EXO-MARS HADT (High Altitude Drop Test)

This balloon mission was part of the qualification and testing phase of the parachute system for ExoMars (Exobiology on Mars) mission, an astrobiology programme by the European Space Agency (ESA) and the Russian space agency Roscosmos. The goals of ExoMars are to search for signs of past life on Mars, investigate how the Martian water and geochemical environment varies, investigate atmospheric trace gases and their sources and by doing so demonstrate the technologies for a future Mars sample-return mission. The first part of the programme was a mission launched in 2016 that placed the Trace Gas Orbiter into Mars orbit and released the Schiaparelli EDM lander. The orbiter is operational but the lander crashed on the planet's surface.

The second part of the programme was planned to launch in July 2020, when the Kazachok lander would have delivered the Rosalind Franklin rover on the surface, supporting a science mission that was expected to last into 2022 or beyond. The descent module requires two main parachutes -each with its own pilot chute for extraction- to help slow it down as it plunges through the martian atmosphere. The 15 meters-wide first stage main parachute will open while the descent module is still travelling at supersonic speeds, and the 35 meters-wide second stage main parachute is deployed once at subsonic speeds. Following separation of the parachutes, the speed must be suitable for the braking engines to safely deliver the landing platform and the rover onto the surface of Mars.

To test the performance of the parachutes before the flight, the UK-based company Vorticity Systems was selected as technical consultant under contract with Thales Alenia Space. A special capsule was built by the firm to perform the drop tests of the parachutes, first from low altitude using an helicopter and then from high altitude using a stratospheric balloon. These missions allowed to test the parachutes and deployment sequence with the same gravitational acceleration and atmospheric density as they will experience on Mars.

After the firsts series was completed in 2019 some anomalies were found on the descending system. As a result on March 2020, it was announced that the second mission was being delayed to 2022 as a result of the problems with the parachutes, which could not be resolved in time for the launch window. After studying the problem and some modifications, a new series of parachute tests were needed which were performed in Oregon during 2020 and from Sweden in 2021. The 2021 test series in Kiruna saw the flawless deployment of the first main parachute provided by Airborne Systems. However, the 35 m-wide second stage parachute provided by Arescosmo experienced one minor damage, likely due to an unexpected detachment of the pilot chute during final inflation, but it still decelerated the drop test vehicle as expected. In the intervening months the pilot chute attachment was changed, and Kevlar reinforcements were replaced with nylon on two rings in the parachute canopy to better match the same strength and elasticity of the parachute fabric, in order to reduce the risk of tearing.

This second series of tests in Oregon, were aimed to test these modifications. After recovering the parachutes was observed only a handful of very tiny and insignificant 1-2 cm sized tears and friction searing on the two parachute canopies. Althought certainly these parachutes will work well as-is without any concern, new adjustments will be made to the designs that would be tested on a new round of high-altitude drop tests to be carried out in 2022. However, the outbreak of war in Ukraine in March 2022 has put this new round of tests on hold indefinitely, since for now the European Space Agency has not yet found a new vector for the launch of the mission, after the agreement with Roscosmos was rescinded.

Balloon launched on: 11/21/2021 at 16:00 utc
Launch site: Madras Municipal Airport, Oregon, US  
Balloon launched by: Near Space Corporation (NSC)
Balloon manufacturer/size/composition: Zero Pressure Balloon  
End of flight (L for landing time, W for last contact, otherwise termination time): 11/21/2021 at 17:30 utc
Balloon flight duration (F: time at float only, otherwise total flight time in d:days / h:hours or m:minutes - ): ~ 3 h
Landing site: In Crook County, Oregon, US

• Double drop test success for ExoMars parachutes ESA website
• Near Space Corporation website