‘7 minutes of terror’

Washington – Seven months after blast-off, Nasa’s Mars 2020 mission was to negotiate its shortest and most intense phase yesterday: the “seven minutes of terror” it takes to slam the brakes and land the Perseverance rover on a narrow target on the planet’s surface.

Entry, descent and landing begins when the spacecraft carrying Perseverance strikes the Martian atmosphere at nearly 20 000km/h. It ends seven minutes later with the rover at rest on the surface.

Touchdown on the Jezero Crater was scheduled for last night. Weather conditions so far appear favourable in the Martian northern hemisphere spring. “This is one of the most difficult manoeuvres we do in this business and almost 50% of the spacecraft that have been sent to the surface of Mars have failed,” Matt Wallace, the mission’s deputy project manager said.

Ten minutes before entering the Martian atmosphere, the spacecraft sheds its cruise stage that supplied the fuel tanks, radios and solar panels. It’s left with a protective aeroshell, carrying the rover and descent stage, and it fires thrusters to ensure its heat shield is forward facing.

At about 130km altitude, it careens into the atmosphere and peak heating occurs about 80 seconds in when the heat shield surface reaches about 1 300°C. Perseverance is tucked away in the aeroshell, experiencing room temperature.

Once the spacecraft has slowed to less than 1 600km/h, the supersonic parachute is deployed.

Perseverance is deploying a new technology called Range Trigger that decides the precise moment to deploy. Asked to name the single most critical event, Nasa’s Allen Chen said: “There’s a lot of concentrated risk in supersonic parachute opening.”