Tech Briefs Magazine - February 2022 - 48

SPINOFF
Answering the Call of Distress
A
s companies and other entities continue
making use of NASA know-how,
spinoffs from the space agency are bound
to bump into each other. That's what happened
as the lifesaving Search and Rescue
Satellite Aided Tracking (SARSAT) system
underwent a major expansion over the
past several years.
The U.S. SARSAT system - and its
global counterpart, COSPAS-SARSAT -
detects and locates distress signals from
emergency beacons and has enabled the
rescue of more than 48,000 people worldwide.
In the United States, more than
10,000 people have been saved since the
first satellite transponders and ground stations
went into effect in 1982.
NASA led the system's creation and
remains the research and development
lead, and the National Oceanic and
Atmospheric Administration (NOAA)
manages the ground stations in the United
Spinoff is NASA's annual publication featuring
successfully commercialized NASA technology. This
commercialization has contributed to the development
of products and services in the fields of health and
medicine, consumer goods, transportation, public safety,
computer technology, and environmental resources.
Software created with NASA expertise improves satellite-based search and rescue system.
States. Historically, SARSAT transponders
have piggybacked on both low-Earth orbiting
satellites and much more distant geostationary
satellites. The first can calculate
a beacon's location, while the second can
immediately receive and relay the distress
message but neither can do both well.
Over the past decade, SARSAT repeaters
have also been added to many of the
world's navigational satellites, which operate
in medium-Earth orbit. The Search and
Rescue Office at NASA's Goddard Space
Flight Center in Greenbelt, MD, assessed
the medium-Earth orbit SARSAT platform
and developed and tested the first ground
station to monitor these new transponders.
This led to a network of such stations that
went online in 2018 as part of the system
run by NOAA. It uses multiple simultaneous
signals to immediately triangulate a
beacon's position. This resulted in nearly
instantaneous detection and location, in
some cases lessening the delay from hours
to minutes. NASA and NOAA continue to
improve the ground system.
As the number of these satellites exceed
the number of antennas dedicated to
them on the ground, the ground network
had to make difficult decisions about
which satellites to track at any given
moment. To solve the problem, NOAA
turned to Greenbelt, MD-based Orbit
Since going into effect in the early 1980s, the
SARSAT system and its international counterpart
COSPAS-SARSAT have enabled the rescue of
more than 48,000 people worldwide including
more than 10,000 in the United States. (Photo:
U.S. Air Force/Senior Airman Sean Sweeney)
Logic Inc., which specializes in software for
scheduling and mission planning.
The company's founders built their
expertise in the field at NASA. Alex and
Ella Herz, the company's President and
Chief Operating Officer, respectively,
worked on payload engineering and operations
as contractors at Johnson Space
Center in the late 1980s and early 1990s,
when scheduling was a major challenge
for space shuttle payloads. The third
founder, Orbit Logic Vice President Doug
George, later worked with Alex to build
the scheduling software for the Vegetation
Canopy Lidar satellite at Goddard (a project
that was ultimately canceled).
When the three founded Orbit Logic in
2000, they set out to create a planning and
scheduling tool flexible enough to be
applied to any space, or even nonspace,
mission. Working with two other companies,
including the maker of Systems Tool
Kit (STK), they built STK Scheduler.
Now, STK Scheduler helps SARSAT
ground stations choose which mediumEarth
orbit satellites to track by weighing
priorities against the limited number of
antennas to generate a pointing schedule
that ensures the highest accuracy for
locating distress signals.
Visit https://spinoff.nasa.gov/softwareimproves-SARSAT
Medium-Earth
orbit satellites added to the
SARSAT system over the past decade or so have
dramatically reduced the time it takes to
respond to signals from emergency beacons like
this one. (Photo: U.S. Coast Guard)
48
Cov
Orbit Logic's STK Scheduler software, based in part on the company founders' long experience with NASA
mission planning, helps a limited number of SARSAT antennas choose which medium-Earth orbit satellites
to track at any given time to maximize accuracy for locating distress signals. (Photo: Orbit Logic)
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Tech Briefs, February 2022

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Tech Briefs Magazine - February 2022

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