How NASA Approaches Deep Space Missions

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...

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Juno: Looking Deep into Jupiter’s Atmosphere

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...

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Trident: Firming up the Triton Flyby

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...

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A New Look at the ‘Pale Blue Dot’

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...

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Boundary Conditions for Emergent Complexity Longevity

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...

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A Nearby ‘Planet’ in Formation

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...

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A Heliophysics Gateway to Deep Space

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...

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In the Days before Centauri Dreams… An Essay by WDK

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...

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Modeling Circulation at Pluto’s Heart

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...

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Of Sails and Supernovae

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...

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New Horizons Parallax Program Targets Proxima Centauri, Wolf 359

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...

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As Spitzer’s Mission Ends, First Light for CHEOPS

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...

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Voyager 2 Recovers

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...

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DART & Hera: Changing an Asteroid’s Trajectory

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...

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OSIRIS-REx: Asteroid Sample Site Flyover

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...

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Dwarf Novae: Mining Kepler Data for New Discoveries

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...

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From Spitzer to JWST’s Early Targets

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...

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Looking Back at the Spitzer Space Telescope

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...

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An Impact-Driven End to ‘Snowball Earth’?

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...

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A Deep Dive into Tidal Lock

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...

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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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