Draper Awarded Patent for Cross Polarizing Star Tracker

CAMBRIDGE, MA—A new method for navigating without GPS has caught the attention of the U.S. Patent Office and earned its inventors a patent.

The invention, called “Cross Polarizing Star Tracker” uses polarized sensors, rather than imaging optics, resulting in a package that is flat and much lighter than a star tracker with conventional optics.

Now, whenever GPS signals are spotty or altogether 
unavailable, the Cross Polarizing Star Tracker promises an alternate way to navigate—which is good news for aircraft, spacecraft, ships at sea and even ground vehicles. This patent complements a full portfolio of GPS denied navigation techniques being developed at Draper.

Navigating by the stars is an ancient practice that relies on the ability to map the night sky and identify stars by their location and brightness. Conventional star trackers, in use for decades on satellites, pose problems in terms of accuracy and power consumption, according to the patent.

The inventors set out to engineer a different approach. Their Cross Polarizing Star Tracker can be produced in various configurations that do not require power-hungry pixelated imaging sensors. Most importantly, this approach can be fabricated on a thin substrate, enabling vertical profiles of less than a millimeter and eliminating the need for bulky, heavy and mechanically complex optics.

The patent states that “the ideal star tracker would be mechanically, electrically and optically simple, small, low in mass and consume little power.” The approach outlined in this patent makes a giant leap towards the ideal star tracker and GPS denied navigation capabilities.

The inventors include J.P. Laine, Greg Blasche, Murali Chaparala, Robin Dawson, Ben Lane, Erik Waldron and Stephen Smith, who are all moving GPS denied navigation techniques forward at Draper.