Aerospace & Defense Technology - December 2021 - 6

CubeSat Technology
Orbit Time
[t=5100 s]
Scheduled Operation:
TTC for 600 s
[t=4500 s]
Scheduled Operation:
MEUWarmUP
[t=900 s]
[t=0, 5400 s]
Figure 1. 1U Cubesat (small enough to hold it in
your hand)
Scheduled Operation:
Image Capture for 180 s
[t=1800 s]
[t=3420 s]
able extent. Owing to the fact that it is
lightweight, you don't need much fuel
to deploy them.
In the beginning, cubesats were exclusively
used in low earth orbit for applications
like remote sensing or communications.
At present they are even
being used in interplanetary missions.
Challenges?
Satellites may need to remain in
space for months or even years. So, we
need to optimize their power consumption.
This can be achieved by designing
small circuits and minimizing components
like ICs and the printed circuit
boards. These electrical components operate
at optimal temperature ranges, but
temperatures in space fluctuate rapidly
within short periods of time from extreme
hot to freezing cold, so this directly
affects their lifespan.
Secondly, radiation from both the sun
and outside the solar system has to be
taken into consideration. The radiation
particles may contain electrons and protons
that penetrate through the satellite,
interacting with the circuitry. This
can cause bit flipping which is related to
data transmission, build charge in materials,
and change the properties of components.
The impact may range from
minor effects to complete shutdown of
the whole system.
Overview of the Satellite's Operation
in Space
For our explanation on the design of
the CubeSat, we have considered a reference
architecture published by the Air
Force Research Lab at Kirtland Air Force
Base in Albuquerque, NM, USA. Figure 2
shows a satellite revolving round the
earth. This Cubesat travels around the
6
Intro
Cov
Scheduled Operation:
Tactical DownLink for 600 s
[t=2820 s]
[t=2580 s]
Scheduled Operation:
Image Processing for 600 s
[t=1980 s]
Figure 2. Satellite orbiting round the Earth
Earth in elliptical orbits. It takes 90 minutes
(5400 seconds) to complete one rotation.
CubeSats are generally used in
low Earth orbit for applications like remote
sensing and communications.
This guarantees ideal conditions for
land observation or communications
and provides better shielding from solar
and cosmic radiation.
Cubesats are loaded into the dispensers
and its power is turned off. Dispenser
systems are used for multiple
satellite launches, where a number of
spacecraft need to be placed in orbit in
a short timeframe. When cubesats are
deployed into orbit, the transmitters are
turned on and power and other tools
get activated. The development team is
responsible to complete the launch and
early operations phase (LEOP) for commissioning
all subsystems and payloads.
Payloads consist of the communication
antennas, receivers, and transmitters.
During the LEOP phase, it is
checked whether the satellite survived
the launch. Further, the satellite is identified
among all other satellites that
may have been deployed simultaneously.
The Launch and Early Operations
phase is one of the most critical phases
of a mission and generally takes a period
of seven weeks.
Additional checks certify that the
solar panels supply sufficient power for
operation. The LEOP phase continues
with a platform commissioning and detumbling
phase. The commissioning
phase performs functional checking of
the end-to-end system, proceeding from
simple to complex operations. Detumbling
is the process of stabilizing the angular
rate of the satellite after orbital insertion.
In this phase, all subsystems of
the CubeSat are checked for their correct
function in orbit. The satellite may
have some rotations induced by the deployment
mechanism.
The CubeSat has to be detumbled to a
stable attitude. Once the satellite is stable,
other actuators such as reaction
wheels can take over for fine attitude
control required for nominal operations.
A reaction wheel is a type of flywheel
used primarily by spacecraft for
three-axis attitude control. They provide
a high pointing accuracy. Attitude
control helps in stabilizing the satellite.
The LEOP finalizes with the commissioning
of the payloads. Operators calibrate
the instruments, and perform tests
to check for the payload function,
power consumption and transmission
of data for safe operations.
There are limitations set in the quantity
of information that can be sent
through a radio channel. Multiple
ground stations are set to maximize the
data exchange between the satellite and
its operators. This leads to the development
of a network of ground stations.
During the satellite operation, it is
pivotal to prepare a proposition for
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Aerospace & Defense Technology - December 2021

Table of Contents for the Digital Edition of Aerospace & Defense Technology - December 2021

Aerospace & Defense Technology - December 2021 - Intro
Aerospace & Defense Technology - December 2021 - Sponsor
Aerospace & Defense Technology - December 2021 - Cov1
Aerospace & Defense Technology - December 2021 - Cov2
Aerospace & Defense Technology - December 2021 - 1
Aerospace & Defense Technology - December 2021 - 2
Aerospace & Defense Technology - December 2021 - 3
Aerospace & Defense Technology - December 2021 - 4
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Aerospace & Defense Technology - December 2021 - 6
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Aerospace & Defense Technology - December 2021 - 40
Aerospace & Defense Technology - December 2021 - Cov3
Aerospace & Defense Technology - December 2021 - Cov4
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