ARLA/CLUSTER: CubeSat australiano vai usar a banda dos 76 GHz, com lançamento previsto para Jlho de 2019

[João Costa > CT1FBF]

Australian CubeSat to use 76 GHz

The IARU Satellite Coordination Panel has announced the amateur radio
frequencies for the Australian 76 GHz CubeSat CUAVA-1 that is expected
to launch in July 2019

CUAVA-1 is a 3U CubeSat and the first CubeSat project of the new ARC
Training Centre for CubeSats, Uncrewed Aerial Vehicles (UAVs), and
their Applications (CUAVA), whose primary aim is the education and
training of people, mostly PhD students, for the space sector.

With significant heritage from the QB50 CubeSat INSPIRE-2, CUAVA-1 is
a 3U CubeSat that will link with the international radio amateur
community for outreach, training, and increased data downloads,
observe the Earth with a novel multi-spectral imager, use a GPS
instrument to explore radio occultation and the reception of GPS
signals scattered off the Earth as well as provide a backup
determination of the CubeSat location, investigate plasma environment
and associated space weather with radiation detectors, and explore the
performance of a new communications payload.

This mission addresses issues of radio technique interesting to the
radio amateur community in the following ways:

1) Global Radio Amateur Participation in Mission and Data Downlinking
We will work with radio amateurs and other groups to receive and
decode the spacecraft beacon and downlinked data, with subsequent
transfer to the internet database (ideally the SatNOGS database).

In detail, the CubeSat will transmit data, especially recent images
over the terrestrial footprint, to participating radio amateurs across
the globe. This will directly involve radio amateurs in the mission
and its success, by greatly increasing the overall amount of
downlinked data available and having the images be directly relevant
to the receiving people. The receiving station and people would be
identified in the database and then acknowledged in any publications
resulting. The mission’s success will thus be directly tied to the
involvement of the international radio amateur community.

In addition, the mission should provide multiple opportunities for
enhanced outreach and training for both the global amateur radio
satellite communities and CUAVA.

2) Student and Radio Amateur Participation in the Groundstation We
will train students and desiring radio amateurs in the setup and use
of a groundstation hosted by the University of Sydney and then have
these people operate the groundstation (including control of the
satellite and managing the uplink and downlink) and transfer
downlinked data into an internet database (ideally the SatNOGS
database).

This will involve existing radio clubs in the training, increasing
their memberships and leading to new clubs and people familiar with
the international radio amateur and satellite communities.

3) Radio Wave Propagation The ionosphere, thermosphere, and lower
atmosphere have multiple effects on the propagation and absorption of
radio waves and microwaves.

This mission will study the electron number density as a function of
position, time of day, and space weather events using the ``radio
occultation’’ of GPS signals and their associated refraction and
attenuation. These data will be published and made available for
ionospheric research via a website, and provided to Australia’s Bureau
of Meteorology and other space weather organisations worldwide. These
data are used to predict maximum and minimum usable frequencies for
radio amateurs (and both commercial and government users).

In addition, the GPS signal attenuation and electron number density
profiles can be used to extract the amount of water as a function of
height and used to predict ordinary weather. This work will also add
to knowledge of the orbital environment via the drag forces and decay
of satellites depending on the gas and plasma densities.

4) Communication Protocols Modulation techniques that will be
investigated for the high-speed communications experiment include
QPSK, 16-QAM and CPFM. If successful, this technology for wavelengths
below 10 cm will increase the data transfer rates by at least 4 orders
of magnitude while also decreasing the sizes of antennas and the
associated spacecraft.

This experiment will be relevant to spacecraft-toground and
inter-spacecraft communication links and is particularly relevant to
radio amateurs, universities, and their students and staff, due to the
dramatic increases in data rates and capabilities and associated
dramatic reductions in costs.

In addition, the use of multiple frequencies is important for rain
(and moisture content) attenuation mitigation techniques, as well as
to provide another data stream for weather prediction.

5) Radiation Effects on Electronic Components The Low Earth Orbit
(LEO) environment is protected from cosmic rays, solar particles, and
particles trapped in the Van Allen Belts by Earth’s magnetic field.

Some portions of LEO do harbour regions of enhanced radiation, in the
auroral zones and the South Atlantic Anomaly (SAA) for example. In
addition, transient solar and magnetospheric particle energization
events, a major component of space weather, can change the radiation
level by orders of magnitude. This radiation can adversely affect
spacecraft which pass through them.

This mission will directly measure the counts of energetic particles
as a function of space weather activity, position, and time of day,
thereby characterising the Earth’s radiation environment. It will also
study the effects of the radiation on the computer and other onboard
electronics. Examples of effects include single event upsets (SEUs),
degraded solar cells, and non-functioning electronics such as radio
receivers and transmitters.

6) Attitude and Position Determination Reception and analysis of GPS
signals by the onboard GPS receiver will determine the spacecraft’s
attitude and location as a function of time, thereby determining the
satellite’s orbit.

Comparisons with NORAD radar-derived orbits will test the on-board GPS
receiver and measure drag and other effects. These orbits are vital
for radio amateurs interested in testing and characterising their
radio equipment, as well as in downloading the satellite beacon and
data signals for transmission via the web to the satellite project and
the international community.

Proposing to downlink telemetry on 9k6 GMSK AX25 on UHF and high speed
downlinks on 2.4 GHz, 5.6 GHz and 76 GHz. Planning a launch from Japan
in July 2019 into a 400km orbit.

These frequencies have been coordinated by the IARU:
Downlinks: 437.075 MHz, 2404.000 MHz, 5840 MHz and 76.800 GHz
Uplinks: 145.875 MHz, 2404.000 MHz and 5660.000 MHz

More information on CUAVA-1 can be found at
https://www.cuava.com.au/
https://twitter.com/Arc_Cuava

IARU Satellite Frequency Coordination Panel
http://www.amsat.org.uk/iaru/