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The High Altitude Balloon Team’s final project objective is to design and build a balloon payload that holds and stabilises a ground-facing radar for surveying purposes. To achieve this, we have to collect abundant amounts of data to help us design a payload enclosure and stabilisation system that will function in the intended operating environment.

Launch 2 of the Balloon Team yielded average quality data. It showed us some trends and a portion of the general behaviour of atmospheric conditions and our payload’s response. Unfortunately, our sampling rate was 2Hz so the highest frequency we could detect was 1Hz. Higher frequency oscillations—which is predominant according to video footage—could not be registered. Despite the limitations of the data collected, we still analysed it as it captured lower frequency oscillations and provided good practise for future data analyses. Future launches will sample data at a frequency of 200Hz.

Analysis of Data

A short-time Fourier transform was performed on the acceleration data in the x-axis (the x-y plane is the horizontal plane) with a time window of 128 seconds (248 data points) and a 64 second overlap between windows. This was then plotted as a 3D surface with logarithmic elevation that is also simultaneously marked out by colour. The resulting plot is shown below.

Graph representing data logged by the high altitude balloon sensor payload


As can be seen from above, there is a slight peak at around t = 9000 samples corresponding to the ratio f/F = 0.19 where F is our sampling frequency of 2Hz. This means at around 16km altitude, there were stronger-than-usual oscillations of 2*0.19 = 0.38Hz. An oscillation frequency of 0.38Hz implies one complete swaying motion every 2.63 seconds, which is comparatively slow and gentle.

At around sample no. 13000, which was taken at 23 km altitude, the amplitude of the signals becomes much higher over the entire frequency spectrum. This is due to the balloon burst and the subsequent chaotic descent during which the payload shook around violently. This was caused by high falling velocity and non-uniform opening of the parachute. However, our mission objective requires stabilisation only while the payload is suspended from the balloon. After the balloon stops providing lift, we desire only that it falls at or slower than 12m/s. Everything else is redundant.

What We Did Right

Although we made mistakes in the lead-up to, during, and after Launch 2, we also did quite a few things right. We will be replicating what we did right for future launches. Telemetry is one area that we believe was done mostly well. The data we got back is a bit iffy but it generally shows a trajectory that is within expectations. It’s also interesting to superimpose altitude against acceleration so we can see the different forces acting on the payload throughout its journey, as below.

A graph describing the acceleration data relative to the balloon's altitude

As is apparent from above, the point where the payload begins to drop in altitude corresponds to massive increases in forces on the payload. This immediately tells us the balloon burst was a chaotic event (confirmed by video). The z-acceleration also switches from oscillating around positive 1g to negative 1g making it clear the payload flipped upside down. This was by design as our payload mounted the parachute at the bottom of the payload enclosure. About halfway through its descent, the payload’s shaking significantly reduced. We believe this is due to a rapid transition from low-density to high-density air, which stabilised the descent by fully opening the parachute.

Although the ascent data was generally good, data of the descent phase is highly suspect due to extremely large errors between each sampling point and very sporadic data logging. Having few data points reduces the reliability of whatever data we’re able to retrieve. We hope to improve our telemetry data by changing to a more reliable and accurate data logger.

Another thing we did quite well is enclosure insulation. We had both external and internal thermometers on our payload. At the most extreme, they measured over 100 degrees difference between the external and internal temperatures. As electronics and batteries begin to fail at the sorts of external temperatures we measured at high altitude (-67 degrees Celsius), we were pleased that our insulation kept the internal temperature at a comfortable 30-40 degrees C. We will definitely be using similar insulation on future launches.

The Next Balloon Launch

The data we’d collected from Launch 2 is not terribly useful but we nonetheless have a mission plan for the next launch. Passive stabilisation is the area of focus for the next launch. Passive stabilisation means there is no external intervention to stabilise the system, i.e. no motors or moving parts to steer the system back into the desired position. A simple example of passive stabilisation is a pendulum; when the mass is moved from its equilibrium position, it will want to move back to it after you let go, and if you let it swing for a while, it will eventually come to rest at its equilibrium position. This is an example of passive stabilisation as the system stabilised itself without needing external intervention.

Passive stabilisation is an important part of the overall stabilisation scheme as it simplifies the active stabilisation system’s job by damping oscillatory motion of all frequencies. Two methods of passive stabilisation are being explored for the next launch:

  1. The first involves extending point masses outward and downward from the bottom four corners of the payload enclosure. This increases the moment of inertia in the horizontal plane and about the vertical axes making it harder for the wind to sway and rotate the payload.
  2. The second is a powered gyroscope-type system contained inside the payload enclosure with the device-to-be-stabilised’s motion coupled to the rotor’s, thus matching the latter’s attitude. In theory, the rotor’s attitude—and therefore, our device’s—should remain constant as long as it maintains high angular momentum. A motor will continuously be driving the rotor so it spins throughout the balloon’s flight.


Overall, we do not consider Launch 2 a 100% success. However, our team is all the richer for having done it. We’ve been taught a valuable lesson on good data collection as our analyses were less than ideal because of flawed collection. In spite of that and regardless of how useful the analyses were, simply doing them is fantastic preparation for analysing the good data that we know we’ll get from our next launch.

We also learnt a lot about mission preparation and execution. Launch 2 was a bit rushed; there were a few hiccups during the balloon inflation and our schedule slipped multiple times. We are now aware of the need to be better prepared not just for the planned sequence of events but also likely contingencies that may arise. This might not eliminate the hiccups on our next launch but it’ll certainly allow us to deal with them more efficiently.

On a more casual note, the trip was just plain fun. We had lively conversations with each other and even had time for board games. Although I may have given you the impression that a balloon launch is stressful and scrupulous, the reality is it was actually quite relaxing. It was like playtime except instead of children’s toys, we played with science-y gadgets and a high-altitude balloon. I, along with everyone on the team, look forward immensely to our next balloon launch where more fun awaits!

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It’s been another busy month at BLUEsat UNSW. This month’s major achievements include our breakthrough with the steering module of the NUMBAT rover, the creation of a successful SDR radio player in the groundstation team and progress on a new magnetorquer project in the ADCS team!


From the Rover CTO

It’s been a fantastic Month for the team and we have reached some major milestones. Earlier this month we received our results for our ERC proposal submission scoring an impressive 24/25. Since then the team have been working hard to put together the preliminary design review document.

We also have been awarded a large grant from the NSW Government of the Chief Scientist and Engineer towards our rover. We hope to put this generous donation to good use.

Thomas Renneberg, Robotics CTO & Mech Chapter Lead

From the Electrical Team

This month we continued our work on a few of the PCBs. After verification of its correct working and some initial configurations last month, the testing of the Generic PCB was handed over to the software members, who have developed working codes for the driving system. In the next phase, bulk production and further testing will be carried out. Progress has also been made in the science module and drive module PCB, which includes finalisation on major design requirements and some research into circuit design. Beyond these, we have also come up with the preliminary wiring scheme of the rover electrical system. Following this, improvements in the power delivery and grounding will be made as the next step.

Jonathan Wong, Rover Electrical Chapter Lead

From the Software Team

Another wonderful month for rover software has seen a breakthrough in testing and operating the new steering module for NUMBAT. In the process, we have also been able to verify other fundamental systems, namely embedded libraries and embedded-CAN implementation.

Elsewhere, progress has been made with altering the ROS library for the Linux-side of our ROS-over-CAN implementation, a lovely collection of GUI widgets/featurettes are in the works and development of the manipulator arm control system has begun!

Simon Ireland, Rover Software Chapter Lead

From the Mechanical Team

The mechanical team has been working on small updates to the rovers suspension system, replacing the old version with our newer, more rigid design. We have also been putting together a prototype of our mechanical manipulator arm and our science module.

Thomas Renneberg, Robotics CTO & Mechanical Chapter Lead

From the Chief Pilot

The older BLUEtongue rover is still under maintenance. We are in the process of debugging the steering system after replacing one of the motors and the arms movement. Some small calibrations to the system are underway to allow us to keep training and testing this coming month.

Sajid Anower, Rover Chief Pilot


From the ADCS Team

In the Reaction Wheel System project, the manufacturing and programming of electronics are just wrapping up, ready for integration and testing of the RWS during the following weeks.

We also have a new magnetorquer project that’s just coming out of the research phase and is now looking to implement a magnetorquer-based ADCS on a CubeSat PCB!

Mark Yeo, ADCS Squad Lead

From the Groundstation Team

Progress has been made in implementing the receive subsystem into the new SDR groundstation.

We have successfully created an SDR radio player, capable of receiving FM radio station emissions (commercial radio stations) and playing the audio. This code can be altered to use the data in different ways, for example saving the audio into a .wav file and outputting to a file, which will be used in later stages to process the data.

We will attempt to receive satellite signals using the current code when there is a pass.

Joerick Aligno, Groundstation Squad Lead

From the High Altitude Balloon Team

The HAB team at BLUEsat kicked off April by initiating new members in the workings of a high-altitude balloon mission.

Data and pictures from the recent flight were analysed. Studying the motion data, like in the attached image, will provide an understanding needed to design separation, stabilisation and parachute deployment systems.

The month concluded with a full team meeting, including with our supervisor Elias, where team lead Adithya set out the expected goals and milestones for the next launch.

Adithya Rajendran, Balloon Squad Lead

From the Satellite Power Team

The past month has seen further progress in the power system of the CubeSat.

Within the separate subsystems, there are a few updates since last month. Slow but steady progress is being made to debug the MPPT (Maximum power point tracking) system.

Debugging is continuing for one of the battery charging systems and one of the other competing designs has its PCB ready to print and its components have been ordered. The thermal subsystem is in its infancy and potential components are being researched. A CAD model has also been drawn up and can be seen in the attached photos.

Harry Price, Satellite Power Squad Lead

BLUEsat Operations & Exec

Secretary’s Update

Its been a busy month for the society with progress across all our teams. On the social events side we’ve had more successful board games nights, whilst from an outreach perspective, we have some interesting things planned for next semester. We will also hopefully be organising team merch soon.

We will be holding an EGM in the near future so some roles will be changing hands, including mine as I graduate at the end of the semester. Consequently, this will probably be my last monthly update as secretary. Its been great and I wish good luck to the incoming executive!

Harry  J.E Day, Secretary

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Modular designs are not a new concept, in fact they are used just about everywhere from your humble desktop computer to scaffolding on the side of a building. But have you ever seen a modular Mars rover? Well BLUEsat’s new NUMBAT Rover is just that.

The chasis of the NUMBAT Mars Rover ready to be wired.

CAD Render of the NUMBAT robot's chasis. CAD render of the NUMBAT Rover, showing modules being inserted into the chasis.
As you can see in the images above, the NUMBAT rover has a series of “Module Slots” which allow for different systems to be easily placed inside the robot.  These modules can be placed at any point inside the rover, there are no limitations stating that the power supply or on-board computer has to be in a specific location.

It should not be understated how useful this is from a design perspective. The modular system allows for all rover systems to be developed independently, without worrying whether they will interfere with other parts.  As long as the components can fit within a standard size module box, which come in a range of lengths, it can be assembled into the rover.  This also opens up the possibility of having “hot swap” modules, which can be rapidly taken out and replaced depending on the rovers needs.  For example between competition tasks the modules for scientific testing and core drilling could be swapped for additional battery modules and a manipulator arm.

But that’s not all this modular design has to offer, it also means that the rover can fulfil a large range of different operating modes just by swapping out systems. Instead of having to design multiple Mars rovers, one modular platform can fit a variety of tasks. Some examples of this include:

  • Stationary science mission – If the wheel modules and arm modules are not installed, their places may be filled with different scientific modules, greatly enhancing the capabilities of the Rover and allowing it to serve as a scientific hub for different experiments.
  • Assembly line worker – If scientific modules and drilling modules are replaced with additional manipulator arms, potentially with inbuilt tools, the Rover can be repurposed as an assembly line machine. The addition of autonomous software and drive capabilities would allow the Rover to function in most situations.
  • Telecommunications relay – addition of multiple antenna could allow the Rover to become a relay for a mars based telecommunications network.

Overall, the BLUEsat Off-World Robotics Team is very proud of our modular Rover and can’t wait to see how it will perform at this years European Rover Challenge.

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It’s been another busy month at BLUEsat UNSW. This month’s major achievements include our GreenSat team’s success at the EngSoc pitch fair, and completion of the NUMBAT Mars Rover’s core mechanical construction.

Members of BLUEsat's rover software team including Elliot Smith, William Miles and Sajid Ibne Anower testing software designed to drive the new NUMBAT rover in UNSW's Willis Annex Maker Space.


From the Rover CTO

BLUEsat UNSW has now enrolled in the European Rover Challenge (ERC), commencing in September of this year. The whole team is looking forward to the competition and getting the NUMBAT rover operational in time.

Thomas Renneberg, Robotics CTO & Mech Chapter Lead

From the Software Team

A excellent month for the rover software team has seen us finalising many components of our system. In embedded, we have made progress with testing hardware libraries for the ADC and PWM modules on the robot’s generic PCBs, as well as developing parts of our CAN bus solution. In backend systems, we are implementing a new driving system to take advantage of our transition to 4-wheel steering which will hopefully be finished and testing within the week. Finally, we have also added a nice little widget to the GUI that will let us know where our rover is facing during its tasks.

Simon Ireland, Rover Software Chapter Lead

From the Mechanical Team

William Miles and Thomas Reneberg carrying the NUMBAT rover with its suspension sytem full assembled.

This month saw the rover mechanical team finalise the manufacturing of the core NUMBAT systems.  With the Chassis, suspension, wheels and steering systems all assembled together, we can begin working on some of the rovers smaller modules.

Thomas Renneberg, Robotics CTO & Mechanical Chapter Lead

From the Electrical Team

It’s been a busy month for BLUEsat’s rover electrical team, with a host of different tasks going on. At the conclusion of the on-boarding workshop earlier this month, we were pleased to see the team doubled in size. A couple of new design projects have unfolded: the drive module PCB which interfaces between the generic PCB and motors; and science module PCB, which is aimed to be a high-tech soil analyser. Testing and assembly are also under way for the NUMBAT rover. The Generic PCB, the brain for almost every module, has successfully delivered PWM signal to a wheel motor via an array of connector boards, which means the drive system is ready for integration. A small part of the team have also been focused on maintenance, repair and review for the old rover, where they gain a lot of new engineering experience.

Jonathan Wong, Rover Electrical Chapter Lead

From the Chief Pilot

The NUMBAT Rover's Generic PCB connected to one of its wheel modules on a desk for electrical testing.
After a bit of panic when our old Battery charger failed, our new charger has arrived and with it Rover training has been resumed. Some of the systems on the old Rover are beginning to show their age,so we are working on porting them over to the new NUMBAT rover for testing.

Sajid Anower, Rover Chief Pilot


From the ADCS Team

Part of a prototype satellite reaction wheel. It features four spining mental disks.
Development on the satellite Reaction Wheel System (RWS) has been going swimmingly, with all RWS mechanical components being manufactured and assembled (pictured). Also, PCBs for the RWS and supporting circuitry have been ordered and are currently being manufactured.

In other news, the ADCS team is currently also researching magnetorquer systems – more on this next month!

Mark Yeo, ADCS Squad Lead

From the High Altitude Balloon Team

This month kicked off with a resoundingly successful high-altitude balloon mission. The launch of our payload delivered amazing pictures and valuable data from over 23km altitude.

Development for the next launch has commenced, with the telemetry project already showing progress in transmitting data and pictures over radio. Other projects include manufacturing an integrated enclosure, building an Arduino-based separation mechanism and implementing payload-stabilisation techniques.

Adithya Rajendran, Balloon Squad Lead

From the GreenSat Team

Recently, BLUEsat’s GreenSat team was offered the opportunity to pitch our project at the project and pitch fair 2018, where we won Most Innovative pitch. Also, we have finally been approved for PC2 lab space in Biosciences building. Meanwhile, work on the darkbox and hotbox is continuing thanks to our new members

Ben Koschnick accepting the prize for "Most Inovative" on stage at the UNSW Engineering Society Pitch Fair.

Ben Koschnick, Greensat Squad Lead

From the Satellite Power Team

This month has been busy for the Satellite Power team, with multiple parts of the system being developed. New members have been inducted and are working on some projects as an intro to BLUEsat and electrical engineering on satellites. The main power system has been making steady progress.

The dummy load is operational. There are 3 competing battery chargers in the works all in different stages: one is in the debugging phase, one’s PCB is being designed in Altium, and one is still in its infancy. The Maximum Power Point Tracking PCB is also slowly being debugged.

There has also been some preliminary work on a thermal system, with some fantastic hand drawn engineering drawings being produced. (see photos)A hand-drawn engineering drawing for a thermal system.

Harry Price, Satellite Power Squad Lead

From the Groundstation Team

The Groundstation team has had slow progress for the past month. Mostly trouble installing GNURadio onto to Macbooks, however we have moved past that stage. We have successfully used the USB dongles to receive and plan to move towards using the USRP over the coming weeks.

Joerick Aligno, Groundstation Squad Lead

BLUEsat Operations & Exec

Secretary’s UpdateBLUEsat UNSW members relax after a busy workday to play board games at one our regular social events.

After a resoundingly successful orientation day the focus for this month has been on settling in our new members. We even had a few newbies interested in joining our media and events team and are hopping to revitalise our school outreach program! (Watch this space for more details).

Our social events have continued to be a resounding success with a massive turn out at our most recent board games night! A massive shout-out to Joshua Khan and Taofiq Huq for making these such a big success. Our social events bring together members from all parts of the society and help foster the exchange of ideas and contacts.

Harry  J.E Day, Secretary

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Recently, GreenSat was offered the opportunity to pitch our project at the project and pitch fair 2018, where we won Most Innovative pitch. This is just one of the many events that have happened at GreenSat in the last 12 months. This week, we will go through everything that has happened including the IAC, payload design, our quest for lab space and more!

Ben Koschnick accepting the prize for "Most Inovative" on stage at the UNSW Engineering Society Pitch Fair.
Winning the “Most Innovative” award at the UNSW Engineering Society Pitch Fair.

GreenSat Who?

For those who have never heard of us before, GreenSat is a program designed to develop the methods and technologies to grow food and other supplies such as medicine in the conditions of orbit or an alien planet. With the limitations of size, mass and power available on a nanosatellite we will be forced to simplify, streamline, refine the art of agriculture in space.

What sets us apart from similar research is the development of agricultural microorganisms adapted to the environment to reduce the engineering requirements. We will achieve this through experimentation with existing organisms and bioengineering new traits specific to these conditions. Already we have plans to begin our first laboratory experiments this semester on nitrogen fixing bacteria. A prototype satellite payload will follow soon after, with our first functioning payload operational by the end of the year.

Payload Design

In the latter half of 2017, we began design work on the first prototype payload for the GreenSat, imaginatively named Mk1. This prototype was designed to be able to handle small 30mm petri dishes. The Mk1 could control the internal pressure and feed nutrients onto the sample to extend the experiement’s lifetime. Twelve separate dishes meant we could take 12 separate experiments to provide a range of solutions or repetition of results.

This payload was finalized and imported into CAD in time for the IAC (check out our daily blogs, starting here) where we presented the concept to an international audience of space scientists and engineers. However, the Mk1 was never built, instead we took the incredible feedback we got and got to work on a new concept, readdressing the problems we thought would be important to reduce the size and complexity.

Such was born the Mk2. This concept will remove the petri dishes in favour of something even smaller. Each sample container will be 5-10mm across and completely sealed. Hopefully, we will be able to grow small amounts of bacteria for an extended period of time using only the materials inside the container without the need for pressure control or a nutrition input. Design is still in it’s early conceptual stage, with a team led by Taofiq building the sensor suite to test separately. The payload is scheduled to be delivered by the end of the year.

Experiments with Cyanobacteria

There is only one thing harder than rocket science, and that is government certification. To achieve a successful experiment will require many ground experiments which must be performed in a PC2 biosciences lab. Thankfully such labs exist on campus and we have always intended to make use of them. Through the tireless efforts of Scarlett and Dr Brendon Burns, we have finally been approved to go through the rigorous safety induction process to get our very own lab space.

To support our biology team, we have been working on designing and building equipment that will allow us to perform experiments on the effects illumination and temperature. These experiments will allow us to more firmly grasp the engineering requirements on the GreenSat payload and design our CubeSat accordingly

With the help of our friend for Flinders University, we were able to design a “Dark Box” to test the bacteria’s response to varying wavelengths and intensities of light. This will allow us to minimise the power input required to illuminate the samples whilst also maximising the growth curves of the sample. Presently Nathan and his team are designing the “Hot Box”, a thermal incubator that will allow us to measure the effect of temperature on the sample. This is particularly important and thermal control is a power-hungry process that may not be possible on a CubeSat, forcing us to design the satellite with that in mind.

Closing Remarks

In 2017, GreenSat has evolved from a loose, barely defined idea into the winner of the Most Innovative project in UNSW. Now 2018 is gearing up to become a year of physical progress, with our team working in the labs and in the workshop to bring GreenSat to life. If you are interested, make sure you follow this link to join us or simply send an email our way.

Students from BLUEsat UNSW's GreenSat Team in the Engineering Design Studio.

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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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