A flight with Nova

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Before the launch

Once a Nova launch has been planned we need to wait for the right weather conditions, specifically the wind needs to be blowing in the right direction and not be too strong. Too much wind in the wrong direction will lead to Nova being rapidly blown towards the coast, so quickly that it does not have time to reach the desired height without risking landing in the sea.
On the day of the launch everything needs to be double checked, from the communications and GPS to the knots that attach Nova to the balloon, everything needs to be right because once we launch the balloon we will have no direct control over it until we pick it up after landing.
The helium balloon is staked to the ground while it is filled with helium and attached to the payload then it's just a case of letting go...

On the way up

As soon as it is launched Nova starts sending back information which we can recieve on the ground and which is also stored on the onboard flight computer. This information contains amongst other things details about Nova's position and speed, whether it has cut down from the balloon yet and if it has deployed its parachutes. It takes about 2 hours to reach a maximum altitude of up to 32Km. On the way up the cameras have a chance to take some stunning shots. It's not all plain sailing though, the wind can give Nova a rough ride as it gets higher, this video shows one of the most turbulent periods of Nova 5's ascent.

As altitude increases pressure drops greatly, eventually causing the balloon to burst, by this point it will have swelled to many times its original size, the two photos below were taken by the upwards facing camera on Nova 5, one shortly after rising through the day's clouds, the other shortly before cut down.

The flight computer can cause Nova to cut down from the balloon before it bursts, it can do this for a variety of reasons, the most likely being that it is getting too close to the coast and there is a chance of landing in the sea if it doesn't cut down early. Based on wind speed predictions for the day a distance limit will have been set after which the cut down is used. There are two cutdowns that work in parallel so if one fails the other will still be able to cut Nova from the balloon. We discovered to our cost what can happens if the cutdowns fail when Nova 2 ended up in the sea.

On the way back down

As Nova starts its descent only one of its three parachutes opens, this means it descends rapidly so it does not get blown too far sideways by the wind. On a command from the flight computer the other two parachutes are deployed for the last section of the descent giving a gentle landing. During the flight a team will have set off towards a predicted landing zone, once Nova is on the ground the range at which we can recieve a signal from it is greatly reduced so the recovery team needs to know roughly where it landed from the last of the information recieved whilst it was still in flight. Once found all that is left to do is take the details from the flight computer and the photos and videos from the cameras.