TURKSAT-3USAT to launch with V/U Linear Transponder

Preparing for TAMSAT linear transponder tests

Preparing for TAMSAT linear transponder tests

TURKSAT-3USAT is a three unit CubeSat built jointly by TURKSAT and the Istanbul Technical University (ITU).

Members of AMSAT-TR (TAMSAT), the Turkish Amateur Satellite Technologies Organisation, have designed and implemented a V/U linear transponder for the satellite to provide amateur radio SSB/CW communications. The transponder input is 145.940-145.990 MHz and the output is 435.200-435.250 MHz, there will be a CW beacon on 437.225 MHz.

TAMSAT V/U Linear Transponder Test

TAMSAT V/U Linear Transponder Test

The VHF/UHF transponder and all other subsystems, except the stabilization, are doubled for redundancy. Where possible, both COTS systems and in-house development are employed.

The power is provided using solar panels and lithium polymer batteries together with super capacitors. Satellite stabilization is accomplished using passive magnetic attitude control system with hysteresis rods. There is a camera payload to take images of the Earth.

TURKSAT-3USAT is expected to launch on April 26 at 0413 UT on a CZ-2D rocket from the Jiuquan Space Center into a 680 km Low Earth Orbit (LEO). The satellite has a de-orbiting system which will make it re-enter the atmosphere at the end of its operational life.

On February 9, 2013 TAMSAT President A. Tahir Dengiz, TA2T, and Vice-President Barış Dinc, TA7W, were at the laboratory in the Istanbul Technical University (ITU) where tests were carried out on the transponder.

TAMSAT team celebrating a successful test

TAMSAT team celebrating a successful test

Further information and pictures of the preliminary testing of the V/U transponder are at
http://www.tamsat.org.tr/tr/turksat-3usat-is-almost-ready/

Read the paper TURKSAT-3USAT: A 3U Communication CubeSat
http://www.nanosat.jp/images/3rd/pdf/%5BNSS-03-0409%5D_TURKSAT-3USAT_A_3U_COMMUNICATION.pdf

Read more on the TAMSAT website which can be seen in Google English at http://tinyurl.com/TurkeyTAMSAT

Facebook https://www.facebook.com/tamsat.amsattr

Twitter https://twitter.com/tamsat_tr

YouTube http://www.youtube.com/user/tamsatvideo

F-2 nanosatellite

Conceptual design of F-2 nanosatellite (by FSpace)

Since 1957, with more than 50 years of exploring space, the lower thermosphere (90-320 km) is the least explored layer of the atmosphere. Satellites and space stations usually orbit at altitude over 320km (to increase orbital lifetime) Atmospheric Explorers were flown in the past in highly elliptical orbits (typically: 200 km perigee, 3000 km apogee); they carried experiments for in-situ measurements but the time spent in the region of interest below 320 km was only a few tens of minutes. Nowadays, sounding rocket flights provide the only in-situ measurements. While they do explore the whole lower thermosphere, the time spent in this region is rather short (a few minutes), there are only a few flights per year and they only provide measurements along a single column. Powerful remote-sensing instruments on board Earth observation satellites in higher orbits (600–800 km) receive the backscattered signals from atmospheric constituents at various altitudes. While this is an excellent tool for exploring the lower layers of the atmosphere up to about 100 km, it is not ideally suited for exploring the lower thermosphere because there the atmosphere is so rarefied that the return signal is weak. The same holds for remote-sensing observations from the ground with lidars and radars.

QB50 is an international network of 50 CubeSats for multi-point, in-situ measurements in the lower thermosphere and re-entry research proposed by the von Karman Institute. It has the scientific objective to study in situ the temporal and spatial variations of a number of key constituents and parameters in the lower thermosphere (90-320 km) with a network of 50 double CubeSats, separated by a few hundred kilometres and carrying identical sensors. QB50 will also study the re-entry process by measuring a number of key parameters during re-entry and by comparing predicted and actual CubeSat trajectories and orbital lifetimes.

The multi-point, in-situ measurements of QB50 will be complementary to the remote-sensing observations by the instruments on Earth observation satellites and the remote-sensing observations from the ground with lidars and radars. All atmospheric models, and ultimately thousands of users of these models, will benefit from the measurements obtained by QB50 in the lower thermosphere.

F-2 is a 2U CubeSat mission proposed by FSpace laboratory, FPT University to participate in QB50 project based on experience of FSpace team working in F-1 CubeSat project. The mission goals are to:

  • Collect scientific data of the lower thermosphere (from 330km down to 90km).
  • Demonstrate practical application of CubeSats, especially in a constellation of 50 CubeSats and a network of multiple ground stations around the world.
  • Providing an opportunity to experiment new technology, Commercial Off The Shelf (COTS) products such as testing a smartphone in space as an onboard computer for a nano-satellite

Besides these goals, F-2 project also has strong educational objectives such as providing hands-on-project experience on a space project to engineering/science students and promoting international cooperation/capacity building among universities around the world.

 

PhoneSat project

NASA Ames Research Center continues work on its PhoneSat project, which is demonstrating the ability to build very-low-cost satellites using Android smartphones as processors.

Ames has built two versions of the PhoneSat – PhoneSat 1, which costs about $3500, and PhoneSat 2, which costs just under $8,000. Both versions are based on HTC Nexus One smartphones. The first PhoneSats are scheduled to be launched aboard an Orbital Sciences Corporation Antares launch vehicle. The launch, funded under the Commercial Orbital Transportation Services (COTS) program, is scheduled for the third quarter of 2012. It will carry two PhoneSat 1 satellites and one PhoneSat 2. A second PhoneSat launch is expected to occur in 2013.

Student High-Voltage Satellite Horyu-2

Horyu-2 Structural Thermal Model

Horyu-2 Structural Thermal Model

The student built amateur radio microsatellite, Horyu-2, featuring a High Voltage (300v) Solar Array experiment and an onboard camera is planned to launch on an H-2A rocket in the Summer.

Built by students at the Kyushu Institute of Technology (KIT) HORYU-2 is 350 * 310 * 315 mm and mass is 7.1 kg. It will be launched into a Sun-Synchronous 680 km orbit with an inclination of 98.2°. The TLE’s for tracking are available at http://kitsat.ele.kyutech.ac.jp/Documents/ground_station/TLE.txt

The satellite’s callsign is JG6YBW and radio amateurs are asked to listen for the 437.375 MHz  (+/- 9 kHz Doppler shift) Morse Code or 1200 bps AX.25 GMSK telemetry downlink.

There will be a monthly competition for those who send data received from the telemetry to the KIT server, via the HORYU-2 telemetry analysis software.

The free HORYU-2 telemetry software and details of the competition can be downloaded from
http://kitsat.ele.kyutech.ac.jp/Documents/information_launch_english.html

Among the experiments to be carried out are:

300V power generation in LEO
In recent years, satellite size and power keep increasing. For large space platforms such as a space station, it is necessary to generate and transmit the power at a high voltage to minimize the Joule heating loss or the increase in the cable mass. It has been known that in LEO a solar array with a negative potential of 100 to 200V with respect to the plasma can suffer electrostatic discharge. Because of this, ISS power system was limited to 160V generation and 120V transmission. Generally speaking the transmission power is proportional to the square of the voltage. For a large space platform which requires 1MW-class power, such as a space hotel or a space factory, power generation at a voltage of 300 to 400V is required. The present HORYU-2 mission, 300V power generation in space without any discharge, is the first space environment test of the new technology that will be strongly demanded in near future. Also, as the satellite power employs higher voltage, there will be more demand for spacecraft charging mitigation

Demonstration of COTS surface potential meter in space (Trek)
This mission demonstrates a surface potential meter in space. The potential meter has been developed by TREK, Inc. aiming for terrestrial commercial application. It is a contact type potential meter with extremely large input impedance so that the contact does not affect the charging state of the specimen. KIT is currently working with TREK, Inc. to convert the potential meter for extreme environments such as space or plasma processing chamber. The in-orbit demonstration is a part of the joint research program. To put the COTS device on HORYU-2, the electronics board and the consumed power have been reduced significantly.

When HORYU-2 passes through the aurora zone, differential charging may develop between the insulator surface and the satellite chassis. The potential meter will measure the potential of the insulator that is the same material to be used for SCM. The two measurements are compared to validate against each other.

Debris observation with debris sensor
This mission aims at detecting the micro-debris impact on the surface of HORYU-2. Space debris has become a serious threat to satellites in orbit. Observation of micro debris less than 1mm has been very difficult. The debris sensor consists of many conductive thin wired laid down in parallel in the area of 8×8 cm. Upon impact, some of the lines are cut and the resistance becomes infinite.

Taking photographs of the Earth
This mission aims at taking the pictures of the Earth using a small CMOS camera. The camera called SCAMP (Surrey Camera Payload). It was developed by University of Surrey, a sister university of KIT. SCAMP takes a picture in a JPEG format of 640×480. From 700km altitude, one pixel corresponds to 1.6km.

Horyu website in Google English http://tinyurl.com/HoryuSatellite

Development of High Voltage Technology Demonstration Satellite, HORYU-2
http://kitsat.ele.kyutech.ac.jp/Documents/Nano-satellite-symposium-Final-paper_nishimura.pdf

Cubesats and low cost launchers open space to many more users

Cubesats and low cost launchers open space to many more usersTowards the end of 2012, a tiny satellite the shape of a cd rack will be blasted into space on top of a converted intercontinental ballistic missile, then be hurled into orbit by a spring-loaded pod. Although dwarfed by communications and military satellites, the launch of the UK Space Agency’s first nanosatellite will mark a milestone: kicking off a satellite industry for the rest of us.

By the time UKube-1 launches, it will have taken less than two years to move from concept to orbit – a dramatic reduction in time compared to most satellite launches – and will open space research to hundreds of organisations.

Clyde Space only got the go-ahead to proceed with its design from the newly formed UK Space Agency in November 2011. But speed is the essence of development in the burgeoning area of nanosatellites and calls for a different approach. The boxy shape of the UK‘s first official ‘cubesat’ is a testament to an approach that is all about using commercial off the shelf (COTS) parts and concepts to open space up to a wider variety of users.

Jamie Bowman, principal embedded systems engineer at UKube-1 participant Steepest Ascent, says: “The use of COTS means the barrier to entry for a small company is lower. Within the cubesat community, we are trying to commercialise the concept.”

Speaking at the 2011 Summer CubeSat Workshop earlier in the year, Clyde Space CEO Craig Clark said the rationale behind UKube-1 is to demonstrate the UK‘s space capability, as well as to encourage students at schools and universities to take part in experiments aboard the probe. The five payloads represent a mix of commercial and academic projects.

For example, alongside a payload that will allow avionics company Astrium to build more secure satellites by using cosmic radiation to generate true random numbers for use in encryption is myPocketQub, a host for experiments that will allow one user every day for a year to upload software and run it. “It’s an open source approach to doing space experimentation,” says Clark.

The payload experiments are coordinated through the Mission Interface Computer (MIC) developed by Steepest Ascent. “The MIC performs all the housekeeping tasks, such as gathering data, processing it and getting it back down to the ground,” says Bowman.

The original concept for the cubesat came from Stanford University professor Bob Twiggs, who worked with colleagues at his institution and Cal Poly to develop the hardware.

According to Cal Poly professor Jordi Puig-Suari, the overall design of the cubesat came down to the availability of components at the end of the 1990s. They settled on a 10cm cube as this could comfortably hold a small stack of PC/104 embedded computer and peripheral boards.

The basic cube, however, proved too restrictive and even the first launch violated the original standard. One of the satellites was a double height or 2U model; the other, an even taller 3U design. But, by adopting the same 10 x 10cm footprint, a 1U, 2U or 3U probes can be loaded into a spring loaded Poly-PicoSatellite Orbital Deployer (P-POD), which can accommodate up to three cubesats. Standardisation on footprint makes booking a launch far less of an issue: it’s still possible to mix and match cubesat sizes within a single P-POD.

By 2010, more than 30 cubesats had made it into orbit. The form factor is now common enough for launch companies to put P-PODs into their rockets without knowing who will rent that space beforehand. Cubesat developers do not have to aim for a specific launch slot; they can develop their system in the knowledge that someone, somewhere will be willing to send it into space. The ready availability of launchers makes it easier for companies to get involved in space projects: one of the reasons why UKube-1 is seen as a useful first step in building the UK‘s expertise in satellite technology.

Steepest Ascent itself was not created as a space company. “But we want to be able to allow people to do signal processing in space,” says Bowman. “We started our first space contract two and a half years ago, developing a payload. Then came the opportunity to fund a PhD position in space technology. Then we thought ‘what about cube satellites?’ And maybe how to communicate between cubesats: you might fly a swarm and want to communicate between them.

“At about the same time, the space innovation and growth team was being formed by the UK Government. Through that, we met Clyde Space, which was leading the UK project and it had a requirement to develop an onboard computer,” Bowman explains.

The focus on low development time and cost results in different approaches than for conventional satellite development. Whereas many large satellites will employ components that have gone through years of testing to determine their behaviour under the levels of intense radiation encountered beyond the Earth’s atmosphere, cubesat developers will often use standard commercial parts. One such part is Texas Instruments’ MSP430 microcontroller. Originally developed for smart energy meters, the mcu has a reputation for very low power consumption, vitally important to a satellite that will be put into a sun synchronous orbit. Deriving all its power from solar panels, the satellite will enter eclipse for some of the day and the designers need to be sure its batteries will not run dry during that time, so the focus is on low power silicon.

“The MSP430 is kind of the mcu of choice for cubesats. A lot of companies have gone down that route, but they don’t do a space version. A lot comes down to how you use COTS in space,” says Bowman.

Companies such as Steepest Ascent put time into finding ways to avoid the problems caused by cosmic radiation that can knock unhardened electronics completely out of action.

One approach to ameliorating the effects of radiation is to use triple modular redundancy (TMR). Three sets of electronic circuit are used for each function and vote on the output to weed out errors caused by stray alpha particles that may flip a control or memory bit.
However, this is expensive to do across the board.

Steepest Ascent has focused its use of TMR on the core hardware state machines and I/O ports. The company chose to use an fpga from Microsemi’s antifuse based SX family. Antifuse devices are commonly used on satellites because the programming elements are almost immune to radiation, so the protection only needs to focus on latches and registers. TMR is used in some of the SX based circuits to ensure ‘the I/O signals are as clean as possible’, says Bowman.

Focused use of TMR makes it possible to relax the radiation hardness requirements on other parts of the board. For the signal processing portion of the MIC, Steepest Ascent chose to go with another fpga.

“We do a lot of mcu and fpga hybrids and we tend to favour doing dsp on fpgas,” says Bowman. “We can do operations in parallel and can tailor bit widths. If 27bit precision is all you need, you have an overhead trying to use a 32bit dsp for those calculations. We do a lot of work on LTE for wireless communications and, in those technologies, it’s probably going to be an array of fpgas, rather than a dsp. You can achieve teraMAC performance and you could not get that from one dsp.”

For the signal processing fpga, Steepest Ascent picked another Microsemi part – this time, the flash based ProASIC 3L. “ProASIC 3L parts are not quite as radiation tolerant as the SX antifuse parts,” says Bowman. “However, it’s still more than what we need for this project, plus we can also get an ARM core onboard.”

Microsemi licenses the ARM Cortex-M1 microprocessor core so that it can be implemented by its fpga customers.

“The ARM core has a lot more processing power than the MSP430,” says Bowman. “But, at the same time, cubesats have to be very, very power efficient. So the idea was to keep the MSP430 running and power down the fpga when it is not needed.”

Runtime checks will monitor the behaviour of the non-TMR circuits and allow one of the processors to power cycle the other if it starts misbehaving. “We took some other precautions, such as not using PLLs: they don’t like space at all,” says Bowman.

The MIC will use several gigabytes of memory – again based on commercial devices. “It’s a complicated design for cubesats,” says Bowman. “We have spent a lot of time on component selection: it’s a matter of gathering different test reports. However, although many 4Gbit devices have been tested, we are using 8Gbit parts. There is a question of how much you can extrapolate from previous tests. We think we have made a sound choice, but we can’t go and test these devices ourselves.”

At the circuit level, the memories are redundant and powered down between uses. According to Clark, a good rule of thumb among the cubesat fraternity is to use different makes of memory as they are unlikely to share identical failure modes.

The UKube-1 project is pressing ahead with the construction of a flight model that should be ready by the end of January and which will be used in environmental tests. Then the final satellite will be put together and enter its testing phase in July. “We are almost in the home straight: it will all happen in the next four or five months,” says Bowman.

After that, the cubesat will be packed into its P-POD ready to be flung out into space, falling into orbit around 650km above the surface of the Earth. According to Clark, the mission is scheduled to last for just one year, but UKube-1 has been designed to last for at least four.

“The mission is dedicated to payloads and gathering data from them and then it will be about gathering performance statistics. After that we would hand it over to the amateur satellite people. We can learn a lot about the process of operating a satellite like this during that time,” says Bowman.

In the UKube-1 mission, the signal processing functions on the main fpga will be fixed. “In future missions, we would look at reprogramming it more regularly to change the algorithms to suit different payloads,” says Bowman. Missions such as UKube-1 will make it possible to explore how techniques traditionally considered too risky to pursue – such as reprogramming fpgas in orbit – can be exploited in future swarms of low cost satellites.

Author
Chris Edwards

Supporting Information

Downloads
39400P16-18.pdf

Websites
http://www.clyde-space.com
http://www.microsemi.com
http://www.steepestascent.com

Companies
Clyde Space Ltd
Microsemi

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