UPSat was the first satellite manufactured in
Greece
Greece,, or , romanized: ', officially the Hellenic Republic, is a country in Southeast Europe. It is situated on the southern tip of the Balkans, and is located at the crossroads of Europe, Asia, and Africa. Greece shares land borders with ...
to be successfully launched into orbit, by the
University of Patras
The University of Patras (UPatras; el, Πανεπιστήμιο Πατρών, ''Panepistímio Patrón'') is a public university in Patras, Greece. It is the third-largest university in Greece with respect to the size of the student body, the s ...
and
Libre Space Foundation (an earlier Greek-made communications satellite, HELMARS-SAT, although entirely constructed by 1999, was not launched due to budget limitations). It was part of the
QB50
A CubeSat is a class of miniaturized satellite based around a form factor consisting of cubes. CubeSats have a mass of no more than per unit, and often use commercial off-the-shelf (COTS) components for their electronics and structure. CubeSats ...
mission with ID GR-02. The UPSat mission was the first satellite launched into orbit made entirely of
open-source software
Open-source software (OSS) is computer software that is released under a license in which the copyright holder grants users the rights to use, study, change, and distribute the software and its source code to anyone and for any purpose. Op ...
and
open-source hardware
Open-source hardware (OSH) consists of physical artifacts of technology designed and offered by the open-design movement. Both free and open-source software (FOSS) and open-source hardware are created by this open-source culture movement and a ...
.
Open-source
The UPSat mission developed an
open-source hardware
Open-source hardware (OSH) consists of physical artifacts of technology designed and offered by the open-design movement. Both free and open-source software (FOSS) and open-source hardware are created by this open-source culture movement and a ...
and software 2U
cubesat
A CubeSat is a class of miniaturized satellite based around a form factor consisting of cubes. CubeSats have a mass of no more than per unit, and often use commercial off-the-shelf (COTS) components for their electronics and structure. CubeSats ...
, minimizing the use of commercial off the shelf components, and providing hardware and software designs under the provisions of the CERN-OHLv2 and GNU-GPLv3 licenses respectfully. The vast majority of its components were designed from scratch in an open-source software and hardware way.
Mission
![UPSat deployment from ISS](https://upload.wikimedia.org/wikipedia/commons/2/29/UPSat_deployment_from_ISS.gif)
UPSat, as part of the
QB50
A CubeSat is a class of miniaturized satellite based around a form factor consisting of cubes. CubeSats have a mass of no more than per unit, and often use commercial off-the-shelf (COTS) components for their electronics and structure. CubeSats ...
cubesat constellation, was launched to the
International Space Station
The International Space Station (ISS) is the largest modular space station currently in low Earth orbit. It is a multinational collaborative project involving five participating space agencies: NASA (United States), Roscosmos (Russia), JAXA ...
at April 18, 2017 11:11 EDT at
Cape Canaveral
, image = cape canaveral.jpg
, image_size = 300
, caption = View of Cape Canaveral from space in 1991
, map = Florida#USA
, map_width = 300
, type =Cape
, map_caption = Location in Florida
, location ...
in Florida, on board an
Atlas V
Atlas V is an expendable launch system and the fifth major version in the Atlas (rocket family), Atlas launch vehicle family. It was originally designed by Lockheed Martin, now being operated by United Launch Alliance (ULA), a joint venture be ...
rocket transferring the
Cygnus cargo spacecraft to dock with the International Space Station with supplies and other scientific experiments. UPSat was released in orbit by the
NanoRacks deployer from the International Space Station at 08:24 UTC 2017-05-18. After 30 minutes, UPSat subsystems commenced normal operations in orbit. The
SatNOGS ground-station network began receiving telemetry signals from UPSat in several ground-stations deployed globally shortly after its deployment. All data and telemetry is publicly available. UPSat decayed at November 13, 2018.
Subsystems
General
![Upsat subsystems](https://upload.wikimedia.org/wikipedia/commons/5/57/Upsat_subsystems.png)
EPS (Electrical Power System)
An EPS designed from scratch around an STM32L1 MCU, utilizing software
MPPT
Maximum power point tracking (MPPT) or sometimes just power point tracking (PPT), is a technique used with variable power sources to maximize energy extraction as conditions vary. The technique is most commonly used with photovoltaic (PV) solar sy ...
, harnessing power from 7 solar panels and having a 3-cell battery system.
OBC (On board Computer)
An OBC designed from scratch around an STM32F4 MCU, with software built around the
FreeRTOS
FreeRTOS is a real-time operating system kernel for embedded devices that has been ported to 35 microcontroller platforms. It is distributed under the MIT License.
History
The FreeRTOS kernel was originally developed by Richard Barry around ...
Operating System
ADCS (Attitude Determination and Control System)
An ADCS designed from scratch around STM32F4 MCU, determining attitude and position through sensor fusion (GPS,
magnetometer
A magnetometer is a device that measures magnetic field or magnetic dipole moment. Different types of magnetometers measure the direction, strength, or relative change of a magnetic field at a particular location. A compass is one such device, o ...
, gyro, sun sensor). The sensor fusion algorithm used is based on an alternative implementation of
Wahba's problem
In applied mathematics, Wahba's problem, first posed by Grace Wahba in 1965, seeks to find a rotation matrix (special orthogonal matrix) between two coordinate systems from a set of (weighted) vector observations. Solutions to Wahba's problem are o ...
, in order to accommodate gyro measurements, as introduced in. This implementation uses a virtual vector base, propagated by the gyro reading, fused with the vectors provided by the sun sensor and the magnetometer, as per
Wahba's problem
In applied mathematics, Wahba's problem, first posed by Grace Wahba in 1965, seeks to find a rotation matrix (special orthogonal matrix) between two coordinate systems from a set of (weighted) vector observations. Solutions to Wahba's problem are o ...
. This forms essentially a complementary filter in
SO(3)
In mechanics and geometry, the 3D rotation group, often denoted SO(3), is the group of all rotations about the origin of three-dimensional Euclidean space \R^3 under the operation of composition.
By definition, a rotation about the origin is a tr ...
between the gyro and the vector measurements. The reference vectors in ECI frame are calculated by and
IGRF model, respectively, given the satellites position is known by the GPS and
SGP4
Simplified perturbations models are a set of five mathematical models (SGP, SGP4, SDP4, SGP8 and SDP8) used to calculate orbital state vectors of satellites and space debris relative to the Earth-centered inertial coordinate system. This set of mod ...
model.
The control system is based on a spin torquer, which is used as a
reaction wheel
A reaction wheel (RW) is used primarily by spacecraft for three-axis attitude control, and does not require rockets or external applicators of torque. They provide a high pointing accuracy, and are particularly useful when the spacecraft must be ...
for pitch control and also to stiffen roll and yaw to the satellite's orbit plane (Gyroscopic torque and momentum bias). Magneto-torquers are also used to dampen the roll and yaw motion while also control pitch angle.
SU (Science Unit)
(see primary payload)
COMM (Communications system)
A COMM designed from scratch around an STM32F4 MCU, using the TI CC1120 transceivers, with contingency around TX operations combined with a custom Antenna deployment system with an integrated GPS antenna.
IAC (Image Acquisition Component)
(see secondary payload)
Structure
The structural sub-system is based on a “hybrid” approach of both Aluminum (frame) and CFRP components (4 faces), built in-house.
Primary payload
On-board UPSat, the primary payload, a science unit is integrated. The science unit (designed by the
University of Oslo
The University of Oslo ( no, Universitetet i Oslo; la, Universitas Osloensis) is a public research university located in Oslo, Norway. It is the highest ranked and oldest university in Norway. It is consistently ranked among the top universit ...
and supplied through the
Von Karman Institute
The von Karman Institute for Fluid Dynamics (VKI) is a non-profit educational and scientific organization which specializes in three specific fields: aeronautics and aerospace, environment and applied fluid dynamics, turbomachinery and propulsi ...
as part of the QB50 program) will be used for plasma measurements during the mission duration. The science unit is a multi-Needle Langmuir Probe instrument works by measuring the current collected individually from four needle probes, placed in front of the satellite's shock front. The collected current is converted to voltage, filtered, digitalized and then sent to the central telemetry system.
Secondary payload
As a secondary payload UPSat sports an embedded Linux board (DART-4460) running a modified version of the
OpenWRT
OpenWrt (from ''open wireless router'') is an open-source project for embedded operating systems based on Linux, primarily used on embedded devices to route network traffic. The main components are Linux, util-linux, musl, and BusyBox. All com ...
operating system controlling a b/w camera (MU9PM-MH) with 1 / 2.5’’ sensor size.
References
External links
UPSat mission website
{{Orbital launches in 2017
Satellites of Greece
CubeSats
Spacecraft launched in 2017
2017 in Greece
Open-source hardware
Free software