UPSat

UPSat

UPSat minutes after deployment from the ISS
Mission type Thermosphere research, part of the QB50 mission
Operator University of Patras, Libre Space Foundation
COSPAR ID 1998-067LX
Website http://upsat.gr
Mission duration TBA
Spacecraft properties
Manufacturer University of Patras, Libre Space Foundation
Launch mass 2kgr
Start of mission
Launch date 2017/04/18
Rocket Atlas-V
Launch site Cape Canaveral
End of mission
Decay date Launch + <6 months
Orbital parameters
Reference system Geocentric
Regime Low Earth
Semi-major axis TBA
Eccentricity TBA
PeriTBA TBA
ApoTBA TBA
Inclination TBA
Period TBA

UPSat is the first satellite manufactured in Greece,[1] by the University of Patras and Libre Space Foundation part of the QB50 mission with ID GR-02. UPSat mission aspires to be the first completely open source satellite ever launched in orbit both software and hardware wise.[2]

Open Source

The UPSat mission, aims to develop an open source hardware and software 2U cubesat, minimizing the use of commercial off the shelf components to minimum, and providing hardware and software designs under the provisions of the CERN-OHLv2 [3] and GNU-GPLv3 [4] licenses respectfully. The vast majority of its components are designed from scratch in an open source software and hardware way.

Mission

Deployment of UPSat the first open source hardware & software satellite in orbit

UPSat as part of the QB50 cubesat constellation was launched to the International Space Station at April 18th, 2017 11:11 EDT at Cape Canaveral in Florida, on board an Atlas-V rocket transferring the Cygnus cargo spacecraft to dock to 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 started receiving telemetry signals from UPSat in several ground-stations deployed globally shortly after its deployment.[5] all data and telemetry is publicly available.


Subsystems

General

UPSat Subsystems diagram

EPS (Electrical Power System) An EPS designed from scratch around an STM32L1 MCU, utilizing software MPPT, 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 FreeRTOS 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, gyro, sun sensor). The sensor fusion algorithm used is based on an alternative implementation of Wahba’s problem, in order to accommodate gyro measurements, as introduced in.[6] 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. This forms essentially a complementary filter in SO(3) between the gyro and the vector measurements. The reference vectors in ECI frame are calculated by[7] and IGRF model, respectively, given the satellites position is known by the GPS and SGP4 model. The control system is based on a spin torquer, which is used as a reaction wheel 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 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.

[8]

Primary Payload

On-board UPSat, the primary payload, a science unit is integrated. The science unit (designed by the University of Oslo and supplied through the Von Karman Institute 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. [9]

Secondary Payload

As a secondary payload UPSat sports an embedded Linux board (DART-4460) running a modified version of the OpenWRT operating system controlling a b/w camera (MU9PM-MH) with 1 / 2.5’’ sensor size. [10]

References

  1. ↑ ""UPSat": O πρώτος δορυφόρος ελληνικής κατασκευής!". euronewsgr.
  2. ↑ "UPSat (QB50 GR02)". space.skyrocket.de.
  3. ↑ "UPSat COMMS hardware license". Github. Retrieved 12 July 2017.
  4. ↑ UPSat OBC software license https://github.com/librespacefoundation/upsat-obc-software/blob/master/LICENSE. Retrieved 12 July 2017. Missing or empty |title= (help)
  5. ↑ "UPSat, an open-source Greek satellite". Space Daily. Retrieved 18 May 2016.
  6. ↑ Marantos, Panos; Koveos, Yannis; Kyriakopoulos, Kostas J. (July 2016). "UAV State Estimation Using Adaptive Complementary Filters". IEEE Transactions on Control Systems Technology. 24 (4): 1214–1226. doi:10.1109/TCST.2015.2480012.
  7. ↑ McClain, David A. Vallado ; with technical contributions by Wayne D. (2007). Fundamentals of astrodynamics and applications (3rd ed. ed.). New York: Springer. p. 281. ISBN 978-0-387-71831-6.
  8. ↑ "Subsystems – UPSat". upsat.gr.
  9. ↑ "UPSat Scientific Unit". UPSat. 25 March 2016. Retrieved 12 July 2017.
  10. ↑ "UPSat Image Acquisition Component". UPSat. 25 March 2016. Retrieved 12 July 2017.
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