Enlarge / Exhaust plumes from the Ariane 6 rocket's main engine rise above the launch pad in French Guiana. (credit: ESA/CNES/Arianespace/P. Piron )

The European Space Agency (ESA) declared success after an Ariane 6 rocket fired its core stage engine in French Guiana for seven minutes on Thursday, clearing one of a handful of remaining hurdles before the new launcher can lift off on its first test flight.

The Ariane 6's inaugural launch, now scheduled for next year, has been delayed repeatedly since ESA approved the new rocket for development in 2014. The test-firing of the Ariane 6 main engine on a launch pad at the Guiana Space Center in South America last week was the most significant test not yet accomplished on the rocket's preflight checklist.

The test lasted 426 seconds—a little more than seven minutes—while a full-size test model of the Ariane 6 rocket remained on its launch pad. In order for the rocket to actually take off, it would need to light its four strap-on solid-fueled boosters. That was not part of the plan for Thursday's test.

Enlarge / Artist's illustration showing the orbital tracks of the European Space Agency's Aeolus satellite. (credit: ESA/ATG medialab )

The European Space Agency deftly guided one of its satellites toward a fiery re-entry into Earth's atmosphere Friday, demonstrating a new method of post-mission disposal to ensure the spacecraft would not fall into any populated areas.

The Aeolus satellite was relatively modest in size and mass—about 1.1 metric tons with its fuel tank empty—but ESA hailed Friday's "assisted re-entry" as proof that the space agency takes the stewardship of space seriously.

When the Aeolus mission was conceived in the late 1990s, there were no guidelines for European satellites regarding space debris or the safety of their re-entry. Aeolus took nearly 20 years to get to the launch pad, operated in space for five years, and now regulations have changed. Future ESA satellites will need to be capable of a targeted re-entry, where rocket engines steer the spacecraft toward a specific patch of ocean or are designed to burn up from aerodynamic heating.

Enlarge / Artist’s illustration shows the ejection of a cloud of debris after NASA’s DART spacecraft collided with the asteroid Dimorphos. (credit: ESO/M. Kornmesser)

Last September, the Double Asteroid Redirect Test, or DART, smashed a spacecraft into a small binary asteroid called Dimorphos, successfully altering its orbit around a larger companion. We're now learning more about the aftermath of that collision, thanks to two new papers reporting on data collected by the European Southern Observatory's Very Large Telescope . The first, published in the journal Astronomy and Astrophysics, examined the debris from the collision to learn more about the asteroid's composition. The second, published in the Astrophysical Journal Letters, reported on how the impact changed the asteroid's surface.

As we've reported previously , Dimorphos is less than 200 meters across and cannot be resolved from Earth. Instead, the binary asteroid looks like a single object from here, with most of the light reflecting off the far larger Didymos. What we can see, however, is that the Didymos system sporadically darkens. Most of the time, the two asteroids are arranged so that Earth receives light reflected off both. But Dimorphos' orbit sporadically takes it behind Didymos from Earth's perspective, meaning that we only receive light reflected off one of the two bodies—this causes the darkening. By measuring the darkening's time periods, we can work out how long it takes Dimorphos to orbit and thus how far apart the two asteroids are.

Before DART, Dimorphos' orbit took 11 hours and 55 minutes; post-impact, it's down to 11 hours and 23 minutes. For those averse to math, that's 32 minutes shorter (about 4 percent). NASA estimates that the orbit is now "tens of meters" closer to Didymos. This orbital shift was confirmed by radar imaging. Earlier this month , Nature published five papers that collectively reconstructed the impact and its aftermath to explain how DART's collision had an outsize effect. Those results indicated that impactors like DART could be a viable means of protecting the planet from small asteroids.