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VELOX-PII CubeSat

VELOX-PII (Picosatellite II) is the first CubeSat of SaRC (Satellite Research Center) at NTU (Nanyang Technological University), Singapore. It was developed under the NTU Undergraduate Satellite Program, which provides an opportunity for students to participate in a multidisciplinary hands-on space project. The objective is to train engineers to support the Singapore space industry. Besides educational objectives, VELOX-PII also contributes as a technology demonstration platform and a design validation for NTU future satellite missions. The mission objective is to qualify several in-house built hardware and software components, such as the fault tolerant power system, attitude determination & control algorithms, fine sun sensor, solar panel, etc. 1) 2)

VELOX is a Latin word meaning “swift” or “rapid”. NTU uses the generic name VELOX for all its pico- and nanosatellites.

In August 2012,the satellite team had completed the development of two flight models (VELOX-P and VELOX-PII) . However, the launch of VELOX-P was postponed by a U.S. launch provider in early 2013. Hence, the NTU project decided to launch VELOX-PII CubeSat first, booked in another launch arrangement, in November, 2013. The expected lifetime of VELOX-PII is 12 months.

SaRC completed building its fourth satellite, VELOX-I, a nanosatellite (after X-SAT, VELOX-P and VELOX-PII), in late 2013.

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Figure 1: Illustration of the VELOX-PII CubeSat (image credit: NTU)

Spacecraft:

VELOX-PII is a 1U CubeSat with a mass of 1.33 kg and dimensions of 10 cm x 10 cm x 11.35 cm. The CubeSat structure uses a hard anodized Al. 7075 chassis, with stainless steel load bearing parts.

The CubeSat is 3-axis stabilized. The ADCS (Attitude Determination and Control Subsystem) features 1 GPS receiver, 2 IMUs (Inertial Measurement Units), 1 dual-FOV sun sensor, 5 coarse sun sensors, and 3 magnetic torquers.

On-board data handling is provided with a 100 MHz 8051 MCU (Microcontroller Unit), 2 GB SD card, UART and I2C data interfaces.

EPS (Electrical Power Subsystem): 5 GaAs panels for 2.4 W peak. A Li-ion battery is used with a capacity of 2600 mAh.

RF communications: VELOX-PII transmits on 9.6 kbit/s BPSK downlink and 1.2 kbit/s AFSK uplink, UHF & VHF dipoles. A CW beacon is provided. Use of the AX.25 packet protocol.

 

Experiment: Technology demonstration platform, new dual-FOV sun sensor, fault tolerant power management system, ADCS.

 

Launch: The VELOX-PII CubeSat was launched as a secondary payload on Nov. 21, 2013 (07:10:11 UTC) on board a Dnepr-1 vehicle from the Dombarovsky (Yasny Cosmodrome) launch site in Russia. The launch provider was ISC Kosmotras. The primary payloads on this flight were DubaiSat-2 of EIAST and STSat-3 of KARI, Korea. 3) 4) 5)

The secondary payloads on this flight were:

• SkySat-1 of Skybox Imaging Inc., Mountain View, CA, USA, a commercial remote sensing microsatellite of ~100 kg.

• WNISat-1 (Weathernews Inc. Satellite-1), a nanosatellite (10 kg) of Axelspace, Tokyo, Japan.

• BRITE-PL-1, a nanosatellite (7 kg) of SRC/PAS (Space Research Center/ Polish Academy of Sciences of Warsaw, Poland.

• AprizeSat-7 and AprizeSat-8, nanosatellites of AprizeSat. AprizeSat-7 and 8 are the ninth and tenth satellites launched as part of the AprizeSat constellation, operated by AprizeSat. The constellation, which was originally named LatinSat, was initially operated by Aprize Argentina; however ownership of the constellation was later transferred to their US parent company AprizeSat. The AprizeSat constellation is used for store-dump communications, and some satellites carry AIS (Automatic Identification System) payloads for Canadian company ExactEarth. The AprizeSat spacecraft were built by SpaceQuest Ltd. Of Fairfax, VA, USA, and each has a mass of 12 kg. 6)

UniSat-5, a microsatellite of the University of Rome (Universita di Roma “La Sapienza”, Scuola di Ingegneria Aerospaziale). The microsatellite has a mass of 28 kg and a size of 50 cm x 50 cm x 50 cm. When on orbit, UniSat-5 will deploy the following satellites with 2 PEPPODs (Planted Elementary Platform for Picosatellite Orbital Deployer) of GAUSS:

- PEPPOD 1: ICube-1, a CubeSat of PIST (Pakistan Institute of Space Technology), Islamabad, Pakistan; HumSat-D (Humanitarian Satellite Network-Demonstrator), a CubeSat of the University of Vigo, Spain; PUCPSat-1 (Pontificia Universidad Católica del Perú-Satellite), a 1U CubeSat of INRAS (Institute for Radio Astronomy), Lima, Peru; Note: PUCPSat-1 intends to subsequently release a further satellite Pocket-PUCP) when deployed on orbit. 7)

- PEPPOD 2: Dove-4, a 3U CubeSat of Planet Labs Inc. (formerly Cosmogia Inc.), San Francisco, CA, USA

MRFOD (Morehead-Roma FemtoSat Orbital Deployer) of MSU (Morehead State University) is a further deployer system on UniSat-5 which will deploy the following femtosats:

- Eagle-1 (BeakerSat), a 1.5U PocketQube, and Eagle-2 ($50SAT) a 2.5U PocketQube, these are two FemtoSats of MSU (Morehead State University) and Kentucky Space; Wren, a FemoSat (1U PocketQube) of StaDoKo UG, Aachen, Germany; and QBSout-1S, a 2.5U PocketQube (400 g) of the University of Maryland testing a finely pointing sun sensor.

• Delfi-n3Xt, a nanosatellite (3.5 kg) of TU Delft (Delft University of Technology), The Netherlands.

• Triton-1 nanosatellite (3U CubeSat) of ISIS-BV, The Netherlands

• CINEMA-2 (KHUSat-1) and CINEMA-3 (KHUSat-2), nanosatellites (4 kg each) developed by KHU (Kyung Hee University), Seoul, Korea for the TRIO-CINEMA constellation. TRIO-CINEMA is a collaboration of UCB (University of California, Berkeley) and KHU.

• GOMX-1, a 2U CubeSat of GomSpace ApS of Aalborg, Denmark

• NEE-02 Krysaor, a CubeSat of EXA (Ecuadorian Civilian Space Agency)

• FUNCube-1, a CubeSat of AMSAT UK.

• HiNCube (Hogskolen i Narvik CubeSat), a CubeSat of NUC (Narvik University College), Narvik, Norway.

• ZACUBE-1 (South Africa CubeSat-1), a 1U CubeSat (1.2 kg) of CPUT (Cape Peninsula University of Technology), Cape Town, South Africa.

• UWE-3, a CubeSat of the University of Würzburg, Germany. Test of an active ADCS for CubeSats.

• First-MOVE (Munich Orbital Verification Experiment), a CubeSat of TUM (Technische Universität München), Germany.

• Velox-P2, a 1U CubeSat of NTU (Nanyang Technological University), Singapore.

• OPTOS (Optical nanosatellite), a 3U CubeSat of INTA (Instituto Nacional de Tecnica Aerospacial), the Spanish Space Agency, Madrid.

• Dove-3, a 3U CubeSat of Planet Labs Inc. (formerly Cosmogia Inc.), San Francisco, CA, USA

• CubeBug-2, a 2U amateur radio CubeSat of Argentina (sponsored by the Argentinian Ministry of Science, Technology and Productive Innovation) which will serve as a demonstrator for a new CubeSat platform design.

• BPA-3 (Blok Perspektivnoy Avioniki-3) — or Advanced Avionics Unit-3) of Hartron-Arkos, Ukraine.

Orbit: Sun-synchronous near-circular orbit of the primary payloads (DubaiSat-2 and STSat-3), altitude = 600 km, inclination = 97.8º, LTDN (Local Time on Descending Node) = 10:30 hours. The effective revisit time of DubaiSat-2 is < 8 days for any ground location with a body-pointing capability of the spacecraft (up to ±45º roll tilt, ±30º pitch tilt).

Due to the large number of satellites on the mission, the Dnepr used a modified fairing which has been split into two platforms. DubaiSat-2 and STSAT-3, the primary payloads, were mounted on the upper platform, with the remaining satellites and the CubeSat dispensers mounted to the lower platform. The gas dynamic shield sits atop the upper platform.

Deployment of CubeSats: Use of 9 ISIPODs of ISIS, 3 XPODs of UTIAS/SFL, 2 PEPPODs of GAUSS, and 1 MRFOD of MSU.

 

Mission status:

• Feb. 3, 2014: The NTU team completed all experiments except the one on the fault tolerant power management subsystem which is intended to do it at later stage (due to risk considerations). 8)

Currently, the VELOX-PII CubeSat is in the nominal housekeeping mode. The team logs the satellite status of all subsystems and stores the data into the onboard SD card. During a good pass over the NTU station, the data of a whole orbit are downloaded for analysis and component performance studies.

• January 2014: The VELOX-PII satellite has been functioning well since launch. The satellite team has conducted various experiments on the satellite, such as navigation algorithm, attitude determination system using fine sun sensor designed in-house, and attitude control system. 9)

• The NTU satellite team successfully established contact with the satellite during the first ground pass at 22:41pm Singapore time. In the second pass at 00:18am on 22 November 2013, the team has successfully communicated with the CubeSat and downloaded the housekeeping data. The information indicated that the satellite’s battery was fully charged and the temperature of the satellite was in the range of 20-40ºC.

 


 

Ground segment:

The ground station is located at NTU with UHF/VHF high-gain cross Yagi-Uda antennas.

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Figure 2: Photo of the NTU ground station with the students involved in the VELOX-PII project (image credit: K.S. Low, NTU)


1) “VELOX-P Picosatellite,” Dec. 20, 2013, URL: NTU, URL: http://www.sarc.eee.ntu.edu.sg/Project/Pages/VELOX-P.aspx

2) http://www.sarc.eee.ntu.edu.sg/Pages/Home.aspx

3) “Dnepr Cluster Mission 2013,” ISC Kosmotras, Nov. 21, 2013, URL: http://www.kosmotras.ru/en/news/149/

4) Robert Christy, “Dnepr Launch 2013 November 21,” Zarya, Nov. 21, 2013, URL: http://www.zarya.info/blog/?p=1745

5) “2013 in spaceflight,” Wikipedia, Nov. 21, 2013, URL: http://en.wikipedia.org/wiki/2013_in_spaceflight#November

6) “Russian Dnepr conducts record breaking 32 satellite haul,” NASA Spaceflight.com, Nov. 21, 2013, URL: http://www.nasaspaceflight.com/2013/11/russian-dnepr-record-breaking-32-satellite-haul/

7) “PUCPSat-1 Satellite Project,” URL: http://inras.pucp.edu.pe/pucpsat1/index.html

8) Information of the VELOX-PII CubeSat project was provided by Kay-Soon Low of NTU.

9) Asia-Pacific Regional Space Agency Forum (APRSAF) News Mail No. 114, January 31, 2014.


The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: ”Observation of the Earth and Its Environment: Survey of Missions and Sensors” (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates.