Thread by @DrChrisCombs

NASA is LIVE with coverage of the Perseverance landing, happening around 2:55p US CT, this is the place to be

Percy about to hit the atmosphere at 3.5 miles/sec (5.5 km/s) and create some serious heat
#CountdownToMars #MarsPerseverance #Perseverance

pscp.tv/w/cv11hDFsWkVw…

The extreme velocity of atmospheric entry will heat the surface of the heat shield to nearly 2,400 F (1,300 C) due to intense shock heating and aerodynamic forces

It’s a tricky part of the mission for many reasons, but our ability to predict/model the physics of these atmospheric entry events is currently limited—it’s a “multi-physics” problem which makes it tough even for our best super-computers to handle

To make matters worse it’s almost impossible to accurately recreate these exact conditions in a sustained experiment on the ground, so we do our best with experiments and computations that we hope get it *mostly* right

With the large uncertainties involved, we have to do a bit of over-engineering

Consider that the Mars Science Laboratory mission (Curiosity) only burned through 10% of its heat shield

Better to do that than the other way around, but still that’s limiting your payload