GATS was granted a patent for a technique that can be used to determine refraction using two celestial light sources.  Various methods, both passive and active, can be used to capture an image of the two sources as the line-of-sight vertically transverses though a refractive portion of the atmosphere.  Each image sample provides the apparent angular distance between the two light sources.  This angular separation as a function of time can be used to determine refraction angle profiles.  The technique is unaffected by sensor platform motion and does not require knowledge of atmospheric extinction (absorbing gases, etc.).  This system has a range of applications including the use of satellites to obtain precise refraction angle measurements on a global scale.  These profiles can be used in deriving/retrieving atmospheric temperature and pressure profiles.

This technique is protected under patent #: US 7,265,820 B1

Successful launch of the AIM Satellite! The AIM spacecraft was inserted perfectly into low-Earth orbit by a Pegasus-XL rocket, dropped from an L-1011 aircraft out of Vandenberg AFB. Checkout procedures are underway and all systems appear nominal. Science measurements will commence in two weeks. GATS designed and operates the SOFIE instrument, and will process and analyze the important science data from this experiment.

View the NASA AIM Press Kit

GATS patents include a calibration technique for infrared sensors that provides for long-term calibration of response (signal/radiance) without the need for an onboard reference source.  Infrared sensing devises such as orbiting instruments must be calibrated throughout their mission lifetime to permit the determination of critical long-term trends in the quantities that they measure.  Typically, an onboard calibrated reference emission source must be used along with special optical viewing paths; this source must exhibit long-term stability from the time that it is built, through launch, and on through a long term mission.  GATS has developed a technique to calibrate certain types of these instruments without the need for such an onboard reference.

The basic requirement for this technique is that the device be in orbit about a celestial body (for example, the earth, mars, etc.) having an atmosphere and a known gravitational field.  The device must view the limb region of the atmosphere with a plurality of spectral bandpass regions.  The radiance emissions in each bandpass are due primarily to the gases in the atmosphere limb region.  These gases must have a known mixing ratios as a function of atmospheric pressure, cause spectral opacity to be different in each bandpass, and, for at least one bandpass, the spectral opacity must be non-linearly proportional to the concentrations of the gases in the atmosphere limb region over some portion of the signal profile.  The temperature/pressure profile is first determined using a differential technique that is insensitive to calibration constant errors.  This temperature profile is then indicative of the absolute radiance emission from the limb and can be used as a calibrated external source for calibrating the instrument response.

In summary, this technique permits accurate calibration without the need for any onboard reference and without the need for the time or equipment required to develop and install the reference in the instrument.  There are no requirements for the instrument to look in special viewing configurations and the calibration can be done during the instrument’s normal viewing.

This technique is protected under patent #: US 6,294,785  B1