Missions to the moon, missions to Mars, robotic explorers to the outer solar system, a mission to the nearest star, and maybe even a spacecraft to catch up to interstellar objects passing through our system. If you think this sounds like a description of the coming age of space exploration, then you'd be correct.

At this moment, there are multiple plans and proposals for missions that will send astronauts and/or probes to all of these destinations to conduct some of the most lucrative scientific research ever performed. Naturally, these mission profiles raise all kinds of challenges, not the least of which is propulsion.

Simply put, humanity is reaching the limits of what conventional (chemical) propulsion can do.

The Parker Solar Probe is the little engine that just keeps going and going by the sun. On September 27th, it made its 17th close approach and skimmed just 7.26 million kilometers (4.51 million miles) above the sun's "surface" layer (called the photosphere).

That's just the latest achievement by the probe, which also became the first-ever spacecraft to fly through a coronal mass ejection—and live to tell the story. That CME pass-through occurred on September 5, 2022, during its 13th approach to the sun.

The spacecraft's most recent accomplishment was set up by a gravity-assist flyby of Venus in late August. During the closest approach, the Parker Solar Probe was moving at 635,266 kilometers per hour (394,735 miles per hour).