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As Spitzer’s Mission Ends, First Light for CHEOPS

by Paul Gilster | Jan 31, 2020 | Deep Sky Astronomy & Telescopes | 7 Comments

Farewell to Spitzer after more than 16 years of infrared observations of the universe. We've recently looked at the observatory's accomplishments (see Looking Back at the Spitzer Space Telescope), but I want to run the photo below to celebrate the team that managed it. Image: Spitzer Project Manager Joseph Hunt stands in Mission Control at NASA's Jet Propulsion Laboratory in Pasadena, California, on Jan. 30, 2020, declaring the spacecraft decommissioned and the Spitzer mission concluded. Credit: NASA/JPL-Caltech. Meanwhile, we have the good news that the European Space Agency's CHEOPS (CHaracterising ExOPlanet Satellite), which was launched from Kourou (French Guiana) on December 18, has completed its early orbit phase, involving instrument tests and calibration, and has now opened its telescope cover, exposing the focal plane to starlight. The space observatory carries a 95-cm long baffle that shields its telescope from stray light and minimizes light contamination from sources like...

Voyager 2 Recovers

by Paul Gilster | Jan 30, 2020 | Missions | 10 Comments

When one of our Voyagers experiences a blip of any kind, it gets my attention. It's not like we have any other options outside the heliosphere right now. Both Voyagers have fault protection software that allows the spacecraft to protect themselves if problematic situations occur. And a problem did indeed surface aboard Voyager 2 on January 25, when there seems to have been a delay in the onboard execution of commands for a scheduled maneuver. The latter was a 360 degree rotation to be executed as a way of calibrating the craft's magnetic field instrument, and the result of the delay was that two systems that consume power at relatively high levels were operating at the same time. Not a good idea. Right now, with power dwindling inexorably, the Voyager missions are both dominated by power management. Hence the shutdown of Voyager 2's science instruments to make up for the power deficit, as reported by the Voyager team on Twitter: Here's the skinny: My twin went to do a roll to...

DART & Hera: Changing an Asteroid’s Trajectory

by Paul Gilster | Jan 29, 2020 | Asteroid and Comet Deflection | 15 Comments

Asteroids are objects of obvious scientific interest, not only for their intrinsic properties but also our need to understand how we can change their motion in space in case one looks like it will come dangerously close to Earth in the future. OSIRIS-REx is extracting all kinds of valuable data from asteroid 101955 Bennu, but we should also keep in mind that Bennu itself is a potentially hazardous object, with a small chance (1-in-2700, according to current estimates) of striking the Earth between 2175 and 2199. Thus the second 'S' in OSIRIS, which stands for 'security', and is all about measuring the factors that affect the object's trajectory. When we get samples from Bennu, we'll have a better idea about the asteroid's chemistry and morphology, useful for understanding the early Solar System as well as assessing how hazardous such an object is. But we need to know more, which is where NASA's Double Asteroid Redirection Test (DART) mission comes in. Here the purpose is planetary...

OSIRIS-REx: Asteroid Sample Site Flyover

by Paul Gilster | Jan 28, 2020 | Asteroid and Comet Deflection | 1 Comment

The latest operations of the OSIRIS-REx spacecraft at asteroid Bennu remind me how powerful a wave we've unleashed in the coupling of robotics and ever more capable spacecraft components. We're not exactly at the stage of 'routine' asteroid missions, but Hayabusa2 and OSIRIS-REx when seen in the context of upcoming missions like NASA's DART experiment and the European Space Agency's Hera are part of our renaissance of this class of object, with results beneficial to science but also practically useful in terms of future impact mitigation. More on DART and Hera tomorrow. Small objects have plenty to say about our future in space, and I haven't even mentioned Lucy, which will be studying multiple Jupiter trojans, or the Psyche mission targeting what may be the exposed core of a planetary embryo, or for that matter, the remarkably successful Dawn, which unlocked so many mysteries at Vesta and Ceres. It goes without saying that having an operational spacecraft in the Kuiper Belt is...

Dwarf Novae: Mining Kepler Data for New Discoveries

by Paul Gilster | Jan 27, 2020 | Deep Sky Astronomy & Telescopes | 11 Comments

Cataclysmic variable stars (CVs) are binary phenomena, usually consisting of a white dwarf that is accreting material out of a nearby companion star. As you would imagine, a wide range of CVs in various stages of accretion and subsequent outburst can be detected. When the accretion disk around the white dwarf becomes unstable, we get what is known as a dwarf nova (DN), and in systems with orbital periods less than two hours, there can be much more violent outbursts, feeding off orbital resonances in the orbit of the two stars. Now we have a newly discovered cataclysmic variable (KSN:BS-C11a) in an interesting configuration, a white dwarf apparently feeding off a brown dwarf companion that is about 10 times less massive. The 'super-outburst' from the dwarf nova turned up in data from the decommissioned Kepler Space Telescope. Grad student Ryan Ridden-Harper (Australian National Observatory), lead author of the paper on this work, likes to refer to this cataclysmic variable as 'a...

From Spitzer to JWST’s Early Targets

by Paul Gilster | Jan 24, 2020 | Deep Sky Astronomy & Telescopes | 28 Comments

Yesterday's post on the Spitzer Space Telescope leads naturally to the targets it produced for its successor. For when Spitzer's mission ends on January 30, we have the far more powerful James Webb Space Telescope, also operating at infrared wavelengths, in queue for a 2021 launch. In many ways, Spitzer has been the necessary precursor for JWST, for it was the need to operate a telescope at extremely low temperatures in order to maximize infrared sensitivity that drove Spitzer design. JWST must maintain its gold-coated beryllium mirror at similarly precise temperatures. With over 8,700 scientific papers published based on Spitzer findings, a number that will continue to grow for many years, a path has been charted that JWST will follow in the form of observations early in its mission. Consider WASP-18b, a gas giant of ten times Jupiter mass in a tight orbit around its star. Data from both Spitzer and Hubble showed in 2017 that the planet is laden with carbon monoxide and all but...

Looking Back at the Spitzer Space Telescope

by Paul Gilster | Jan 23, 2020 | Deep Sky Astronomy & Telescopes | 5 Comments

The Spitzer Space Telescope, which is to end its mission on January 30, has a special place in my memory. I was making a trip to the Jet Propulsion Laboratory as part of the research for my Centauri Dreams book when I noticed on a monitor a countdown -- still in days -- for the launch of Spitzer, then known as the Space Infrared Telescope Facility (SIRTF). The observatory was launched on the 25th of August, 2003. I remember hot Pasadena weather, a conversation with aerospace legend Adrian Hooke (he was a member of the Kennedy Space Center launch team for Apollo 9, 10, 11 and 12, among much else), a rousing talk with Humphrey "Hoppy" Price about interstellar possibilities. So many good conversations, some serious interviews, and a growing enthusiasm for interstellar flight. But Spitzer had my attention because it was the next mission, one of the Great Observatory missions which included the Hubble Space Telescope, the Compton Gamma Ray Observatory, the Chandra X-ray Observatory, and...

An Impact-Driven End to ‘Snowball Earth’?

by Paul Gilster | Jan 22, 2020 | Asteroid and Comet Deflection | 5 Comments

The oldest preserved impact structure on Earth appears to be at Yarrabubba in Western Australia, where a magnetic anomaly about 20 kilometers in diameter has been interpreted to be a remnant of an original impact crater 70 kilometers across. Here, what had been an approximate age of 2.65 to 1.075 billion years has now been constrained to 2.229 billion years, making Yarrabubba 200 million years older than the next oldest impact. A team led by Timmons Erickson (Curtin University) analyzed the minerals zircon and monazite at the site. Their sample showed shock recrystallization (in the form of so-called neoblasts) from an asteroid strike, the analysis of which allowed them to pin down the structure’s age. A paper just out in Nature Communications reports on the team’s use of uranium-lead (U–Pb) dating to investigate the age of the shock features and impact melt. A global climate change may have occurred as a result of this impact, perhaps one with consequences for so-called ‘snowball...

A Deep Dive into Tidal Lock

by Paul Gilster | Jan 20, 2020 | Uncategorized | 33 Comments

Mention red dwarf habitable zones and tidal lock invariably comes up. If a planet is close enough to a dim red star to maintain temperatures suitable for life, wouldn't it keep one face turned toward it in perpetuity? But tidal lock, as Ashley Baldwin explains in the essay below, is more complex than we sometimes realize. And while there are ways to produce temperate climate models for such planets, tidal lock itself is a factor in not just M-dwarfs, but K- and even G-class stars like the Sun. Flip a few starting conditions and Earth itself might have been in tidal lock. The indefatigable Dr. Baldwin keeps a close eye on the latest exoplanet research, somehow balancing his astronomical scholarship with a career as consultant psychiatrist at the 5 Boroughs Partnership NHS Trust (Warrington, UK). Read on to learn a great deal about where current thinking stands on a subject critical to the question of red dwarf habitability. by Ashley Baldwin "Tidal locking", "captured rotation" or...

A Possible Proxima Centauri c

by Paul Gilster | Jan 16, 2020 | Exoplanetary Science | 22 Comments

While we continue to labor over the question of planets around Alpha Centauri A and B, Proxima Centauri -- that tiny red dwarf with an unusually interesting planet in the habitable zone -- remains a robust source of new work. It’s surely going to be an early target for whatever interstellar probes we eventually send, and is the presumptive first destination of Breakthrough Starshot. Now we have news of a possible second planet here, though well outside the habitable zone. Nonetheless, Proxima Centauri c, if it is there, commands the attention. A new paper offers the results of continuing analysis of the radial velocity dataset that led to the discovery of Proxima b, work that reflects the labors of Mario Damasso and Fabio Del Sordo, who re-analyzed these data using an alternative treatment of stellar noise in 2017. Damasso and Del Sordo now present new evidence, working with, among others, Proxima Centauri b discoverer Guillem Anglada-Escudé, and incorporating astrometric data from...

New Planets from Old Data

by Paul Gilster | Jan 15, 2020 | Exoplanetary Science | 13 Comments

We rightly celebrate exoplanet discoveries from dedicated space missions like TESS (Transiting Exoplanet Survey Satellite), watching the work go from initial concept to first light in space and early results. But let's not forget the growing usefulness of older data, tapped and analyzed in new ways to reveal hidden gems. Thus recent work out of the Carnegie Institution for Science, where Fabo Feng and Paul Butler have mined the archives of the Ultraviolet and Visual Echelle Spectrograph survey of 33 nearby red dwarf stars, a project operational from 2000 to 2007. The duo have uncovered five newly discovered exoplanets and eight more candidates, all found orbiting nearby red dwarf stars. Two of these are conceivably in the habitable zone, putting nearby stars GJ180 and GJ229A into position as potential targets for next-generation instruments. Both of these stars host super-Earths (7.5 and 7.9 times the mass of Earth), with orbital periods of 106 and 122 days respectively. Like the...

A Satellite for Eurybates

by Paul Gilster | Jan 14, 2020 | Outer Solar System | 7 Comments

3548 Eurybates is a Jupiter trojan, one of the family of objects that have moved within the Lagrange points around Jupiter for billions of years (the term is libration, meaning these asteroids actually oscillate around the Lagrange points). Consider them trapped objects, of consequence because they have so much to tell us about the early Solar System. The Lucy mission aims to visit both populations (the 'Greeks' and the 'Trojans') at Jupiter's L4 and L5 Lagrangians when it heads for Jupiter following launch in 2021. Image: During the course of its mission, Lucy will fly by six Jupiter Trojans. This time-lapsed animation shows the movements of the inner planets (Mercury, brown; Venus, white; Earth, blue; Mars, red), Jupiter (orange), and the two Trojan swarms (green) during the course of the Lucy mission. Credit: Astronomical Institute of CAS/Petr Scheirich (used with permission). Right now the focus is on Eurybates as mission planning continues, for we've just learned thanks to the...

Orange Dwarfs: ‘Goldilocks’ Stars for Life?

by Paul Gilster | Jan 13, 2020 | Uncategorized | 57 Comments

Our Sun is a G2V type star, or to use less formidable parlance, a yellow dwarf. It was inevitable that as we began considering planets around other stars (well before the first of these were discovered), we would imagine solar-class stars as the best place to look for life, but attention has swung to other possibilities in recent years, especially toward red dwarfs, which comprise a high percentage of all the stars in the galaxy. Now it seems that the problems of M-dwarfs are causing a reconsideration of the class in between, the K-class orange dwarfs. Alpha Centauri B is such a star, although its proximity to Centauri A may raise problems in planet formation that we have yet to observe. Fortunately, our long-distance exploration of the Centauri stars is well underway, and we should have new information about what orbits the two primary stars here within a few short years. If we were to find a habitable zone rocky world around Centauri B, one thing that makes it interesting is the...

New Entry in High Precision Spectroscopy

by Paul Gilster | Jan 10, 2020 | Exoplanetary Science | 12 Comments

As if I don't have enough trouble figuring out acronyms, I now have to figure out how to pronounce acronyms. The issue comes up because a new NASA instrument now in use at Kitt Peak National Observatory is a spectrograph built at Penn State called NEID. Now NEID stands for NN-EXPLORE Exoplanet Investigations with Doppler spectroscopy. Here we have an acronym within an acronym, for NN-EXPLORE itself stands for the NASA-NSF Exoplanet Observational Research partnership that funds NEID. Here's the trick: The acronym NEID is not pronounced 'NEE-id' or 'NEED' but 'NOO-id.' The reason: Kit Peak is on land owned by the Tohono O'odham nation, and the latter pronunciation honors a verb that means something close to 'to see' in the Tohono O'odham language. As a person fascinated with linguistics, I'm delighted to see this nod to a language whose very survival is threatened by the small number of speakers (count me as one infinitely cheered by the resurrection of Cornish, for example). And as...

TOI 700 d: A Possible Habitable Zone Planet

by Paul Gilster | Jan 9, 2020 | Exoplanetary Science | 23 Comments

Among the discoveries announced at the recent meeting of the American Astronomical Society in Hawaii was TOI 700 d, a planet potentially in the habitable zone of its star. TOI stands for TESS Object of Interest, reminding us that this is the first Earth-size planet the Transiting Exoplanet Survey Satellite has uncovered in its data whose orbit would allow the presence of liquid water on the surface. The Spitzer instrument has confirmed the find, highlighting the fact that Spitzer itself, a doughty space observatory working at infrared wavelengths, is nearing the end of its operations. Thus Joseph Rodriguez (Center for Astrophysics | Harvard & Smithsonian): "Given the impact of this discovery - that it is TESS's first habitable-zone Earth-size planet - we really wanted our understanding of this system to be as concrete as possible. Spitzer saw TOI 700 d transit exactly when we expected it to. It's a great addition to the legacy of a mission that helped confirm two of the TRAPPIST-1...

Discovery of TESS Mission’s First Circumbinary Planet

by Paul Gilster | Jan 7, 2020 | Exoplanetary Science | 11 Comments

TOI 1338b is a great catch, a circumbinary world that turned up in TESS data and was announced at the ongoing meeting of the American Astronomical Society in Hawai'i. Ravi Kopparapu (NASA GSFC) describes the discovery process in the essay below. The system lies 1,300 light years out in the constellation Pictor, with the planet transiting the larger star. Dr. Kopparapu's work on exoplanet habitability is well known to Centauri Dreams readers. See, for example, his How Common Are Potential Habitable Worlds in Our Galaxy?, which ran in 2014. He followed this up with a look at an unusual multi-planet system (Ravi Kopparapu: Looking at K2-72). Analyzing habitable zone possibilities around different kinds of stars, as well as modeling and characterizing exoplanet atmospheres, plays a major role in his research interests. Here Dr. Kopparapu tells us about the new world and the significant role of an intern in its discovery, reminding us that the opportunities for young scientists to make a...

Some Thoughts on Science Fiction Visuals

by Paul Gilster | Jan 3, 2020 | Culture and Society | 23 Comments

With the conclusion of The Man in the High Castle's TV version, I've been having a few conversations about the ins and outs of turning the novel into a considerably bloated series. Or maybe I should say simply that when I realized at the end of the first season that, having made their choices and essentially filmed their version of the book, the producers were now going to go for further seasons, I was dismayed. Who would be making the choices now that the original author was not available, and how would the plot unfold? An ongoing series can do this well, of course -- consider the absorbing tale unfolding in The Expanse -- but going well outside the boundaries of a foundational novel can often be asking for trouble. While I wasn't much taken with the way The Man in the High Castle's plot played out on TV, I did go ahead and watch every episode because I found the visuals so entrancing. The idea of a Japanese occupied California was fully realized, with touches like the Japanese...

Charter

In Centauri Dreams, Paul Gilster looks at peer-reviewed research on deep space exploration, with an eye toward interstellar possibilities. For many years this site coordinated its efforts with the Tau Zero Foundation. It now serves as an independent forum for deep space news and ideas. In the logo above, the leftmost star is Alpha Centauri, a triple system closer than any other star, and a primary target for early interstellar probes. To its right is Beta Centauri (not a part of the Alpha Centauri system), with Beta, Gamma, Delta and Epsilon Crucis, stars in the Southern Cross, visible at the far right (image courtesy of Marco Lorenzi).

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