7 Minutes of Terror: The Challenges of Getting to Mars

Summary

The '7 minutes of terror' describes the intense and precise sequence of events during the Mars rover landing. Engineers explain the complex process of slowing the spacecraft from 13,000 miles per hour to a soft touchdown on the Martian surface, with no real-time communication with Earth. The spacecraft faces extreme conditions, including high speeds and intense heat, requiring innovative methods like the skycrane maneuver to safely land the rover. The entire sequence is guided by onboard computers and executed with incredible precision, with no room for error, making it one of the most challenging feats in space exploration.

Takeaways

• 😀 The Entry, Descent, and Landing (EDL) phase of a Mars mission is often called the '7 minutes of terror,' as it involves complex, high-risk maneuvers.
• 😀 The vehicle must transition from 13,000 miles per hour to zero in just seven minutes, relying entirely on pre-programmed automation with no help from Earth.
• 😀 The heat shield of the spacecraft reaches temperatures of 1600 degrees Fahrenheit as it encounters extreme aerodynamic drag while entering the atmosphere.
• 😀 Mars' atmosphere presents a unique challenge: it's thick enough to create drag but too thin to slow down the spacecraft enough for a safe landing.
• 😀 A super-sonic parachute, the largest ever built, is deployed to help slow the spacecraft, withstanding forces up to 65,000 pounds despite its own light weight of only 100 pounds.
• 😀 The parachute opens at such a speed that it creates a 'neck-snapping' 9G force.
• 😀 After parachute deployment, the heat shield must be jettisoned, as it obstructs the vehicle's radar, which needs to take precise altitude and velocity measurements.
• 😀 The parachute only slows the spacecraft to about 200 miles per hour, still far too fast for a safe landing, so rocket engines are used for the final descent.
• 😀 The rocket engines need to perform a 'divert maneuver' to avoid the parachute and slow the descent, positioning the rover to land vertically on the surface.
• 😀 The skycrane maneuver, involving a tether, is used to lower the rover onto the Martian surface while keeping the descent stage at a safe distance to avoid creating a dangerous dust cloud.

Q & A

What is the main challenge during Mars entry, descent, and landing (EDL)?

The main challenge is the '7 minutes of terror', where the spacecraft must travel from the top of Mars' atmosphere to the surface in just seven minutes, slowing down from 13,000 miles per hour to zero with no help from Earth, relying entirely on pre-programmed instructions and automation.

Why is the 7-minute entry phase considered so dangerous?

The 7-minute phase is considered dangerous because it requires perfect timing and choreography. The spacecraft has to slow down rapidly while navigating through the Martian atmosphere, with every step needing to work perfectly, or the mission could fail.

What role does the heat shield play in the Mars landing process?

The heat shield protects the spacecraft during entry by absorbing intense heat from atmospheric friction, reaching temperatures as high as 1600 degrees Fahrenheit. This is critical to prevent the spacecraft from burning up while slowing down.

What is the significance of Mars' atmosphere in the landing process?

Mars' atmosphere is difficult to work with because it is thin enough that it can't fully slow down the spacecraft but thick enough to cause dangerous aerodynamic forces. Engineers must manage this delicate balance to avoid spacecraft destruction or an unsuccessful landing.

How does the parachute assist in the Mars landing?

The parachute, the largest and strongest supersonic parachute ever built, helps slow the spacecraft down from around 13,000 miles per hour to 200 miles per hour. However, it's not enough to slow it down fully, requiring further maneuvers to safely land.

What happens after the parachute deploys?

Once the parachute deploys, the spacecraft experiences a dramatic deceleration, and the heat shield is jettisoned to allow radar to measure altitude and velocity for the next stages of the landing sequence.

Why does the spacecraft need to 'cut off' the parachute?

The parachute needs to be cut off because it can only slow the spacecraft down to 200 miles per hour, which is still too fast for a safe landing. To further decelerate, the spacecraft turns on its rocket engines.

What is the 'divert maneuver' during the landing process?

The 'divert maneuver' involves the spacecraft flying off to the side to reduce both horizontal and vertical velocities. This maneuver ensures the spacecraft moves straight down and can use radar to safely land.

What is the skycrane maneuver, and why is it used?

The skycrane maneuver involves lowering the rover on a tether from the descent stage 20 meters above the surface, allowing it to land safely without disturbing the dust or damaging its instruments. This method avoids the risk of the descent stage crashing into the rover.

What happens when the rover touches down on Mars?

When the rover touches the surface, the descent stage is still on a collision course with it, so the tether is cut immediately to prevent any damage. The descent stage is then flown to a safe distance to avoid any danger to the rover.