When I first watched the XPrize flight in 2004 (!!) on a tiny pixelated video over an ISDN connection, I thought we would only be a couple of years away from regular space tourism. I never would have dreamt that chatbots would pass the Turing test before Virgin Galactic became operational. Predicting technological advancements is hard.
>Following liftoff, Virgin Galactic’s carrier plane VMS Eve transported VSS Unity to an altitude of about 50,000ft. Eve then dropped Unity which then fired its own rocket motor and ascended to suborbital space. Passengers aboard experienced approximately 3Gs.<p>suborbital, would still be an amazing experience though.
Is it feasible for them to build an orbital version?<p>I want the concept of launching from altitude to work because it seems like the heavy atmosphere part has different requirements and so having another vehicle to help with that seems intuitive.<p>I also wonder if you could make orbital flight with this type of system more achievable if the delivery aircraft and/or the rocket had scramjet ability so that it was more efficient.
> Galactic 02 is a suborbital flight. However, despite VSS Unity not reaching orbit, the trajectory allows passengers to experience several minutes of weightlessness at an altitude high enough for them to see the Earth’s curvature<p>Glad they acknowledged that, never realized how close commercial airplane flights were to that
I see a lot of discussion/arguments on the definition of space here. Allow me to fill in few relevant details of how "space" is defined.<p>There is no clear definition of a boundary between space and not-space. Some like to use the definition of "space" as "no-meaningful atmosphere". Note that the atmosphere does extended very far indeed into what we typically deem "space". Typically we model gases (like the atmosphere) as discrete packets of continuous properties. If density is below a very low threshold, we can't do that, and have to model gases using rarified models (where gas behaves more like individual particles). If we use the 1976 Standard Atmosphere model this happens at above 86km. Therefore to atmospheric scientists, space is 86km.<p>Now let's say you're building an orbital space plane. To stay aloft, your gravity opposing forces come from two sources: aerodynamic lift and centrifugal force. When you go faster, both forces increase, so for every altitude, there's a speed which keeps you aloft. However lift force is a function of density, and density drops with altitude. Therefore there is a point where aerodynamic lift is essentially meaningless compared with the centrifugal. At this point, you are more of a orbital vehicle than an aerodynamic one, so we can say that you are "in orbit". This altitude is The Kalman line. The important thing to note is that the Kalman Line is a definition prescribed to a specific vehicle (the Bell X-2, although it is rarely discussed in that context). Changing the weight and lift properties change it. Hence the boundary is very fuzzy and the exact source of definition changes depending on how it's calculated. It's also been calculated based on aerothermal heating considerations, and based on the operational limits of air-breathing engines. Therefore, it's been cited as 83km, 86km, 90km and 100km depending on the specific source. A key takeaway here is that The Kalman Line is a speed as well as an altitude, so it doesn't even make sense to use this as a boundary in a suborbital context. But for orbital scientists/engineers, you safely say that's space is not below 80km, and certainly above 100km.<p>Now imagine you are the US Air force and some of your pilots flew an experimental aircraft (the X-15) 90km altitude, and you want to put astronaut wings on them to gain some inter-service rivalry clout. Well for you, the definition of space is then 90km.<p>Now let's say you are the FAA and want to quantify where your jurisdiction ends. Well, pick an arbitrary definition based on Kalman's notes. 100km should be good enough for your needs.<p>Now let's say you are a satellite engineer and want a definition where your satellites will actually stay in orbit for a few trips around the earth without thrust corrections. Pretty hard to do at 80km, there's too much air. As it turns out the lowest sustained circular orbits occur at around 125 km. So 125 km is a good definition of space for you.<p>There's some much needed historical context. Now let the useless arguments surrounding the pedantry of fuzzy definitions continue.
Whilst its to the edge of space where weightlessness is only experienced for a few minutes, in terms of scalable processes for the masses to experience space, this seems to be one approach that could scale up quickly.
What a massive waste of the limited carbon budget we have remaining as a species. The techno-optimists who think this is bootstrapping more humanity-serving missions (like a colony on Mars or the Moon) are lying to themselves. We are squeezing every last resource that makes Earth livable to enrich a few people short-term, but we will all suffer for this in the next few decades.