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SpaceX launches stuff into earth's orbit, and to enter orbit you must be traveling very fast horizontally -- it is not enough to merely escape the earth's atmos
by chrismartin 10y ago
SpaceX launches stuff into earth's orbit, and to enter orbit you must be traveling very fast horizontally -- it is not enough to merely escape the earth's atmosphere by ascending vertically. The first stage travels hundreds of miles 'downrange' of the launch site (as well as up) in order to achieve the required horizontal velocity. Most orbital launches are aimed over an ocean, so that if something goes wrong the fiery bits don't land in a populated area, hence the need for a landing barge.
If the first stage were to "fly" all the way back to land after separating from the second stage, that would require some combination of a heavier/stronger rocket to hold more fuel, and a reduced payload capacity to orbit.
Blue Origin only does short, up-and-down flights -- they are not trying to achieve orbit so there is no need for horizontal travel. They can simply shut off the rocket and fall back to the launch site.
- wcoenen 10y ago> If the first stage were to "fly" all the way back to land after separating from the second stage You write it as a hypothetical, but that's actually how SpaceX landed their first first booster. It was Falcon 9 Flight 20, which deployed 11 Orbcomm satellites. Infographic of the trajectory: https://i.imgur.com/D9BdO86.png https://i.imgur.com/D9BdO86.png
- mileycyrusXOXO 10y agoThanks for sharing that infographic. I was literally just wishing I had some way to visualize the trajectory when I read your comment.
- paulmd 10y agoInterestingly, NASA also considered that as a potential abort mode for the Shuttle ("RTLS" - return to launch site). Minus the vertical landing of course. It was the first option that would be available in the event of a failure, immediately after SRB separation. The vehicle would execute a Powered Pitch-Around maneuver and then jettison the external tank, timing things so that they would run out of fuel and the vehicle would have its proper CG for gliding. The astronauts considered it extremely risky to say the least. NASA actually wanted to try it on STS-1 (a manned flight on a system that had never been tested before) to see if it worked. In the words of the mission commander: "Let’s not practice Russian roulette, because you may have a loaded gun there." Which carries a lot of weight from a man who was willing to risk a lunar landing. http://www.tested.com/science/space/460233-space-shuttles-controversial-launch-abort-plan/ http://www.tested.com/science/space/460233-space-shuttles-co... https://en.wikipedia.org/wiki/Space_Shuttle_abort_modes#Return_to_launch_site_.28RTLS.29 https://en.wikipedia.org/wiki/Space_Shuttle_abort_modes#Retu... Previous HN discussion: https://news.ycombinator.com/item?id=8447479 https://news.ycombinator.com/item?id=8447479
- TrevorJ 10y agoYep - it mostly depends on the available fuel left over after the orbital insertion. Not an option on all missions.