The latest Planetary Post with Robert Picardo: The Planetary Post – Carl Sagan’s Pale Blue Dot | The Planetary Society
A reading of Carl Sagan’s Pale Blue Dot by Star Trek’s Robert Picardo, who also serves as a member of The Planetary Society Board of Directors and is the host of our monthly email newsletter, The Planetary Post.
The Cassini spacecraft takes a wonderful image of the Saturn, its rings, and the small moon Mimas:
Saturn’s icy moon Mimas is dwarfed by the planet’s enormous rings.
Because Mimas (near lower left) appears tiny by comparison, it might seem that the rings would be far more massive, but this is not the case. Scientists think the rings are no more than a few times as massive as Mimas, or perhaps just a fraction of Mimas’ mass. Cassini is expected to determine the mass of Saturn’s rings to within just a few hundredths of Mimas’ mass as the mission winds down by tracking radio signals from the spacecraft as it flies close to the rings.
The rings, which are made of small, icy particles spread over a vast area, are extremely thin – generally no thicker than the height of a house. Thus, despite their giant proportions, the rings contain a surprisingly small amount of material.
Mimas is 246 miles (396 kilometers) wide.
This view looks toward the sunlit side of the rings from about 6 degrees above the ring plane. The image was taken in red light with the Cassini spacecraft wide-angle camera on July 21, 2016.
The view was obtained at a distance of approximately 564,000 miles (907,000 kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 31 degrees. Image scale is 34 miles (54 kilometers) per pixel.
The Cassini mission is a cooperative project of NASA, ESA (the European Space Agency) and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colorado.
For more information about the Cassini-Huygens mission visit saturn.jpl.nasa.gov and www.nasa.gov/cassini. The Cassini imaging team homepage is at ciclops.org.
Credit: NASA/JPL-Caltech/Space Science Institute
A huge underground deposit of water has been detected on Mars:
Mars Ice Deposit Holds as Much Water as Lake Superior
Frozen beneath a region of cracked and pitted plains on Mars lies about as much water as what’s in Lake Superior, largest of the Great Lakes, researchers using NASA’s Mars Reconnaissance Orbiter have determined.
Scientists examined part of Mars’ Utopia Planitia region, in the mid-northern latitudes, with the orbiter’s ground-penetrating Shallow Radar (SHARAD) instrument. Analyses of data from more than 600 overhead passes with the onboard radar instrument reveal a deposit more extensive in area than the state of New Mexico. The deposit ranges in thickness from about 260 feet (80 meters) to about 560 feet (170 meters), with a composition that’s 50 to 85 percent water ice, mixed with dust or larger rocky particles.
Fast Facts:
› Water ice makes up half or more of an underground layer in a large region of Mars about halfway from the equator to the north pole.
› The amount of water in this deposit is about as much as in Lake Superior. It was assessed using a radar aboard a NASA spacecraft orbiting Mars.
› This research advances understanding about Mars’ history and identifies a possible resource for future astronauts.
At the latitude of this deposit — about halfway from the equator to the pole — water ice cannot persist on the surface of Mars today. It sublimes into water vapor in the planet’s thin, dry atmosphere. The Utopia deposit is shielded from the atmosphere by a soil covering estimated to be about 3 to 33 feet (1 to 10 meters) thick.
“This deposit probably formed as snowfall accumulating into an ice sheet mixed with dust during a period in Mars history when the planet’s axis was more tilted than it is today,”
said Cassie Stuurman of the Institute for Geophysics at the University of Texas, Austin. She is the lead author of a report in the journal Geophysical Research Letters.
Mars today, with an axial tilt of 25 degrees, accumulates large amounts of water ice at the poles. In cycles lasting about 120,000 years, the tilt varies to nearly twice that much, heating the poles and driving ice to middle latitudes. Climate modeling and previous findings of buried, mid-latitude ice indicate that frozen water accumulates away from the poles during high-tilt periods.
Martian Water as a Future Resource
The name Utopia Planitia translates loosely as the “plains of paradise.” The newly surveyed ice deposit spans latitudes from 39 to 49 degrees within the plains. It represents less than one percent of all known water ice on Mars, but it more than doubles the volume of thick, buried ice sheets known in the northern plains. Ice deposits close to the surface are being considered as a resource for astronauts.
“This deposit is probably more accessible than most water ice on Mars, because it is at a relatively low latitude and it lies in a flat, smooth area where landing a spacecraft would be easier than at some of the other areas with buried ice,”
said Jack Holt of the University of Texas, a co-author of the Utopia paper who is a SHARAD co-investigator and has previously used radar to study Martian ice in buried glaciers and the polar caps.
The Utopian water is all frozen now. If there were a melted layer — which would be significant for the possibility of life on Mars — it would have been evident in the radar scans. However, some melting can’t be ruled out during different climate conditions when the planet’s axis was more tilted.
“Where water ice has been around for a long time, we just don’t know whether there could have been enough liquid water at some point for supporting microbial life,” Holt said.
Utopia Planitia is a basin with a diameter of about 2,050 miles (3,300 kilometers), resulting from a major impact early in Mars’ history and subsequently filled. NASA sent the Viking 2 Lander to a site near the center of Utopia in 1976. The portion examined by Stuurman and colleagues lies southwest of that long-silent lander.
Use of the Italian-built SHARAD instrument for examining part of Utopia Planitia was prompted by Gordon Osinski at Western University in Ontario, Canada, a co-author of the study. For many years, he and other researchers have been intrigued by ground-surface patterns there such as polygonal cracking and rimless pits called scalloped depressions — “like someone took an ice-cream scoop to the ground,” said Stuurman, who started this project while a student at Western.
Clue from Canada
In the Canadian Arctic, similar landforms are indicative of ground ice, Osinski noted,
“but there was an outstanding question as to whether any ice was still present at the Martian Utopia or whether it had been lost over the millions of years since the formation of these polygons and depressions.”
The large volume of ice detected with SHARAD advances understanding about Mars’ history and identifies a possible resource for future use.
“It’s important to expand what we know about the distribution and quantity of Martian water,” said Mars Reconnaissance Orbiter Deputy Project Scientist Leslie Tamppari, of NASA’s Jet Propulsion Laboratory, Pasadena, California. “We know early Mars had enough liquid water on the surface for rivers and lakes. Where did it go? Much of it left the planet from the top of the atmosphere. Other missions have been examining that process. But there’s also a large quantity that is now underground ice, and we want to keep learning more about that.”
Joe Levy of the University of Texas, a co-author of the new study, said,
“The ice deposits in Utopia Planitia aren’t just an exploration resource, they’re also one of the most accessible climate change records on Mars. We don’t understand fully why ice has built up in some areas of the Martian surface and not in others. Sampling and using this ice with a future mission could help keep astronauts alive, while also helping them unlock the secrets of Martian ice ages.”
SHARAD is one of six science instruments on the Mars Reconnaissance Orbiter, which began its prime science phase 10 years ago this month. The mission’s longevity is enabling studies of features and active processes all around Mars, from subsurface to upper atmosphere. The Italian Space Agency provided the SHARAD instrument and Sapienza University of Rome leads its operations. The Planetary Science Institute, based in Tucson, Arizona, leads U.S. involvement in SHARAD. JPL, a division of Caltech in Pasadena, manages the orbiter mission for NASA’s Science Mission Directorate in Washington. Lockheed Martin Space Systems of Denver built the spacecraft and supports its operations.
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New views from Cassini of the bands and swirls of Saturn‘s north pole and of the clouds of Saturn’s moon Titan:
Saturn’s north polar region displays its beautiful bands and swirls, which somewhat resemble the brushwork in a watercolor painting.
Each latitudinal band represents air flowing at different speeds, and clouds at different heights, compared to neighboring bands. Where they meet and flow past each other, the bands’ interactions produce many eddies and swirls.
The northern polar region of Saturn is dominated by the famous hexagon shape (see PIA11682) which itself circumscribes the northern polar vortex – seen as a dark spot at the planet’s pole in the above image – which is understood to the be eye of a hurricane-like storm (PIA14946).
This view looks toward the sunlit side of the rings from about 20 degrees above the ring plane. The image was taken with the Cassini spacecraft wide-angle camera on Sept. 5, 2016 using a spectral filter which preferentially admits wavelengths of near-infrared light centered at 728 nanometers.
The view was obtained at a distance of approximately 890,000 miles (1.4 million kilometers) from Saturn. Image scale is 53 miles (86 kilometers) per pixel.
The Cassini mission is a cooperative project of NASA, ESA (the European Space Agency) and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colorado.
For more information about the Cassini-Huygens mission visit saturn.jpl.nasa.gov and www.nasa.gov/cassini. The Cassini imaging team homepage is at ciclops.org.
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Watching Summer Clouds on Titan
NASA’s Cassini spacecraft watched clouds of methane moving across the far northern regions of Saturn’s largest moon, Titan, on Oct. 29 and 30, 2016.
Several sets of clouds develop, move over the surface and fade during the course of this movie sequence, which spans 11 hours, with one frame taken every 20 minutes. Most prominent are long cloud streaks that lie between 49 and 55 degrees north latitude. While the general region of cloud activity is persistent over the course of the observation, individual streaks appear to develop then fade. These clouds are measured to move at a speed of about 14 to 22 miles per hour (7 to 10 meters per second).
There are also some small clouds over the region of small lakes farther north, including a bright cloud between Neagh Lacus and Punga Mare, which fade over the course of the movie. This small grouping of clouds is moving at a speed of about 0.7 to 1.4 miles per hour (1 to 2 meters per second).
Time-lapse movies like this allow scientists to observe the dynamics of clouds as they develop, move over the surface and fade. A time-lapse movie can also help to distinguish between noise in images (for example from cosmic rays hitting the detector) and faint clouds or fog.
In 2016, Cassini has intermittently observed clouds across the northern mid-latitudes of Titan, as well as within the north polar region — an area known to contain numerous methane/ethane lakes and seas see PIA19657 and PIA17655. However, most of this year’s observations designed for cloud monitoring have been short snapshots taken days, or weeks, apart. This observation provides Cassini’s best opportunity in 2016 to study short-term cloud dynamics.
Models of Titan’s climate have predicted more cloud activity during early northern summer than what Cassini has observed so far, suggesting that the current understanding of the giant moon’s changing seasons is incomplete.
The mission will continue monitoring Titan’s weather around the 2017 summer solstice in Titan’s northern hemisphere.
The movie was acquired using the Cassini narrow-angle camera using infrared filters to make the surface and tropospheric methane clouds visible.
The Cassini mission is a cooperative project of NASA, ESA (the European Space Agency) and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colorado.
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Check out the cool animated clips of Mars weather in action created by Justin Cowart of The Planetary Society from still images taken by the HRSC (High/Super Resolution Stereo Colour Imager) on the Mars Express spacecraft orbiting the Red Planet:
Here are a couple of examples:
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