LituanicaSAT-1 was one of the first two

Lithuania Lithuania (; lt, Lietuva ), officially the Republic of Lithuania ( lt, Lietuvos Respublika, links=no ), is a country in the Baltic region of Europe. It is one of three Baltic states and lies on the eastern shore of the Baltic Sea. Lithuania ...

n satellites (other one being

LitSat-1 LitSat-1 was one of the first two Lithuanian satellites (other one being Lituanica SAT-1). It was launched aboard the second Cygnus spacecraft along with 28 Flock-1 CubeSats aboard an Antares 120 carrier rocket flying from Pad 0B at the Mid-A ...

). It was launched along with the second Cygnus spacecraft and 28 Flock-1 CubeSats aboard an Antares 120 carrier rocket flying from Pad 0B at the Mid-Atlantic Regional Spaceport on Wallops Island 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 ...

. The launch was scheduled to occur in December 2013, but later was rescheduled to 9 January 2014 and occurred then. The satellite was broadcasting greetings of Lithuanian president, Mrs. Dalia Grybauskaitė. The satellite was deployed from the International Space Station via the NanoRacks CubeSat Deployer on February 28, 2014. All LituanicaSAT-1 subsystems have been turned on, tested and proved to be working properly. The mission is considered a complete success by its team of engineers. The mission ended upon the reentry and disintegration of the satellite on July 28, 2014.

Description

The satellite conforms to standard 1U size cubesat form factor as to the latest cubesat design specifications. The satellite does not have any active systems except the antenna deployment mechanism that is engaged 30 minutes after deployment sequence. Both attitude and thermal control sub-systems are implemented passively for simplicity and safety. The total mass of the body including the equipment within it is 1,090 g.

Subsystems

Attitude determination and control

LituanicaSAT-1 uses passive magnetic attitude control system consisting of permanent magnets that create a control torque and soft magnets that provide dampening torque using

hysteresis Hysteresis is the dependence of the state of a system on its history. For example, a magnet may have more than one possible magnetic moment in a given magnetic field, depending on how the field changed in the past. Plots of a single component of ...

effect. Following attitude sensors are implemented for attitude determination: * PS-MPU-6000A MEMS motion sensor * PS-MPU-9150A MEMS motion sensor * L3GD20 MEMS three-axis digital output gyroscope * HMC5883L three-axis digital magnetometer

Command and data management

There are two on board computers in LituanicaSAT-1 due to redundancy requirements: the flight computer based on

ARM Cortex-M4F The ARM Cortex-M is a group of 32-bit RISC ARM processor cores licensed by Arm Holdings. These cores are optimized for low-cost and energy-efficient integrated circuits, which have been embedded in tens of billions of consumer devices. Though ...

microcontroller and secondary (back-up) computer based on an

Atmel Atmel Corporation was a creator and manufacturer of semiconductors before being subsumed by Microchip Technology in 2016. Atmel was founded in 1984. The company focused on embedded systems built around microcontrollers. Its products included micr ...

ATMega2560 microcontroller. The flight computer is the central control unit of the satellite responsible for maintaining the normal operating mode of the satellite, monitoring and control of energy resources, control of attitude determination sub-system and performance of telecommands received from the satellite ground station in Vilnius University,

. Secondary flight computer is based on Arduino. It ensures limited but safe functionality of the satellite in case of the main CPU failure and will also take and record the first pictures made from space, as well as control the radio beacon of the satellite.

Payload

The main payload is

amateur radio Amateur radio, also known as ham radio, is the use of the radio frequency spectrum for purposes of non-commercial exchange of messages, wireless experimentation, self-training, private recreation, radiosport, contesting, and emergency communic ...

FM mode V/U voice repeater. It operates on 145.950 MHz uplink (PL 67 Hz CTCSS) and 435.180 MHz downlink. The FM repeater subsystem identifies itself with callsign LY5N. The first filter of repeaters receiver is 15 kHz wide, second is 12 kHz. The transmit filter is set to +/- 5 kHz, and bandwidth to 10 kHz, but this width depends highly on the incoming signal width, for example if the uplink signal is 15 kHz wide, it will be cut down with 12 kHz filter. The repeater payload was engineered and developed by Žilvinas Atkočiūnas and Žilvinas Batisa. Due to temperature changes, the downlink frequency may be shifted down by 5 kHz.

Power supply subsystem

The power supply sub-system includes a GomSpace Nanopower P31u power board with a lithium-ion battery and solar cells.

Communications subsystem

Comm subsystem consists of

AX.25 AX.25 (Amateur X.25) is a data link layer protocol originally derived from layer 2 of the X.25 protocol suite and designed for use by amateur radio operators. It is used extensively on amateur packet radio networks. AX.25 v2.0 and later occupies t ...

transceiver and corresponding antennas. He-100 COTS transceiver is used for establishing and maintaining radio communication with the ground station. The key technical specifications of the radio transceiver are as follows: * Operating frequencies: TX: 437 MHz / RX: 144 MHz * Sensitivity: -104.7 dBm @ BER 10-3 * Transmit power: 100 mW – 2 W * Receive power: < 200 mW * Data transfer rate: 9600 bit/s * Data protocol: AX.25 * Operating temperature: from -30 to +70 °C

Antennas

There are 4 monopole antennas on LS-1: three UHF antennas and one VHF antenna. Each antenna is made of approx. 0.2 mm thick and 5 mm wide spring steel measurement tape. In deployed configuration, all UHF antennas are pointed towards the Z+ body axis direction and VHF antenna is pointed toward –Z body axis.

Mission control

The satellite is commanded from Vilnius University amateur radio station, LY1BWB. Ground control software is written in Erlang and has a web interface, served by

Yaws Yaws is a tropical infection of the skin, bones, and joints caused by the spirochete bacterium ''Treponema pallidum pertenue''. The disease begins with a round, hard swelling of the skin, in diameter. The center may break open and form an ulce ...

. The source code of the software is partly available for public use. Communication is done using custom protocol, which is built on top of reduced set of

and handles full-duplex data transfer, when required. Recent versions of ground control software support direct upload of binary

telemetry Telemetry is the in situ data collection, collection of measurements or other data at remote points and their automatic data transmission, transmission to receiving equipment (telecommunication) for monitoring. The word is derived from the Gr ...

files, which were collected and sent to ground control by amateur radio operators worldwide.

OSCAR status

On June 8, 2014, AMSAT-NA OSCAR number administrator Bill Tynan, W3XO, stated that "LituanicaSAT-1 has met all of the requirements for an OSCAR number" and assigned the designation of LO-78 (LituanicaSAT-OSCAR 78) to the satellite. The team of engineers subsequently announced that it will try to keep the onboard FM repeater operative for the rest of the mission.

References

External links

Project web page

LituanicaSAT-1 YouTube channel

A three-dimensional view of the satellite
{{use dmy dates, date=August 2013 2014 in Lithuania Spacecraft launched in 2014 Satellites orbiting Earth First artificial satellites of a country Satellites of Lithuania Student satellites Satellites deployed from the International Space Station