FOR CENTURIES, astronomers gazed from afar at the planets, moons, comets, and asteroids and could only speculate about
their physical nature. Looking through telescope eyepieces, anyone could see that other planets had atmospheres. But atmospheres
made of what? How hot and dense were they? How fast did their winds blow? And how did the atmospheres change
over the seasons?
Astronomers eventually found a way to study planetary atmospheres from Earth: spectroscopy. Light is collected by a telescope and split into its component
wavelengths, or spectrum, much as a toy prism spreads sunlight into a rainbow. Patterns in the spectrum reveal detailed information
about the temperature, composition, and motions of atmospheres millions to billions of miles away.
Infrared Heterodyne Spectroscopy at Goddard
A team of scientists at NASA's Goddard Space Flight Center in Greenbelt, MD, probes planetary atmospheres using a technique
called infrared heterodyne spectroscopy (IRHS). This technique is at the heart of a device called the NASA/Goddard Heterodyne
Instrument for Planetary Wind and
Composition, or HIPWAC.
The powerful HIPWAC instrument operates at observatories such as the NASA Infrared
Telescope Facility and the National Astronomical Observatory of Japan Subaru Telescope
on the summit of Mauna Kea, Hawaii. HIPWAC has made valuable observations of a variety of solar system bodies, including Mars,
Jupiter, Saturn, Titan, Neptune, and Venus.
This web site explains the IRHS technique, the HIPWAC instrument, and what they are revealing about the solar system.
It also provides information for researchers interested in pursuing collaborative research with the NASA/Goddard HIPWAC team.
Observatories operating at the summit of Mauna Kea include, pictured here from left to right, the Subaru Telescope,
the twin Keck telescopes, and the NASA Infrared Telescope Facility. HIPWAC has operated at both the Subaru and IRTF facilities.
Credit: Kelly E. Fast
The Heterodyne Instrument for Planetary Wind and Composition (HIPWAC) project is part of the Planetary Systems Laboratory (Code 693) in the Solar System Exploration Division (Code 690) at
NASA's Goddard Space Flight Center in Greenbelt, Maryland.