This video is about why it’s harder to successfully land spacecraft on Mars than on Earth, or Venus, or the Moon, or Titan, or asteroids.
It all comes down to atmospheric density! When there’s no atmosphere, you can do a powered descent in a flimsy tinfoil spacecraft like the Lunar Module, and when there’s plenty of atmosphere you can do an unpowered descent via heat shield and parachutes like the space shuttle, Apollo command module, Soyuz, Huygens, etc.
But on Mars with its thin air, you have to do both powered & unpowered descent, getting the worst of both worlds.
Learn more in this video by MinutePhysics