> Nothing got hot enough to start showing up in the visible spectrum (good).
The new grid fins undergo the same amount of heating, they're just better able to cope with the heat. The reduced heat in this case was due to the much lower energy entry profile (the partial boostback burn killed a large chunk of the stage's velocity prior to reentry, combined with the fact that it was a lower energy orbit in the first place).
Thanks Josh. I went back and reviewed the Iridium 1 footage and saw that even the Aluminum fins had no trouble with this particular launch and recovery option. I am looking forward to seeing the first GTO launch with a booster that has them.
The new grid fins undergo the same amount of heating, they're just better able to cope with the heat. The reduced heat in this case was due to the much lower energy entry profile (the partial boostback burn killed a large chunk of the stage's velocity prior to reentry, combined with the fact that it was a lower energy orbit in the first place).