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Exploring the Contact Paradox

by Paul Gilster | Feb 28, 2020 | Uncategorized | 92 Comments

Keith Cooper is a familiar face on Centauri Dreams, both through his own essays and the dialogues he and I have engaged in on interstellar topics. Keith is the editor of Astronomy Now and the author of both The Contact Paradox: Challenging Assumptions in the Search for Extraterrestrial Intelligence (Bloomsbury Sigma), and Origins of the Universe: The Cosmic Microwave Background and the Search for Quantum Gravity (Icon Books) to be published later this year. The Contact Paradox is a richly detailed examination of the history and core concepts of SETI, inspiring a new set of conversations, of which this is the first. With the recent expansion of the search through Breakthrough Listen, where does SETI stand both in terms of its likelihood of success and its perception among the general public? Paul Gilster Keith, we're 60 years into SETI and no contact yet, though there are a few tantalizing things like the WOW! signal to hold our attention. Given that you have just given us an...

G 9-40b: Confirming a Planet Candidate

by Paul Gilster | Feb 26, 2020 | Exoplanetary Science | 10 Comments

M-class dwarfs within 100 light years are highly sought after objects these days, given that any transiting worlds around such stars will present unusually useful opportunities for atmospheric analysis. That's because these stars are small, allowing large transit depth -- in other words, a great deal of the star's light is blocked by the planet. Studying a star's light as it filters through a planetary atmosphere -- transmission spectroscopy -- can tell us much about the chemical constituents involved. We'll soon extend that with space-based direct imaging. While the discoveries we're making today are exciting in their own right, bear in mind that we're also building the catalog of objects that next generation ground telescopes (the extremely large, or ELT, instruments on the way) and their space-based cousins can examine in far greater depth. And it's also true that we are tuning up our methods for making sure that our planet candidates are real and not products of data...

How NASA Approaches Deep Space Missions

by Paul Gilster | Feb 24, 2020 | Missions | 7 Comments

Centauri Dreams reader Charley Howard recently wrote to ask about how NASA goes about setting its mission priorities and analyzing mission concepts like potential orbiter missions to the ice giants. It's such a good question that I floated it past Ashley Baldwin, who is immersed in the evolution of deep space missions and moves easily within the NASA structure to extract relevant information. Dr. Baldwin had recently commented on ice giant mission analysis by the Outer Planets Advisory Group. But what is this group, and where does it fit within the NASA hierarchy? Here is Ashley's explanation of this along with links to excellent sources of information on the various mission concepts under analysis for various targets, and a bit of trenchant commentary. By Ashley Baldwin Each of the relevant NASA advisory groups has its own page on the NASA site with archives stuffed full of great presentations. The most germane to our discussion here is the Outer Planets Assessment Group (OPAG). My...

Juno: Looking Deep into Jupiter’s Atmosphere

by Paul Gilster | Feb 21, 2020 | Outer Solar System | 4 Comments

We're learning more about the composition of Jupiter's atmosphere, and in particular, the amount of water therein, as a result of data from the Juno mission. The data come in the 1.25 to 22 GHz range from Juno's microwave radiometer (MWR), depicting the deep atmosphere in the equatorial region. Here, water (considered in terms of its component oxygen and hydrogen) makes up about 0.25 percent of the molecules in Jupiter's atmosphere, almost three times the percentage found in the Sun. All of this gets intriguing when compared to the results from Galileo. You'll recall that the Galileo probe descended into the Jovian atmosphere back in 1995, sending back spectrometer measurements of the amount of water it found down to almost 120 kilometers, where atmospheric pressure reached 320 pounds per square inch (22 bar). Unlike Juno, Galileo showed that Jupiter might be dry compared to the Sun -- there was in fact ten times less water than expected -- but it also found water content increasing...

Trident: Firming up the Triton Flyby

by Paul Gilster | Feb 19, 2020 | Outer Solar System | 48 Comments

It's not a Triton, or even a Neptune orbiter, but Trident is still an exciting mission, a Triton flyby that would take a close look at the active resurfacing going on on this remarkable moon. Trident has recently been selected by NASA's Discovery Program as one of four science investigations that will lead to one to two missions being chosen at the end of the study for development and launch in the 2020s. These are nine-month studies, and they include, speaking of young and constantly changing surfaces, the Io Volcanic Observer (IVO). The other two missions are the Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy (VERITAS) mission, and DAVINCI+ (Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging Plus). Each of these studies will receive $3 million to bring its concepts to fruition, concluding with a Concept Study Report, at which point we'll get word on the one or two that have made it to further development and flight. The NASA Discovery...

A New Look at the ‘Pale Blue Dot’

by Paul Gilster | Feb 18, 2020 | Culture and Society | 3 Comments

The 30th anniversary of the famous 'Pale Blue Dot' image of Earth, which took place on February 14, is an appropriate occasion for the newly updated image below, which brings the latest methods to bear on the data Voyager 1 presented us. Our planet takes up less than a single pixel and for that reason is not fully resolved. The rays of sunlight due to scattering within the camera optics intersect with Earth, reminding us that from Voyager's position 6 billion kilometers from home, the Earth/Sun separation was only a matter of a few degrees. Image: For the 30th anniversary of one of the most iconic images taken by NASA's Voyager mission, a new version of the image known as "the Pale Blue Dot." Planet Earth is visible as a bright speck within the sunbeam just right of center and appears softly blue, as in the original version published in 1990. This updated version uses modern image-processing software and techniques to revisit the well-known Voyager view while attempting to respect...

Boundary Conditions for Emergent Complexity Longevity

by Paul Gilster | Feb 14, 2020 | Culture and Society | 52 Comments

We usually think about habitability in terms of liquid water on the surface, which is the common definition of the term 'habitable zone.' But even in our own system, we have great interest in places where this is not the case (e.g. Europa). In today's essay, Nick Nielsen begins with the development of complex life in terms not just of a habitable zone, but what some scientists are calling an 'abiogenesis zone.' The implications trigger SETI speculation, particularly in systems whose host star is nearing the end of its life on the main sequence. Are there analogies between habitable zones and the conditions that can lead not just to life but civilization? These boundary conditions offers a new direction for SETI theorists to explore. by J. N. Nielsen Recently a paper of some interest was posted to arXiv, "There's No Place Like Home (in Our Own Solar System): Searching for ET Near White Dwarfs," by John Gertz. (Gertz has several other interesting papers on arXiv that are working...

A Nearby ‘Planet’ in Formation

by Paul Gilster | Feb 12, 2020 | Exoplanetary Science | 5 Comments

330 light years from the Sun is the infant planet 2MASS 1155-7919 b, recently discovered in Gaia data by a team from the Rochester Institute of Technology. It’s a useful world to have in our catalog because we have no newborn massive planet closer to Earth than this one. Circling a star in the Epsilon Chamaeleontis Association, 2MASS 1155-7919 b is thought to be no more than 5 million years old, orbiting its host at roughly 600 times the Earth/Sun distance. A stellar association like Epsilon Chamaeleontis is a loose cluster, with stars that have a common origin but are no longer gravitationally bound as they move in rough proximity through space. RIT graduate student Annie Dickson-Vandervelde is lead author on the discovery paper: “The dim, cool object we found is very young and only 10 times the mass of Jupiter, which means we are likely looking at an infant planet, perhaps still in the midst of formation. Though lots of other planets have been discovered through the Kepler mission...

A Heliophysics Gateway to Deep Space

by Paul Gilster | Feb 11, 2020 | Missions | 13 Comments

Are missions to the Sun particularly relevant to our interstellar ambitions? At the current state of our technology, the answer is yes. Consider Solar Cruiser, which is the planned NASA mission using a solar sail that could maintain non-Keplerian orbits, allowing it to investigate the Sun's high latitudes. And throw in the European Space Agency-led Solar Orbiter, which left our planet early Monday (UTC) on a United Launch Alliance Atlas V rocket, lifting off from Launch Complex 41 at Cape Canaveral Air Force Station in Florida. Herewith the gorgeous arc of ascent: Image: Launch of the ESA/NASA Solar Orbiter mission to study the Sun from Cape Canaveral Air Force Station in Florida on Feb. 9, 2020. Credit: Jared Frankle. Missions to the Sun allow us to explore conditions close to a star and, significantly, deep in its gravity well, where interesting things can happen. When we discuss one way of propelling a sail beyond the heliosphere, the irony is that an Oberth maneuver, which takes...

In the Days before Centauri Dreams… An Essay by WDK

by Paul Gilster | Feb 7, 2020 | Deep Sky Astronomy & Telescopes | 16 Comments

Wes Kelly has pursued a lifetime interest in flight through the air, in orbit and even to the stars. Known on Centauri Dreams as 'wdk,' Wes runs a small aerospace company in Houston (Triton Systems,LLC), founded for the purpose of developing a partially reusable HTOL launch vehicle for delivering small satellites to space. The company also provides aerospace engineering services to NASA and other customers, starting with contracts in the 1990s. Kelly studied aerospace engineering at the University of Michigan after service in the US Air Force, and went on to do graduate work at the University of Washington. He has been involved with early design and development of the Space Shuttle, expendable launch systems, solar electric propulsion systems and a succession of preliminary vehicle designs. With the International Space Station, he worked both as engineer and a translator or interpreter in meetings with Russian engineering teams on areas such as propulsion, guidance and control. In...

Modeling Circulation at Pluto’s Heart

by Paul Gilster | Feb 6, 2020 | Outer Solar System | 7 Comments

The dataflow from New Horizons has been abundant enough that we are now drilling down to atmospheric models that may explain the dwarf planet’s topography. Mention topography on Pluto and the first thing that leaps to mind is Tombaugh Regio, and a new paper in the Journal of Geophysical Research Planets actually takes us into its role in the formation of regional weather patterns on the icy orb. For at the heart of Pluto’s weather appears to be the terrain often called Pluto’s ‘heart,’ from the distinctive shape it imposes upon the landscape. Pluto’s atmosphere, 100,000 times thinner than ours, is primarily nitrogen, with but small amounts of carbon monoxide and methane. Tombaugh Regio is covered by nitrogen ice, which warms during the day, turning to vapor that condenses in Pluto’s night to once again form ice. The researchers, led by Tanguy Bertrand, an astrophysicist and planetary scientist at NASA’s Ames Research Center in California and the study’s lead author, liken the process...

Of Sails and Supernovae

by Paul Gilster | Feb 4, 2020 | Sail Concepts | 37 Comments

When we consider pushing a sail to 20 percent of lightspeed, which is the target velocity for Breakthrough Starshot, it's interesting to think about how laser propulsion differs from sunlight. After all, while constructing a huge laser array presents numerous challenges on Earth, we already have a star to work with, and sail technology that is beginning to be tested in space. Consider, too, that we have operational spacecraft like the Parker Solar Probe that are exploring regions close to the Sun, helping us learn more about heat shields, even as we plan missions like Solar Cruiser, whose sail would enable interesting non-Keplerian orbits near the Sun. Wouldn't it be easier to find ways to use our Sun's own energies to drive our starship by getting a boost from gravitational effects? A closer look reveals the power of solar sails in nearby space (i.e., within the system), while illuminating the problems at interstellar distances. For getting a solar sail up to the highest possible...

New Horizons Parallax Program Targets Proxima Centauri, Wolf 359

by Paul Gilster | Feb 3, 2020 | Deep Sky Astronomy & Telescopes | 37 Comments

In a few short months, New Horizons will be almost 8 billion kilometers out, a distance that still boggles the mind until we remember that Voyager 1 has reached 22.2 billion kilometers (over 148 AU). Then, of course, we're humbled again with the thought that the inner Oort Cloud is thought to be between 2,000 and 5,000 AU from the Sun, with an outer edge that could extend as far as halfway to the nearest star. That star, Proxima Centauri, is 268,770 AU from us. As New Horizons hunts Kuiper Belt objects for the next flyby, the spacecraft is now being used to perform parallax studies to detect the apparent 'shift' in the relative position of nearby stars as compared with what we see on Earth. Earth's orbit is about 300 million kilometers in diameter, so we see that apparent shift by comparing observations taken half a year apart. That's a pretty decent baseline, but if we extend the baseline, as now with New Horizons, we can see better parallax effects, and thus tighten the distance...

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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