If you're saying that moles/m^3 of CO2 might be constant while pmm of CO2 is increasing, that implies that atmospheric pressure at sea level is dropping. And it isn't.
You cannot put air at 2 km and then at 20 km high! Of course the second layer will just flow down until it's supported by the first layer, which is in turn supported by the ground. So your question doesn't really make physical sense.
For context, the predecessor of SpaceShipTwo reached an altitude of over 100km in June 2004, becoming the first commercial venture to put a person in space [1]. A few months after that, Virgin got involved and it seemed like commercial passenger spaceflight was just a few years away. 14 years and two fatal accidents [2,3] later, the 80 km flight seems to pale in comparison to those expectations. In that time we’ve seen the rise of SpaceX and Blue Origin, whose aspirations and capabilities look set to far exceed those of Virgin Galactic. As impressive as this spaceplane is, its competitors are starting to make it look like the product of some (very expensive) backyard tinkering.
Right now Blue Origin and Virgin Galactic are in about the same place, with SpaceShipTwo ahead of New Shepard in terms of test flights (and presumably crew rating). Both will provide suborbital tourist flights.
SpaceX isn't in that game; they're trying to get the Falcon 9 crew-rated for orbital flights. If Blue Origin's New Glenn ever gets off the ground, they may pursue an orbital crew rating as well.
Blue Origin is presently spending a great deal of money developing New Glenn. I would be very surprised if we don't see a flight test of the "v1.0" full scale rocket before 2025.
Virgin Galactic has nothing in development with anywhere near the velocity capability for low earth orbit. Going up in a parabola to 100 km or 150 km and then coming back down again, a few hundred km down range, is a very different sort of delta-v requirement versus putting something in a stable orbit.
They are in "about the same place" for things that are flying now, but for the next generation beyond that, Blue Origin is far ahead.
Few doubts given their benefactor's unlimited resources, but it's worth remembering how unexpected SpaceX's successes were.
I'm mainly pointing that it's odd to compare aspirations with accomplishment. I've thought about climbing Everest, and even planned a route and bought some gear, but that doesn't put me in the same category as Norgay or Hillary.
They were originally aiming for 100km, and at early space tourism conferences (about a decade ago) would point out that other competitors (e.g. Lynx, at the time) weren't actually going to 100km so couldn't claim they were going to space (they would do this reliably, and to the growing annoyance of the audience who didn't want audience-question time hijacked for Virgin PR, e.g. in a Q&A panel that had a Lynx team member onboard, a virgin person would always ask a question like 'Just to confirm, you're not flying above 100km, the altitude at which space starts?').
However, the performance of Spaceship 2's engines has fallen short of the original design goal, making it incapable of reaching 100km, so they are now using a different definition of Space for PR purposes.
There are other attempts at disposal of dead satellites that don’t rely on a long-shot like the BFR [1]. Besides, maneuvering a big heavy spacecraft like that to match orbits with a bunch of little satellites would be tremendously wasteful in terms of fuel. A much better use would be to remove larger satellites like defunct communications satellites. These are actually a much bigger danger to orbital space as well. See this event for example [2], which generated over 2000 pieces of debris large enough to track and many more of a smaller size. Small satellites are not nearly as dangerous because when they are defunct their low mass causes them to renter faster.
(FYI I’m a PhD student in the lab that built the satellite in the article.)
It seems YouTube's statement here is really disingenuous. When they say "We are working with MITOpenCourseWare and Blender Foundation to get their videos back online." they mean that they are holding these non-profit organizations' video hosting rights hostage until they agree to enable ads!
https://news.ycombinator.com/item?id=17347560
