Plus conjunction, a deep space void, asteroids, and monarch butterflies.

#01 FOOTPRINTS

+ Every time I check it seems that the estimate for when humans first entered North America moves earlier. The most recent evidence comes from "ghost tracks" made by humans in what is now the Arizona desert. The prints got their name because they only show up when it is damp, and seem to disappear when the soil dries out. Researchers were able to show that the prints were made 21,000 - 23,000 years ago by examining the seeds of a wetland plant entombed in the same layer of the ground. This makes the footprints the oldest evidence of humans in the Americas and pegs their arrival before the last glacial maximum.

#02 MARSQUAKES

+ Only a few years ago we didn't understand the interior of Mars well enough to know if Marsquakes occurred on the surface. Thanks to the Insight lander, we now know that Mars still rubles sometimes! Insight detected a 4.1 magnitude quake last week, the largest of many detected since the spacecraft landed in 2018. 

+ The Ingenuity helicopter stopped a flight attempt before it got off the ground after its servo motors showed some anomalous behavior.

+ Further troubleshooting efforts will have to wait. Every couple of years Mars goes into "conjunction" meaning that the sun is positioned between Mars and Earth and no signals can be sent between the two planets. Conjunction started yesterday and will last a couple of weeks, enforcing an astronomically mandatory communications blackout period.

#03 DEEP SPACE

+ Astronomers have discovered a mysterious 500 light-year wide void in our galaxy. The best guess right now is that it was formed after a giant supernova explosion, or someone was trying to come up with a cool opening scene for their new sci-fi novel.

#04 ASTEROID TROUBLE

+ Archeologists have unearthed evidence that an ancient Middle Eastern city known as Tall el-Hammam was likely destroyed by an asteroid. Its been known for some time that something bad happened there thousands of years ago due to the existence of "a jumbled layer of charcoal, ash, melted mudbricks and melted pottery." In addition, the archeologists identified microscopic diamond-like structures and spherules composed of vaporized iron and melted sand, features that are normally more closely associated with nuclear blasts. All of this points towards a highly energetic firestorm that could only have been created by an asteroid, probably similar in scale to the infamous Tunguska event in 1908 where an asteroid exploded above the forests of Siberia.

#05 MONARCHS

+ Combat veterans in California are teaming up on a mission to save California's Monarch butterflies. "I wanted to use the land to do something good... This was something where we could do something for the environment, do something for butterflies and do something to better people's lives."

#06 A GOOD BOOK

+ For a number of years in the 1920s, the around-the-world speed record was held by a blimp that completed a circuit in 21 days. Not content with this state of affairs, Harold Gatty and Wiley Post succeeded in breaking the record in only 8 days, an adventure which they cataloged in Around the World in 8 Days: The Flight of the Winnie Mae. Completing the feat involved flying blind for hours in fog over the ocean, navigating the featureless and poorly mapped plains of Russia, staying awake for countless hours, basically all the things that make for a heroic tale. This book was an entertaining peek into the golden age of aviation when powered flight was still an adventure and record-setting attempts garnered the world's attention.

"I turned to my little table, picked up my logbook and pencil, and made the first notation. It was a nice black book, and  I had all my tables ruled in red on the back pages....

In the first column under 'G.c.t' (Greenwich civil time), I made the entry: 8:55:21.

In the last column under 'Remarks' I wrote, 'Took off 4:55 daylight saving time, set course 63 deg, visibility poor.'"

And with that simple statement, the adventure had begun!

That's all for this week! You can respond to this email to tell me about anything you liked or didn't like, tell me about a project you're working on, or suggest a story. You might also forward this email to a friend so they can subscribe too!

- Evan Hilgemann