CAESAR (Comet Astrobiology Exploration Same Return) New Frontiers 3 or NF3) is a mission to carry samples of a comet back to Earth. The comet is 67P/Churyumov-Gerasimenko (67P). By design, it focuses on the return trip rather than data gathering at the comet given that investigation of samples using earthbound equipment has the potential to learn much more about the material. Its design borrows ideas from OSIRIS-REx but also aims to return with samples of comet volatiles, requiring "air-tight" containment back to Earth. Its Sample Acquisition System (SAS) consists of a robotic arm with gear to scratch the surface (with ripper tines), gather material with gas jets into a container and inspect the container with a camera aimed into the container (CANCAM).
The project was one of two chosen for further study as a possibility for the fourth NASA' New Frontiers mission, NF4. It would launch in 2024, reach the comet in 2029, carry out observation and collection until 2032 and return to Earth in 2038. It would use an ion engine powered by solar power.