SpaceX tries out its new SuperDraco rocket engine

SpaceX has test-fired its advanced new SuperDraco engine, to be used on the Dragon spacecraft

SpaceX, the California company that is developing the reusable Dragon spacecraft, recently test-fired its new SuperDraco engine. Presently, the Dragon capsule is equipped with less-advanced Draco engines, which are designed for maneuvering the spacecraft while in orbit and
during reentry. The SuperDraco, however, is intended to allow the astronauts to escape if an emergency occurs during the launch.
Plans call for eight of the engines to be installed in the outer side walls of the Dragon. Together, these will create 120,000 pounds (54,431 kg) of axial thrust. Should something go wrong with the Falcon launch rocket while the spacecraft is lifting off, the SuperDracos will fire, allowing the Dragon to separate and fly to safety.

SpaceX claims that the new engines will have several advantages over those used by other spacecraft. For starters, they will remain attached to the Dragon throughout the entire launch, unlike other systems that are jettisoned within a few minutes of lift-off. They can also be restarted multiple times within one flight, and have the ability to deep throttle, which should reportedly provide the astronauts with "precise control and enormous power."
Additionally, like the Dragon and the Falcon, the SuperDracos will be reusable - one set should be good for numerous flights. If one of them does fail, the escape system is designed to still work successfully using the remaining seven.
Besides their use in emergencies, the engines could also be used to perform precise "propulsive landings" on Earth or other planets. In this scenario, by varying the downward thrust of the engines, astronauts could gradually lower the Dragon to the ground.

The SuperDraco engine was developed using a US$75 million grant that NASA's Commercial Crew Program awarded to SpaceX last April. The ground tests were conducted at the company's Rocket Development Facility in McGregor, Texas, where the engine sustained full-duration, full-thrust firing, and performed multiple demonstrations of deep throttling.
Some of those tests can be seen in the video below.