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| Webb Eyeballs Nearby Solar System |
It was in 2017 that astronomers first discovered the most intriguing solar system in the cosmos (outside of our own, of course). The system is a litter of seven planets orbiting a small, dim star known as Trappist-1, located just 39 light years from Earth—right next door as these things go. All of the planets are similar in size to Earth and all orbit close to the warming fires of their star—near enough that they are within the so-called Goldilocks zone, where temperatures are not too hot and not too cold for liquid water to exist. Determining if life too exists on such hospitable worlds requires studying the starlight that streams through their atmospheres as they orbit in front of Trappist-1, looking for the spectral signature of organic chemicals such as methane or carbon dioxide. When the Trappist-1 system was discovered, however, astronomers did not have an observatory up to that task, but now they do, in the form of the James Webb Space Telescope.
As Nature reports this week, Webb astronomers recently turned their attention to the Trappist-1 system, so far studying Trappist-1b, the closest planet to the star, and Trappist-1g, the sixth closest. Their findings to date: neither planet has a thick hydrogen atmosphere. That's a good thing, because if they were indeed heavy in hydrogen, they would be more like a mini-Neptune, making them much less likely to harbor life. Further observations of the two worlds, and their five sibling planets, will determine if they have any atmospheres at all and, if they do, what their chemical fingerprints are. “We needed this first look to know what we’re dealing with,” astronomer Knicole Colón of NASA’s Goddard Space Flight Center told Nature. “Within the next year, we’ll have a family portrait."
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| Twin Water Worlds Spotted |
The Trappist-1 worlds are not the only exoplanets making headlines this week. Also in the news are a pair of planets orbiting the star Kepler-138, located 218 light years from Earth. The planets, known as Kepler 138 c and Kepler 138 d are just two of more than 5,000 known exoplanets, but as NASA reports, a new paper in Nature Astronomy argues that they are standouts. The reason: both appear to have surfaces covered in water.
Astronomers analyzed the twin worlds, first discovered in 2014, in two ways: by the transit method—or studying the dip in starlight as the planets orbit in front of Kepler 138; and the radial velocity method—analyzing the wobble they cause in their parent star as they revolve around it. Both of those methods showed that the pair of planets are about three times the size of Earth, with twice the mass, but much lower densities. The leading explanation for that density difference is that the planets are not dry worlds made principally of metal and rock, but covered in a surface ocean.
The closest analogy, the astronomers say, are the Jovian moon Europa and the Saturnian moon Enceladus, both of which are covered by surface oceans underneath a rind of ice. Kepler 138 c and d, however, orbit much closer to their parent star, so the surface would be hotter and thawed. As always, the search for Earth-like life on alien worlds abides by a simple dictum: follow the water. Where that exists, biology could too.
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| U.S. and France Collaborate on Revolutionary Satellite |
The water world we know best, of course, is our own, and as of 3:46 a.m. PT this morning, we set about working to know it better still. That was the moment, as NASA reports, that the SWOT (Surface Water and Ocean Topography) satellite blasted off aboard a SpaceX Falcon 9 rocket to begin a three year campaign to study the height and health of freshwater bodies and oceans across 90% of the Earth’s surface. Jointly built by NASA and the Centre National d’Études Spatiales (CNES), the French space agency, SWOT will send back about one terabyte of data per day.
SWOT's work is essential: measuring sea level rise, coastal safety, and the well-being of lakes and rivers, especially their rising or—as a result of climate change-related droughts—falling levels. Today, investigators have data on only a few thousand of the world’s lakes; over the course of its three-year primary mission, SWOT will study millions. “Warming seas, extreme weather, more severe wildfires—these are only some of the consequences humanity is facing due to climate change,” said NASA Administrator Bill Nelson in a statement. “SWOT is the realization of a long-standing international partnership that will ultimately better equip communities so that they can face these challenges.”
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| Leak in Soyuz Spacecraft Imperils Space Station Crew |
Things got dicey on Wednesday aboard the International Space Station (ISS) when, as NASA reports, exterior cameras detected a stream of icy particles jetting away from the attached Soyuz spacecraft and telemetry indicated a drop in pressure in the ship's coolant tank—making a leak of the fluid the likely source of the plume. Coolant is necessary to regulate the temperature inside the spacecraft, especially during the fiery heat of reentry.
The development could spell danger for three of the crew members: Russian cosmonauts Sergey Prokopyev and Dmitry Petelin, and American astronaut Frank Rubio, all of whom blasted off the for station aboard the now damaged Soyuz in September. The spacecraft in which crew members arrive remains attached to the station and serves both as their ride home when their rotation is over and as a lifeboat if an emergency aboard the station forces them to bail out early. Four other crew members aboard the ISS arrived in a SpaceX Dragon spacecraft, which remains attached to the station, but could not accommodate any more passengers if escape became necessary.
For now, NASA and Roscosmos, the Russian space agency, are studying the problem, analyzing telemetry and examining the Soyuz with a camera attached to one of the station’s robotic arms. If the Soyuz is ultimately deemed not to be flight worthy, Roscosmos would have to jettison it and send up an unpiloted replacement spacecraft. For now, Prokopyev, Petelin, and Rubio remain effectively trapped aboard the station, with no way home until the ship is fixed or the replacement is sent.
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