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Tiny satellites ushering in a new space revolution

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Re: Tiny satellites ushering in a new space revolution

#41

Post by kobeya »

snrplfth wrote: post #36
kobeya wrote: post #23

Earlier quoted context omitted.

When collisions are more frequent than once per orbit you get effects where more than one collision cause a bit of debris to have itself lifted. MOST debris is deorbited, but a small fraction is lifted into a higher orbit overall. As these collide with other objects the total mass of the system might go down (from reentry), but the number of objects and the frequency of collision goes up, continuing the process of so…

Not how orbits work. A collision can't cause, for example, an object with a circular orbit at 400km (passive reentry regime) to become fragments with a circular orbit at, say, 2000km (non-passive reentry regime.) Like snaily said, all fragments originating from a collision will still pass through the point of collision, which, if it is still in the upper atmosphere, will lead to reentry. Orbital debris is actually ve…

Multiple collisions. Multiple.

Re: Tiny satellites ushering in a new space revolution

#42

Post by kobeya »

vanderZwan wrote: post #35
kobeya wrote: post #23

Earlier quoted context omitted.

When collisions are more frequent than once per orbit you get effects where more than one collision cause a bit of debris to have itself lifted. MOST debris is deorbited, but a small fraction is lifted into a higher orbit overall. As these collide with other objects the total mass of the system might go down (from reentry), but the number of objects and the frequency of collision goes up, continuing the process of so…

> more frequent than once per orbit My gut feeling says that statistically, even just going from one impact to two impacts being likely would require an immense density of satellites, let alone having more collisions than that. Then there's also the fact that every impact would have a loss of kinetic energy (because it gets converted to heat as the objects deform), which would also make a reduction in orbit likely. I…

https://en.wikipedia.org/wiki/Kessler_syndrome

Re: Tiny satellites ushering in a new space revolution

#43

Post by Snowdax »

Nanite wrote: post #18
currydove wrote: post #14

Earlier quoted context omitted.

The other comments that are replying to you have it fairly accurate. It's not widely known but it isn't a secret either: the point of the doves is to be deployed en masse and with more capability with every subsequent build. A quick refresh in the constellation means there is fresh hardware in space every so often. This means the intention is indeed for re-entry into the atmosphere after the operational lifespan of t…

It seems Planet currently only relies on passive de-orbiting, how long are sats expected to stay in orbit? And are active de-orbiting options being considered?

Between 6 months and 4 years ideally. 25 years max. If you can't prove reentry within 25 years in simulations you do not fly on the rocket at all in the first place.

Re: Tiny satellites ushering in a new space revolution

#44

Post by snrplfth »

kobeya wrote: post #41
snrplfth wrote: post #36

Earlier quoted context omitted.

Not how orbits work. A collision can't cause, for example, an object with a circular orbit at 400km (passive reentry regime) to become fragments with a circular orbit at, say, 2000km (non-passive reentry regime.) Like snaily said, all fragments originating from a collision will still pass through the point of collision, which, if it is still in the upper atmosphere, will lead to reentry. Orbital debris is actually ve…

Multiple collisions. Multiple.

The proportion of fragments that would have their orbits boosted, through multiple collisions, to an orbit higher than the upper atmosphere, is trivial. Nearly every angle of collision between two objects in orbit lowers their periapses. The risk of Kessler Syndrome doesn't come from objects in upper-atmosphere orbits somehow getting boosted out through collision chains, it comes from collisions between objects already in higher orbits not strongly affected by atmospheric drag (>600km).

Re: Tiny satellites ushering in a new space revolution

#45

Post by Snowdax »

kobeya wrote: post #41
snrplfth wrote: post #36

Earlier quoted context omitted.

Not how orbits work. A collision can't cause, for example, an object with a circular orbit at 400km (passive reentry regime) to become fragments with a circular orbit at, say, 2000km (non-passive reentry regime.) Like snaily said, all fragments originating from a collision will still pass through the point of collision, which, if it is still in the upper atmosphere, will lead to reentry. Orbital debris is actually ve…

Multiple collisions. Multiple.

It can me infinite collisions. It does not matter. Conservation of momentum still applies. The system of collisions only have a finite amount of energy. And it's chaotic rather than engineered. So it's not cumulative, much more likely to happen at numerous different angles cancelling previous collision trajectories out.

Re: Tiny satellites ushering in a new space revolution

#50

Post by ant6n »

westmeal wrote: post #6
kumarvvr wrote: post #3

That is a pretty cool engineering feet. Never knew a shoe box sized telescope can give such detailed pictures. They have sent about 200 satellites, cost "six figures" each, so an estimate of 200,000 a piece, they have spent about 40 million dollars, excluding the price of launches. The data collected is definitely worth the price IMO. Imagine the ability to monitor storms and hurricanes, analyze their data and update…

Global surveillance networks.

This does seem reminiscent of some Bond movie: some young company/genius supposedly wants to save the world via a fleet of satellites tracking all sorts of environmental issues, a company called Planet (a logo written in greenery in their office). Then it turns out there's actually a nefarious reason for all this, like total surveillance of everybody etc.
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