¶Is the Universe flat or closed? Rather than being flat, in which two parallel lines will never cross, as modern cosmology predicts, a controversial new paper in Nature Astronomy re-analyzes data from the Planck space telescope and suggests instead that the Universe is closed—that it curves in on itself like an ellipsoid, in which parallel lines on the surface will eventually cross and return to where they started. The shape of the Universe is dependent on whether or not the density of matter and dark matter is enough to gravitationally balance outward expansion (likely from dark energy). The theory of Inflation predicts a very large and flat Universe close to this critical energy density. This new paper’s reanalysis of gravitational lensing in Cosmic Microwave Background data from the Planck satellite suggests that the Universe may be 5% over the critical density. While the original Planck team also noticed the lensing, they attribute the observation to a statistical fluke. Other current methods of calculating curvature still indicate flatness. Quanta Magazine has a good analysis and discussion, and notes that the majority of researchers feel “that the weight of evidence points to the Universe being flat.” Interestingly, the shape of a universe determines the value of Pi that will be measured in it. In a flat universe (with no other matter to mess up measurements), one gets the precise mathematical value of Pi, but in a closed universe, a measured circumference will be smaller than predicted by 2πr, and all the angles of a galaxy-spanning triangle will add up to more than 180°.
“It's not my fault I haven't had a chance to measure the curvature of this particular universe.”
¶Hayabusa 2 is headed home. After spending 16 months interrogating the near-earth asteroid Ryugu in every way a robotic clown car of experiments can imagine, the spacecraft is headed back to Earth to return multiple samples collected from the Cg-type asteroid. Ryugu’s orbit ranges from .96 AU to 1.41 AU with a period of 474 days, coming within just 95,400 km of Earth at its closest (just 1/4 LD), but is currently 1.7 AU away. Hayabusa will spend the next year closing that distance to Earth and will eject its sample capsule into the atmosphere in December 2020. The Hayabusa 2 mission follows in the footsteps of the groundbreaking Hayabusa mission which, despite being plagued with multiple technical difficulties, managed to return 1,500 grains of extra-terrestrial material from the asteroid Itokawa. The current six-year mission has gone much more smoothly than its predecessor and continues JAXA’s (likely very prescient) focus on robotic NEO exploration and mining.
¶Another unattributed Martian gaseous emission. Even as seasonal variations in Martian atmospheric methane remain a mystery (cf. Issue #18), odd variations have been detected in another atmospheric constituent: oxygen. Over the last three Martian years (~5 Earth years), Curiosity’s Sample Analysis at Mars (SAM) portable chemistry lab has detected “significant seasonal and interannual variability [in oxygen levels], suggesting an unknown atmospheric or surface process at work” (paper). “[W]e think it has to be something in the surface soil that changes seasonally because there aren’t enough available oxygen atoms in the atmosphere to create the behavior we see.” NASA’s press release goes into more detail. It’s presumed to be an abiotic process, but, look, we’re not saying it’s aliens… but it’s aliens.
- A YouTube VR experience from Scott Manley showing what it would look like if you could see all Earth-orbiting satellites.
- The Three Body Problem may have been solved by AI (paper), “up to 100 million times faster than a state-of-the-art solver.” (The sci-fi novel is still excellent—especially the sequel—and is now becoming an animated TV show.)
- The star S5-HVS1 had a dramatic encounter with Sagittarius A*, the supermassive black hole at the center of the Milky Way, and has been kicked out of the galaxy at 6 million km/h (paper), becoming the fastest Main Sequence hyper-velocity star discovered. That’s 0.5% c!
- The Habitat, a Gimlet podcast about six volunteers picked to live on a fake red planet. (The free soundtrack consists solely of different covers of Space Oddity, which are all now stuck in our heads… simultaneously.)
- DIY: Download and explore data from the Parker Solar Probe taken closer to the Sun than ever before.
- NASA’s free software catalog has been updated for 2019-2020, including new VR tools and autonomous navigation software in their list of recent releases (and is, of course, included in our Awesome Space list).
- HEATED is a newsletter by Emily Atkin “for people who are pissed off about the climate crisis.” A recent issue was about the EPA’s new “transparency” policy that forbids the usage of scientific research that includes confidential data about human subjects, making them unable to use health data to justify regulations around air pollution or climate change.
- If I Touched the Moon, What Would It Feel Like?
- Meet Rosie, Rocket Lab’s new super-fast carbon fiber booster processing robot. Related: a video tour of their NZ launch facilities.
- The Hiding Place. A lyrical exploration inside Onkalo, the first storage facility for highly radioactive nuclear waste designed to survive for 100,000 years. “Sometimes we bury materials in order that they may be preserved for the future. Sometimes we bury materials in order to preserve the future from them.”
The last full shot of Ryugu by Hayabusa 2, taken November 18, as it departs for its year-long journey home.