![]() The audacious sky crane maneuver would be a great feat in any action movie. Any error could mean the mission is lost. There is only one chance for a smooth landing. When the control center in Pasadena, California receives the message that entry has begun, Perseverance will already be on the ground. Radio signals from the spacecraft need about 11 minutes to travel in one direction. Experts have to sit and watch what’s happening more than 200 million kilometers away. The flight team can’t interact with the spacecraft on Mars. Once the rover has touched down, the tethers are cut and the sky crane flies off to land somewhere else on the surface.Įntry, descent and landing takes just seven minutes – the so-called seven minutes of terror. Upon approach of Mars’ surface, the sky crane will lower Perseverance down about 7 meters. The rover is connected to the crane by nylon tethers. Four thrusters keep the crane properly oriented. Roughly two kilometers above the planet’s surface, a sky crane comes into play. Later, parachutes will deploy to slow it down even more. The heat shield will surpass 1,000 degrees Celsius. Once the spacecraft enters the atmosphere it will be slowed down by friction. The highlight of this year’s Mars exploration is the landing of the NASA rover “Perseverance” on February 18. ![]() Perseverance will arrive at Mars’ Jezero Crater with Ingenuity attached to its belly. Ingenuity, a technology experiment, will be the first aircraft to attempt controlled flight on another planet. Every two weeks, we have to look in the opposite direction to see the Moon, and the ground beneath our feet is then tilted the opposite way as well.NASA’s Mars 2020 Perseverance rover (shown in artist’s illustration) is the most sophisticated rover NASA has ever sent to Mars. The tilted ramp works the same as the tilted “platform” of the Earth beneath our feet. If you turn around, the horizon appears to tilt the opposite way. In front of you, the horizon looks higher on the right and lower on the left. Earth has a tilt of 23.5 degrees on its axis, which means that when we observe the Moon from Earth, it’s a little like we’re standing sideways on a ramp. The tilt of the Moon’s orbit contributes to this, but it’s mostly due to the tilt of our Earth. We call this motion “libration in latitude.”įinally, the Moon appears to tilt back and forth like a metronome. The 5 degree tilt of the Moon’s orbit also causes it to appear to nod, as though it were saying “yes.” The tilt sometimes brings the Moon above Earth’s northern hemisphere, and sometimes below Earth’s southern hemisphere, allowing us to see slightly more of the northern or southern hemispheres of the Moon. We call this motion “libration in longitude.” When the Moon is farthest from Earth and orbiting at its slowest, its rotation gets a little ahead, and we see a bit more of its western side. When the Moon is at its closest to Earth and moving most quickly along its orbital path, the Moon itself doesn’t rotate quite fast enough to keep entirely the same side facing us, and we get to see a little more of the eastern side of the Moon. The Moon’s rate of rotation around its own axis, though, always stays the same. Because the Moon's orbit is not perfectly circular, its distance from Earth and its speed in orbit both change slightly throughout the month.
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