Why couldn’t the capsule with the asteroid samples open the parachute properly?

Engineers found out what happened to the parachute of the OSIRIS-REx capsule, which brought samples of the asteroid Bennu to Earth. Due to the incorrect connection of the wires, the order of its opening was violated. However, the reliability of the design made it possible to avoid a disaster.

The parachute and capsule of the OSIRIS-REx mission. Source: NASA/Keegan Barber

Parachute opened with problems

During the landing of the OSIRIS-REx probe capsule, which took place on September 24 this year, the parachute opened with problems. This did not prevent it from making a soft landing as planned, but still, NASA experts are extremely interested in identifying the reasons for this situation.

They carefully studied the video of the descent and found out why the parachute did not open properly. The reason turned out to be an error in the design of the system, which was supposed to slow down the capsule, which had a high speed even after aerodynamic braking. 

The system should work in two stages to do this. At the first one, at an altitude of 30 km, a small drogue parachute was opened, which slowed down the spacecraft slowly enough but could provide such a speed at which the opening of the main dome would not lead to its separation. It was supposed to happen at an altitude of 3 km.

What are the problems?

The problems started due to confusion with the word “main”. In relation to a small parachute, it was used in one place to designate a device for opening it and in another for firing. And of course, the wires from the controller to the devices were simply mixed up.

As a result, at an altitude of 30 km, the device tried to fire off the drogue parachute, which was still in its compartment, which led to its disconnection. The capsule continued to fall without it until the main parachute began to open at an altitude of 2,750 m. The drogue flew away at that moment.

Fortunately, the main parachute of the OSIRIS-REx capsule was designed with a margin of safety. It opened up properly and could withstand the additional loads. It was risky, but finally the device landed a minute earlier than planned. 

Fortunately, the capsule with the samples remained unharmed. Now scientists are studying what OSIRIS-REx brought back from its journey, especially paying attention to organic compounds. They want to find out if asteroids can be carriers of life in the Universe.

According to www.space.com

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