Pluto: The Impact of Craters

NASA - New Horizons Mission logo.

October 13, 2015

There are many ways scientists investigate a planet they’re seeing for the first time, and this is one example. With a flyby mission you can’t probe the ice on the surface or analyze samples, so you have other methods to determine a planet’s makeup and age – and gain insight into how it involved into the world it is today. Analyzing craters can help us understand the age of a planet’s surface.

Image above: This portrait of Pluto is in enhanced color, to illustrate differences in the composition and texture of Pluto’s surface. Image Credit: NASA/JHUAPL/SwRI.

A surface with more craters indicates that it’s older, geologically, than a less-cratered surface. Pluto displays many good examples of this concept. Any guesses as to which parts of Pluto mission scientists think are younger?

If you went with the informally named Sputnik Planum – the left half of Pluto’s “heart” feature – as a young geologic unit, then you are on the right track. So far we have not identified any obvious craters on Sputnik Planum. We can also try to put an actual date on a surface (e.g., that a given surface is 1 billion years old), but this is more difficult because it requires some knowledge of how often impactors (chunks of space debris) of a certain size hit the surface to make craters.

Image above: These close-up images of Pluto and Charon illustrate the effect of lighting geometry on the appearance of craters. Image Credits: SwRI/Kelsi Singer.

Age-dating based on craters is complicated by a number of other factors as well. I will highlight one big issue here: How one “sees” craters is affected by lighting over the planet’s surface. Just like on Earth, the lighting on Pluto and Charon changes both with latitude and over the course of the day. When the sun is directly overhead, there are very few shadows cast and it is hard to see topography, but that overhead lighting makes it much easier to see dark or bright markings. The opposite is true when the sun hits the surface at a shallow angle near sunrise or sunset: topography is easy to see, but bright and dark colorations are often washed out.

Because New Horizons flew by Pluto so quickly (in just a few hours out of Pluto’s day, which is 6.4 Earth days), our highest-resolution pictures were all taken under the same lighting conditions. The northern latitudes of Pluto and Charon have the sun mostly overhead, while near the equator the sun hits the surface at an angle. This gives the effect that craters in the north look flatter and have stronger dark/bright contrasts, while craters near the equator look more 3-D.

Image above: Kelsi Singer, NASA's blogger from the New Horizons science team, writer of this article.

There are many other complicating factors, such as variable image resolutions and variable surface erosion or degradation. Even fragments of surface material ejected while creating a “primary” crater can pose a problem because they may litter the surface and make smaller, so-called “secondary craters” that influence crater statistics. We are taking all of these factors into account as we map Pluto and Charon’s craters and mine this data to learn more about the history and evolution of these amazing, mysterious worlds.

For more information about New Horizons, visit: http://www.nasa.gov/mission_pages/newhorizons/main/index.html

Images (mentioned), Text, Credits: NASA/Kelsi Singer.

Greetings, Orbiter.ch

Hubble’s Planetary Portrait Captures New Changes in Jupiter’s Great Red Spot

NASA - Hubble Space Telescope patch.

Oct. 13, 2015

Scientists using NASA’s Hubble Space Telescope have produced new maps of Jupiter – the first in a series of annual portraits of the solar system’s outer planets.

Jupiter in 4k Ultra HD

Video above: This new portrait of Jupiter was produced from observations made using NASA’s Hubble Space Telescope. Video Credits: NASA/ESA/Goddard/UCBerkeley/JPL-Caltech/STScI.

Collecting these yearly images – essentially the planetary version of annual school picture days for children – will help current and future scientists see how these giant worlds change over time. The observations are designed to capture a broad range of features, including winds, clouds, storms and atmospheric chemistry.

Already, the Jupiter images have revealed a rare wave just north of the planet’s equator and a unique filamentary feature in the core of the Great Red Spot not seen previously.

“Every time we look at Jupiter, we get tantalizing hints that something really exciting is going on,” said Amy Simon, a planetary scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “This time is no exception.”

Simon and her colleagues produced two global maps of Jupiter from observations made using Hubble’s high-performance Wide Field Camera 3. The two maps represent nearly back-to-back rotations of the planet, making it possible to determine the speeds of Jupiter’s winds. The findings are described in an Astrophysical Journal paper, available online.

Image above: Jupiter at a glance. Image Credits: NASA, ESA, A. Simon (GSFC), M. Wong (UC Berkeley), and G. Orton (JPL-Caltech).

The new images confirm that the Great Red Spot continues to shrink and become more circular, as it has been doing for years. The long axis of this characteristic storm is about 150 miles (240 kilometers) shorter now than it was in 2014. Recently, the storm had been shrinking at a faster-than-usual rate, but the latest change is consistent with the long-term trend.

The Great Red Spot remains more orange than red these days, and its core, which typically has more intense color, is less distinct than it used to be. An unusual wispy filament is seen, spanning almost the entire width of the vortex. This filamentary streamer rotates and twists throughout the 10-hour span of the Great Red Spot image sequence, getting distorted by winds blowing at 330 miles per hour (150 meters per second) or even greater speeds.

In Jupiter’s North Equatorial Belt, the researchers found an elusive wave that had been spotted on the planet only once before, decades earlier, by Voyager 2. In those images, the wave is barely visible, and nothing like it was seen again, until the current wave was found traveling at about 16 degrees north latitude, in a region dotted with cyclones and anticyclones. Similar waves – called baroclinic waves – sometimes appear in Earth’s atmosphere where cyclones are forming.

(Click on the image for enlarge)

Image above: In Jupiter’s North Equatorial Belt, scientists spotted a rare wave that had been seen there only once before. It is similar to a wave that sometimes occurs in Earth’s atmosphere when cyclones are forming. This false-color close-up of Jupiter shows cyclones (arrows) and the wave (vertical lines). Image Credits: NASA/ESA/Goddard/UCBerkeley/JPL-Caltech/STScI.

“Until now, we thought the wave seen by Voyager 2 might have been a fluke,” said co-author Glenn Orton of NASA’s Jet Propulsion Laboratory in Pasadena, California. “As it turns out, it’s just rare!”

The wave may originate in a clear layer beneath the clouds, only becoming visible when it propagates up into the cloud deck, according to the researchers. That idea is supported by the spacing between the wave crests.

In addition to Jupiter, the researchers have observed Neptune and Uranus, and maps of those planets also will be placed in the public archive. Saturn will be added to the series later. Hubble will dedicate time each year to this special set of observations, called the Outer Planet Atmospheres Legacy program.

Image above: The movement of Jupiter’s clouds can be seen by comparing the first map to the second one. Zooming in on the Great Red Spot at blue (left) and red (right) wavelengths reveals a unique filamentary feature not previously seen. Image Credits: NASA/ESA/Goddard/UCBerkeley/JPL-Caltech/STScI.

“The long-term value of the Outer Planet Atmospheres Legacy program is really exciting,” said co-author Michael H. Wong of the University of California, Berkeley. “The collection of maps that we will build up over time will not only help scientists understand the atmospheres of our giant planets, but also the atmospheres of planets being discovered around other stars, and Earth’s atmosphere and oceans, too.”

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, in Washington.

To access the Outer Planet Atmospheres Legacy program images and data, visit: https://archive.stsci.edu/prepds/opal/

For images and more information about Hubble, visit: http://www.nasa.gov/hubble and http://hubblesite.org/ and http://www.spacetelescope.org/

Related multimedia is available at: http://svs.gsfc.nasa.gov/goto?12021

Images (mentioned), Video (mentioned), Text, Credits: NASA/Nancy Neal-Jones/Elizabeth Zubritsky/JPL/Preston Dyches/Space Telescope Science Institute/Ray Villard.

Best regards, Orbiter.ch

Worlds Apart

NASA - Cassini Mission to Saturn patch.

Oct. 13, 2015

Although Mimas and Pandora, shown here, both orbit Saturn, they are very different moons. Pandora, "small" by moon standards (50 miles or 81 kilometers across) is elongated and irregular in shape. Mimas (246 miles or 396 kilometers across), a "medium-sized" moon, formed into a sphere due to self-gravity imposed by its higher mass.

The shapes of moons can teach us much about their history. For example, one explanation for Pandora's elongated shape and low density is that it may have formed by gathering ring particles onto a dense core.

This view looks toward the unilluminated side of the rings from 0.26 degrees below the ring plane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on July 26, 2015.

The view was obtained at a distance of approximately 485,000 miles (781,000 kilometers) from Pandora. Image scale is 3 miles (5 kilometers) per pixel. Mimas is 904,000 miles (1.4 million kilometers) from the spacecraft in this image. The scale on Mimas is 5.4 miles (8.4 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 http://saturn.jpl.nasa.gov or http://www.nasa.gov/cassini . The Cassini imaging team homepage is at http://ciclops.org and http://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens

Image, Text, Credits: NASA/JPL-Caltech/Space Science Institute/Tony Greicius.

Greetings, Orbiter.ch

New Horizons Picks Up Styx

NASA - New Horizons Mission logo.

Oct. 9, 2015

NASA Spacecraft Observes Pluto’s Smallest Moon

New images from NASA’s New Horizons reveal the size and shape of Pluto’s smallest moon, Styx.

Styx – also the faintest of Pluto’s five moons – was discovered using the Hubble Space Telescope in 2012, when New Horizons was more than two-thirds into its voyage to Pluto. The Styx images downlinked on Oct. 5, 2015, were taken by the Long Range Reconnaissance Imager (LORRI) on July 13, approximately 12.5 hours before New Horizons’ closest approach to Pluto.

Image above: This Long Range Reconnaissance Imager (LORRI) composite image of Pluto’s smallest moon, Styx, was taken July 14, 2015, when the New Horizons spacecraft was 391,000 miles (631,000 kilometers) from the tiny moon. The image reveals a highly-elongated satellite, roughly 4.5 miles [7 kilometers] across in its longest dimension and 3 miles [5 kilometers] in its shortest dimension. For context, the orbits of Pluto’s moons are shown above. Image Credits: NASA/JHUAPL/SwRI.

At that time, the spacecraft was still 391,000 miles (631,000 kilometers) from Styx, making it difficult even for the powerful LORRI camera to see details on such a small moon. “Although it may not look like much, the new composite image of Styx reveals a highly-elongated satellite, roughly 4.5 miles [7 kilometers] across in its longest dimension and 3 miles [5 kilometers] in its shortest dimension,” said New Horizons Project Scientist Hal Weaver, of the Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland.

Styx’s measured brightness, combined with this new size estimate, suggest this tiny moon has a highly reflective, icy surface, similar to what was previously found for two of Pluto’s other small moons, Nix and Hydra.

New Horizons spacecraft on way to deep space. Image Credit: NASA

Using these new images, together with the many measurements of Styx’s brightness taken over several months during New Horizons’ approach to Pluto, the science team hopes to unravel more details about this small moon’s shape and rotational properties. “Ultimately, we hope to learn more about all four of Pluto’s small moons, to understand their similarities and differences, how they formed, and how they evolved,” says New Horizons Principal Investigator Alan Stern, of the Southwest Research Institute, Boulder, Colorado.

The New Horizons spacecraft is currently 3.1 billion miles (5 billion kilometers) from Earth, with all systems healthy and operating normally.

For more information about New Horizons, visit: http://www.nasa.gov/mission_pages/newhorizons/main/index.html

Images (mentioned), Text, Credits: NASA/Lillian Gipson.

Best regards, Orbiter.ch

Hubble Sees an Aging Star Wave Goodbye

NASA - Hubble Space Telescope patch.

Oct. 9, 2015

This planetary nebula is called PK 329-02.2 and is located in the constellation of Norma in the southern sky. It is also sometimes referred to as Menzel 2, or Mz 2, named after the astronomer Donald Menzel who discovered the nebula in 1922.

When stars that are around the mass of the sun reach their final stages of life, they shed their outer layers into space, which appear as glowing clouds of gas called planetary nebulae. The ejection of mass in stellar burnout is irregular and not symmetrical, so that planetary nebulae can have very complex shapes. In the case of Menzel 2 the nebula forms a winding blue cloud that perfectly aligns with two stars at its center. In 1999 astronomers discovered that the star at the upper right is in fact the central star of the nebula, and the star to the lower left is probably a true physical companion of the central star.

For tens of thousands of years the stellar core will be cocooned in spectacular clouds of gas and then, over a period of a few thousand years, the gas will fade away into the depths of the universe. The curving structure of Menzel 2 resembles a last goodbye before the star reaches its final stage of retirement as a white dwarf.

Hubble and the sunrise over Earth

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, in Washington.

For more information on the Hubble Space Telescope, visit:

http://www.nasa.gov/hubble

http://hubblesite.org/

http://www.spacetelescope.org/

Image, Video, Credits: ESA/Hubble & NASA, Acknowledgement: Serge Meunier/Text Credits: European Space Agency/NASA/Ashley Morrow.

Greetings, Orbiter.ch

New Horizons Finds Blue Skies and Water Ice on Pluto

NASA - New Horizons Mission logo.

Oct. 9, 2015

The first color images of Pluto’s atmospheric hazes, returned by NASA’s New Horizons spacecraft last week, reveal that the hazes are blue.

“Who would have expected a blue sky in the Kuiper Belt? It’s gorgeous,” said Alan Stern, New Horizons principal investigator from Southwest Research Institute (SwRI), Boulder, Colorado.

Image above: Pluto’s Blue Sky: Pluto’s haze layer shows its blue color in this picture taken by the New Horizons Ralph/Multispectral Visible Imaging Camera (MVIC). The high-altitude haze is thought to be similar in nature to that seen at Saturn’s moon Titan. The source of both hazes likely involves sunlight-initiated chemical reactions of nitrogen and methane, leading to relatively small, soot-like particles (called tholins) that grow as they settle toward the surface. This image was generated by software that combines information from blue, red and near-infrared images to replicate the color a human eye would perceive as closely as possible. Image Credits: NASA/JHUAPL/SwRI.

The haze particles themselves are likely gray or red, but the way they scatter blue light has gotten the attention of the New Horizons science team. “That striking blue tint tells us about the size and composition of the haze particles,” said science team researcher Carly Howett, also of SwRI. “A blue sky often results from scattering of sunlight by very small particles. On Earth, those particles are very tiny nitrogen molecules. On Pluto they appear to be larger — but still relatively small — soot-like particles we call tholins.”

Scientists believe the tholin particles form high in the atmosphere, where ultraviolet sunlight breaks apart and ionizes nitrogen and methane molecules and allows them to react with one another to form more and more complex negatively and positively charged ions. When they recombine, they form very complex macromolecules, a process first found to occur in the upper atmosphere of Saturn’s moon Titan. The more complex molecules continue to combine and grow until they become small particles; volatile gases condense and coat their surfaces with ice frost before they have time to fall through the atmosphere to the surface, where they add to Pluto’s red coloring.

In a second significant finding, New Horizons has detected numerous small, exposed regions of water ice on Pluto. The discovery was made from data collected by the Ralph spectral composition mapper on New Horizons.

Image above: Water Ice on Pluto: Regions with exposed water ice are highlighted in blue in this composite image from New Horizons' Ralph instrument, combining visible imagery from the Multispectral Visible Imaging Camera (MVIC) with infrared spectroscopy from the Linear Etalon Imaging Spectral Array (LEISA). The strongest signatures of water ice occur along Virgil Fossa, just west of Elliot crater on the left side of the inset image, and also in Viking Terra near the top of the frame. A major outcrop also occurs in Baré Montes towards the right of the image, along with numerous much smaller outcrops, mostly associated with impact craters and valleys between mountains. The scene is approximately 280 miles (450 kilometers) across. Note that all surface feature names are informal. Image Credits: NASA/JHUAPL/SwRI.

“Large expanses of Pluto don’t show exposed water ice,” said science team member Jason Cook, of SwRI, “because it’s apparently masked by other, more volatile ices across most of the planet. Understanding why water appears exactly where it does, and not in other places, is a challenge that we are digging into.”

A curious aspect of the detection is that the areas showing the most obvious water ice spectral signatures correspond to areas that are bright red in recently released color images. “I’m surprised that this water ice is so red,” says Silvia Protopapa, a science team member from the University of Maryland, College Park. “We don’t yet understand the relationship between water ice and the reddish tholin colorants on Pluto's surface.”

The New Horizons spacecraft is currently 3.1 billion miles (5 billion kilometers) from Earth, with all systems healthy and operating normally.

New Horizons is part of NASA’s New Frontiers Program, managed by the agency’s Marshall Space Flight Center in Huntsville, Alabama.  APL designed, built, and operates the New Horizons spacecraft and manages the mission for NASA’s Science Mission Directorate. SwRI leads the science mission, payload operations, and encounter science planning.

Related articles:

New Horizons Team Finds Haze, Flowing Ice on Pluto:
http://orbiterchspacenews.blogspot.ch/2015/07/new-horizons-team-finds-haze-flowing.html

Perplexing Pluto: New ‘Snakeskin’ Image and More from New Horizons:
http://orbiterchspacenews.blogspot.ch/2015/09/perplexing-pluto-new-snakeskin-image.html

For more information about New Horizons mission, visit: http://www.nasa.gov/mission_pages/newhorizons/main/index.html

Images (mentioned), Text, Credits: NASA/Lillian Gipson.

Cheers, Orbiter.ch

AAUSAT5 CubeSat starts its space mission

ISS - International Space Station logo / AAUSAT5 CubeSat logo.

9 October 2015

According to radio transmissions received by radio amateurs around the world, AAUSAT5 is alive and kicking! The student-built AAUSAT5 CubeSat was deployed from the International Space Station (ISS) on 5 October at 16:05 CET, together with ESA’s  technology demonstration CubeSat GomX-3. Both CubeSats have now started their mission in space.

The AAUSAT5 team has decoded the telemetry data received and have confirmed the good conditions of the satellite, including battery voltage and temperature.

AAUSAT5 deployment

CubeSats, small satellites having the size of a cube 10x10x10 (or multiples of it), are gaining increasing popularity in the space sector. They can be used as a cheaper and faster way – with respect to conventional satellites of bigger size and higher cost - to demonstrate the use of miniaturised technology in space for a number of applications. These include the new radio technology to be demonstrated by GomX-3, eventually aimed at supporting the identification of the positioning of civilian aircraft and measuring telecommunication satellite signal quality, and that of AAUSAT5, tracking ships at open sea using the Automatic Identification System (AIS).

ESA CubeSats deployed from the ISS

CubeSats are also an excellent way for university students to gain experience in the full life-cycle of a space project – from design to launch and operations – before they start their space professions. Since 2012 the ESA Education Office supports students across Europe in the development of CubeSats through the Fly Your Satellite! programme. ESA mentors the students of the selected CubeSat teams, facilitates the transfer of know-how from professional specialists to the students, offers access to test facilities, sponsors the students in the international travel needed for their CubeSat project, and provides launch opportunities. With AAUSAT5, ESA’s Education Office is inaugurating a new branch of the initiative: Fly Your Satellite from the ISS!

AAUSAT5 and GomX-3 are the first ESA CubeSat projects to be launched from the ISS.

For further information on ESA’s Fly Your Satellite! Programme contact:

Piero Galeone, ESA Head of Tertiary Education Unit
Email: Piero.galeone@esa.int

You can hear a radio signal recording from AAUSAT5 on Soundcloud:
https://soundcloud.com/esaops/2015-10-05-19-40-utc-pass-cut

More information:

Fly Your Satellite from the ISS programme: http://www.esa.int/Education/CubeSats_-_Fly_Your_Satellite/Fly_Your_Satellite_from_the_ISS_programme

AAUSAT5 CubeSat: http://www.esa.int/Education/CubeSats_-_Fly_Your_Satellite/AAUSAT5_CubeSat

AAUSAT5 mission: http://www.esa.int/Education/CubeSats_-_Fly_Your_Satellite/AAUSAT5_mission

Meet the team: AAUSAT5: http://www.esa.int/Education/CubeSats_-_Fly_Your_Satellite/Meet_the_team_AAUSAT5

Delivery to Houston: http://www.esa.int/Education/Student_satellite_wins_green_light_for_Station_deployment

Launch to the ISS: http://www.esa.int/Education/Student_satellite_soon_to_take_off_to_International_Space_Station

AAUSAT5 - Main/Home Page: http://www.space.aau.dk/aausat5/

Images, Text, Credits: ESA/NASA.

Greetings, Orbiter.ch