Re: China lands (reusable) rocket during an orbital launch

"a425couple"  wrote in message news:[email protected]...

Wow!  I thought Musk was many years ahead.

from
https://www.space.com/space-exploration/launches-spacecraft/making-history-china-lands-rocket-during-an-orbital-launch-for-1st-time-ever
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The SpaceX recovery process requires the booster to separate while still 
carrying sufficient fuel for its landing, and thus not available to 
accelerate the spacecraft. For high and heavy missions requiring maximum 
performance all fuel will be burned for lift and the booster expended. The 
landing on the unmanned ship is a spectacular stunt but not the first time 
boosters have been saved. The Shuttle's boosters burned all their fuel for 
lift and then came down by parachute for recovery and reuse.

https://www3.nasa.gov/centers/kennedy/pdf/167446main_SRBships06.pdf.

The booster floats upright because the top end is sealed to hold the rocket 
engine pressure. Divers plug the nozzle and pump in air that empties the 
water and makes it float level, then it's taken back to fly again.

The main hydrogen burning engines are part of the Shuttle and reusable. Only 
the empty fuel tank was wasted. Artemis uses up old Shuttle engines and then 
new improved versions.
https://www.nasa.gov/reference/space-launch-system-rs-25-core-stage-engine/
"Engine manufacturer L3Harris Technologies is under contract to produce 24 
new RS-25 engines."

The Apollo program developed controlled flight on vertical jet / rocket 
thrust.
https://www.nasa.gov/history/50-years-ago-the-lunar-landing-training-vehicle/

The problem of balancing a rocket on its exhaust is called an inverted 
pendulum, the Segway is an example.
https://en.wikipedia.org/wiki/Inverted_pendulum