Quote from: Alberto-Girardi on 04/15/2023 09:20 pmGreat find. But have the FAA or SpaceX ever called the flight suborbita?FWIW... The FAA launch license is neutral. The FAA WR (published concurrently), refers to "Starship Orbital Test Flight...", and also specifically refers to booster as suborbital.Think most of us know what a significant effort this is and what it portends--whether or not this first attempt succeeds. Trolls, ankle biters and barnyard lawyers trying to minize that based on questionable self-serving interpretations just makes them look small and is a distraction.
Great find. But have the FAA or SpaceX ever called the flight suborbita?
There are rules for orbital flights, and slightly different rules for suborbital ones. I haven't waded through the permit yet, so I don't know if there's any verbiage in there that sheds light on the issue....
Another issue: I'd guess that SpaceX would like to be as gentle on the tiles as possible, in the interest of getting as much hypersonic data before a failure as possible. That implies hitting entry interface with as modest an amount of energy as possible. If that requires giving the aforementioned ankle-biters something to chew on, so be it. But I have to admit that I would smile if I saw their tears.
SpaceX is projecting things onto the Mega Bay. Looks like a calibration alignment grid ahead of whatever they plan to project.nsf.live/starbase
Just another night at Mega Bay🚀
Hey, I know that shape!
Elon, get off the projector controls! 😅
Think most of us know what a significant effort this is and what it portends--whether or not this first attempt succeeds. Trolls, ankle biters and barnyard lawyers trying to minize that based on questionable self-serving interpretations just makes them look small and is a distraction.
It actually honours Elon's habit to alway be as honest as possible.
Quote from: sebk on 04/15/2023 01:44 pmNope. You are totally wrong.To have perigee below sea level and be able to do 3/4 of the circle around the Earth after standard rocket launch (Space-guns, X-30 NASP-like spaceplanes or other Sci-Fi solutions notwithstanding) you must have apogee at ~320km or higher. Otherwise your trajectory would be too shallow. Wrong. Impossible for a pure impulsive launch (e.g. space gun) but not for any real launch vehicle, which has tens of minutes of burn time, and outside the atmosphere can vector thrust arbitrarily. Whilst eccentricity and plane changes performed within the burn to orbit are expensive in terms of delta V, physics will not stop you. You can - for example - insert directly into an orbit with an apogee above your current altitude and descending, and thus never reach apogee.
Nope. You are totally wrong.To have perigee below sea level and be able to do 3/4 of the circle around the Earth after standard rocket launch (Space-guns, X-30 NASP-like spaceplanes or other Sci-Fi solutions notwithstanding) you must have apogee at ~320km or higher. Otherwise your trajectory would be too shallow.
The confusion is because we don't have a good word to describe trajectories that have orbital speed and energy but also have a velocity vector direction that will result in entering the atmosphere before a complete revolution.Such trajectories are much better described as "orbital" than "suborbital", but neither is completely accurate.
ICBMs dont fly more than half around the globe.
Quote from: edzieba on 04/15/2023 02:27 pmQuote from: sebk on 04/15/2023 01:44 pmNope. You are totally wrong.To have perigee below sea level and be able to do 3/4 of the circle around the Earth after standard rocket launch (Space-guns, X-30 NASP-like spaceplanes or other Sci-Fi solutions notwithstanding) you must have apogee at ~320km or higher. Otherwise your trajectory would be too shallow. Wrong. Impossible for a pure impulsive launch (e.g. space gun) but not for any real launch vehicle, which has tens of minutes of burn time, and outside the atmosphere can vector thrust arbitrarily. Whilst eccentricity and plane changes performed within the burn to orbit are expensive in terms of delta V, physics will not stop you. You can - for example - insert directly into an orbit with an apogee above your current altitude and descending, and thus never reach apogee.Wrong. As I wrote, this applies to everything behaving like a rocket. In fact, it'd be more doable with a space gun (realistically it must be either some type of EM gun or nuclear) than with a rocket: guns always have perigee below ground level, you must raise it later. And no rocket burns for tens of minutes. The longest ascent burns approaches 20m and it takes less than 1/10 of the full circle to ascent. Way too little to cut the exoatmospheric part of the flight below half circle which would be required to play games with lowering perigee without raising apogee.And yes, you can insert into an apogee of an orbit, that's not a problem at all (and rockets without upper stage restart capability did this in the past). The thing is, you can't then have the perigee not only under ground but even in the significant atmosphere (i.e. below 90km) and do a 270° around the Earth. If you wanted to go for less than half circle, then you're free to do so. But with 270° flight you're limited by the reality that perigee is necessarily 180° from the apogee. If you insert to an overhead apogee, your perigee will be at the antipode of your launch site, 180° away. Obviously, you're not doing 270° if your perigee is only 180° away and underground. It must be above the ground, and significantly at that.The way to have the lowest perigee (if this is your particular goal; it's not even Starship goal to begin with) while keeping apogee below the set level (235km here) is to have it roughly half-way between your splashdown/landing site and your launch site (give or take 5°). Apogee then must be about half way of your flight.
I wonder if SpaceX Will attempt to catch Starship upper stage in the future? The reason I say this is because of the way they word it on the website. Only mentioning catching Super heavy and not Starship.
<snip>The confusion is because we don't have a good word to describe trajectories that have orbital speed and energy but also have a velocity vector direction that will result in entering the atmosphere before a complete revolution.Such trajectories are much better described as "orbital" than "suborbital", but neither is completely accurate.<snip>
Quote from: envy887 on 04/15/2023 11:48 amThe confusion is because we don't have a good word to describe trajectories that have orbital speed and energy but also have a velocity vector direction that will result in entering the atmosphere before a complete revolution.Such trajectories are much better described as "orbital" than "suborbital", but neither is completely accurate.Why not just say "orbital velocity on a suborbital trajectory".
Too me, orbital is simple. Orbits are when the path is stable due simply to physics. No additional forces are required. (Yes, station keeping in LEO is required to overcome drag...but it's negligible for the sake of this argument.) If the perigee is low enough that atmospheric drag will cause re-entry, then by definition it is not orbital.
Suborbital trajectory means the intentional flight path of a launch vehicle, reentry vehicle, or any portion thereof, whose vacuum instantaneous impact point does not leave the surface of the Earth.Deorbit means the flight of a vehicle that begins with the final command to commit to a perigee below 70 nautical miles (approximately 130 kilometers), and ends when all vehicle components come to rest on the Earth.
