The Russia incident was a warning.

On a winter morning in 2013, a meteor the size of a four-story building screamed across the country, exploding near the city of Chelyabinsk and injuring more than 1,600 people amid widespread property damage.

The chunk of rock and iron, which was 60 feet across, served as a violent reminder that Earth, bombarded daily with tons of space-going debris, periodically intersects with large planet killers—and a significant portion of those remain undocumented.

After years of study and discussion, NASA has launched its first effort to spare Earth the kind of calamity that extinguished the dinosaurs, crashing a space probe into an asteroid to alter its speed and course. The Double Asteroid Redirection Test (DART) lifted off Nov. 23 local time aboard a SpaceX rocket from California and will cruise for 10 months to a binary asteroid system.

The idea is that if humans have adequate time to react—decades of notice being preferable—enough energy can be transferred into a speeding rock to alter its trajectory and make it miss Earth, avoiding catastrophe up to and including an extinction-level event.

Mars landing missions only succeed about half the time, a rate largely determined by the entry, descent and landing (EDL) phase, according to the researchers who designed Tianwen-1's control systems.  They published their guidance, navigation and control approach for Tianwen-1 on October 16 in Space: Science & Technology.

"The EDL phase, which begins at the Mars atmosphere interface and ends with a surface touchdown, is crucial for a Mars landing mission," said Xiaolei Wang, researcher professor at Beijing Institute of Control Engineering.

Wang explained that most failures occur during this phase, typically because the communication delay between Mars and Earth is too large to accommodate the time urgency of the EDL phase.

"The spacecraft must perform autonomous guidance, navigation and control (GNC) to provide reliable key event triggers, as well as accurate and reliable state estimates to implement accurate and reliable trajectory and attitude controls," Wang said.

Blazing along at space-record speeds that would get it from Earth to the Moon in under an hour, NASA's Parker Solar Probe completed its 10th close approach to the sun on Nov. 21, coming within 5.3 million miles (8.5 million kilometers) of the solar surface.

The close approach (known as perihelion), also at a record distance, occurred at 4:25 a.m. EST (8:25 UTC), with Parker Solar Probe moving 364,660 miles per hour (586,864 kilometers per hour).

Engineering teams have completed additional testing confirming NASA's James Webb Space Telescope is ready for flight, and launch preparations are resuming toward Webb's target launch date of Wednesday, Dec. 22, at 7:20 a.m. EST.

Additional testing was conducted this week to ensure the observatory's health following an incident that occurred when the release of a clamp band caused a vibration throughout the observatory.

On Wednesday, Nov. 24, engineering teams completed these tests, and a NASA-led anomaly review board concluded no observatory components were damaged in the incident. A "consent to fuel" review was held, and NASA gave approval to begin fueling the observatory. Fueling operations will begin Thursday, Nov. 25, and will take about 10 days.

The Webb Space Telescope is an international partnership with the European and Canadian space agencies. It will explore every phase of cosmic history—from within our solar system to the most distant observable galaxies in the early universe, and everything in between. Webb will reveal new and unexpected discoveries, and help humanity understand the origins of the universe and our place in it.