I’ve been digging into NASA’s Small Spacecraft Strategic Plan out of continuing interest in missions that take advantage of miniaturization to do things once consigned to large-scale craft. And I was intrigued to learn about the small spacecraft deployed on Apollo 15 and 16, two units developed by TRW in a series called Particles and Fields Subsatellites. Each weighed 35 kilograms and was powered by six solar panels and rechargeable batteries. The midget satellites were deployed from the Apollo Command and Service Module via a spring-loaded container giving the units a four foot-per-second velocity. Apollo 15’s operated for six months before an electronics failure ended the venture. The Apollo 16 subsatellite crashed on the lunar surface 34 days into its mission after completing 424 orbits. Here I thought I knew Apollo history backwards and forwards and I had never run into anything about these craft. It turns out that smallsats – usually cited as spacecraft with weight up to 180...

Some 900 light years away in the constellation Puppis, the planet WASP-121b is proving an interesting test case as we probe ever deeper into exoplanetary atmospheres. As has been the case with so many early atmosphere studies, WASP-121b, also known as Tylos, is a hot-Jupiter, with a year lasting about thirty Earth hours, in a vise-like tidal lock that leaves one side always facing the star, the other away. What we gain in two new studies of this world is an unprecedented map of the atmosphere’s structure. At stake here is a 3D look into what goes on as differing air flows move from one side of the planet to the other. A jet stream moves material around its equator, but there is a separate flow at lower altitudes that pumps gas from the hottest regions to the dark side. “This kind of climate has never been seen before on any planet,” says Julia Victoria Seidel (European Southern Observatory), lead author of a paper that appears today in Nature. Seidel points out that we have nothing...

Someone asked me the other day what it would take to surprise me. In other words, given the deluge of data coming in from all kinds of observatories, what one bit of news would set me back on my heels? That took some reflection. Would it surprise me, my interlocutor persisted, if SETI fails to find another civilization in my lifetime? The answer to that is no, because I approach SETI without expectations. My guess is that intelligence in the universe is rare, but it’s only a hunch. How could it be anything else? So no, continuing silence via SETI does not surprise me. And while a confirmed signal would be fascinating news, I can’t say it would truly surprise me either. I can work out scenarios where civilizations much older than ours do become known. Some surprises, of course, are bigger than others. Volcanoes on Io were a surprise back in the Voyager days, and geysers on Enceladus were not exactly expected, but I’m talking here about an all but metaphysical surprise. And I think I...

What catches your eye in this description of an exoplanetary system? Start with a ‘hot Jupiter,’ with a radius 0.87 times that of our Jupiter and an orbit of 7.1 days. This is WASP-132b, confirmed in 2016, and first discovered through the labors of the Wide-Angle Search for Planets program. Subsequent confirmation came through the CORALIE spectrograph installed on the Euler telescope at the European Southern Observatory’s La Silla site. This world orbits a K-class star 403 light years out in Lupus. The CORALIE measurements gave hints of another giant planet in a long period orbit. The system came still further into focus in 2021, when observations from TESS (Transiting Exoplanet Survey Satellite) showed a transiting super-Earth with a diameter of 1.8 Earth radii in a tight orbit of 1.01 days. The mass of the planet, as measured by the HARPS spectrograph at La Silla, is six times that of Earth. So we have both a hot-Jupiter and a super-Earth hugging the star, along with an outer gas...

Last Friday’s post on K-dwarfs as home to what researchers have taken to calling ‘superhabitable’ worlds has caught the eye of Dave Moore, a long-time Centauri Dreams correspondent and author. Readers will recall his deep dives into habitability concepts in such essays as The “Habitability" of Worlds and Super Earths/Hycean Worlds, not to mention his work on SETI (see If Loud Aliens Explain Human Earliness, Quiet Aliens Are Also Rare). Dave sent this in as a comment but I asked him to post it at the top because it so directly addresses the topic of habitability prospects around K-dwarfs, based on a quick survey of known planetary systems. It's a back of the envelope overview, but one that implies habitable planets around stars like these may be more difficult to find than we think. by Dave Moore To see whether K dwarfs made a good target for habitable planets, I decided to look into the prevalence and type of planets around K dwarfs and got carried away looking at the specs for 500...

We think of Earth as our standard for habitability, and thus the goal of finding an ‘Earth 2.0’ is to identify living worlds like ours orbiting similar Sun-like stars. But maybe Earth isn’t the best standard. Are there ways planets can be more habitable than our own, and if so where would we find them? That’s the tantalizing question posed in a paper by Iva Vilović (Technische Universität Berlin), René Heller (Max-Planck-Institut für Sonnensystemforschung) and colleagues in Germany and India. Heller has previously worked this issue in a significant paper with John Armstrong (citation below); see as well The Best of All Possible Worlds, which ran here in 2020. The term for the kind of world we are looking for is ‘superhabitable,’ and the aim of this study is to extend the discussion of K-class stars as hosts by modeling the atmospheres we may find on planets there. While much attention has focused on M-class red dwarfs, the high degree of flare activity coupled with long pre-main...