Starlink deorbiting satellite - StarCatcher?

Starlink represents unprecedented constellation even compared with to other proposed constellations by an order of magnitude. Furthermore, SpaceX seems to favor a single orbital altitude of 550km with three inclinations for initial deployment, abandoning higher 1200km orbits. Although they plan to actively deorbit ageing satellites, use atmospheric drag to ensure passive deorbiting in less than 25 years, and use active orbit avoidance, any collision  near such orbit would quickly cause cascading effect and bring down whole Starlink constellation through well known Kessler syndrome. Not to mention almost immediate evacuation of ISS.

Leolabs presentation of LEO space debris

So SpaceX must plan for active removal of inactive satellites or other orbital artifacts that represent danger to the constellation. Unlike other proposals, SpaceX has the following unique advantages:

• it has the cheapest launcher per mass to orbit
• it has many launches to the same orbital inclination (for Starlink satellite deployments)
• it mass produces Starlink satellite bus (with estimated cost of 500000USD per satellite, which is close to more complex cubesats)
• its Starlink satellites already have significant deltaV budget (measured in hundreds of m/s)

So it seems straightforward for SpaceX to iteratively design and test a version of Starlink satellite without communications payload. Instead such satellite(s) would feature a capture mechanism (probably a robotic arm) and increased propellant tanks to more deltaV budget. Such satellite could be stacked and launched together with current Starlink satellites. But its primary purpose would be to rendezvous with failed Starlink satellite, capture with robotic arm, and reduce it velocity so that both reenter the atmosphere.Once perfected, the same design could be easily deployed to any target with similar inclination. With beefed up deltaV, it could be used to capture upper rocket stages. Help clean up SSO, GTO (using 28.5 inclination) and ISS orbital inclinations just as secondary payload on existing launches. There is a clear and rather straightforward technological path for upgrading Starlink propulsion by switching from Krypton to Iodine, but that I will cover in separate post.

The game changer is the low cost of such solution. SpaceX will need to develop such a system for maintenance of Starlink orbits. With projected cost of half a million dollars for manufacturing and half a million per launch, SpaceX could offer deorbiting price between one and two million USD per orbital item. For example, it could deorbit whole original Iridium constellation with just two Falcon 9 launches. At that price point, garbage collection and disposal becomes cost effective for old government satellites and upper stages. Just one such launch per year (which is really a minor expense for US government) would greatly reduce generation of additional orbital debris caused by gradual disintegration of old satellites and upper stages in LEO. The same StarCatcher design could be used in GEO for capturing and dragging non-functional satellites from GEO arc to graveyard orbit.