theos The Edge of Space theos

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As well as the aims of the project, there were two main criteria we needed to keep in mind when
choosing our components, namely;

  • Monetary budget: £500
  • Mass budget: 1kg max, with a target weight of 0.5kg

    The mass budget is a balance of what is achievable and what is a safe weight to have falling to the
    ground bearing in mind that, although highly unlikely to land anywhere other than in a rural location,
    we do not wish to cause any damage or harm to people or their property.

    Of primary importance is our ability to recover the payload and as a consequence of this we have included
    two tracking devices in the payload. After extensive research, we chose all our components based on
    their performance, weight and price bearing in mind how large a balloon we could afford and how much they
    can lift.

    When it came to price however, we found that achieving all of our aims was going to be extremely
    difficult within budget. Fortunately, we managed to secure the generous support
    of a number of companies who could supply the components we desired. Details of our components and
    where they can be purchased are listed below. Please also visit our sponsors page to find links to
    their websites.

    This sign (below) is attached to the top of the payload incase it is found by someone before us. This is
    particularly important should our tracking devices fail; we should eventually get it back.


    Xexun TR102-2:
    We chose this as our primary tracking device due to a number of factors; weight, size, price, high
    accuracy positioning and most importantly, it transmits altitude data rather than just longitude and latitude.

    The reason we wanted altitude data in the tracking data is so that when we receive transmissions we
    will know if it is still descending or if it has reached the ground.

    The Xexun TR102-2 was purchased from

    iPhone 3 with ViewRanger app:
    Our back-up tracking device is an iPhone 3 generously donated to the project by a member of staff
    in the department which will be running the ViewRanger app.

    The ViewRanger app also transmits altitude data but also stores position data when out of signal
    range. The app is available for iPhone, Android and Symbian smartphones.

    Position Logging 

    Garmin eTrex H:
    The most important feature for a position logger in this project is that it continues to log through the
    entire flight i.e. to the maximum flight altitude (>30km). It is quite rare for GPS devices to operate at
    altitudes >18km due to limits imposed on civilian GPS use. This device is confirmed to work
    above this altitude by other users and Garmin directly.

    The Garmin eTrex H was purchased from

    Temperature Logging 

    Lascar EL-USB-TC:
    We chose this temperature logger because it fits our needs perfectly, weighing approximately 70g and
    costing significantly less than other temperature loggers capable of recording temperatures as low as
    -200C (-328F).

    The EL-USB-TC data logger meets our temperature data acquisition aims and was provided by
    DATAQ Intruments.

    Pressure logging 

    The MSR145 is one of the few pressure data loggers on the market that is capable of measuring
    pressures as low as our payload will experience. This capability, and its small size and light weight
    make it the perfect component for our project.

    The pressure logger was provided by MSR:

    Acceleration logging 

    The MSR145 is also able to measure tri-axial acceleration which we hope to use, in combination with
    the flight footage, to identify when the payload reaches the stratosphere. At this point there should be
    very little wind (and turbulence) and so acceleration readings should become negligible.

    Humidity Logging 

    Lascar EL-USB-2:
    We chose this humidity data logger because of its small size, light weight, low price and, primarily,
    because it can make readings down to 0%RH.

    The Lascar EL-USB-TC humidity data logger was provided by Lascar Electronics:


    Tachyon XC HD Head Cam:
    One of our aims was to achieve high definition footage of the curvature or the Earth from near space.
    With the Tachyon XC HD we will achieve this.

    Important features of this camera with respect to this project are a 6 hour battery life, light weight and
    a resolution of 1280 x 720 recording at 30fps.

    The head cam was provided by Tachyon XC:

    NB. This can be purchased in the UK at:

    Canon PowerShot A430:
    An important aim for us is to get an undistorted image of the curvature of the Earth. Due to the nature
    of video cameras, the edge of images can be distorted so we will include a basic Canon camera
    to take pictures at regular intervals to achieve undistorted images.

    The standard firmware on a camera such as this is not capable of doing this, so we have loaded
    CHDK firmware onto the camera to facilitate this.


    Two 1600g Hwoyee meteorological balloons:
    Hwoyee meteorological balloons are high-quality meteorological balloons, ideal for near space balloon
    flights and so were a natural choice.

    The size of the balloon required is defined by the weight of the payload; the heavier the payload, the larger
    the balloon needed. We had to carefully balance the weight of our payload specification so that
    we could afford the necessary balloons for two separate flights.

    The balloon was supplied by Random Engineering:


    4ft rocket man high altitude payload recovery parachute:
    The weight of the payload defined the minimum size of parachute we require for a safe final descent
    rate. This specific parachute was chosen because, unlike most parachutes (primarily designed for rocket
    flights), it has a loop sewn into the apex of the chute to attach the balloon to.

    The parachute was purchased from


    Blinking LED's:
    To help us recover the payload, should it get dark before it is found, we decided to get four small magnetic
    LED buttons to go on the outside of the payload. They are small, lightweight and have sufficient battery life.

    The LED's were purchased from

    Jaffa Tape:
    We want the payload to be brightly coloured to help us find it but also to be highly visible, should it come
    down in a less than ideal location. Wrapping the payload in Gaffer tape is ideal for waterproofing the foam
    and adding strength to the payload. We therefore decided to use Jaffa Tape since it combines these attributes.

    Another way to help us find the payload is to include a buzzer. We bought a simple 12V buzzer and 9V battery from

    Hand warmers & Cord:
    To help maintain the internal temperature of the payload at a level suitable for the electronics, hand warmers
    are the obvious solution. NB: After testing we decided that the components in our highly insulated payload
    generate enough heat to maintain the internal temperature so we left out the hand warmers.

    The hand warmers and cord were supplied by Random Engineering:

  • contact:   Prof. Vik Dhillon, Department of Physics & Astronomy, University of Sheffield, Sheffield S3 7RH, UK     Tel: +44 (0)114 2224528     Email: vik.dhillon .at.