Space Technology Special Report - September 2024 - 16

Space Lasers
The Transport Layer is a resilient
mesh network in LEO that allows
information to flow quickly and
securely around the globe and
connects to ground stations. Mesh
satellite networks provide resilience
because data can be rerouted if one
satellite is compromised or destroyed.
The second constellation, the Tracking
Layer, does remote sensing and
observation, with infrared sensors
to spot and track missile threats.
Another example of using laser
links to network LEO and GEO
satellites is the SpaceDataHighway
(SDH), a public-private partnership
between the European Space
Agency and Airbus. The commercial
service utilizes the European
Data Relay System (EDRS) to
provide high bandwidth capability
to LEO satellites and airborne
platforms by means of optical
communications via the EDRS-A
and EDRS-C geostationary satellites
and ground stations in Europe.
Proliferated Commercial
Satellite Constellations
Starlink, an ambitious project
initiated by SpaceX, has made notable
strides in its mission to provide highspeed
internet to every corner of
the globe. As of July 2023, 4,487
Starlink satellites are operating in low
Earth orbit, with the newest versions
of the satellites networked to each
other with lasers. SpaceX anticipates
the total number of satellites in the
Starlink network to grow to between
12,000 and 42,000 eventually.
SpaceX founder Elon Musk
tweeted last year, " Laser links in
orbit can reduce long-distance
latency by as much as 50%, due to
higher speed of light in vacuum &
shorter path than undersea fiber. "
The Starlink project is
groundbreaking and transformative,
but it is not without competition.
One of the biggest competitors is
OneWeb, a UK-based company that
also aims to build a satellite network
for global broadband service. Another
formidable rival is Amazon's Project
16 SEPTEMBER 2024
Fast steering mirrors require
Fast Steering Mirrors
With Sensors using Eddy Current Technology
Mirror
Pivot
precision position data to rapidly
adjust mirror position, which is
usually actuated by electromagnetic
voice coils. Extremely sensitive
sensors can accurately measure the
mirror position with extremely fine
resolution in the sub-micron range.
The system is designed so that the
Sensors
Two precisely matched sensors of a measuring channel are positioned
opposite each other on the back of a Fast Steering Mirror (FSM) in two
coordinate axes. As the FSM actuators drive the mirror about the center
flexure, the mirror moves away from one sensor of an axis and toward
the other sensor by an equal amount.
(Image: Kaman Precision Products)
Kuiper, which plans to deploy over
3,000 satellites for similar purposes.
Furthermore, China's state-run space
agency is also working on a global
broadband service called Tianlink. Each
of these competitors brings unique
strategies and resources to the table,
thereby contributing to an increasingly
dynamic and competitive landscape
in satellite-based internet services.
Aiming the Narrow Laser Beam
All these developments depend
on the remarkable quality of laser
light - the extraordinarily straight
and narrow beam of light that can
be focused on a distant target,
transmitting data at incredible speeds
and low latency, with minimal signal
loss due to beam divergence.
And yet, it is the narrowness of the
laser that makes it so difficult to acquire
and maintain a line-of-sight link over
distances of thousands of kilometers.
Aiming the transmitter and receiver
is challenging due to the extreme
precision required and because the
system must quickly and smoothly
adjust as the host satellites and
spacecraft move at high velocity in
different directions relative to each
other and to ground stations. And
the high-precision components must
reliably stand up to the rigorous
demands of space launches and
the harsh space environment.
performance of the sensors remains
unaffected by the severe temperature
fluctuations in the space environment.
As shown in Figure 1, electronically
matched sensors, using eddy current
technology, are positioned in pairs on
opposite sides of the pivot point of the
mirror and equidistant from this point.
The sensor-to-target relationship is
such that as the target moves away
from one sensor, it simultaneously
moves towards the other an
equal amount. The two pairs of
sensors are positioned in two axes
set perpendicularly to provide
precise x-y tilt/tip position data.
Operating in differential mode,
the sensors eliminate or reduce
common mode effects, such as
piston action, and signal noise.
Taking Aim at the Future
Kaman Precision Products, through
its Measuring line of business,
developed its line of differential
position measuring systems over 30
years ago. Kaman has continually
refined the performance capabilities
of these renowned products to
meet the increasing requirements
of the space and defense markets.
The product line now boasts three
exceptional products including the
KD-5100 family, with over 100krad
TID capability and a rich 3-decades
space heritage including the Mars
2020 Rover, as well as its COTS
version, the DIT5200L, a low noise,
affordable LEO-capable system, and
our new digital KD-5690 system.
This article was written by Rick
Williams, Senior Manager, Business
Development, Kaman Precision
Products (Middletown, CT). For more
information, visit www.kaman.com.
SPACE TECHNOLOGY SPECIAL REPORT
http://www.kaman.com
Space Technology Special Report - September 2024

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