Physics Today Daily Edition
Ars Technica: At nearly 1 zettabyte (1 billion terabytes) per gram, DNA has a significantly higher data storage density than conventional storage systems. And the molecule is extremely robust: Fragments that are thousands of years old have been sequenced. The successful encoding of binary data as DNA base pairs in 2010 opened up the potential for using the molecule for long-term data storage. Now Microsoft is purchasing 10 million strands of DNA from Twist Bioscience, a biotech startup that has developed a machine for producing custom strings of DNA. Twist has been producing DNA for biology research labs. Currently, the price is roughly $0.10 per base, but Twist hopes to reduce that cost to $0.02. Reading the data involves traditional genetic sequencing, which costs about $1000 per genome. In initial tests with Twist, Microsoft says it has succeeded in retrieving all the data that had been encoded in the DNA. The price of storage means that commercial use is still a ways off, but improvements in both creating and sequencing DNA molecules will likely lead to lower costs.
New York Times: On 25 April, China's National Development and Reform Commission and its National Energy Administration released guidelines to halt the planned construction of about 200 coal power plants. Plants that are already under construction can be completed, but any project that has yet to be approved or begin construction has been canceled. Although the nixed plants would have added 105 GW to China's power grid, the plants that are currently being constructed will add 190 GW. The announcement is part of China's effort to cut its carbon emissions. China's rapid economic growth has spurred construction of coal plants over the last decade. But during the recent slowdown, many current plants have been operating only 40–50% of the time. China has also begun promoting the construction of wind turbines and solar farms as nonpolluting alternatives to coal power.
National Geographic: Since its discovery in 2005, Makemake has had an odd distinction: It was the only dwarf planet outside of the asteroid belt thought to have no moon. It has now lost that distinction. Alex Parker of the Southwest Research Institute was examining data from two hours of Hubble Space Telescope observations when he saw evidence of an object orbiting the dwarf planet. The data have already revealed that the moon is 160 km in diameter. Further observations of the moon should provide clues as to whether it formed in place around Makemake or was pulled in by the dwarf planet's gravity. More data could also provide information about the moon's mass, which would then allow for more accurate calculations of Makemake's mass and density. The discovery of the moon explains an unusual variation in Makemake's heat signature that did not correlate with any warm, dark areas on Makemake's otherwise brightly reflective, ice-covered surface.
Los Angeles Times: For the last 17 years, the Cosmic Ray Isotope Spectrometer (CRIS) on NASA's Advanced Composition Explorer spacecraft has been detecting particles approaching Earth. In that time, it has identified more than 30 000 particles of ordinary iron-56 and just 15 particles of radioactive iron-60. But the radioactive isotopes provided enough information for researchers working with CRIS to determine a source. Heavy elements such as iron are created in supernova explosions, but it takes the shock wave of a second supernova to accelerate the atoms and turn them into cosmic rays. The 2.6-million-year half-life of iron-60 allowed researchers to determine that the supernovae that launched the iron particles toward Earth occurred within 2 million years of each other and were relatively nearby. The finding closely matches a separate study that recently suggested a nearby star went supernova roughly 2.3 million years ago.