AAUSat-3: Difference between revisions
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It has shown real improvement and is now capable of sampling and decoding in real time. First metrics shows a capacity of around 6000 AIS messages/hour on average. |
It has shown real improvement and is now capable of sampling and decoding in real time. First metrics shows a capacity of around 6000 AIS messages/hour on average. |
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''' 25 February 2014''': one year up in space. AAUSAT3 is fully functioning and AIS measurements are done on a regular basis. A ground station has been established at Thule (Qaanaaq), Greenland for extended download capacity. Energy production is now stable but rather low stable, so the mission is interleaved with hours or days for charging batteries. New uploaded algorithms now show reception of approx 8000 messages/hour and real time performance which means that decoding takes less time than sampling and is carried out in parallel. Due to the ground station at Thule it is possible to carry out real-time supervision around Greenland: measuring and downloading at the same time. So only a few seconds after detection the information is available in Aalborg at our MCC. |
''' 25 February 2014''': one year up in space. AAUSAT3 is fully functioning and AIS measurements are done on a regular basis. A ground station has been established at Thule (Qaanaaq), Greenland for extended download capacity. Energy production is now stable but rather low stable, so the mission is interleaved with hours or days for charging batteries. New uploaded algorithms now show reception of approx 8000 messages/hour and real time performance which means that decoding takes less time than sampling and is carried out in parallel. Due to the ground station at Thule, it is possible to carry out real-time supervision around Greenland: measuring and downloading at the same time. So only a few seconds after detection the information is available in Aalborg at our MCC. |
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The mission continues. |
The mission continues. |
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Revision as of 16:57, 2 October 2017
 | This article may require copy editing for grammar, style, cohesion, tone, or spelling. (May 2017) |
 AAUSAT3 flight model | |
| Mission type | Technology |
|---|---|
| Operator | Aalborg University |
| COSPAR ID | 2013-009B |
| SATCAT no. | 39087 |
| Website | www |
| Mission duration | 6 months planned |
| Spacecraft properties | |
| Spacecraft type | 1U CubeSat |
| Manufacturer | Aalborg University |
| Launch mass | 1 kilogram (2.2 lb) |
| Start of mission | |
| Launch date | 25 February 2013, 12:31 UTC[1] |
| Rocket | PSLV-CA C20 |
| Launch site | Satish Dhawan FLP |
| Contractor | ISRO |
| Orbital parameters | |
| Reference system | Geocentric |
| Regime | Low Earth |
| Perigee altitude | 775 kilometres (482 mi) |
| Apogee altitude | 793 kilometres (493 mi) |
| Inclination | 98.62 degrees |
| Period | 100.40 minutes |
| Epoch | 21 November 2013, 01:03:17 UTC[2] |
AAUSAT3 is the third CubeSat built and operated by students from Aalborg University in Denmark. It was launched on 25 February 2013 from Satish Dhawan Space Centre in India on a PSLV rocket (no C20). AAUSAT3 carries two AIS receivers as the main payload.
AAUSAT3 is made solely by students.
The educational objective
The primary purpose of construction of satellites at Aalborg University is to give the students engineering capabilities beyond what is normally achieved within a masters program. All design, implementation and manufacturing have been carried out by students with two exceptions: manufacturing of mechanical structure (carried out by department workshop in alu7075) and the raw non-mounted PCBs.
The scientific objective
To answer the question - Is it possible to receive AIS signals from a 1U cubesat?
History
Student satellite activities at Aalborg University (AAU) started in 2003 as a result of AAU's involvement in the first pure Danish research satellite, Ørsted, which was successfully launched in 1999.
AAUSAT3's predecessor was
- AAU CubeSat(launched 2003)
- AAUSAT-II(launched 2008).
Students from AAU did also participate in SSETI EXPRESS(launched 2005) - a student satellite initiative from ESA Education.
The construction of AAUSAT3 began in 2007.
Operations
| File:Aisfromaausat3-8march2013.png 8124 AIS messages received in 11 hours on 8. March 2013. |
AAUSAT3 was launched 25 February 2013 on PSLV C20. As the time of writing operations has been a success. 9000 AIS messages are received on daily basis and downloaded to the MCC located in Aalborg Denmark. All subsystems have been tested and are running.
The first 100 days of operation had been very successful. No degradation of the satellite had been observed, all subsystems were working and the primary payload - an AIS receiver - was working correctly. The mission will continue until further notice.
Two critical situations have taken place during the first 100 days:
28 February 2013 06:08: the very last beacon for some days was received. During the last 24 hours, battery voltage was decreasing and temperature readings did indicate that AAUSAT3 was steady pointing the sixth side without solar cells towards the sun. During the last pass over Aalborg, it was observed that battery voltage was slowly decreasing.
The situation was discussed and analysed during the day and it was decided to instruct AAUSAT3 on all upcoming passes to switch off beacon mode because it was using power (radio).
No further attempt was taken to gain contact during the weekend because if very slow charging was taking place it should have peace to regain to normal mode. All passes were supervised.
There was total silence until 4 March at 17:52 where the ground station in Aalborg did request and did receive a beacon. The beacon did show an uptime of 1 day 19 hours and that everything was working ok and more than 7000 AIS messages were received. Everything went back to normal. The requested beacon did also show a high number of reboots - which we think was due to low battery voltage.
Due to this event AAUSAT3 is now by intention set to tumble very slow - 2 rotations for every orbit (approx 100 minutes) - to avoid a repetition of the situation.
24 May 2013: the power system (EPS) onboard AAUSAT3 rejected to handle multi-frame communication packages from ground. During 4 passes (500 minutes) the students analyzed the situation and inspected the C source for the EPS server and a solution was found. One proper crafted package was sent to AAUSAT3 and normal situation for the EPS was re-established. During the event, the rest of the satellite was - due to the decentralised design - working perfectly. The team expect a bit flip to be the case.
During the first 100 days close to 800,000 AIS packages has been received and downloaded.
10-11 June 2013: two new SW images for the SDR AIS receiver (AIS2) was uploaded without problems. It takes approx 1.5 paths to upload a full AIS receiver.
It has shown real improvement and is now capable of sampling and decoding in real time. First metrics shows a capacity of around 6000 AIS messages/hour on average.
25 February 2014: one year up in space. AAUSAT3 is fully functioning and AIS measurements are done on a regular basis. A ground station has been established at Thule (Qaanaaq), Greenland for extended download capacity. Energy production is now stable but rather low stable, so the mission is interleaved with hours or days for charging batteries. New uploaded algorithms now show reception of approx 8000 messages/hour and real time performance which means that decoding takes less time than sampling and is carried out in parallel. Due to the ground station at Thule, it is possible to carry out real-time supervision around Greenland: measuring and downloading at the same time. So only a few seconds after detection the information is available in Aalborg at our MCC.
The mission continues.
See [1] for more information
Satellite Subsystem Strategy
AAUSAT3 is based on a non-centralized concept with no dedicated master. The idea behind this approach is to achieve a modular satellite which in many cases will be able to function even when certain subsystems fail. For that reason, the must-have subsystem (EPS and COM) are by purpose designed simple and very robust whereas subsystems like AIS2 are quite more complex and therefore must be a design of higher complexity and nature then have a higher failure rate.
The power system(EPS) acts as intelligent supervisor and watchdog. AAUSAT3 consists of several sub-systems:
| EPS | Electronic Power Supply | at90can128 | 8 MHz | FreeRTOS | 32kB add RAM | |
| COM | Communication Module | at90can128 | 16 MHz | FreeRTOS | 32 kB added RAM | ADF702x radio |
| ADCS1 | Attitude Determination and Control 1 | at90can128 | 8 MHz | FreeRTOS | 32 kB added RAM | detumbling |
| ADCS2 | Attitude Determination and Control 2 | arm 7 | x0 MHz | FreeRTOS | xx kB added RAM | determination and control |
| AIS1 | Automatic Identification System | at90can128 | 8 MHz | FreeRTOS | 32 kB added RAM | ADF702x for AIS receive |
| AIS2 | Automatic Identification System | BF537 | XXX MHz | μClinux | ADF702x for AIS receive | Receive all channels simultaneously |
| LOG | Onboard logging system | FreeRTOS | ||||
| FP | FlightPlanner | FreeRTOS |
On the ground segment there is:
- CDH: Command and Datahandling System
- GND: Ground Station
- MCC: Mission Control Center
All internal and satellite to ground station is carried out using CSP protocol which is a spin of AAUSAT3.
Technical Facts
| Dimensions | 100 × 100 × 113 mm Cubesat standard |
| Mass | 800 gram |
| Expected lifetime | Minimum 1 month, extended until end of lifetime |
| Attitude determination system | Sun sensors, gyro sensors, magnetometers |
| Attitude control system | Magnetic coils |
| Power | Solar-cell panels located in satellite surface |
| Batteries | Li-ion 8.2V 2200 mAh |
| Power bus | 3.3 and 5V regulated |
| Antenna COM - UHF tx/rx | dipole (be-cu) |
| Antenna AIS (VHF) | dipole (be-cu) |
HAM information
- Callsign: OZ3CUB
- Up/downlink: 437.425 MHz
- Bit rate: 1200-19200 bit/s (default 2400, is operated at 9600, 19200 has been tested positive as well)
- CSP FM CW TLM
See also
References
- ^ McDowell, Jonathan. "Launch Log". Jonathan's Space Page. Retrieved 21 November 2013.
- ^ Peat, Chris (21 November 2013). "AAUSAT3 - Orbit". Heavens Above. Retrieved 21 November 2013.