Falcon 9 first stage reaches a max altitude of 150-160 km. Too low.
It seems the problem isn't deorbiting (yet), it's tracking. >10 cm we can
track from ground based stations and avoid via maneuvers (not ideal, but
not the wolf closest to the sled). <1 cm can be dealt with via shielding
or redundancy. It's <10 & >1 cm that's the problem. Too small to track,
big enough for a mission kill (6cm ball of Al is 500g, at 8km/s that's 16
MJ of KE, aka a dead satellite).
Also, that graphic is outdated. Current Starlink plans are to start with
1600 satellites at 550 km, then 2800 at 1150 km, and 7500 at 340 km.
Notice how they avoid the worst part of the "Traffic Jam."
I'm guessing the mega-constellation providers (SpaceX at the forefront) are
going to have enough of an incentive to solve this problem - at their
altitude. SpaceX is planning on doubling the number of active satellites
in orbit around the Earth with just their first wave. Sure part of the
plan is that some of the satellites will die (or be DOA) and have to be
deorbited, but eventually the scales are going to tip enough such that it
makes economic sense to find ways to actively deal with space junk.
Lasers have been brought up. I think developing and launching 5 to 10
satellites to actively protect a constellation of 1600 makes sense. Equip
them with ~100 km lasers and radar powerful enough to pick up objects >1 cm
in diameter at that distance (and a control system capable of hitting the
correct side of a spinning 6cm bolt with a laser at 100 km - the real
challenge) and then just let them go to work. It won't placate alarmists,
but using lasers with a max effective range of ~100 km would put these
satellites out of the range of earth - no military application.
Once the technology is developed and deployed by the mega constellation
provider, it could be sold to governments to clear altitudes that don't
necessarily interest the company.
On Thu, May 2, 2019 at 10:56 PM Craig Fink <webegood@xxxxxxxxx> wrote:
On Thu, Apr 4, 2019 at 10:29 AM Norman Yarvin <yarvin@xxxxxxxxxxxx> wrote:
On Wed, Apr 03, 2019 at 10:14:23PM -0700, Craig Fink wrote:If Falcon 9 first stage is totally reusable, and can squirt out, lets say
On Mon, Apr 1, 2019 at 5:27 PM Keith Henson <hkeithhenson@xxxxxxxxx>wrote:
swatter
I seek wisdom in this matter. Not considering the political problems,
are ablation lasers up to the task? I think either the laser or a
redirection mirror would have to be in space and at an altitude about
the same as the junk in order to hit it head-on.
Sure, but it's not nearly as much fun as going up with a giant fly
and slapping the object out of orbit.
Put yourself in the place of someone who has to pay for it, and what's
"fun" might get revisited. Sending up a Falcon 9 first stage just to
de-orbit a stray bolt isn't going to happen, but a laser zap might.
And those military applications that Henry thinks of as political
downsides... well, by some people's thinking they're political
upsides, and there's certainly "fun" to be had there. (Though beware
of wanting too much of that sort of "fun"; you might get it.)
between 10 and 100 puffs of Gas (Oxygen or Hydrogen or WhatEver) between
separation and Entry Burn every launch, LEO would be debris free in very
little time. Every time something goes up, between 10 to 100 other objects
go down, just a little bit. Don't tell Henry, he doesn't like Hydrogen Snow.
--
Craig Fink
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