Sure, I'd be happy to provide more information on the Merlin Vacuum engine and upcoming SpaceX missions.

The Merlin Vacuum engine, also known as the MVac, is a modified version of the Merlin 1D engine that is optimized for use in the vacuum of space. It is used as the second-stage engine on the Falcon 9 rocket and is responsible for powering the rocket's upper stage to achieve orbital velocity.

The MVac engine has a nozzle optimized for vacuum conditions and uses a different mixture ratio of liquid oxygen and rocket-grade kerosene compared to the Merlin 1D engine. It produces up to 210,000 pounds of thrust in a vacuum and is capable of multiple restarts in space, making it a key component in SpaceX's reusable rocket technology.

The MVac engine was designed and manufactured in-house by SpaceX, with input from NASA and other industry experts. The cost of developing and manufacturing the engine is not publicly available, but SpaceX has stated that its focus on reusable rocket technology has helped to significantly reduce the overall cost of its rocket launches.

As for upcoming SpaceX missions, here is a list of some of the notable missions planned for the remainder of 2023:
- CRS-27: A cargo resupply mission to the International Space Station (ISS) using a Falcon 9 rocket. The launch is currently scheduled for June 2023.
- Sentinel-6 Michael Freilich: A joint mission between NASA, the European Space Agency, and several other organizations to launch a satellite that will study sea level rise and ocean currents. The launch is currently scheduled for September 2023.
- Crew-7: A crewed mission to the ISS using a Falcon 9 rocket and a Crew Dragon spacecraft. The launch is currently scheduled for November 2023.
- DART: A NASA mission to test a technique for deflecting asteroids that could potentially pose a threat to Earth. The launch is currently scheduled for November 2023.
- Europa Clipper: A NASA mission to study Jupiter's moon Europa, which is believed to have a subsurface ocean that could potentially support life. The launch is currently scheduled for December 2023.

Please note that these dates are subject to change, and SpaceX may add additional missions to its launch schedule throughout the year.
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