May 11, 2017

Second PILOT flight in Australia: smooth lift-off and landing for a 33 hours and 40 minutes flight

The conclusion of an epic human, technical and scientific adventure in Australia, riddled with challenges and rewarded with success!

The Pilot science gondola carried out its second universe observation flight, over Australia this time. It was launched on Sunday 16th April at 6.15 am (Saturday 15th around 10.45 pm Paris time). It was planned to fly for over 30 hours and exceeded expectations after flying for 33 hours and 40 minutes.

Ground teams started flight preparations on Saturday 15th at 10.30 pm (3 pm Paris time).

The gondola enjoyed a smooth lift-off thanks to the CNES Balloons operations team and soared majestically through the beautiful Australian sky.

Following a “daytime ceiling” flight at a peak altitude of 39 km, the balloon descended to its “night-time ceiling” for the night, between 31 and 34 km high.

The ballons operational team experts limited the descent caused when the helium naturally cooled down during the night by jettisoning the ballast added specifically for that purpose. This operation was necessary to balance the balloon’s carried mass with the balloon’s buoyancy (provided by the helium). It allowed the science team to carry on with their observations with limited decline in performance.

CNES had never before flown such a large balloon, with such a heavy load (over 1 ton), on a flight this high (around 40 km) involving an in-flight day-night transition. At sunrise, the balloon was able to gain altitude as planned, and reached a record height of over 40 km during a second daytime ceiling phase. The team put an end to the flight just before it reached 33 hours and 40 minutes of flight time, the current limit for open high-altitude balloon flights (which should get longer soon).

The gondola and its instruments were operated in real-time during the entire flight by the Pilot team’s experts who had designed them. This allowed for a fully optimised flight to make as many observations as possible.

At the end of the flight, the gondola landed on its (suspended) feet, on a big ranch: a very flat and arid area without any tree that would make landing difficult. It was another fine example of successful navigation from the operations team. Upon landing, the gondola tipped over on its side and dragged for only a few metres; the perfect landing!

As early as Saturday, a recovery team made up of experts had gone ahead by road to the landing area, about 1,000 km from the Alice Springs launch station. They were then promptly brought to the landing site by helicopter, so they could close up the parachute to prevent it from catching the wind and dragging the gondola during the following night. The team also secured the instrument, which appeared to be undamaged by the landing, as seen on the featured photograph taken by a member of the recovery team. Even the instrument’s prominent baffle suffered no damage.

The gondola was recovered the following day (Tuesday 18th April) and brought back to Alice Springs on Friday 21st April in the evening. The landing site was about 1,000 km from Alice Springs, 1,700 km by road.

The equipment was inspected on base the day after its safe return. Then, some of the instruments were removed and sent to the United States in preparation for the French-American Firebal 2017 balloon campaign scheduled for September. Finally, Pilot’s mirror was cleaned and the gondola was prepared to be shipped back to France. It is scheduled to leave Australia in May and reach France in June or July.

The first scientific observations are very encouraging and include the galactic plane, the Magellanic Cloud, and other astrophysical sources of great interest for the science team (much like the ones observed by other missions like Planck and BICEP).

Comparative observations on targets from the first flight in Canada (2015) showed significant improvements between the two flights when it came to the instrument’s performance and the team’s observation strategy.

The mission only suffered a few telemetry losses, more than during the first flight. But this inconvenience in no way diminished the abundance of data collected, since all of it was stored on board and recovered right after landing for further analysis.

Engineers and scientists from CNES, CNRS, and CEA making up the Pilot team and their colleagues from balloon operations were all delighted by this campaign. Our Australian friends from CSIRO and UNSW, who welcomed them to the Alice Springs launch station and helped them throughout the project, were also very happy with the results.
This marks the end of a challenging and successful adventure in Australia!


Pilot soaring into the Australian sky




Securing the helium tank after landing





PILOT gondola all wrapped up and ready to go for its return trip to France