Inertial Stellar Compass

{{Infobox spacecraft instrument|Name=Inertial Stellar Compass|Function=Advanced spacecraft navigation system for attitude determination and orientation recovery|Mass=2.5 kg|Power_consumption=3.5 W}}{{Short description|Spacecraft navigation system}}

Inertial Stellar Compass (ISC) was a proposed{{Cite web |title=Inertial Stellar Compass |url=https://www.jpl.nasa.gov/missions/inertial-stellar-compass/ |access-date=2024-11-25 |website=NASA Jet Propulsion Laboratory (JPL) |language=en-US}} instrument for an advanced navigation system designed to allow spacecraft to operate more autonomously by enabling precise attitude determination with an accuracy of better than 0.1 degrees across all three axes.{{Cite book |last1=Brady |first1=T. |last2=Buckley |first2=S. |last3=Tillier |first3=C. |chapter=Ground validation of the inertial stellar compass |date=2004 |title=2004 IEEE Aerospace Conference Proceedings (IEEE Cat. No.04TH8720) |chapter-url=https://ieeexplore.ieee.org/document/1367607 |publisher=IEEE |pages=214–226 |doi=10.1109/AERO.2004.1367607 |isbn=978-0-7803-8155-1}} It also provides the capability to recover orientation after a power loss.{{Cite web |title=ST6 - NASA Science |url=https://science.nasa.gov/mission/space-technology-6 |access-date=2024-11-25 |website=science.nasa.gov |language=en-US}}

The ISC is small in size and consumes low power to operate. The ISC was developed by NASA as part of New Millennium program's Space Technology 6 project in collaboration with Charles Stark Draper Laboratory.{{cite journal |date=2002 |title=The Inertial Stellar Compass: A New Direction in Spacecraft Attitude Determination |url=https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1899&context=smallsat |format=PDF|journal=16th Annual USU Conference on Small Satellites |access-date=November 6, 2022 }}{{cite web |url=https://www.jpl.nasa.gov/missions/inertial-stellar-compass/ |title=Inertial Stellar Compass |author= |date= |publisher=Jet Propulsion Laboratory |access-date= 7 January 2018 }}

The instrument functions with a combination of a miniaturized star tracker and gyroscopes. It uses a wide field-of-view active pixel star camera and a micro electromechanical system to determine the real-time stellar attitude (orientation) of the spacecraft. It has a mass of {{cvt|2.5|kg}} and requires 3.5 W power.

In 2007, it was successfully deployed and fully operational in space aboard the TacSat-2 spacecraft.{{Cite web |date=2007-01-06 |title=Draper Lab inertial stellar compass in first space flight |url=https://www.militaryaerospace.com/home/article/16724795/draper-lab-inertial-stellar-compass-in-first-space-flight |access-date=2024-11-25 |website=Military Aerospace |language=en}}

As the New Millennium Program had its budget cancelled in 2009,{{Cite web |author1=Nola Taylor Tillman |date=2019-02-12 |title=NASA's New Millennium Program: Taking Risks to Reduce Future Danger |url=https://www.space.com/new-millennium-program.html |access-date=2024-11-25 |website=Space.com |language=en}} it is unclear whether development of this instrument is ongoing.