@Anthony_Bonato 1 was originally considered prime.
The problem is, prime numbers have a number of useful properties (e.g., any composite number has a unique prime factorization) - except for 1, which had to be excluded every time.
So they ended up changing the definition to exclude 1.
@JulianRLewis@PaulsonJonathan@Anthony_Bonato Jonathan's argument is the strongest, but also to some degree it's a decision because it makes the rest of the math line up better. Like eg 0^0=1, you can argue that from limits but you can also argue against it from different limits. =1 tends to work better so that's the norm.
@Robotbeat aiui because of the engine-out they intentionally went to a trajectory that aims directly at the landing site without in-space burn. So it's not quite showing 100% engine-out capability, instead they chose a lower delta-V option just in case they needed it
@pintleinjector When it went engine-out on ascent, they changed to a different trajectory that already aims for the landing site without in-space relight. That's how I understand it anyway, that's what they meant by "the ascent wasn't nominal but we're still on a pre-envisioned trajectory"
@_nightjuice_@CSI_Starbase@TrentTelenko Mostly because we're looking at things that are much brighter, same reason you don't see stars during the day. Then also because the satellites themselves might be in the shadow of the Earth (you can only see them around sunset/sunrise)