Scientific Ballooning

CNES prepares a balloon launch campaign in Australia

Alice Springs, Australia.- Almost 30 years after the last campaign performed in the island, the balloon division of the French Space Agency CNES will be returning this March to Australia to launch three stratospheric balloons in a campaign denominated "Austral 2017". The scientific effort will take place from the facilities of the Australian Balloon Launch Station (ABLS) located in Alice Springs, in the center of the island, with support from the University of New South Wales, in charge of the management of the base.

The effort involves the participation of near 90 people including the operational and payload support team from CNES, a small suport team from the Canadian Space Agency, European and Canadian scientists and visitors. As part of an arrangement made between NASA and CNES, the french agency can use the high bay building constructed by NASA in 2009, which will be destined to prepare the scientific instruments to be flown, while the adjacent hangar will serve for flight train integration and operational activities.

The main driver for this new campaign, was the scientific team behind the PILOT telescope whom after a very succesful first flight performed in 2015 from Timmins, Canada, asked CNES about the possibility of making a second flight with his instrument, but this time from the southern hemisphere. The change of location is a fundamental factor to observe a section of the sky that is inaccessible from the northern hemisphere.

A look to our galaxy center from the south

PILOT -which stands for Polarized Instrument for Long wavelength Observation of the Tenuous interstellar medium- is a balloon-borne telescope aimed to measure for the first time the submillimetre polarized emission of dust grains in the interstellar medium.

It was developed by CNES in partnership with the Astrophysics and Planetology Research Institute (IRAP) in Toulouse, and the collaboration of the Institut d'Astrophysique Spatiale (IAS) and the Commissariat à l'Energie Atomique (CEA) both from France, the University of Rome La Sapienza, from Italy and the University of Cardiff, from the United Kingdom.

At left we can see an scheme of the fully instrumented payload.

PILOT consists of a primary mirror of one meter diameter and a set of detectors comprising 2048 bolometers cooled to 0.3 degrees Kelvin. These sensors, originally developed for the PACS (Photoconductor Array Camera and Spectrometer) instrument on board the Herschel satellite, will allow measurements at 240 and 550 microns with an angular resolution of a few minutes of arc.

The operational objective for PILOT on this campaign will be to perform a flight enduring between 25 and 32 hours at an altitude of 39.5 km. To achieve this goal, CNES will make use of a 803Z balloon model manufactured by Zodiac, which with a volume of 800.000 cubic meters is the largest one currently available for the program capable of transport a payload of 1 ton to that altitude. Also to support the long range flight a relay station will be setup in Longreach, a city located 1000 km East of Alice Springs.

Although PILOT is the main mission for the campaign, it will not be the only instrument to be launched.

Meet CARMEN and CLIMATE

To maximize the scientific outcome from the huge logistical effort that requires to perform a balloon launch campaign in such a remote location, CNES will launch -along with PILOT- other two balloon-borne missions, for the benefit of several laboratories and universities from Canada and Europe. I will only make a brief mention of the objectives of these missions, reserving for upcoming publications a more detailed account of each flight.

CARMEN is a multi-instrumental gondola developed by the CNES based on concepts such as modularity and flexibility, whose objective is to allow the transport of multiple experiments of different type, in a single platform..

Manufactured using a light but strong alloy of metallic tubes (known as "barres/boules" or "bars and balls" in english), it was the logical evolution and culmination of many years of CNES expertise in gondola design.

Below these lines we can see an scheme of the distribution of payloads onboard CARMEN for the Austral 2017 campaign.

The goal set for CARMEN is to achieve a flight time of between 15 and 18 hours, at an altitude of 36.8 km. The balloon to be used for this purpose is a model 402Z also made by Zodiac. With a volume of 400,000 m3 it is able to raise a mass of up to 800 kg.

As the campaign developes we will make a detailed description of the different instruments carried by CARMEN. However, in a brief resume we can say that these payloads will be mostly instruments provided by several universities through the Canadian Space Agency, and a french-built module denominated CASOLBA devoted to the in-flight calibration of solar cells.

A last topic also worth of mention is that unlike what occurs with most balloon-borne payloads or instruments, CARMEN is not an acronym, but a real NAME. As incredible as can sound, the gondola designers wanted to give it a character, even a certain grace. Endowed by design with multiple assets to seduce and a "de facto" versatility, CARMEN was a name which reflected for them the synthesis of all these qualities.

The third gondola participating of the campaign is also a multi-instrumental platform, denominated CLIMATE (Combined Laser and In situ Measurements in the ATmospherE). It combines 10 scientific experiments developed in different European laboratories but with the same objective: to study concentrations of the main greenhouse species (H2O, CO2 and CH4) and characterize the stratospheric aerosols.

The flight profile for CLIMATE will be a little more complex. A 150Z balloon measuring 150.000 cubic meters of volume will be used for a nominal ascent to 33.6 km and from that point will be performed a controled slow descent until reach 17 kms, when the flight will be terminated. Total expected flight time would be between 7 and 10 hours.

The global campaign will be formally initiated in March 11 and will end on April 21, while the operational launch window would open on March 27 and will be closed on April 15. The planned launch order will be first CLIMATE, then CARMEN and finally PILOT. However in function of the scientific goals of each mission, and according to the evolution of the weather during the campaign the order can be changed.

So ends, the brief summary of what we should expect from the next CNES campaign.

As allways, stay tuned to StratoCat in the next weeks for more news directly from the operations field as launches occur.

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Note: I want to express my deepest thanks to Stephane Louvel, head of the CNES operational team now in Australia, which provided much of the information and images presented here.

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