Tech Briefs Magazine - March 2023 - 37

Robotics & Automation
Lunar Surface Navigation System
Reverse-ephemeris approach enables low-cost lunar navigation solution.
Langley Research Center, Hampton, VA
S
cientists at NASA's Langley Research
Center have developed a novel concept
for a lunar navigation system based on the
reverse-ephemeris technique. Typically,
range-related signal measurements from
the Earth's surface are used to locate and
track orbital objects (satellites) and establish
the ephemeris describing their orbits.
For this reverse-ephemeris lunar navigation
concept, the process is reversed to give lunar
surface position fixes using the known
ephemeris of a satellite in lunar orbit.
In conventional GPS navigation systems,
the GPS satellite transmits ephemeris
data to a receiver on Earth for determining
position at the receiver location.
For the reverse-ephemeris approach, the
receiver becomes the transmitter, and the
satellite instead serves more as a fixed reference
position with a known ephemeris.
This simplifies the satellite requirements
and mitigates potential navigational disruptions
that can otherwise arise in navigation
systems that utilize satellite-based
communications, for example, from interference,
jamming, etc.
The design consists of lunar surface
S-Band (2,400 2,450 MHz) 10 W transceivers
ranging with analog translating transponders
on a three-satellite constellation
in frozen elliptical orbits to provide continuous
coverage with service to 300 simultaneous
users over 1.8 MHz of bandwidth at
the transponder. Digital bases systems are
possible too. As compared to GPS-based
navigation requiring four or more satellites
costing hundreds of millions of dollars,
the new NASA concept is based on
using only three smallsats.
Reverse-ephemeris navigation uses range and range rate measurement to obtain lunar surface position
fixes and navigation using a known ephemeris of an orbiting object or satellite. (Image: NASA)
Only a few inexpensive smallsats are
required to implement a lunar navigation
system based on this concept. Lunar
navigation systems will be needed for
future Moon missions, including, for example,
for rover navigation, mining operations,
exploration, etc. The inventors
have conducted analytical simulations to
demonstrate the versatility of this innovation
when used to support route determination
for various autonomous or
manned lunar surface operations.
NASA is actively seeking licensees to
commercialize this technology. Please
contact Licensing Concierge at AgencyPatent-Licensing@mail.nasa.gov
or call
at 202-358-7432 to initiate licensing discussions.
For more information, visit
https://technology.nasa.gov/patent/
LAR-TOPS-361.
Electronic Skin Sensor Decodes Human Motion
This system can track the motion of the entire body with a small sensory network.
Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
A
powered, single-strained
electronic
skin sensor was developed that can
capture human motion from a distance.
The strain sensor, placed on the wrist, decodes
complex five-finger motions in real
time with a virtual 3D hand that mirrors the
original motions. The deep neural network
boosted by rapid situation learning (RSL)
ensures stable operation regardless of its
position on the surface of the skin.
Conventional approaches require multiple
sensor networks that cover the entire
curvilinear surfaces of the target area.
Tech Briefs, March 2023
Topographical
change
Epicentral
motion
Sensor
Signal
Skin-like
sensor
Skin
The sensor collecting epicentral motion. (Image: KAIST)
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37

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Tech Briefs Magazine - March 2023

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