So instead of having to launch new satellites to replace the deorbited ones ever couple of years, do they have to send new ones every couple of months? Or can the functioning ones maintain their orbits somehow and this is only for the malfunctioning ones?
It sounds like this corresponds to an atmospheric contraction. They are lowering to avoid extending the lifetime of possible debris, but that also probably means the regular lifetime is not shortened. They are just staying in the designed density to match their designed service lives. The field of view of the satellites will be reduced, but presumably they have enough units up there to maintain full coverage.
This is distinct from the FCC application they have made for another Starlink shell in VLEO (~330km) for another 15000 satellites to better serve cellular phones.
At 480km there will be increased drag, even as we get closer to the solar minimum. The trade-off may be between using propellant for collision avoidance vs using it to counter altitude loss and for station keeping.
Maybe it is also linked to the falling altitude of the ISS? 480km is about the upper bound of its altitude but they seem unlikely to actually raise it that high before it is deorbited.
is it conceivable that collision avoidance maneuvers become cheaper in fuel consumption by using the slightly less thin atmosphere to steer a satellite (only use propellant for attitude control, less direct linear acceleration?
i.e. if the propellant consumption for collision avoidant steering at 550 km in practice turns out to be higher than the consumption to negate the drag incurred for using atmosphere for steering, it could be a logical choice.
Yes, you can do that. But you do need to alter your attitude for long periods and that usually means you point away from the optimal position for the solar panels and for the antennas pointing towards the ground. So yes, but only at the cost of some loss of efficiency.
> ion thrusters that prevent them from losing altitude as long as they are operational
Unintentional tautology. A satellite is by definition operational as long as it can station keep.
That said, yes, they should be able to station keep with ions alone. But also, ion propulsion still requires propellant. Until we figure out orbital magnetic suspension, it’s all reaction engines.
There has been some research (IIRC by ESA) for using the upper atmosphere to feed a ion engine. That way you should be able to put satellites even lower as long as they have enough power from solar panels and are functional.
