It was new to me but it does seem to be a thing:
https://www.swpc.noaa.gov/phenomena/geomagnetic-storms
During storms, the currents in the ionosphere, as well as the energetic particles that precipitate into the ionosphere add energy in the form of heat that can increase the density and distribution of density in the upper atmosphere, causing extra drag on satellites in low-earth orbit.
I’m waiting for Scott Manley to make a YouTube video explaining it this week!
I would have thought they would have factored the potential for increased drag into their launch plans.
I guess they underestimate the height margin they would need.
An expensive mistake.
Love Scott Manley!
Hey, I called it:
Argon is cheaper than Krypton, which is cheaper than Xenon (the usual choice). It’s about 1% of Earth’s atmosphere, and basically a byproduct of O2/N2 liquification (it has other uses, but not so much to drive up the cost).
Good to see them constantly reevaluating previous mass/cost trades. Cheaper launch, cheaper solar, etc. all affect the right choice.
Though interestingly, they’re claiming 50% efficiency, which is pretty much in the same ballpark as Xenon thrusters. They must have made improvements in other areas to keep the efficiency flat.
Only 21 of these per Falcon 9 launch (compared to 50+ for V1). But they have 4x the capacity, so it’s an overall win. Still, clearly they’re depending on Starship in the long run.