Rocket Engine

SpaceX
1-Gen: Merlin 1D (active on Falcon 9, Falcon heavy), open-cycle, LOX and RP1 (Kerosene). Sea Level Thrust: 845 kN. Seal Level Specific Impulse: 282 sec. Propellent Densification tech.
2-Gen: Raptor (will be active on starship, currently run on SN5 prototype), full-flow staged combustion cycle. LOX and Liquid Methan. Sea Level Thust: 3,050 kN. Sea Level Specific Impusle: 334 sec. Support deep throttlng to 20% rated thrust. 3D printed components include propellant valves, turbopump parts and injector system.
Control system: cold-gas reaction control system, grid fins, re-entry burn to slow down the speed, S-band and C-band communication systems.
Additive Manufacturing: SpaceX use additive manufacture to reduce cost, eliminate needs to outsource, protect intellectual property, allow for stricker quality control, and reduced times. SpaceX use Direct Metal Laser Sintering (DMLS). Appliction: main engine chamber of escape rocket, the SuperDraco rockets are printed out of Inconel; main oxidizer valve of Merlin 1D; (2 days of manufacture compared to traditional 2 months)

NASA
Space Launch System (SLS). Use upgrading RS-25 engine from Aerojet Rockeydyne, also known as Space Shuttle main engine. Liquid Oxygen and Liquid Hydrogen. Thrust: 2278 kN. Sea Level Specific Impulse: above 366 sec. Throttling: 67%-109%. Will be active on Artemis mission, Mars mission, deep space misions.

Terms
Specific Impulse: ISP = Total Impusle/ propellant weight = integral(F*dt)/ (propellant_mass*g0) = Veq/ g0 = F_thrust/ (propellant_m_dt * g0).
Trans-Lunar Injection Maneuver.
S-band Communications.

Reference
https://spaceflight101.com/spacerockets/falcon-9-ft/
https://spaceflight101.com/spx/spacex-raptor/
https://www.youtube.com/watch?v=yiUUZxp7bLQ
https://en.wikipedia.org/wiki/RS-25
https://hackaday.com/2019/02/13/the-impossible-tech-behind-spacexs-new-engine/

News

Virgin Orbit's rocket has failed on its first attempt to get into space
LauncherOne rocket failed on May 25 after seven years of development and testing. After released from a Boeing 747, it ignited and fell into the sea. The rocket had previouly been dropped from the plane, but this was the first time it was ignited.

Rockey Lab's 13th launch ends in failure
The vehicle started losing speed and it dropped in altitude on Jult 4. The anomaly occured at six minute after launch. Rocket Lab has put 53 spacecraft into low Earth orbit on 12 separate missions. This was the first major failure for the company.

NASA and Boeing complete orbital flight test reviews
Three primary anomalies: 2 software coding errors (Mission Elapsed Timer, Service Module Disposal Burn), 1 unanticipated loss of space-to-ground communication capability.
Test and Simulation: need greatedr hardware and software integration testing; using max. amount of flight hardware available; review subsystem behaviors and limitations; address any identified simulation gaps.
Requirements: assessment of all software requirements with multiple logic conditions to ensure test coverage.