Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our
      fascinating universe is featured, along with a brief explanation
                    written by a professional astronomer.

                              2021 February 16

                     Perseverance: Seven Minutes to Mars
                           Video Credit: NASA, JPL

   Explanation: How hard is it to land safely on Mars? So hard that many
   more attempts have failed than succeeded. The next attempt will be on
   Thursday. The main problem is that the Martian atmosphere is too thick
   to ignore -- or it will melt your spacecraft. On the other hand, the
   atmosphere is too thin to rely on parachutes -- or your spacecraft will
   crash land. Therefore, as outlined in the featured video, the
   Perseverance lander will lose much of its high speed by deploying a
   huge parachute, but then switch to rockets, and finally, assuming
   everything goes right, culminate with a hovering Sky Crane that will
   slowly lower the car-sized Perseverance rover to the surface with
   ropes. It may sound crazy, but the Curiosity rover was placed on Mars
   using a similar method in 2012. From atmospheric entry to surface
   touch-down takes about seven minutes, all coordinated by an onboard
   computer because Mars is too far away for rapid interactive
   communication. During this time, humans on Earth will simply wait to
   hear if the landing was successful. Last week, UAE's Hope spacecraft
   successfully began orbiting Mars, followed a day later by the Chinese
   Tianwen-1 mission, which will likely schedule a landing of its own
   rover sometime in the next few months.

                      News: NASA Perseverance Coverage
                 Tomorrow's picture: light pillar with flare
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Phillip Newman Specific rights apply.
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                             & Michigan Tech. U.
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