Welcome to a new edition of Inside Space. Our List of the 100 Most Essential Twitter Accounts in Space is growing. In recent days, I've added the BoldlyGo Institute, a space science and exploration nonprofit founded by former NASA director Jon Morse; Karl Battams, a computational science who studies "comets, asteroids, Sun, space weather & more," and Loren Grush, who covers space for The Verge. Who else do you think should be on the list? Reply to this email and let me know!
1. Elon Musk appeared to backtrack on his "Nuke Mars" idea on Wednesday, saying instead that we could use satellites equipped with solar reflectors to warm up the red planet. When he first floated the "Nuke Mars" idea, the SpaceX CEO suggested dropping nuclear weapons on Mars' poles to warm up the planet’s atmosphere with the eventual goal of making it more habitable for humans. But on Wednesday, Musk clarified that "Nuke Mars" "refers to a continuous stream of very low fallout nuclear fusion explosions above the atmosphere to create artificial suns." He also said that satellites could be used to the same effect. "Might make sense to have thousands of solar reflector satellites 🛰 to warm Mars vs artificial suns (tbd)," he tweeted. However, scientists argue that releasing Mars’ CO2 – Musk’s goal in these ideas – wouldn’t be enough to terraform the red planet. – INSIDE
A version of this story first appeared on the Inside Daily Brief, the twice-a-day newsletter that brings the top news of the day directly to your inbox.
2. Private companies working on the development of NASA's Space Launch System (SLS) said the rocket is unlikely to make its maiden flight until early 2021. The first launch of the SLS was scheduled for the second half of 2020, a date that already represented a delay of about two years. Robert Broeren, the integrated product team lead for SLS stages at Boeing, said engineers will test the rocket's core stage in the second or third quarter of 2020. Meanwhile, Jeff Foote, vice president of NASA programs at Northrop Grumman, said the core stage will likely arrive at the Kennedy Space Center for launch preparations in late 2020. NASA Administrator Jim Bridenstine had already indicated that the first launch of the SLS may be pushed back to 2021. – SPACE NEWS
3. NASA Administrator Jim Bridenstine hailed nuclear propulsion as a "game-changer" for space exploration. Spacecraft powered by fission reactors could potentially reach Mars in about four months – about half the time of a possible trip using chemical propulsion. A faster trip would mean that astronauts would not be exposed to as much harmful radiation. "That gives us an opportunity to really protect life," Bridenstine said. In May, the House Appropriations Committee approved $125 million in funding for NASA's nuclear thermal propulsion development program. – SPACE
4. Scientist Karl Battams tweeted a GIF of a comet that got vaporized upon approaching the sun. "Of course I was on a 3-day vacation when this stunning Kreutz sungrazing comet zoomed through the LASCO cameras. Sadly, its fate was the same as 99% of sungrazers: total vaporization," Battams wrote. (The LASCO instruments are aboard NASA's Solar and Heliospheric Observatory) In later tweets, Battams explained that the comet did not hit the sun because its orbit meant that it was at a distance of around 700,000 kilometers from the sun but, most importantly, because "by the time it was close to the Sun, there was nothing tangible left but dust." – CNET
5. According to a new study, Martian mineral deposits indicate that water flowed on Mars three or four billion years ago. Data gathered by the Mars Reconnaissance Orbiter point to the presence of silica minerals on the surface of Mars. These minerals indicate that liquid water was once abundant on the red planet, said Briony Horgan, a professor at Purdue University. Meanwhile, the presence of surface water suggests that simple life may have developed at around the same time as it did on Earth. "We hope that the Mars 2020 mission will be able to look more closely at these minerals, and begin to answer exactly what conditions existed when Mars was still young," Horgan said. – CNN
6. The U.S. Space Command – the agency that will precede President Trump's Space Force – officially launches on Aug. 29. Vice President Mike Pence and Pentagon officials made the announcement on Tuesday during a meeting of the National Space Council. The Senate confirmed Air Force Gen. John Raymond to be the command's first leader. Pence said Congress will soon authorize the creation of the Space Force as a new military branch to "ensure that our nation is prepared to defend our people, defend our interests, and to defend our values in the vast expanse of space." – USATODAY
7. Russia plans to launch a new version of its Soyuz rocket tonight. The booster will be used to transport crews to the International Space Station (ISS) starting in spring 2020. "The Soyuz 2.1a booster, equipped with a new digital flight control system and upgraded engines, is replacing the Soyuz FG booster that has been used for decades to launch crews into space," NASA said in a statement. In its uncrewed maiden flight, the Soyuz 2.1a will transport a Russian humanoid robot named Fedor. Liftoff is scheduled for 11:38 p.m. EDT. – SPACE
8. At 8:27 a.m EDT, NASA astronauts Nick Hague and Andrew Morgan stepped out of the International Space Station for a 6.5-hour spacewalk to install a docking port to receive the new Boeing and SpaceX crew ships. "Not just another day in the office for a duo of astronauts as they spacewalk outside the @Space_Station to install a docking port to the orbiting outpost that'll provide room for future arrivals of @Commercial_Crew spacecraft," tweeted NASA. A SpaceX Dragon Cargo delivered the Boeing-built docking port to the ISS last month. You can watch the spacewalk live here. – NASA
9. McDonald's has launched a limited-edition "Discover Space with Snoopy" Happy Meal. The meal features Charles Schulz's comic strip dog as the "world-famous astronaut" and "the first beagle on the moon," and includes toys or books themed around NASA's current and future missions. The Happy Meal is part of NASA's efforts to promote science, technology, engineering and mathematics (STEM) education. – COLLECT SPACE
10. Image of the Day: Check out this image of Saturn's moon Rhea posted by Kevin Jill, a software engineer at NASA's Jet Propulsion Laboratory. The image was taken by the Cassini spacecraft in 2007.
Written and curated by Eduardo Garcia in New York. Eduardo is a graduate of the Columbia Journalism School M.A. Science program and writes regularly for the New York Times Climate Fwd: newsletter. In one of his previous lives, Eduardo worked as a Reuters correspondent in Latin America for nearly a decade.
Editor: David Stegon (senior editor at Inside, whose reporting experience includes cryptocurrency and technology).