Engineering Lunar Network 2.0
Artemis and other moon missions will need high-speed communications
When
Neil Armstrong uttered one of the most famous sentences in human
history, he did so via a microphone in his helmet and a
3-kilogram VHF-band radio in his backpack. The radio linked to a
rig in the lunar lander, which launched microwave signals on a
325,000-kilometer journey to Earth.
That radio was a tech marvel. In a package just 35 by 15 by 3.2
centimeters, its designers fit two AM receivers, two AM
transmitters, either an FM receiver or an FM transmitter, and
also a telemetry system that transmitted spacesuit status and
physiological data about the astronaut. While those specs might
not seem so dazzling today, kindly remember that this radio was
designed (by RCA) in the mid-1960s. The whole thing was done
without integrated circuits, which were available in the
mid-1960s and used extensively elsewhere in the Apollo program
but were still relatively uncommon and expensive.
The astronauts’ backpack radios were just a small piece of a
sprawling communications infrastructure assembled by NASA in the
1960s. For the Apollo missions, during the moon walks, the heart
of the communications system was the rig in the lunar lander,
known as the Lunar Module Communications System. It communicated
not only with the astronauts’ radios but also had microwave
links to the orbiting command module and to Earth, through a
globe-spanning network of more than 30 dish antennas called the
Manned Space Flight Network.
A memorable feature of the Apollo communication system was the
S-band erectable antenna, which was connected to the lunar
module’s radio system. Stowed as a cylinder 25 by 100 cm, it was
unfurled on the moon into a 3-meter-diameter parabolic dish
covered with a very fine, flexible, gold-plated mesh. The
erectable antenna had a transmit gain of 34 decibels, about 12
dB better than the “steerable” antenna mounted on the lander.
The higher gain was needed to accommodate color-TV signals,
along with the voice and data channels. Unfortunately, the first
time the antenna was used, there wasn’t much video to broadcast.
As he was setting up the camera, astronaut Alan Bean
accidentally aimed it at the sun and burned out its image tube.
“Here is the TV,” he said. “And it’s pointing toward the sun.
That’s bad.” After the mishap, NASA equipped future Apollo TV
cameras with a lens cap.
One of the more poignant stories of Apollo’s communications
involved a radio amateur in Kentucky: Larry Baysinger, W4EJA. By
day, Baysinger, who had an interest in radio astronomy, was the
station engineer at WHAS AM in Louisville. On the evening of 20
July 1969, Basinger managed to pick up not the powerful S-band
signal from the lunar lander but rather the weak VHF signals
from Neil Armstrong’s backpack radio on the moon. For 35 minutes
he listened to the astronauts’ conversation, and even heard them
being congratulated by President Richard Nixon. The feat is all
the more remarkable considering Baysinger’s rig—a rebuilt
20-year-old Army surplus tank radio and a steerable antenna he
built out of aluminum tubing and chicken wire.
With dozens of missions planned for the next decade, Jet
Propulsion Laboratory has partnered with the Italian aerospace
company Argotec to design a satellite-based lunar network
Now Earth-to-moon communications are poised for a new era. With
dozens of missions planned for the next decade, the Jet
Propulsion Laboratory has partnered with the Italian aerospace
company Argotec to design a satellite-based lunar network that
would provide coverage to most of the moon at any given time.
The plan calls for 24 satellites to move in four highly
elliptical orbits, relaying signals between the lunar surface
and Earth. The network wouldn’t be very fast—it would deliver
tens of megabits per second, which is less than a decent fiber-to-the-home
hookup.
But the Argotec-JPL concept is just one of several budding
initiatives to design future lunar communications
infrastructure, including proposals to serve future lunar
residents. These explorers would need enormously powerful data
links to conduct experiments, control remote equipment, receive
and issue warnings about dangerous space weather, rescue
stranded surface travelers, and even combat homesickness. The
largest project to return humans to the moon, NASA’s Artemis,
has already spawned several proposals for such lunar networks.
NASA itself has developed an architecture it calls LunaNet,
which it recently shared with industrial and government
partners. And the Japan Aerospace Exploration Agency recently
awarded separate contracts to ArkEdge Space and Warpspace Co. to
perform studies for robust and technologically advanced lunar
networks.
It’s not too much of a stretch to envision these future moon
dwellers gaping at the landing sites of the Apollo missions.
There, amid the lander descent stages, nail clippers, US $2
bills, and vomit bags, they’ll see the S-band erectable
antennas, television cameras, and lunar rovers. With their
21st-century smartphones, they might even take selfies alongside
some of the most remarkable communications gear of the 20th.
GLENN ZORPETTE -
Engineering Lunar Network 2.0 (ieee.org) |
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TACS is a leading top consultancy in the field of information, communication
and energy technologies (ICET).
The heart of our consulting spectrum comprises strategic,
organizational, and technology-intensive tasks that arise from the use of new
information, communication and energy technologies.
The major emphasis in our work is found in innovative consulting and
implementation solutions which result from the use of modern information,
communication and energy technologies.
TACS
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on technology for strategic decisions
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innovations forward as part of our service offerings to customers
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competence in the ICET sector
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