const MARS_PAD_SITE: Readonly<{ presentationTime: 1133.5211610867814 }>
The instant the scene is composed for, in J2000 seconds: the Sun 3° above
the horizon and west of MARS_PAD, so the descent is shot into a sunset.
It is solved for that one site, which is why the scene stages the seeded
pad rather than whatever record carries its id.