April 2013: Phobos & Deimos

Launch of Deimos from Oakfield Academy in Frome
Launch of Deimos from Oakfield Academy in Frome

Phobos and Deimos, named after the moons of Mars, were the two balloons launched for the MARSBalloon pilot project that took place between February and May 2013. Between them the two balloons were carrying 140 student experiments from primary schools, secondary schools and universities in the Bath/Bristol area.

Both balloons were launched on Friday 22nd March from Oakfield Academy in Frome at a time when the jetstream was blowing in a north-easterly direction. Deimos was released first, with Phobos following just 30 minutes later. Phobos ascended to 26km altitude before the balloon burst, releasing the payload to descend by parachute down to a soft landing in Fenny Compton, Warwickshire with a total flight time of 2 hours, 40 minutes. Phobos and its experiments were safely recovered from a field by the chase team two hours later.

Despite only being launched 30 minutes earlier, the poor weather conditions made Deimos take a very different path, becoming vertically “trapped” inside a cloud with snow buildup increasing the weight of the payload; preventing further ascent. This caused Deimos to travel considerably further North than Phobos and the additional cooling effect of the snow led to the premature failure of the batteries in the tracking system. Deimos landed in a field in Nottinghamshire which unfortunately had no mobile phone signal and so the backup tracking system (based on a smartphone) also failed to report the landing site. With the failure in both tracking systems the MARSBalloon team sadly had to declare Deimos lost.

Remarkably, Deimos was discovered six months later by Simon Jacklin, a farm worker in Nottinghamshire. After spending months on the edge of the field, the balloon payload was finally discovered after being run over by a large agricultural mower. Mr Jacklin, commenting upon his discovery, said it was “something you don’t usually find in a hedge bottom!”. A video about the flight, loss and subsequent recovery of Deimos is embedded below.

The MARSBalloon team learned important lessons from the flights of Phobos and Deimos and have worked hard on improvements to the tracking systems and launch procedures to prevent a Deimos-like episode from happening again in future MARSBalloon flights. As is true of many engineering projects; you never learn from a success!

Temperature readings from the two on-board sensors on Phobos
Temperature readings from the two on-board sensors on Phobos. The Tropopause is the boundary between the troposphere and the stratosphere above which the air temperature starts to increase with altitude. The majority of Earth’s weather occurs below this boundary.
Pressure data recorded by two sensors on-board Phobos
Pressure data recorded by two sensors on-board Phobos. The minimum pressure experienced was 17mBar (for comparison the average surface pressure of Mars is 6mBar).
Flight path of Phobos as recorded by its on-board GPS.
Flight path of Phobos as recorded by its on-board GPS. Phobos initially flew west due to strong ground level winds but eventually rose into the north-easterly jetstream (above 10km). The sharp left turn towards the landing site occurred after the balloon burst and the payload dropped, by parachute, back down into the westerly ground winds.

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