The Atomic Engine: US Unveils Nuclear Rocket to Dominate Space!

Recommendable! However, this technology is still in development.

NASA: Pushing the Limits of Sub-Kilowatt Electric Propulsion Technology to Enable Planetary Exploration and Commercial Mission Concepts

Good news!

"NASA has developed an advanced propulsion technology to facilitate future planetary exploration missions using small spacecraft. Not only will this technology enable new types of planetary science missions, one of NASA’s commercial partners is already preparing to use it for another purpose—to extend the lifetimes of spacecraft that are already in orbit. ...
Small spacecraft using the NASA-H71M electric propulsion technology will be able to independently maneuver from low-Earth orbit (LEO) to the Moon or even from a geosynchronous transfer orbit (GTO) to Mars. ..."

Pushing the Limits of Sub-Kilowatt Electric Propulsion Technology to Enable Planetary Exploration and Commercial Mission Concepts - NASA Science Northrop Grumman NGHT-1X engineering model Hall-effect thruster operating in Glenn Research Center Vacuum Facility 8. The design of the NGHT-1X is based on the NASA-H71M Hall-effect thruster.

Left: NASA-H71M Hall-effect thruster on the Glenn Research Center Vacuum Facility 8 thrust stand. Right: Dr. Jonathan Mackey tuning the thrust stand prior to closing and pumping down the test facility.

Raytheon to build revolutionary rotating detonation engine for DARPA

Recommendable!

"DARPA has contracted Raytheon to develop a practical version of a revolutionary air-breathing rotating detonation engine called Gambit, which would have no moving parts and could lead to lighter missiles with longer ranges at lower cost. ...

In an [Rotating Detonation Engine], a combustible mixture of fuel and air is introduced into a gap between two coaxial cylinders, with the gap sealed at one end and the other end forming into a nozzle. When the mixture is ignited, it burns in a very special way. The combustion takes the form of a supersonic wave that travels around inside the gap. As more fuel and air is introduced at the top, the wave continues going around in the gap, producing more and more heat and pressure, and is forced down until it exits through the nozzle, creating thrust. ..."

Raytheon to build revolutionary rotating detonation engine for DARPA

Toroidal propellers: A effective noise reduction and gain in efficiency in air and water

Good news! It is not really new and still too expensive for now.

"... Sharrow Marine has been getting frankly spectacular results from boat propellers that use toroidal loops instead of standard blades. After several years of development, the company has now tested its props against hundreds of standard propellers, and the difference is incredible. Sharrow's props simply don't create tip vortices – a major source of energy loss and a surprisingly large component in the overall noise of an outboard engine. ...
The drawback here is price; they cost US$4,999 a pop regardless of which model, where a regular propeller might go for closer to US$500. ..."

The gain in efficiency is ridiculous in the water at midrange RPMs, filling in a pronounced hole in a boat's acceleration curve and conserving huge amounts of energy

Toroidal propellers: A noise-killing game changer in air and water These strangely-shaped twisted-toroid propellers look like a revolutionary (sorry) advance for the aviation and marine sectors. Radically quieter than traditional propellers in both air and water, they're also showing some huge efficiency gains.

Toroidal propellers: a radically quieter and more efficient design that can boost fuel economy by 20% when swapped onto a marine motor