Our Mission

Launch the Sentinel, a carefully designed space probe, to space to retrieve and capture invaluable data and images.

IBM has collaborated with the Imperial College Electrical Engineering Department to incorporate its image recognition technology and cloud capabilities with low-cost, durable electronics,  in-order to build a groundbreaking cognitive probe which can identify potential hazards. The Sentinel will use its collected data to warn responsible authorities and first-responders in cases of emergency such as forest fires or flooding so that. The sentinel will also analyze social feeds on Twitter to draw a deeper insight into the nature of an unfolding event.

We successfully launched the sentinel from Churchill College grounds in Cambridge, on the 19th June. We were incredibly lucky with the weather and wind conditions. Our plucky little Sentinel landed just north of Hockley, narrowly avoiding being plunged into the depths of the Thames estuary.

Launch system

Our probe will launch from Churchill College, Cambridge using a polymer, latex (cis-1,4-polyisoprene), balloon and helium gas. Due to the decrease in pressure at high altitudes, the balloon will need to be able to expand sufficiently and remain elastic until we have reached a sufficient height. Depending on the type of latex used, the approximate glass transition temperature ranges anywhere from -40 degrees celsius to -67 degrees celsius. The glass transition temperature is the temperature at which amorphous materials harden and move to a more crystalline form, evidently decreasing the material’s elasticity. This is a concern however our lithium energiser batteries can only withstand up to -40 degrees celsius anyway so the exact type of latex shouldn’t be a problem. We will also be encasing the probe in a layer of polystyrene to provide insulation. This is because the Stratosphere is counterintuitively warmer at higher altitudes due to the Ozone Layer at around 30km absorbing high levels of UV radiation. Therefore the probe will be experiencing temperatures of around -45 degrees celsius to -60 degrees celsius at an altitude of 11-20km and will need adequate insulation. Although polystyrene can be coated with a hydrophobic spray in order to protect the individual pellets from breaking off (due to crystallised water vapour), this sort of measure is only needed if the probe were to be submerged in water or subjected to a very high humidity and not for our purposes (i.e contact with a cloud).

The helium will be of a purity of approximately 99.995% in order to allow the balloon burst calculations (using the HabHub program - http://habhub.org/calc/) to be as accurate as possible since the program assumes certain constants and densities. Although ‘vanilla’ hydrogen is less dense than ‘vanilla’ helium, diffuses out of the balloon at a slower rate and is cheaper on average, hydrogen is slightly more reactive and combustible than helium and helium can still give us the minimum lift of approximately 5m/s that we need in order to maintain an upward trajectory in the face of strong winds etc.

Processing and Communications

The data that our Pi gathers embarks on a long and arduous journey, not just through the void of space (well, the Stratosphere at least; that's space in my book), but through various pieces of software and hardware to reach its ultimate goal: some Tweets!

First our PITS board and corresponding software broadcasts our desired message via the in-built LoRa radio transmitter. We tune into the signal using SDR#, which produces an audio translation.

This requires a USB SDR (software defined radio) dongle; we used the FunCube Pro+ to great effect. The audio can then be passed into the concisely-named dl-fldigi, which is a piece of software that takes as an input the audio from the computer's sound device and translates it into (almost) the original message.

Luckily for us, the fun doesn't stop there, as dl-fldigi provides the option to write the output log to a text file. We then parse this file using a python script into JSON. 

Now, to get this JSON information into our Watson IoT platform, we need to communicate with one of the provided NodeRED IoT nodes. These nodes operate using the MQTT protocol, so our final step is to set up an MQTT broker and broadcast our messages using another python script! If all goes well, we can now tweet our original message using the Twitter node. Hurrah!

On-board Hardware

Our payload will contain a number of model A+ Raspberry Pis, however we have yet to decide on how many we will take on the voyage to the Stratosphere as it depends on the number of pins that we require to drive all of our sensors. As for the sensors, the Sentinel will routinely collect the following atmospheric readings:

  1. Altitude (in metres)

  2. Pressure (in pascals)

  3. Temperature (in degrees celsius and fahrenheit) 

  4. Acceleration & Rotation 

  5. Luminosity (in lux)

  6. Magnetic Flux

In addition to these readings we will be recording our GPS location as well collecting images at various points along the Sentinel's flight path which will be done using a system of Raspberry Pi camera modules. 

The finished probe equipped with a Raspberry Pi, GPS, LoRa antennae, OLED display and GoPro.

The finished probe equipped with a Raspberry Pi, GPS, LoRa antennae, OLED display and GoPro.

Sensors connected on breadboard

Sensors connected on breadboard

FUNcube USB Dongle

FUNcube USB Dongle

GPS Transmitter and Receiver

GPS Transmitter and Receiver