The Challenge of ‘Twilight Asteroids’

by | Jul 29, 2022 | | 13 Comments

We have the Zwicky Transient Facility at Palomar Observatory to thank for the detection of the strikingly named 'Ayló'chaxnim (2020 AV2). This is a large near-Earth asteroid with a claim to distinction, being the first NEO found to orbit inside the orbit of Venus. I love to explore the naming of things, and now that we have 'Ayló'chaxnim (2020 AV2), we have to name the category, at least provisionally. The chosen name is Vatira, which in turn is a nod to Atira, a class of asteroids that orbit entirely inside Earth's orbit. Thus Vatira refers to an Atira NEO with orbit interior to Venus. As to the 'Ayló'chaxnim, it's a word from indigenous peoples whose ancestral lands took in the mountainous region where the Palomar Observatory is located. I'm told by the good people at Caltech that the word means something like 'Venus Girl.' On June 7, people of Pauma descent gathered for a ceremony at the observatory, having been asked by the team manning the Zwicky Transient...

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Getting There Quickly: The Nuclear Option

by | Jul 26, 2022 | | 38 Comments

Adam Crowl has been appearing on Centauri Dreams for almost as long as the site has been in existence, a welcome addition given his polymathic interests and ability to cut to the heart of any issue. His long-term interest in interstellar propulsion has recently been piqued by the Jet Propulsion Laboratory's work on a mission to the Sun's gravitational lens region. JPL is homing in on multiple sailcraft with close solar passes to expedite the cruise time, leading Adam to run through the options to illustrate the issues involved in so dramatic a mission. Today he looks at the pros and cons of nuclear propulsion, asking whether it could be used to shorten the trip dramatically. Beamed sail and laser-powered ion drive possibilities are slated for future posts. With each of these, if we want to get out past 550 AU as quickly as possible, the devil is in the details. To keep up with Adam's work, keep an eye on Crowlspace. by Adam Crowl The Solar Gravitational Lens amplifies signals from...

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Solar Gravitational Lens: Sailcraft and In-Flight Assembly

by | Jul 22, 2022 | | 20 Comments

The last time we looked at the Jet Propulsion Laboratory’s ongoing efforts toward designing a mission to the Sun’s gravitational lens region beyond 550 AU, I focused on how such a mission would construct the image of a distant exoplanet. Gravitational lensing takes advantage of the Sun’s mass, which as Einstein told us distorts spacetime. A spacecraft placed on the other side of the Sun from the target exoplanetary system would take advantage of this, constructing a high resolution image of unprecedented detail. It’s hard to think of anything short of a true interstellar mission that could produce more data about a nearby exoplanet. In that earlier post, I focused on one part of the JPL work, as the team under the direction of Slava Turyshev had produced a paper updating the modeling of the solar corona. The new numerical simulations led to a powerful result. Remember that the corona is an issue because the light we are studying is being bent around the Sun, and we are in danger of...

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Getting Down to Business with JWST

by | Jul 19, 2022 | | 32 Comments

So let’s get to work with the James Webb Space Telescope. Those dazzling first images received a gratifying degree of media attention, and even my most space-agnostic neighbors were asking me about what exactly they were looking at. For those of us who track exoplanet research, it’s gratifying to see how quickly JWST has begun to yield results on planets around other stars. Thus WASP-96 b, 1150 light years out in the southern constellation Phoenix, a lightweight puffball planet scorched by its star. Maybe 'lightweight' isn’t the best word. Jupiter is roughly 320 Earth masses, and WASP-96b weighs in at less than half that, but its tight orbit (0.04 AU, or almost ten times closer to its Sun-like star than Mercury) has puffed its diameter up to 1.2 times that of Jupiter. This is a 3.5-day orbit producing temperatures above 800 ?. As you would imagine, this transiting world is made to order for analysis of its atmosphere. To follow JWST's future work, we’ll need to start learning new...

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Probing the Galaxy: Self-Reproduction and Its Consequences

by | Jul 12, 2022 | | 35 Comments

In a long and discursive paper on self-replicating probes as a way of exploring star systems, Alex Ellery (Carleton University, Ottawa) digs, among many other things, into the question of what we might detect from Earth of extraterrestrial technologies here in the Solar System. The idea here is familiar enough. If at some point in our past, a technological civilization had placed a probe, self-replicating or not, near enough to observe Earth, we should at some point be able to detect it. Ellery believes such probes would be commonplace because we humans are developing self-replication technology even today. Thus a lack of probes would indicate that there are no extraterrestrial civilizations to build them. There are interesting insights in this paper that I want to explore, some of them going a bit far afield from Ellery's stated intent, but worth considering for all that. SETA, the Search for Extraterrestrial Artifacts, is a young endeavor but a provocative one. Here...

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Two Close Stellar Passes

by | Jul 8, 2022 | | 31 Comments

Interstellar objects are much in the news these days, as witness the flurry of research on ‘Oumuamua and 2I/Borisov. But we have to be cautious as we look at objects on hyperbolic orbits, avoiding the assumption that any of these are necessarily from another star. Spanish astronomers Carlos and Raúl de la Fuente Marcos dug several years ago into the question of objects on hyperbolic orbits, noting that some of these may well have origins much closer to home. Let me quote their 2018 paper on this: There are mechanisms capable of generating hyperbolic objects other than interstellar interlopers. They include close encounters with the known planets or the Sun, for objects already traversing the Solar system inside the trans-Neptunian belt; but also secular perturbations induced by the Galactic disc or impulsive interactions with passing stars, for more distant bodies (see e.g. Fouchard et al. 2011, 2017; Królikowska & Dybczy?ski 2017). These last two processes have their sources beyond...

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The Great Venusian Bug Hunt

by | Jul 5, 2022 | | 31 Comments

Our recent focus on life detection on nearby worlds concludes with a follow-up to Alex Tolley's June essay on Venus Life Finder. What would the sequence of missions look like that resulted in an unambiguous detection of life in the clouds of Venus? To answer that question, Alex takes the missions in reverse order, starting with a final, successful detection, and working back to show what the precursor mission to each step would have needed to accomplish to justify continuing the effort. If the privately funded VLF succeeds, it will be in the unusual position of making an astrobiological breakthrough before the large space organizations could achieve it, but there are a lot of steps along the way that we have to get right. by Alex Tolley In my previous essay, Venus Life Finder: Scooping Big Science, I introduced the near-term, privately financed plan to send a series of dedicated life-finding probes to Venus' clouds. The first was a tiny atmosphere entry vehicle with a dedicated...

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Drilling into Icy Moon Oceans

by | Jul 1, 2022 | | 52 Comments

While we talk often about subsurface oceans in places like Europa, the mechanisms for getting through layers of ice remain problematic. We'll need a lot of data through missions like Europa Clipper and JUICE just to make the call on how thick Europa's ice is before determining which ice penetration technology is feasible. But it's exciting to see how much preliminary work is going into the issue, because the day will come when one or another icy moon yields the secrets of its ocean to a surface lander. By way of comparison, the thickest ice sheet on Earth is said to reach close to 5,000 meters. This is at the Astrolabe Subglacial Basin, which lies at the southern end of Antarctica's Adélie Coast. Here we have glacial ice covering continental crust, as opposed to ice atop an ocean (although there appears to be an actively circulating groundwater system, which has been recently mapped in West Antarctica). The deepest bore into this ice has been 2,152 meters, a 63 hour continuous...

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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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