“Dark energy makes up the majority of the cosmos, but we don’t actually know what it is,” said Jason Rhodes, a senior research scientist at NASA’s Jet Propulsion Laboratory in Southern California. “By narrowing down possible explanations, Roman could revolutionize our understanding of the universe – and dark energy is just one of the many topics the mission will explore!”

After World War II, as jet engines gained popularity, aerodynamicists used jet engines to turn the propellers on some aircraft. This propulsion system is called a turboprop.

Researchers at NASA's Jet Propulsion Laboratory raced drones controlled by artificial intelligence (A.I.) against a professional human pilot.

Scientists expect that as long as sunlight reaches them, solar sails will keep accelerating to much higher speeds than what is provided by traditional propulsion methods using chemical or nuclear fuel.

But what if the most powerful propulsion system in NASA’s toolbox produces less than one pound of thrust while reaching speeds of up to 200,000 mph? What if it costs less, carries more, and uses less fuel?

In-space electric propulsion can reduce the amount of fuel, or propellant, needed by up to 90% compared to chemical propulsion systems.

Chemical propulsion uses a fuel and an oxidizer, converting energy stored in the chemical bonds of the propellants, to produce a short, powerful thrust.

Chemical propulsion uses a fuel and an oxidizer, converting energy stored in the chemical bonds of the propellants, to produce a short, powerful thrust, or what we see as fire.

This is the first time solar propulsion has been successfully demonstrated in Earth's orbit.

To overcome drag, airplanes use a propulsion system to generate a force called thrust.