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When you think of outer space, what would you relate it to? My guess is physics, astronomy and maybe black holes. What about subjects such as biology, ecology or geology? Sure, the exploration of our galaxy relies heavily on spacecrafts that bring astronauts there. However, in recent years, scientists have been studying planets both in and out of our solar system in search for the ones habitable for human beings. Their soil composition, native microbes and physical properties are being studied. A renowned example would be Mars.

An artists impression of the planet TRAPPIST-1f.

The TRAPPIST-1f is one of the planets in the TRAPPIST-1 system, discovered in early 2017 by NASA’s Spitzer Space Telescope.

Illustrated above is the possible surface of the planet.

Image credits: NASA/JPL-Caltech

In the GreenSat team, there are currently more biologists than engineers. However, in BLUEsat UNSW as a whole, the engineering teams dwarf the biology team, which could make the experience quite daunting when you first get on board. Since we are only a small division of students, each of us work on our own individual projects rather than working in pairs or groups. Such projects may include researching growth rates of certain bacteria species, finding out how chemicals circulate through plants with the help of microorganisms or even coming up with a simple experimental plan for our future projects. Sounds fun right?!

So how exactly do we work with the engineers? While the engineers come up with how to build the awesome gadgets and devices, we are the ones to relay them the parameters of those builds. The beginning of all scientific projects starts with the solid foundation of background research. In this part of the study, both biologists and engineers take part in as we all have our own areas of expertise, so everyone can share our discoveries afterwards during meetings. After combining our research, the engineers will be informed of the requirements needed for the devices built before deciding on how to build it, what materials are needed, how should the design look (we even have an Industrial Design student helping us out!) and a deadline for its completion. Subsequently, testing and modifications are needed to ensure the satellite is in full function for launch.

As a biologist, my knowledge of physics and mathematics is very limited, which is why communication between the engineering and biology departments is vital. No, we don’t use scientific terminology in Latin or sophisticated 50-page experiments to confuse them. Instead, we try to present the general idea of our work to them in simple words and then go into greater detail. Effective science communication is after all an important skill learnt as science students, as you are not always presenting to your fellow scientists.

If you think this sounds easy, then don’t stop reading, because the duration of these procedures combined could take years! In 2016, as part of the QB50 mission, UNSW launched its CubeSat – EC0, of which from research to finalising the build took around 5 years. During the background research stage, problems upon problems are faced and we need to keep searching for solutions. One of the many challenges faced sometimes is creating more problems upon finding a fix, which is very frustrating. In addition, don’t forget about the spacecraft’s objective in space. You don’t want to launch a device and just let it burn up in the atmosphere for nothing. Subsequent monitoring and communication with it through telecommunications systems are crucial to ensure that it is functioning properly in space.

An artists impression of UNSW's EC0 satellite.

Close-up image of the UNSW-EC0.

Image credits: ASCER, UNSW

If you are a scientist interested in the space race, there is no need to worry about fitting into the world of engineers. There is always help needed and you will always find a cool project to work on. Does this tickle your fancy? Join the GreenSat team to find out how you can get involved!

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Following on from my previous blog post on Hybrid Rockets, I’ve been working on putting together a functional prototype. The core aim of my thesis is to evaluate the performance of various 3d printed Fuel grains.  As such, this prototype had to be able to handle a variety of different fuel cores.  The results weren’t perfect, but I was able to get some fantastic data from my research. This blog will provide an overview of my prototype rocket engine with a nice video at the end of it being fired.

In the image below it can be seen that hybrid rockets consist of a few distinct parts:

  • Oxidizer tank – Holds a variety of oxidizers for the system. For this test I am using Gaseous oxygen, but Hydrogen peroxide or Liquid oxygen are also great choices.
  • Pumping unit – Pressurizes the oxidizer. The Oxidizer tank that I am using is already pressurized so I can skip this stage.
  • Solid Fuel core – A Tube or hollowed out section of a fuel material. There are many types of fuel that a hybrid rocket can utilize, from paraffin wax to Polyethylene. For my thesis I am examining 3d printed fuel cores, so I have chosen to use ABS plastic.
  • Nozzle – Channels the expanding gasses from the system, accelerating them to supersonic speeds. The test prototype in this article has a ceramic nozzle, but due to a lack of a pre-combustion ignition stage, it cannot be used.


Diagram depicting a hybrid rocket engine. From left to right: Oxidiser Tank, Pumping unit, solid fuel core, nozzle
Hybrid Rocket Engine

The first step of this project was to 3D print a fuel core. The construction of the core is quite simple, being a 50mm tube of ABS plastic with a 10mm hollow core. Both the lead in and lead out of the core had a bevel to allow for better oxidizer flow.  The print took 8hrs total and used 150g of ABS plastic.

A 3D Printer printing a fuel core.
3d Printing Fuel Grain


With the core printed, the components could be assembled. From left to right we have the rockets nozzle, the fuel core and housing unit, the oxidizer inlet and a oxidiser lead-in to prevent blowback.  All parts are commonly available pipe fittings.


From left to right: rockets nozzle, the fuel core and housing unit, the oxidizer inlet and a oxidiser lead-in to prevent blowback.
Engine Components

With the parts assembled, I secured them to an aluminium bed attached to an elevated stand. The oxygen tank was then attached to the system.

The rocket engine parts assembled and attached to an aluminium plate.
Engine Test bench

For the test itself I removed the nozzle. Experimentation with igniting the system revealed that the nozzle prevented initial combustion. Future experiments will have a pre-combustion ignition stage, likely using a spark plug assembly near the oxidizer inlet.

The assembled rocket engine with the nozzle removed ready to fire.
Ready For Firing

With the system assembled it was ready to fire. I recommend turning on captions in the video for more information about the process.


The results of this experiment have been good. I was able to demonstrate that the ABS fuel core could be ignited and that the experimental setup works as intended.  Pay attention to this blog in the next few months as I continue to improve on this experimental setup.

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Welcome to our February monthly update, its been another busy month at BLUEsat UNSW. As well as an amazing o-week, our teams have made massive progress across the board. Highlights include our Balloon Team’s launch on the 3rd of March, and major progress in the construction of the NUMBAT Mars Rover.

RoverNewly constructed chassis of the NUMBAT Mars Rover.

From the Mechanical Team

The mechanical team has been busy this Month assembling the chassis and drive systems of our rover.  We have also been conducting training of our new members, teaching them how to use different CAD packages as well as manufacturing techniques such as laser cutting, 3d printing and CNC routing.

Thomas Renneberg, Robotics CTO & Mech Chapter Lead

From the Software Team

The rover software team have been preparing for BLUEsat’s orientation day. We have an Arduino workshop prepared for the day. The weeks following will also contain some introductory workshops to how we operate, including a seminar or two on the Robotic Operating System (ROS).

Meanwhile, we have continuing development on a number of key rover systems including the GUI and embedded ROS. In addition, we received two new members (Yubai & Daigo) and are looking forward to even more with the start of the new semester!Altium render of the NUMBAT Rover side module board

Simon Ireland, Rover Software Chapter Lead

From the Electrical Team

The electrical team has made progress in a few projects. We received two new members and introduced them to the society. With their help we’ve also fixed some components on our old Mars Rover BLUEtongue 2.0 so that it can be driven properly. The last major PCBs for the NUMBAT Rover – the side module board – has been designed and is being reviewed. Assembly is scheduled to take place in around 2 weeks.

We’re also starting the work on testing and programming the generic PCB, which will be an priority task this semester. After the electronics induction, we expect to get more of the members working on it.

Jonathan Wong, Rover Electrical Chapter Lead

Rover Electrical Team Lead Jonathan Wong with a new member and the BLUEtongue 2.0 rover, conducting repairs.

From the Chief Pilot

The rover was run each week. Some range testing was attempted, but no conclusive derivation was possible. The team has started debugging the arm. The schedule for the rover training and testing is in the works and is expected to come out soon.

Sajid Anower, Rover Chief Pilot


From the CTO (Satellites)

The satellite team this month have been busy crafting an exciting program for the new 2018 BLUESat member Intro Day. With activities spanning across the fields of engineering, science, and operations, the satellite team should be proud of themselves.

Timothy Guo, Chief Technical Officer – Satellites

From the High Altitude Balloon TeamDisassembled High Altitude Balloon Payload on a desk in UNSW's Willis Annex.

February was a fairly busy month for the HAB team. Rigging and parachute configurations were finalised. Tracking systems were tested and found to be working perfectly with some tweaking. An APRS transmitter, which updates GPS location over the amateur radio network, a commercial SPOT GPS tracker, as well as an old mobile phone, running a live GPS tracking application, are all being used on the launch. A launch date has been set for the 3rd and 4th of March, and final preparations, as well as integration testing, are currently taking place. Stay tuned for the outcome of the mission in the next update!

Adithya Rajendran, Balloon Squad Lead

From the Green Sat Team

GreenSat is moving forward, designing an temperature-controlled incubator for biological samples. We are also building a sensor suite prototype to test the electrical system. The biology team is aiming to get into the labs soon to begin working on cynobacteria samples.

Ben Koschnick, Greensat Squad Lead

From the Satellite Power TeamA dumy load used by our Satellite Power Team to test their designs.

Satellite power team has recently finished work on an electronic dummy load. We are planning to use it to test a battery charging design and a maximum power point tracker also developed by the team in the coming semester.

We also prepared for orientation day, with a complete introduction to electronics planned. New members will get a taste for electronics design by making a range finder. They will prototype the circuit, design the PCB and then manufacture it all over two weekends.

Declan Walsh, Satellite Power Squad Lead

From the Groundstation Team

Groundstation has opted to shift towards Software Defined Radio (SDR), which employs the use of USRP receivers and software demodulation. The original setup consists of radio transceivers and the various equipment needed to operate them.

This new setup offers the following advantages:

  • Better control of the demodulation stages
  • More options for processing of data
  • Easier to interface with computers

The use of SDR has been explored by some current members in the past. However it is a foreign concept to the majority of our team. We plan to place a greater focus on SDR starting with the training of new and existing members.

Joerick Aligno, Groundstation Squad Lead

From the ADCS Team

The ADCS team has been working on finalising the designs of the support PCBs to be manufactured in the next few weeks. Initial electrical and mechanical designs for the reaction wheel PCB are also in the works.

Mark Yeo, ADCS Squad Lead

BLUEsat Operations & Exec

The BLUEsat UNSW o-week stall, you can see a mars rover wheel and a satellite reaction wheel on the table.

Secretary’s Update

February has certainly been a busy month for the society. O-Week was a massive success with over a 150 new sign ups, many of whom will hopefully be attending our orientation day on the 3rd of March! A big thank you to everyone who helped at our o-week stall. All of the teams have also been preparing workshops for our orientation day.

In other news our last social event was a big success with many people attending and our regular blog posts have been going well! I’m looking forward to expanding the media team in 2018, and am looking for people to help with our outreach program and website.

Harry  J.E Day, Secretary

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The idea of intelligent alien life has been an exciting topic in the world of science fiction for a very long time. In reality, if there are any forms of extraterrestrial life within our solar system, they will most likely be microbial.

It has been hypothesised that life could have existed on both Mars and Venus, when the environmental conditions were similar to the early Earth. However, the climates of both Venus and Mars rapidly changed, with the latter getting colder and the atmosphere thinning, and the former getting hotter as the atmosphere got thicker. Until recently, it was believed that both Mars and Venus no longer had any liquid water. Sounds pretty inhospitable, right?

Surprisingly, the recent discovery of hydrated perchlorate salts suggests that briny liquid water is actually still present on Mars, flowing just below the surface only when the temperature reaches above -23oC. It has been hypothesised that potential Martian life may be halophilic (thriving in high salinity), living inside salt crystals, as they are in the image below.

Pinkish-red sodium chloride (NaCl) crystals.
Image 1: These pinkish-red crystals of sodium chloride (NaCl) are coloured by millions of halobacteria. The bacteria survive inside the salt crust, in California’s Owens Valley.


As for our ‘sister planet’, Venus: the build-up of CO2 and runaway greenhouse effect in the Venusian atmosphere resulted in the planet’s current surface temperature of 467oC and atmospheric pressure 90-100 times that of Earth, with highly concentrated sulphuric acid clouds (with pH 0 or below). Although this sounds hellish, there is a section of Venusian cloud, 50-65km above the surface, where the temperature ranges between 30-70oC, with pressure similar to Earth’s surface, where water vapour may be present. ‘Dark streaks’, containing microbe-sized, non-spherical particles have also been observed (see Image 2). Since 20% of small particles in Earth’s upper atmosphere are living bacterial cells, there has been speculation that these ‘dark streaks’ could be an indication of life in Venus’ clouds.

The planet Venus as captured by NASA's Pioneer Venus Orbiter in 1979
Image 2: Image captured by NASA’s Pioneer Venus Orbiter (1979).

In contrast, Enceladus, an icy moon orbiting Saturn has a global ocean beneath the ice crust, and active plumes. Due to tidal heating from Saturn’s gravitational field, Enceladus’ oceans have the potential to nurture multi-cellular organisms.

However, although NASA’s mantra – “follow the water” – suggests that life cannot exist without liquid water, other biosignatures (e.g. ozone, hydrogen, methane) are also important in determining a planet’s habitability. Biosignatures are substances that are unlikely to be produced abiotically (derived from sources that are not biologically active), and can be markers of life.

In 2004, methane was discovered in the Martian atmosphere. Most of the methane on Earth is produced by methanogens, which are extremophiles – organisms that thrive in extreme conditions – that metabolise hydrogen and carbon dioxide to produce methane. Methanogens do not require aerobic conditions (meaning they do not require air or oxygen), light, or organic nutrients, which means they could potentially survive just below the topsoil on Mars.

On Venus, the presence of both sulphur dioxide (SO2) and hydrogen sulphide (H2S) is unusual. These two substances have a high affinity for reacting together. One explanation for the presence of both substances is the presence of microbes that can metabolise sulphur into sulphuric acid. Another possibility could be that Venusian microbes are similar to the sulphur-oxidising bacteria that existed in Earth’s ancient oxygen-poor oceans, or the hydrogen sulphide-oxidising thermophiles (heat-loving microbes) present in hot springs.

Additionally, Enceladus’ plumes have been confirmed as the product of hydrothermal activity, due to the 1-2% presence of molecular hydrogen (H2). On Earth, hydrothermal vents producing hydrogen gas are home to methanogenic microorganisms, and are believed to be the origin of life!

Computer model of Enceladus’ plumes. Showing a cross section of the moon's crust.
Image 3: Model of Enceladus’ plumes, the proposed connection to hydrothermal vents, and liquid water ocean beneath the thick icy crust. From

However, radiation is the most significant challenge facing any potential extraterrestrial life forms.

The levels of UV radiation on Venus are extremely high, due to its’ proximity to the Sun. However, the thick atmosphere reflects a lot of radiation away, and the sulphur compounds from the clouds may act as ‘sunblock’ for potential microbial life. Despite this, life on Venus is still quite unlikely, and would be extremely difficult to detect.

Due to the lack of atmosphere, radiation exposure on the surface of Mars is 30µSv per hour (or 200 msV over 180 days) during solar minimum, compared to 20mSv per year on Earth. Although water and methane are present, life on Mars is extremely unlikely.

Ultimately, the most likely place for life in the solar system is below the icy surface of Enceladus. This is because the thick icy crust blocks most harmful UV and gamma radiation, removing the most difficult obstacle from the equation of microbial survival. Compounded by the overwhelming presence of water and potential hydrothermal vents, Enceladus seems to be the most ideal home for extraterrestrial life in our solar system.

Closer to home, our GreenSat team is currently working towards creating a satellite habitat for nitrogen-fixing bacteria. Although the Earth’s surface and some of the atmosphere is mostly habitable, once you reach space, it is a different story entirely. Our aim is to eventually develop the technologies to grow food in Earth’s orbit, or on another planet (provided that we do not colonise/wipe out any existing life forms on that planet, of course). More info can be found here.

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BLUEsat’s High-Altitude Balloon is equipped with a remote separation mechanism. Its function is to detach the payload from the balloon when we want, which gives us better control of the balloon. In the case of problems during the launch (e.g. unexpected changes in weather conditions), the ability to force the payload to separate gives us the chance to drop the payload. This article will explain the construction and operation of the separation mechanism.

The following flowchart describes the Separation Mechanism:

System flowchart of the seperation mechanism for the High Altitude Balloon. It begins with recieving a DTMF signal via an SDR Dongle on the Raspebry Pie. This can then trigger the circuit to cut the rope.
System Flowchart

The operation of the separation mechanism can be summarised as:

  1. Send a radio wave signal (433MHz) with DTMF signal
  2. The separation mechanism system receives the radio signal
  3. Nichrome wire heats up and burns rope after receiving signal.

The mechanism is split into two main modules:

  • DTMF Detection (3 blocks on the left)
  • Rope Burning Electronics (5 blocks on the right + Raspberry Pi Zero)

IMPORTANT: Read, understand and follow the laws regarding radio transmission for your country + area before attempting to transmit. There may be regulations regarding transmission output power, interference, frequency use.

DTMF Detection

The DTMF detection subsystem, as the name implies, detects radio waves with a DTMF signal embedded in. It encompasses the following concepts:

  • Reception of radio waves
  • Conversion to computer data
  • Processing of that data

Background Information


Dual Tone Multi Frequency Table. The combination of frequencies represents a number of the chart.
DTMF Table

Above is the DTMF table. By playing one of the Upper and Lower frequencies together, you can represent one of the following numbers/symbols. For example: to indicate 1, play a 697Hz and 1209Hz sine wave at the same time.

We send a DTMF sequence of numbers via radio waves (frequency modulation of 433MHz carrier wave with DTMF tones). If the DTMF sequence is correct, the output GPIO pin (Input/Output Pins) on the Raspberry Pi will change.

Equipment on Balloon:

  • Raspberry Pi w/ Portable Power supply
  • Software Defined Radio (SDR) USB
    • Such as the: NooElec NESDR Mini SDR & DVB-T USB Stick
  • Antenna (ideally receives 400MHz)

Software on the Raspberry Pi:

Equipment on Ground:

  • Radio Transceiver
  • Antenna for transmission
  • Lead Acid Battery
DTMF detection flowchart
DTMF detection flowchart

How it works:

  1. The SDR USB outputs 8-bit I/Q samples, which represent sine and cosine waves. librtlsdr allows for the SDR USB to send these I/Q samples to the host computer (the Raspberry Pi).
  2. These I/Q samples are then processed by rtl_fm (which is part of the librtlsdr package) which demodulates the signal and outputs sound data.
  3. The sound data is then processed by multimon-ng which decodes the DTMF signal (if present). If there is a DTMF signal it will output a character corresponding to the number.
  4. The character output is passed into the dtmf_separation code, which alters the output GPIO pin voltage accordingly.

Rope Burning Electronics

The Rope Burning Electronics takes in the GPIO pin output from the DTMF Detection subsystem and outputs a voltage to the Solid State Relay terminals. In the current configuration the Rope Burning Electronics can be summarised as a switch where:

  • When the GPIO pin is on (3.3V), the Solid State Relay is closed (electrical connection exists)
  • When the GPIO pin is off (0V), the Solid State Relay is open (no electrical connection)

Equipment on Balloon

  • DTMF Detection System (from above)
  • Separation Mechanism PCB (pictured below)
  • Lithium Ion Battery
  • Solid State Relay
  • Nichrome Wire
CAD Render of the custom PCB used by the seperation mechanism.
Separation Mechanism PCB

Background Information

N-Channel MOSFET

The MOSFET circuit diagram symbol

A MOSFET has 3 terminals, the Drain, Gate and Source.

The simple way to explain the operation of the MOSFET is though the relationship between the Drain-Source resistance and the Gate-Source voltage.

When there is no voltage difference between the Gate and Source, the Drain-Source resistance is large. As we increase voltage across the Gate and Source, the resistance across the Drain and Source decreases.

There is some physics which explains this phenomena, which you can read about here.


Relays are electro-mechanical components that are used to control electrical connection. They have two states: not activated (open, no electrical connection) and activated (closed, electrical connection exists).

Applying certain voltages to the input terminals, changes the state.

Note that we are using a solid state relay, which does not use mechanical components but functions very similar to a Mechanical relay.

Application to the Separation Mechanism

Circuit Diagram of the Seperation Mechanism, consisting of a 6V power source, a number of resistors, the SSR Relay, and 15V power source and the Nichrome wire.
Separation Mechanism Circuit Diagram

The Raspberry Pi operates on active low. That is, the default state of the GPIO Pin is high (outputting 3.3V), only when the DTMF sequence is received, the GPIO Pin is activated and turns low (0V).

  • When high, the Gate-Source Voltage is 3.3V causing the Drain-Source resistance to be small, which is treated as a short circuit. The output to the Solid State relay (below the 1k resistor) will be connected to 0V, which will not activate the relay.
  • When low, the Gate-Source Voltage will be 0V causing the Drain-Source resistance to be large, which is treated as an open circuit. The output to the Solid State Relay will be connected to the 6V battery through the 1k Resistor, which will activate the relay.

Activating the relay supplies 15V through the Nichrome wire (which is wrapped around the rope). This heats the Nichrome Wire, reaching temperatures high enough to melt through the rope.


Despite sounding simple, remotely burning a rope encompasses many areas of knowledge, Software, Electrical and Telecommunications. There are plans of future iteration to utilise Arduino and GPS coordinates to force separation. If you want to read more about the Balloon, you can read about it on the Balloon Page.

If you are interested in space, join BLUEsat by following the instructions here.

We actively ensure that every thing BLUEsat does and encourages remains legal. It is important to – as mentioned earlier – read, understand and follow the laws regarding radio transmission in your area and country.

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Welcome to our monthly updates, we are going to trial one of these each month to keep you updated on what’s going on at BLUEsat! January has certainly been a busy time for all of our teams here.


From the Mechanical Team

Its been a fantastic month of development. Our team finalised the rovers suspension system, a component that we anticipate will provide a great deal of stability to the platform (see image). Additionally our laser cut Chassis parts have arrived, and after a bit of post machining will be ready for fitment tests and total chassis construction. Looking ahead, the team plans to have the top and base plate of the chassis manufactured in the next few weeks.

Thomas Renneberg, Robotics CTO & Mech Chapter Lead

A screenshot of a serial terminal displaying output from BLUEsat's ROS over CAN system. Succesfully transmitting a message. The text reads "Recived Full Message. Join 'Hello CAN', pwm 100"

From the Software Team

Steady progress is being made across the team. We’ve had a few key developments in the CAN bus network, with our embedded system for publishing ROS messages now sending and the on-board computer receiving and routing the packets (the latter part in final testing). Rover Software still has a few members filtering back from holiday and with the addition of some new members (Oliver and Saksham) joining, we should have a interesting year ahead.

Simon Ireland, Rover Software Chapter Lead

A collage of images. Top left is a wooden prototype of the NUMBAT Rover with Bus PCBs laid out, right is a PCB, bottom left is testing a DC-DC converter for the BLUEtounge Rover and bottom right is a range of DC-DC converters.

From the Electrical Team

Its been a good start of the year. Altium training is on the way, and a few design projects have been proposed for the coming semester, including a pair of side module circuit boards and some optional ones such as power line filter and arm module boards. Work on power module and connector boards should be resumed shortly. There has also been a focus on DC-DC converters testing and renewal, both for BLUEtongue droving and NUMBAT construction.

Jonathan Wong, Rover Electrical Chapter Lead

From the Chief Pilot

Rover Droving has finally started again after a hiatus, and we’ve have had a number people interested in Droving. Over the last few weeks, it has been particularly difficult to get the Rover to get started, and on 27 January, the step-up transformer from the power supply to the NUC was found to be busted. A new transformer has since been ordered and arrived, and if things go according to plan, we will start full-fledged from this month. Also, I plan to start breaking down the ERC rules into smaller tasks so we can practise them.

Sajid Anower, Rover Chief Pilot

SatelliteThe Stratospheric Balloon Payload, complete with sensor loggers, etc in an insulating container.

From the Stratospheric Balloon Team

This month was very productive for balloon team. All our subsystems, including a Raspberry Pi-based data-logger and radio-controlled separation mechanism, were completed and integrated. Ultra-low-temperature testing was conducted in a laboratory fridge set to -70C over the period of 30th-31st January in order to simulate stratospheric temperature conditions that will be experienced on a flight. This testing highlighted some weaknesses in our payload construction, such as power supplies not operating at low temperatures, and measures will be taken to remedy them. We had planned a launch for early February, but that has been pushed back to late February due to unforeseen circumstances not pertaining to our development.

Adithya Rajendran, Balloon Squad Lead


From the Green Sat Team

Steady progress has been made on designing experiments for the biology team. With help from our friends at Flinders University we designed a incubator capable of controlling the intensity and wavelength of light available for a sample. This will give us valuable information about the on-board conditions required on the GreenSat and minimise the energy requirements of the payload.

Ben Koschnick, Greensat Squad LeadDeclan Walsh working on the dummy load.

From the Satellite Power Team

The satellite power team focussed on completing several prototype designs this month. The designs for a variable test load were finalised and the components ordered. Prototype designs of a Lithium battery charger were also completed with testing of the design to occur next month. Finally, testing of the teams power regulators in low temperatures was also undertaken in conjunction with balloon team.

Declan Walsh, Satellite Power Squad Lead

From the Groundstation Team

Laser Communication

We have achieved transmission of:

  • Serial Data: Laser on/off is used to send binary data (1’s and 0’s). By reading the voltage across a photoresistor, we can obtain the binary data.
  • Audio Data: By controlling the voltage through the laser, we can control the intensity of the laser, which we can obtain analogue data.

We plan to improve on both systems to a point where we can implement either into a PCB.

Balloon Telemetry

Recently, the Groundstation team has partnered with the Balloon team to implement telemetry. We have decided to use a ‘Pi in the Sky’ telemetry board to send data from the payload which is received and processed by a ‘USRP SDR’. We will research how to use the ‘Pi in the Sky’ board over the coming weeks.

Joerick Aligno, Groundstation Squad LeadCAD rendering of a PCB for BLUEsat's ADCS v3

From the ADCS Team

Development of Reaction Wheel v3 is underway with 5 PCBs already designed. These boards contain the supporting hardware for the reaction wheel board, including power supply and regulation, an on-board computer (OBC), a data logging sensor board, an ADCS central hub and a mini groundstation for communicating to and commanding the reaction wheel while the experiment is in motion.

Mark Yeo, ADCS Squad Lead

Operations & Exec

Secretary’s Update

Its certainly been a busy start to the year. The main focus of the media and events team has been ramping up to o-week, and we have a lot planned for that with more to be finalised in the coming weeks!

We’ve also been trailing a new on-boarding approach where we will be running a structured session every three weeks rather than accepting new members every week. This came as a result of a survey we did last year on onboarding and our recruitment process and aims to help improve member retention in the first few months. It should also give our team leads more time to focus on their projects in between. A big thanks you to Taofiq for spearheading that project!

Our regular social evenings are going well, and we had a very successful “Jackbox Games” night a few weeks back after our Saturday workday.

Finally I’m very pleased to see the first release of our monthly updates and our email news letter! These should help improve awareness of the societies projects, recruit new members, and improve our internal communication between teams. I’m looking forward to seeing them in the following months.

Harry  J.E Day, Secretary

A CAD rendering of the NUMBAT Mars Rover in "space"


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Whether it is a microscopically-small bacterium, a 90-metre-tall Redwood Tree, a 750-legged millipede or just a human, it is well known water and carbon compounds are critical molecules for survival. However, in addition to these elements (oxygen, hydrogen and carbon), nitrogen cannot be forgotten as an essential element to life itself. Nitrogen’s importance should not be surprising, considering that ~78% of the atmospheric make-up of this planet is gaseous nitrogen. It would be implausible not to have it as a building block for life on Earth when it is in such great abundance. The GreenSat team is currently working on an exciting project investigating nitrogen processes and its importance in agriculture, with the potential of growing crops for human consumption in space.

Nitrogen’s importance cannot be underplayed. For example, it is a fundamental component that makes up DNA. DNA consists of four nitrogenous1 bases (Fig 1) and these four units attribute to making every living being on this planet unique. DNA’s two strands (Fig 2) contain a unique line of code made of these four bases: A, C, G, and T (Fig 1). It is the combination of these units and the unique sequences they are in that makes up genes and genomes of whole organisms. The sequence of these bases in DNA is the fundamental difference between a human and a mouse, or a human and a banana (although the genetic similarity between a human and a mouse is ~90% and between a human and a banana is 50%!). In addition to making up DNA’s structure, nitrogen is essential to life because it is a component in the structure of proteins-includes enzymes that break down the food we eat and antibodies that fight diseases that invade our bodies (Fig 3).


Diagram representing the molecular structure four nitrogenous bases that make up DNA. (Adenine, Thymine, Cytosine, and Guanine)
Fig 1: The four nitrogenous bases that make up DNA. The units A, T, C and G are known as Adenine, Thymine, Cytosine and Guanine respectively. They all contain nitrogen as seen, however each has a different number or positioning of nitrogen on the carbon rings.


Diagram breaking down DNA into strands and then showing how the nitrogen bases exist in those strands.
Fig 2: DNA’s structure is a double helix, represented by the two ribbon-like strands (i). The nitrogenous bases that run over the entire length of both strands of DNA are opposite each other on each strand and are what bond the two strands together(ii). One base is on one strand of DNA and the other complimentary base is opposite on the other strand of DNA. The bases pair together A with T and G with C, held together by hydrogen bonds (iii).


The irony is that even though this life-depended element may be the majority of the atmosphere’s composition, the vast majority of living organisms (including humans) cannot obtain and use it from the air. All atmospheric nitrogen that is taken in when we breathe is just exhaled again. Nitrogen in the atmosphere exists as a gas, N2, with a triple bond between two nitrogen molecules and this gaseous, stable and inert state cannot be broken down by most living organisms because it requires a lot of energy to pull this molecule apart and use the nitrogen atoms.

Nitrogen helps make up protein structures including those that make antibodies.
Fig 3: Nitrogen is in many proteins that we need to survive. Proteins are structural chains made in our cells and are usually represented as curled helix and coils (left). They form very specific structures despite looking like a chaotic mess, and an example of a very important protein is an antibody (right). There are many different types of antibodies and each with their own unique shape especially designed to attack a specific disease as shown.


Humans and other mammals can only take in nitrogen when it is in an organic form (Fig 4). All the nitrogen that animals need and use is made accessible by bacteria (also known as harmless ‘bugs’) living in soils. They are the only living things that can take gaseous nitrogen from the air and combining it with hydrogen or other elements to make inorganic compounds (Fig 4). These compounds are subsequently taken up from the soils through the roots of plants, such as vegetables or grasses, and turned into usable organic compounds for building DNA or proteins. The process by which bacteria can convert gaseous nitrogen into inorganic compounds (such as ammonia) is known as nitrogen fixation and is carried out by multiple specific groups of bacteria known as nitrogen-fixing bacteria (Fig 4). It is because of these bacteria we get our nitrogen source, whether it is directly eating plant products (such as vegetables) or through eating livestock and other animals (such as fish) that have eaten plant matter, thus carrying the nitrogen through the food chain. Without these bacteria that live in soils we would not be able to get the nitrogen source we need to stay alive and healthy.



Atmospheric Nitrogen is transformed by nitrogen-fixing bacteria into inorganic nitrogen compounds which are then transformed into organic componds by plants.
Fig 4: Simple diagram of nitrogen fixation showing different nitrogen states created firstly by bacteria and secondly by plants.The organic compounds can then be obtained by organisms such as mammals (e.g. humans) when consuming plants such as cereal crops (e.g. corn).

GreenSat is currently focusing on the potential of nitrogen-fixing bacteria due to the vital process of nitrogen fixation in agriculture. Nitrogen is a fundamentally important element to life on Earth and we cannot exist without it- although this cannot be necessarily said for life on other planets without a nitrogen-rich atmosphere. Nevertheless, from a huge ecosystem narrowed down to an individual species, to a single organism, to a small cell and lastly to DNA, nitrogen is abundant and necessary for life on Earth.

1containing nitrogen

– Scarlett Li-Williams


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One objective of the BLUEsat High-Altitude Ballooning Mission is to acquire data about flight dynamics and atmospheric characteristics. The payload includes an assortment of sensors connected to a Raspberry Pi, which logs the sensor outputs to an SD card to collect the required data during flight.

Assembled High Altitude Balloon Sensor System
Assembled Sensor System

The code was written in Python and the necessary modules had to be installed to interface the code with the sensors, which will be covered here for each sensor. Please refer to our GitHub repository for all our code related to this project.

Getting Started

First, purchase a good-quality SD card from a reputable seller. I prefer to use a 32GB card so there is extra room for future uses, but if you are using it to record your flight with a Pi Camera, then I would recommend a 64GB card due to the storage requirements of the HD video and images.

This tutorial assumes you are going to be using the Raspbian Stretch OS on your SD card. Download the latest version from the Raspberry Pi website here, and extract the image file from within.

Download Etcher from here. Connect your SD card to your computer, select the image file that you extracted above and select the drive as your SD card. Hit “Flash!” and allow it to complete the flashing and validating process. Alternatively, you can use Win32 Disk Imager.

Now insert your SD card into your Pi and power it up.

Before starting work with your Pi, make sure your software is up to date. First connect your Pi to the internet (if your model doesn’t have WIFI, you can use a USB WIFI dongle or ethernet).

Open a terminal window and enter:
sudo get-apt update

sudo get-apt upgrade

Both of these commands may take a while since they download/install files (make sure your internet stays connected).

Next we will install a python module to communicate over I2C.

sudo pip install smbus2

The next command will install I2C tools.

sudo apt-get install i2c-tools

Next enable I2C on the Pi:

sudo raspi-config

Look for I2C under Interfaces, enable and reboot when prompted.

The following command will show you the hexadecimal addresses of all connected I2C devices. This will be useful in later stages after wiring up I2C sensors.

sudo i2cdetect -y 1


I will now detail the setup process for each sensor.


The DHT22 is a combined temperature and humidity sensor. This module by DFRobot has all required resistors already attached and a removable plug for easy connection, and will be mounted externally on our payload.

DHT22 Humidity & Temperature Sensor module from DFRobot
DHT22 module from DFRobot

You will need to download the following python class to interface with the sensor, available here. It is also included in our code repository named “” under the DHT22 directory.

The PIGPIO daemon must be running for your scripts to work. Start it by typing the following into a terminal:

sudo pigpiod


The BMP280 is a precision barometric pressure sensor with ±1 hPa absolute accuracy. The breakout board offers both I2C and SPI digital communication interfaces.

BMP280 Temprature Sensor Breakout Board
BMP280 breakout board

First install a python library to use the sensor. Download/copy this file to your Pi, available here.

Then open a terminal and navigate to the folder in which the file is saved. Run the following command and wait until install completes:

sudo pip install RPi.bme280-0.1.3.tar.gz


The MPU9250 is a 9-axis motion tracker: Gyroscope + Accelorometer + Compass. We used a GY-91 module, which combines the BMP280 and MPU9250 sensors into a single board.

GY-91 breakout board containing both BMP280 and MPU9250 sensors
GY-91 breakout board containing both BMP280 and MPU9250 sensors

First install the MPU9250 python library. If connected to the internet, run this command:

sudo pip install FaBo9Axis_MPU9250

If the Pi has no internet, download this repository as a ZIP file and copy over to the Pi. Then navigate to the folder it is saved in within a terminal and run:

sudo pip install

You can check which python modules are installed by running:
pip list

PT100 RTD Temperature Sensor with MAX31865 Amplifier Board

The PT100 sensor is a platinum “resistance temperature detector” (RTD). A piece of platinum in the probe changes resistance according to the temperature, and has a resistance of 100 ohms at 0 degrees Celsius (hence the name ‘PT100’). This resistance is amplified and converted to a digital signal by the MAX31865 board, which allows SPI connection with the Pi. The probe was mounted outside our enclosure to measure external temperature.

A PT100 connected to a MAX31865 on a bread board
PT100 connected to the MAX31865 board

Refer to the following document for wiring instructions, available here. Make sure you carefully cut the appropriate trace on your board, using a blade or box cutter of some kind, and short the respective pads as instructed by the guide.

Wiring diagram of the MAX31865 connecting to the raspberry pi. Left is MAX31865 right is Raspberry Pi. Wires are: VIN to 5V, GND to GND, CLK to SCLK, SDO to MISO, SDI to MOSI, CS to CEO.
Wiring the MAX31865 to the Raspberry Pi

The original python module to interface with the sensor can be found here, but it won’t work since some code needs to be added/changed. A working version can be found in our repository linked at the start, named “” within the MAX31865 directory.

Ensure that your logging script will be in the same folder as this python module to read the digital output of the MAX31865.

Putting it all together

The in-flight power source for our Pi is a 5000mAh USB power bank, and the various boards were arranged onto a Perma-Proto HAT for a neat final assembly.

Sensor boards mounted on the Perma-Proto HAT
Sensor boards mounted on the Perma-Proto HAT

You will also see some bash scripts in our code repository which automate various processes, such as starting all logging scripts together, removing existing CSV files or killing all script processes. You can experiment by creating your own bash scripts that do cool things. You need to give these files permission to execute by using the following command from the command line:

chmod +x

Then run it using this:


Also, it is simple to join multiple CSV files using this command (order of filenames is important as they will be joined in that order):

cat file1.csv file2.csv > combined.csv

Or you can combine all CSV files in the folder using:

cat *.csv > combined.csv

Concluding Remarks

I hope this tutorial has been useful for you. Whilst you may use our code, you are encouraged to develop your own scripts to improve your learning experience. If you intend to perform multiple functions using your on-board computer (e.g. sensor logging, photography/recording), then I recommend using separate hardware to implement these functions for greater reliability in the event of system failure during flight. Furthermore, you may wish to add a DS18B20 digital temperature sensor to measure internal temperature, which was not covered in this tutorial. You may also want to script automated logging upon startup of the pi, but further functionality will be left to the imagination and experimentation of the reader.

For any technical inquiries, you can contact us at:

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Most conventional spacecraft use one of two chemical rocket designs, liquid fuel or solid fuel. Both designs rely on the same core principle, a highly reactive fuel is supplied with an oxidising agent and then ignited. For a liquid rocket both the fuel and the oxidiser are kept in liquid or gaseous forms and then mixed together before ignition. A solid rocket has the two components premixed and compacted into a solid core. Both designs have advantages and disadvantages, but did you know that there exists a third type of chemical rocket?

This rocket is known as a hybrid rocket and it takes the advantages of the previous two types and mixes them together.

Diagram of a hybrid rocket engine. It shows fuel flowing from the oxidser tank to the pumping unit then through the flow channel that contains the solid fuel core.
Hybrid Rocket Engine


The hybrid rocket has a solid core of fuel which has a oxidiser pumped through it. Typical oxidisers include gaseous oxygen or liquid oxygen that is vaporized. As the oxidiser is in either a gaseous or vaporised form, it is easily able to cover the surface area of the fuel core. The fuel in the presence of this oxidiser is now able to be ignited, generating thrust. As you can see in the diagram below, such a rocket is an exceptionally simple device, requiring minimal pumping or mixing.

So why choose this hybrid engine over conventional designs? As I mentioned earlier a hybrid rocket takes many of the advantages offered by its two colleagues. A few of the most notable are listed below.

  • Simplicity of design – Whilst not as simple as a solid rocket, a hybrid rocket is far less complex in design than an equivalent liquid rocket. This is due to its single flowing fluid and lack of mixing chamber.
  • Controllability – Unlike a solid rocket, a hybrid rocket can easily be controlled by the flow of oxidiser within the system. This gives it similar characteristics to liquid rockets.
  • Safety – The clear mechanical separation, and different phase states of the oxidiser and fuel allow hybrid rockets to be far safer than either solid or liquid fuel designs.
  • Port design and custom regression rate – By changing the geometry of the oxidisers flow channel, different fuel regression rates may be achieved with minimal changes to the greater system.

However the most interesting advantage offered by these rockets is something quite new to the market, 3d printing. You see the fuel in a hybrid rocket can be almost any polymer. This means that materials such as abs plastic or petg can be used as fuel. Not only are these readily accessible, but they can also be 3d printed with almost any home setup.

Yes that’s right, you can 3d print a rocket at home. In fact 3d printed hybrid rockets are becoming very common amongst both universities as well as actual spacecraft companies. For instance Gilmour space, an Australian rocket company, has been developing such a rocket for several years now and plans to launch in 2018. 3d printing offers a world of new possibilities for hybrid rockets with the ability to custom design thrust profiles and times for any rocket using hybrid propulsion. An example of the complexity that 3d printing can offer is shown in the picture below.

3D Printed Rocket Fuel for a hybrid rocket.
3D Printed Rocket Fuel <>

Hybrid rockets are a fantastic propulsion method, and there are many new end exciting ways that they will be developed in the coming years. My mechanical engineering honours thesis will see me conduct more research into this area, likely looking into different 3d printed designs for these rockets. Stay tuned to these blogs in 2018 for more hybrid rockets!

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Yes, the first question you are thinking of is correct. This is totally illegal. But this is super easy, educational, and takes so little time that you will be done before they catch you. The aim of this blog is to introduce radio communication fundamentals, and secondly to show off what we do here at BLUEsat UNSW, except we do this in a completely legal fashion. A demonstration of the finished product can be seen later in this article, or you can scroll down to see if you are too curious.


So, we must talk about what makes this illegal. We encourage readers to take measures in order to satisfy regulations.

  • Pirating: this is simply the act of reproducing a copyrighted work without the permission of the owner. This can be addressed by either avoiding any transmission of copyrighted material, or get their permission.
  • Licensing: certain frequencies are restricted from transmission. There are allocated frequencies open to the public known as CB frequencies. Additionally, a wider range of frequencies are available to individuals with a radio license.
  • Power: this will affect how far your transmission will reach and how dangerous to people and equipment nearby. A very simple solution is to buy a ‘dummy load’ or simply earn a radio license.

Setting up the USRP

Unfortunately, using a USRP is not as simple as plugging it into your computer, you will first need to install the relevant drivers so your computer can recognise the device.

First, you will need to download Zadig, which is a USB driver installer. Zadig ensures that the USRP is recognised by the computer and GNU radio companion.

Next you will need to download the relevant USRP drivers for your operating system. Drivers have to be installbed before you open Zadig with the USRP plugged into your computer. You may find that no devices are listed, if this is the case click options and list all devices.

Finding USRP device using Zadig.

Search through the devices to find the USRP, it may appear under different names, we found that sometimes it registered as WestBridge. Then it is simply a matter of clicking upgrade driver. If your GNU radio has trouble connecting to the USRP, the solution is to actually repeat process and it should work.

Correct settings to use the USRP in Zadig. The driver is WinUSB and the top drop down is set to "USRP B200"

It is good to note that every time the USRP is replugged into your computer, it will have to undergo an initialisation in GNU radio, taking about a minute or two. Afterwards however, it should only take a few seconds to start transmitting.

Building Script

GNU Radio window displaying the script to use the USRP.

Setting up GNU radio companion is quite simple and just continuously transmits a specified wav file on loop until cancelled. You can download this file here, or continue reading to see what was done.

First you must add a wav file source, we used a copyright free song found on youtube and converted it to a wav file. If you have downloaded our GNUradio companion file, you will have to find a song to upload it into the source.

Next, is the addition of the NBFM (Narrow Band FM) transmit and rational resampler block. Images below show how these blocks have been configured to optimise quality.

The properties for the NBFM Transmit block in GNU Radio. ID is analog_nbfm_tx_0, Tau is 75e-6, max deviation is 5e3 and preemphasis high corner is -1.0.Rational Resampler block properties in GNU Radio. The type is Complex->Complex, the interpolation is in(samp_rate*1.05) and the decimation is audio_rate*audio_interp.
Finally we added a UHD (USRP sink). For the purpose of this article and transmitting a song legally, we have chosen a frequency in the citizen band and limited gain so that our pirate transmission will not be too annoying to everyone outside of the BLUESat room

General tab of the USRP Sink in GNU Radio. The input type is "Complex float32" the wire format is "Automatic", Clock Rate is "Default", Num Mboards is 1, Num Channels is 1 and the Samp Rate is "samp_rate".RF Options tab of the USRP Sink in GNU Radio. The Ch0 settings are: Center Freq = freq, Gain Value = gain, Gain Type = Absolute (db), Antenna = TX/RX and Bandwidth is "samp_rate"
You will also see in the image of the complete system that there are a few variables and GUI sliders which limited for simplicity so you only see a small GUI window, which gives you the ability to change frequency or gain while transmitting.

It really is as simple as that.


This is the final product of all the hard work.

If you found this interesting

BLUESat UNSW regularly produces blog material to publicise ourselves and to demonstrate learning opportunities. Our previous Groundstation article taught you how to produce a waterfall plot on GNU radio. If you want to know more about our satellite groundstation you can read about it on the Groundstation page.

If you are interested in learning more about BLUESat, follow the links on our page and leave an expression of interest.

We actively ensure that every thing BLUESat does and encourages remains legal. This is why you see us using a copyright free song, transmitted on a CB frequency at low power for a short period of time. While the low power doesn’t effect the legality, it does minimise any disruptions and impacts to other users of the CB frequency.

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