Pluto’s small mass allows hundreds of tons of atmospheric nitrogen to escape into space each hour leading scientists to try to answer this question:  Where does all the nitrogen come from? 

The New Horizons probe is equipped with seven scientific instruments: three optical instruments, including the ALICE spectrograph, two plasma detectors, a solar wind sensor and a radiometer. The probe was launched January 19, 2006, from Florida and on July 14 was close to the dwarf planet.

The spectrograph ALICE works in the ultraviolet (500.1800 Å) range, and is equipped with a HORIBA Jobin Yvon  diffraction grating. Alice is a light spectrograph (4.5 kilograms) of low power (4.4 watts) developed by SWRI (Southwest Research institute) for the study of the atmosphere: determination of atomic and molecular compounds and their relative abundances.
The key optical component of the ALICE instrument is the toroidal holographic replica diffraction grating manufactured by HORIBA Jobin Yvon in 2005. The development of this grating batch was the result of a fruitful collaboration between the Southwest Research Institute in the US, and HORIBA Jobin Yvon’s team.

The ALICE diffraction grating, with a groove density of 1600 gr/mm, made on a metallic material substrate to minimize the weight, was optimized to work in a Rowland Circle type imaging spectrograph. Thanks to the holographic recording and space-qualified (TRL 9) replication process, the ALICE grating exhibited low stray light and no ghost. The active grating area is 35 mm in the dispersion direction by 20 mm in the spatial dimension. The spectrograph uses the first diffraction order through the full spectral bandpass 70 nm – 205 nm. The spectral resolution was measured between 0.98 and 1.25 nm with a spectral resolving power of 55-200.

The ALICE spectrometer is the same spectrometer type of the one used in Rosetta, from the European Space Agency, which is flying around the 67P/Churyumov-Gerasimenko comet.
After 10 years of life, and more than 9 years of operation in space during the NEW HORIZONS journey, the ALICE holographic replica grating has maintained its initial high performance and continues to bring extraordinary discoveries  to the scientific community.

For more information please visit http://pluto.jhuapl.edu/ or http://www.swri.org/
For more information please visit http://www.swri.org/press/2005/alice.htm

HORIBA Jobin Yvon S.A.S. company, part of HORIBA Scientific (HORIBA Group), is a world leading supplier of spectroscopic and, analytical instruments and diffractive optics for research and industry.
HORIBA Jobin Yvon designs, manufactures and tests a large range of scientific diffraction gratings for Lasers, space flight and Synchrotron applications. HORIBA Jobin Yvon has been selected and has participated in a large number of NASA or ESA space-flight missions due to its long-standing reputation in developing very high performance diffraction gratings for spectrographs.