Planetary and Asteroid Studies

NASA-funded Study Explains Saturn’s Epic Tantrums

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This series of images from NASA’s Cassini spacecraft shows the development of a huge storm of the type that erupts about every 30 years on Saturn. Credit: NASA/JPL-Caltech/SSI

The long-standing mystery of why Saturn seethes with enormous storms every 30 years may have been solved by scientists working with data from NASA’s Cassini mission. The tempests, which can grow into bright bands that encircle the entire planet, are on a natural timer that is reset by each subsequent storm, the researchers report.

In 140 years of telescope observations, great storms have erupted on Saturn six times. Cassini and observers on Earth tracked the most recent of these storms from December 2010 to August 2011. During that time, the storm exploded through the clouds, eventually winding its way around Saturn.

In a paper published online today in the journal Nature Geoscience, scientists describe the effect they believe is responsible for the periodic outbursts. The basic idea is that water vapor is heavier than the hydrogen and helium that make up the bulk of Saturn’s atmosphere, so once each giant storm dumps its huge mass of rain, the air within the clouds is left lighter than the atmosphere below. For a time, this situation shuts off the process of convection — in which warm, moist air rises, and cool, dense air sinks — that creates new clouds and storms.

“For decades after one of these storms, the warm air in Saturn’s deep atmosphere is too wet, and too dense, to rise,” said Cheng Li, a graduate student at the California Institute of Technology in Pasadena, who led the study. “The air above has to cool off, radiating its heat to space, before its density is greater than that of the hot, wet air below. This cooling process takes about 30 years, and then come the storms.”

Li thinks the episodic nature of the storms indicates Saturn’s deep atmosphere contains more water, relative to the other atmospheric constituents, than Jupiter. The researchers suggest Saturn’s extra-wet interior might explain why the planet has such epic tantrums, whereas Jupiter does not. If Saturn’s deep atmosphere were drier, scientists would expect continuous, smaller storms, as observed on Jupiter, Li said. Instead, Saturn’s outbursts are episodic and quite explosive.

Other observations by ground and space-based telescopes have hinted at a wet interior for Saturn. “Previous studies using spectroscopy have shown that Saturn’s interior is enriched in methane and other volatiles, by two or three times, compared to Jupiter. From there, it’s a short leap to expect that Saturn is also rich in oxygen, which is also a volatile and a big part of every H2O molecule,” said Andrew Ingersoll, a member of the Cassini science team, also at Caltech, who co-authored the paper with Li. Volatiles are elements and chemical compounds that change from solid to liquid or gas at relatively low temperatures.

Scientists are interested in understanding the amount of oxygen and other volatile ingredients in Saturn and Jupiter. These ingredients provide important clues about the formation of the two planets — which are thought to have formed before all the others — and conditions in the early solar system.

The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. JPL, a division of Caltech, manages the mission for NASA’s Science Mission Directorate in Washington. 

For previous news and images related to Saturn’s giant storm:

For more information about Cassini, visit:


Dawn in Excellent Shape One Month After Ceres Arrival

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Artist’s concept of Dawn above Ceres around the time it was captured into orbit by the dwarf planet in early March. Since its arrival, the spacecraft turned around to point the blue glow of its ion engine in the opposite direction. Image credit: NASA/JPL

Since its capture by the gravity of dwarf planet Ceres on March 6, NASA’s Dawn spacecraft has performed flawlessly, continuing to thrust with its ion engine as planned. The thrust, combined with Ceres’ gravity, is gradually guiding the spacecraft into a circular orbit around the dwarf planet. All of the spacecraft’s systems and instruments are in excellent health.

Dawn has been following its planned trajectory on the dark side of Ceres — the side facing away from the sun — since early March. After it entered orbit, the spacecraft’s momentum carried it to a higher altitude, reaching a maximum of 46,800 miles (75,400 kilometers) on March 18. Today, Dawn is about 26,000 miles (42,000 kilometers) above Ceres, descending toward the first planned science orbit, which will be 8,400 miles (13,500 kilometers) above the surface.

The next optical navigation images of Ceres will be taken on April 10 and April 14, and are expected to be available online after initial analysis by the science team. In the first of these, the dwarf planet will appear as a thin crescent, much like the images taken on March 1, but with about 1.5 times higher resolution. The April 14 images will reveal a slightly larger crescent in even greater detail. Once Dawn settles into the first science orbit on April 23, the spacecraft will begin the intensive prime science campaign.

By early May, images will improve our view of the entire surface, including the mysterious bright spots that have captured the imaginations of scientists and space enthusiasts alike. What these reflections of sunlight represent is still unknown, but closer views should help determine their nature. The regions containing the bright spots will likely not be in view for the April 10 images; it is not yet certain whether they will be in view for the April 14 set.

On May 9, Dawn will complete its first Ceres science phase and begin to spiral down to a lower orbit to observe Ceres from a closer vantage point. 

Dawn previously explored the giant asteroid Vesta for 14 months, from 2011 to 2012, capturing detailed images and data about that body.

Dawn’s mission is managed by NASA’s Jet Propulsion Laboratory, Pasadena, California, for NASA’s Science Mission Directorate in Washington. Dawn is a project of the directorate’s Discovery Program, managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama. UCLA is responsible for overall Dawn mission science. Orbital ATK Inc., in Dulles, Virginia, designed and built the spacecraft.

The German Aerospace Center, Max Planck Institute for Solar System Research, Italian Space Agency and Italian National Astrophysical Institute are international partners on the mission team. For a complete list of mission participants, visit:

More details about Dawn’s trajectory are available at:

More information about Dawn is online at: 

NASA’s OSIRIS-REx Mission Passes Critical Milestone

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Artist concept of OSIRIS-REx, the first U.S. mission to return samples from an asteroid to Earth. Image Credit: NASA/Goddard

NASA’s groundbreaking science mission to retrieve a sample from an ancient space rock has moved closer to fruition. The Origins Spectral Interpretation Resource Identification Security Regolith Explorer (OSIRIS-REx) mission has passed a critical milestone in its path towards launch and is officially authorized to transition into its next phase.

Key Decision Point-D (KDP-D) occurs after the project has completed a series of independent reviews that cover the technical health, schedule and cost of the project. The milestone represents the official transition from the mission’s development stage to delivery of systems, testing and integration leading to launch. During this part of the mission’s life cycle, known as Phase D, the spacecraft bus, or the structure that will carry the science instruments, is completed, the instruments are integrated into the spacecraft and tested, and the spacecraft is shipped to NASA’s Kennedy Space Center in Florida for integration with the rocket.

“This is an exciting time for the OSIRIS-REx team,” said Dante Lauretta, principal investigator for OSIRIS-Rex at the University of Arizona, Tucson. “After almost four years of intense design efforts, we are now proceeding with the start of flight system assembly. I am grateful for the hard work and team effort required to get us to this point.”

OSIRIS-REx is the first U.S. mission to return samples from an asteroid to Earth. The spacecraft will travel to a near-Earth asteroid called Bennu and bring at least a 60-gram (2.1-ounce) sample back to Earth for study. OSIRIS-REx carries five instruments that will remotely evaluate the surface of Bennu. The mission will help scientists investigate the composition of the very early solar system and the source of organic materials and water that made their way to Earth, and improve understanding of asteroids that could impact our planet.

OSIRIS-REx is scheduled for launch in late 2016. The spacecraft will reach Bennu in 2018 and return a sample to Earth in 2023.

“The spacecraft structure has been integrated with the propellant tank and propulsion system and is ready to begin system integration in the Lockheed Martin highbay,” said Mike Donnelly, OSIRIS-REx project manager at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “The payload suite of cameras and sensors is well into its environmental test phase and will be delivered later this summer/fall.”

The key decision meeting was held at NASA Headquarters in Washington on March 30 and chaired by NASA’s Science Mission Directorate.

On March 27, assembly, launch and test operations officially began at Lockheed Martin in Denver. These operations represent a critical stage of the program  when the spacecraft begins to take form, culminating with its launch. Over the next several months, technicians will install the subsystems on the main spacecraft structure, comprising avionics, power, telecomm, thermal systems, and guidance, navigation and control.

The next major milestone is the Mission Operations Review, scheduled for completion in June. The project will demonstrate that its navigation, planning, commanding, and science operations requirements are complete.

The mission’s principal investigator is at the University of Arizona, Tucson. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, will provide overall mission management, systems engineering and safety and mission assurance for OSIRIS-REx. Lockheed Martin Space Systems in Denver will build the spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program. NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages New Frontiers for the agency’s Science Mission Directorate.

OSIRIS-REx complements NASA’s Asteroid Initiative, which aligns portions of the agency’s science, space technology and human exploration capabilities in a coordinated asteroid research effort. The initiative will conduct research and analysis to better characterize and mitigate the threat these space rocks pose to our home planet.

Included in the initiative is NASA’s Asteroid Redirect Mission (ARM), a robotic spacecraft mission that will capture a boulder from the surface of a near-Earth asteroid and move it into a stable orbit around the moon for exploration by astronauts, all in support of advancing the nation’s journey to Mars. The agency also is engaging new industrial capabilities, partnerships, open innovation and participatory exploration through the NASA Asteroid Initiative.

NASA also has made tremendous progress in the cataloging and characterization of near Earth objects over the past five years. The president’s NASA budget included, and Congress authorized, $20.4 million for an expanded NASA Near-Earth Object (NEO) Observations Program, increasing the resources for this critical program from the $4 million per year it had received since the 1990s. The program was again expanded in fiscal year 2014, with a budget of $40.5 million. NASA is asking Congress for $50 million for this important work in the 2016 budget.

NASA has identified more than 12,000 NEOs to date, including 96 percent of near-Earth asteroids larger than 0.6 miles (1 kilometer) in size. NASA has not detected any objects of this size that pose an impact hazard to Earth in the next 100 years. Smaller asteroids do pass near Earth, however, and some could pose an impact threat. In 2011, 893 near-Earth asteroids were found. In 2014, that number was increased to 1,472.

In addition to NASA’s ongoing work detecting and cataloging asteroids, the agency has engaged the public in the hunt for these space rocks through the agency’s Asteroid Grand Challenge activities, including prize competitions. During the recent South by Southwest Festival in Austin, Texas, the agency announced the release of a software application based on an algorithm created by a NASA challenge that has the potential to increase the number of new asteroid discoveries by amateur astronomers.

For more information about the OSIRIS-REx mission, visit:


For more information about the ARM and NASA’s Asteroid Initiative, visit:

NASA Releases Tool Enabling Citizen Scientists to Examine Asteroid Vesta

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Vesta Trek’s interface allows explorers to fly around and even skim the surface of Vesta. Image credit: NASA

NASA has announced the release of Vesta Trek, a free, web-based application that provides detailed visualizations of Vesta, one of the largest asteroids in our solar system. 

NASA’s Dawn spacecraft studied Vesta from July 2011 to September 2012. Data gathered from multiple instruments aboard Dawn have been compiled into Vesta Trek’s user-friendly set of tools, enabling citizen scientists and students to study the asteroid’s features. The application includes:

— Interactive maps, including the ability to overlay a growing range of data sets including topography, mineralogy, abundance of elements and geology, as well as analysis tools for measuring the diameters, heights and depths of surface features and more

— 3-D printer-exportable topography so users can print physical models of Vesta’s surface 

— Standard keyboard gaming controls to maneuver a first-person visualization of “flying” across the surface of the asteroid

Vesta Trek was developed by NASA’s Lunar Mapping and Modeling Project (LMMP), which provides mission planners, lunar scientists and the public with analysis and data visualization tools for our moon, spanning multiple instruments on multiple missions. Vesta Trek represents the first application of LMMP’s capabilities to another world beyond the moon. LMMP-based portals for other worlds in our Solar System are currently in development.

“There’s nothing like seeing something with your own eyes, but these types of detailed data-visualizations are the next best thing,” said Kristen Erickson, Director, Science Engagement and Partnerships at NASA Headquarters in Washington. “We’re thrilled to release Vesta Trek to the citizen science community and the public, not only as a scientific tool, but as a portal to an immersive experience that, just by the nature of it, will allow a deeper understanding of Vesta and asteroids in general.”

NASA’s Dawn spacecraft is continuing its exploration in the asteroid belt, after arriving at the dwarf planet Ceres on March 6. As Dawn conducts its mapping and measurements of Ceres, LMMP will continue to work closely with the Dawn mission.

The Lunar Mapping and Modeling Project is managed by NASA’s Solar System Exploration Research Virtual Institute, headquartered at NASA’s Ames Research Center in Moffett Field, California. LMMP’s development team is based at NASA’s Jet Propulsion Laboratory in Pasadena, California. JPL also manages the Dawn mission for NASA. LMMP is funded by and receives direction from the Planetary Science Division of NASA’s Science Mission Directorate and the Advanced Exploration Systems program in NASA’s Human Exploration and Operations Mission Directorate, at NASA Headquarters in Washington.

To explore Vesta Trek, visit:

For more information about the Dawn mission, visit:

To learn more about the Solar System Exploration Research Virtual Institute, visit:

Saturn Spacecraft Returns to the Realm of Icy Moons

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A dual view of Saturn’s icy moon Rhea marks the return of NASA’s Cassini spacecraft to the realm of the planet’s icy satellites. This follows nearly two years during which the spacecraft’s orbits carried it high above the planet’s poles. Those paths limited the mission’s ability to encounter the moons, apart from regular flybys of Titan.

Cassini’s orbit will remain nearly equatorial for the remainder of 2015, during which the spacecraft will have four close encounters with Titan, two with Dione and three with the geyser-moon, Enceladus.

The two views of Rhea were taken about an hour-and-a-half apart on Feb. 9, 2015, when Cassini was about 30,000 to 50,000 miles (50,000 to 80,000 kilometers) away from the moon. Cassini officially began its new set of equatorial orbits on March 16.

The views show an expanded range of colors from those visible to human eyes in order to highlight subtle color variations across Rhea’s surface. In natural color, the moon’s surface is fairly uniform. The image at right represents the highest-resolution color view of Rhea released to date.

The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA’s Jet Propulsion Laboratory in Pasadena, California, manages the mission for the agency’s Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena. The Cassini imaging operations center is based at the Space Science Institute in Boulder, Colorado.

More information about Cassini, visit:

NASA Spacecraft Detects Aurora and Mysterious Dust Cloud around Mars

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Artist’s conception of MAVEN’s Imaging UltraViolet Spectrograph (IUVS) observing the “Christmas Lights Aurora” on Mars. MAVEN observations show that aurora on Mars is similar to Earth’s “Northern Lights” but has a different origin. Image Credit: University of Colorado


NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft has observed two unexpected phenomena in the Martian atmosphere: an unexplained high-altitude dust cloud and aurora that reaches deep into the Martian atmosphere.

The presence of the dust at orbital altitudes from about 93 miles (150 kilometers) to 190 miles (300 kilometers) above the surface was not predicted. Although the source and composition of the dust are unknown, there is no hazard to MAVEN and other spacecraft orbiting Mars.

“If the dust originates from the atmosphere, this suggests we are missing some fundamental process in the Martian atmosphere,” said Laila Andersson of the University of Colorado’s Laboratory for Atmospherics and Space Physics (CU LASP), Boulder, Colorado.

The cloud was detected by the spacecraft’s Langmuir Probe and Waves (LPW) instrument, and has been present the whole time MAVEN has been in operation. It is unknown if the cloud is a temporary phenomenon or something long lasting. The cloud density is greatest at lower altitudes. However, even in the densest areas it is still very thin. So far, no indication of its presence has been seen in observations from any of the other MAVEN instruments.

Possible sources for the observed dust include dust wafted up from the atmosphere; dust coming from Phobos and Deimos, the two moons of Mars; dust moving in the solar wind away from the sun; or debris orbiting the sun from comets. However, no known process on Mars can explain the appearance of dust in the observed locations from any of these sources.

Map of MAVEN aurora on Mars

A map of IUVS’s auroral detections in December 2014 overlaid on Mars’ surface. The map shows that the aurora was widespread in the northern hemisphere, not tied to any geographic location. The aurora was detected in all observations during a 5-day period.

Image Credit: University of Colorado

MAVEN’s Imaging Ultraviolet Spectrograph (IUVS) observed what scientists have named “Christmas lights.” For five days just before Dec. 25, MAVEN saw a bright ultraviolet auroral glow spanning Mars’ northern hemisphere. Aurora, known on Earth as northern or southern lights, are caused by energetic particles like electrons crashing down into the atmosphere and causing the gas to glow.

“What’s especially surprising about the aurora we saw is how deep in the atmosphere it occurs – much deeper than at Earth or elsewhere on Mars,” said Arnaud Stiepen, IUVS team member at the University of Colorado. “The electrons producing it must be really energetic.”

The source of the energetic particles appears to be the sun. MAVEN’s Solar Energetic Particle instrument detected a huge surge in energetic electrons at the onset of the aurora. Billions of years ago, Mars lost a global protective magnetic field like Earth has, so solar particles can directly strike the atmosphere. The electrons producing the aurora have about 100 times more energy than you get from a spark of house current, so they can penetrate deeply in the atmosphere.

The findings are being presented at the 46th Lunar and Planetary Science Conference in The Woodlands, Texas.

MAVEN was launched to Mars on Nov. 18, 2013, to help solve the mystery of how the Red Planet lost most of its atmosphere and much of its water. The spacecraft arrived at Mars on Sept. 21, and is four months into its one-Earth-year primary mission.

“The MAVEN science instruments all are performing nominally, and the data coming out of the mission are excellent,” said Bruce Jakosky of CU LASP, Principal Investigator for the mission.

MAVEN is part of the agency’s Mars Exploration Program, which includes the Opportunity and Curiosity rovers, the Mars Odyssey and Mars Reconnaissance Orbiter spacecraft currently orbiting the planet.

NASA’s Mars Exploration Program seeks to characterize and understand Mars as a dynamic system, including its present and past environment, climate cycles, geology and biological potential. In parallel, NASA is developing the human spaceflight capabilities needed for its journey to Mars or a future round-trip mission to the Red Planet in the 2030’s.

MAVEN’s principal investigator is based at the University of Colorado’s Laboratory for Atmospheric and Space Physics, and NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the MAVEN project. Partner institutions include Lockheed Martin, the University of California at Berkeley, and NASA’s Jet Propulsion Laboratory.

For images related to the findings, visit:


New Desktop Application Has Potential to Increase Asteroid Detection, Now Available to Public

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NASA’s Asteroid Data Hunter contest series was part of NASA’s Asteroid Grand Challenge, which is focused on finding all asteroid threats to human populations and knowing what to do about them. (Image Credit: NASA)

PRESS RELEASE (NASA) – A software application based on an algorithm created by a NASA challenge has the potential to increase the number of new asteroid discoveries by amateur astronomers.

Analysis of images taken of our solar system’s main belt asteroids between Mars and Jupiter using the algorithm showed a 15 percent increase in positive identification of new asteroids.

During a panel Sunday at the South by Southwest Festival in Austin, Texas, NASA representatives discussed how citizen scientists have made a difference in asteroid hunting. They also announced the release of a desktop software application developed by NASA in partnership with Planetary Resources, Inc., of Redmond, Washington. The application is based on an Asteroid Data Hunter-derived algorithm that analyzes images for potential asteroids. It’s a tool that can be used by amateur astronomers and citizen scientists.

The Asteroid Data Hunter challenge was part of NASA’s Asteroid Grand Challenge. The data hunter contest series, which was conducted in partnership with Planetary Resources under a Space Act Agreement, was announced at the 2014 South by Southwest Festival and concluded in December. The series offered a total of $55,000 in awards for participants to develop significantly improved algorithms to identify asteroids in images captured by ground-based telescopes. The winning solutions of each piece of the contest combined to create an application using the best algorithm that increased the detection sensitivity, minimized the number of false positives, ignored imperfections in the data, and ran effectively on all computer systems.

“The Asteroid Grand Challenge is seeking non-traditional partnerships to bring the citizen science and space enthusiast community into NASA’s work,” said Jason Kessler, program executive for NASA’s Asteroid Grand Challenge. “The Asteroid Data Hunter challenge has been successful beyond our hopes, creating something that makes a tangible difference to asteroid hunting astronomers and highlights the possibility for more people to play a role in protecting our planet.”

Catalina Sky Survey telescope

The Big Dipper rising behind the Catalina Sky Survey 60″ telescope. 

Image Credit: Catalina Sky Survey, University of Arizona

The data hunter challenge incorporated data provided by the Minor Planet Center (MPC), at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, and images provided by the Catalina Sky Survey, an astronomical survey project run by the University of Arizona, Tucson, and focused on the discovery and study of near-Earth asteroids and comets.

“We applaud all the participants in the Asteroid Data Hunter challenge. We are extremely encouraged by the algorithm created and it’s already making a difference. This increase in knowledge will help assess more quickly which asteroids are potential threats, human destinations or resource rich,” said Chris Lewicki, president and chief engineer at Planetary Resources. “It has been exciting for our team to work with NASA on this project, and we also look forward to future space-based systems leveraging these results.”

Astronomers find asteroids by taking images of the same place in the sky and looking for star-like objects that move between frames, an approach that has been used since before Pluto was discovered in 1930. With more telescopes scanning the sky, the ever-increasing volume of data makes it impossible for astronomers to verify each detection by hand. This new algorithm gives astronomers the ability to use computers to autonomously and rapidly check the images and determine which objects are suitable for follow up, which leads to finding more asteroids than previously possible.

“The beauty of such archives is that the data doesn’t grow stale, and with novel approaches, techniques and algorithms, they can be harvested for new information. The participants of the Asteroid Data Hunter challenge did just that, probing observations of the night sky for new asteroids that might have slipped through the software cracks the first time the images were analyzed,” said Jose Luis Galache of the MPC. “Moreover, this software can now be used to analyze new images and is available to any observer who wants to use it. The Minor Planet Center applauds these efforts to provide superior tools to all, and looks forward to receiving new asteroid observations generated with them.”

The desktop software application is free and can be used on any basic desktop or laptop computer. Amateur astronomers may take images from their telescopes and analyze them with the application. The application will tell the user whether a matching asteroid record exists and offer a way to report new findings to the Minor Planet Center, which then confirms and archives new discoveries.

Through NASA’s asteroid initiative, the agency seeks to enhance its ongoing work in the identification and characterization of near-Earth objects for further scientific investigation. This work includes locating potentially hazardous asteroids and identifying those viable for redirection to a stable lunar orbit for future exploration by astronauts using NASA’s Space Launch System rocket and Orion spacecraft. The Asteroid Grand Challenge, one part of the asteroid initiative, expands the agency’s efforts beyond traditional boundaries and encourages partnerships and collaboration with a variety of organizations.

The algorithm contests were managed and executed by NASA’s Center of Excellence for Collaborative Innovation (CoECI). CoECI was established at the request of the White House Office of Science and Technology Policy to advance NASA’s open innovation efforts and extend that expertise to other federal agencies. CoECI uses the NASA Tournament Lab (NTL) for its advanced algorithmic and software development contests. Through its contract with the Crowd Innovation Lab at Harvard University, NTL uses Appirio’s Crowdsourcing platform powered by Topcoder to enable a community of more than 750,000 designers, developers and data scientists to create the most innovative, efficient and optimized solutions for specific, real-world challenges faced by NASA. Data storage of the Catalina Sky Survey data was provided by Amazon Web Services.

The new asteroid hunting application can be downloaded at:

For information about NASA’s Asteroid Grand Challenge, visit:

NASA Spacecraft Becomes First to Orbit a Dwarf Planet

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NASA Spacecraft Becomes First to Orbit a Dwarf Planet

Latest News From NASA’s Jet Propulsion Laboratory

NASA’s Dawn spacecraft has become the first mission to achieve orbit around a dwarf planet. The spacecraft was approximately 38,000 miles (61,000) kilometers from Ceres when it was captured by the dwarf planet’s gravity at about 4:39 a.m. PST (7:39 a.m. EST) Friday.Mission controllers at NASA’s Jet Propulsion Laboratory in Pasadena, California received a signal from the spacecraft at 5:36 a.m. PST (8:36 a.m. EST) that Dawn was healthy and thrusting with its ion engine, the indicator Dawn had entered orbit as planned.

“Since its discovery in 1801, Ceres was known as a planet, then an asteroid and later a dwarf planet,” said Marc Rayman, Dawn chief engineer and mission director at JPL. “Now, after a journey of 3.1 billion miles (4.9 billion kilometers) and 7.5 years, Dawn calls Ceres, home.”

In addition to being the first spacecraft to visit a dwarf planet, Dawn also has the distinction of being the first mission to orbit two extraterrestrial targets. From 2011 to 2012, the space-craft explored the giant asteroid Vesta, delivering new insights and thousands of images from that distant world. Ceres and Vesta are the two most massive residents of our solar system’s main asteroid belt between Mars and Jupiter.

The most recent images received from the spacecraft, taken on March 1, show Ceres as a crescent, mostly in shadow because the spacecraft’s trajectory put it on a side of Ceres that faces away from the sun until mid-April. When Dawn emerges from Ceres’ dark side, it will deliver ever-sharper images as it spirals to lower orbits around the planet.

“We feel exhilarated,” said Chris Russell, principal investigator of the Dawn mission at the University of California, Los Angeles (UCLA). “We have much to do over the next year and a half, but we are now on station with ample reserves, and a robust plan to obtain our science objectives.”

Dawn’s mission is managed by JPL for NASA’s Science Mission Directorate in Washington. Dawn is a project of the directorate’s Discovery Program, managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama. UCLA is responsible for overall Dawn mission science. Orbital ATK Inc., in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, Max Planck Institute for Solar System Research, Italian Space Agency and Italian National Astrophysical Institute are international partners on the mission team.

For a complete list of mission participants, visit:

For more information about Dawn, visit:


NASA’s New Horizons Spacecraft Begins First Stages of Pluto Encounter

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PRESS RELEASE (NASA/JPL) – NASA’s New Horizons spacecraft recently began its long-awaited, historic encounter with Pluto. The spacecraft is entering the first of several approach phases that culminate July 14 with the first close-up flyby of the dwarf planet, 4.67 billion miles (7.5 billion kilometers) from Earth.

“NASA first mission to distant Pluto will also be humankind’s first close up view of this cold, unexplored world in our solar system,” said Jim Green, director of NASA’s Planetary Science Division at the agency’s Headquarters in Washington. “The New Horizons team worked very hard to prepare for this first phase, and they did it flawlessly.”

NASA’s New Horizons is the first mission to Pluto and the Kuiper Belt of icy, rocky mini-worlds on the solar system’s outer frontier. This animation follows the New Horizons spacecraft as it leaves Earth after its January 2006 launch, through a gravity-assist flyby of Jupiter in February 2007, to the encounter with Pluto and its moons in summer 2015. (Image Credit: NASA/JHUAPL)

The fastest spacecraft when it was launched, New Horizons lifted off in January 2006. It awoke from its final hibernation period last month after a voyage of more than 3 billion miles, and will soon pass close to Pluto, inside the orbits of its five known moons. In preparation for the close encounter, the mission’s science, engineering and spacecraft operations teams configured the piano-sized probe for distant observations of the Pluto system that start Sunday, Jan. 25 with a long-range photo shoot.

The images captured by New Horizons’ telescopic Long-Range Reconnaissance Imager (LORRI) will give mission scientists a continually improving look at the dynamics of Pluto’s moons. The images also will play a critical role in navigating the spacecraft as it covers the remaining 135 million miles (220 million kilometers) to Pluto.

“We’ve completed the longest journey any spacecraft has flown from Earth to reach its primary target, and we are ready to begin exploring,” said Alan Stern, New Horizons principal investigator from Southwest Research Institute in Boulder, Colorado.

LORRI will take hundreds of pictures of Pluto over the next few

Timeline of the approach and departure phases — surrounding close approach on July 14, 2015 — of the New Horizons Pluto encounter. Image Credit: NASA/JHU APL/SwRI
Timeline of the approach and departure phases — surrounding close approach on July 14, 2015 — of the New Horizons Pluto encounter.
Image Credit: NASA/JHU APL/SwRI

months to refine current estimates of the distance between the spacecraft and the dwarf planet. Though the Pluto system will resemble little more than bright dots in the camera’s view until May, mission navigators will use the data to design course-correction maneuvers to aim the spacecraft toward its target point this summer. The first such maneuver could occur as early as March.

“We need to refine our knowledge of where Pluto will be when New Horizons flies past it,” said Mark Holdridge, New Horizons encounter mission manager at Johns Hopkins University’s Applied Physics Laboratory (APL) in Laurel, Maryland. “The flyby timing also has to be exact, because the computer commands that will orient the spacecraft and point the science instruments are based on precisely knowing the time we pass Pluto – which these images will help us determine.”

The “optical navigation” campaign that begins this month marks the first time pictures from New Horizons will be used to help pinpoint Pluto’s location.

Throughout the first approach phase, which runs until spring, New Horizons will conduct a significant amount of additional science. Spacecraft instruments will gather continuous data on the interplanetary environment where the planetary system orbits, including measurements of the high-energy particles streaming from the sun and dust-particle concentrations in the inner reaches of the Kuiper Belt. In addition to Pluto, this area, the unexplored outer region of the solar system, potentially includes thousands of similar icy, rocky small planets.

More intensive studies of Pluto begin in the spring, when the cameras and spectrometers aboard New Horizons will be able to provide image resolutions higher than the most powerful telescopes on Earth. Eventually, the spacecraft will obtain images good enough to map Pluto and its moons more accurately than achieved by previous planetary reconnaissance missions.

APL manages the New Horizons mission for NASA’s Science Mission Directorate in Washington. Alan Stern, of the Southwest Research Institute (SwRI), headquartered in San Antonio, is the principal investigator and leads the mission. SwRI leads the science team, payload operations, and encounter science planning. New Horizons is part of the New Frontiers Program managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama. APL designed, built and operates the spacecraft.

For more information about the New Horizons mission, visit:
NASA’s New Horizon’s Webpage

NASA’s Pluto–Kuiper Belt Mission Webpage

Dwayne Brown
Headquarters, Washington

Michael Buckley
Johns Hopkins University Applied Physics Laboratory, Laurel, Md.

Maria Stothoff
Southwest Research Institute, San Antonio

Dawn Spacecraft Begins Approach to Dwarf Planet Ceres

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• Dawn has entered its approach phase toward Ceres
• The spacecraft will arrive at Ceres on March 6, 2015

PRESS RELEASE (NASA/JPL) – NASA’s Dawn spacecraft has entered an approach phase in which it will continue to close in on Ceres, a Texas-sized dwarf planet never before visited by a spacecraft. Dawn launched in 2007 and is scheduled to enter Ceres orbit in March 2015.

Dawn recently emerged from solar conjunction, in which the spacecraft is on the opposite side of the sun, limiting communication with antennas on Earth. Now that Dawn can reliably communicate with Earth again, mission controllers have programmed the maneuvers necessary for the next stage of the rendezvous, which they label the Ceres approach phase. Dawn is currently 400,000 miles (640,000 kilometers) from Ceres, approaching it at around 450 miles per hour (725 kilometers per hour).

The spacecraft’s arrival at Ceres will mark the first time that a spacecraft has ever orbited two solar system targets. Dawn previously explored the protoplanet Vesta for 14 months, from 2011 to 2012, capturing detailed images and data about that body.

“Ceres is almost a complete mystery to us,” said Christopher Russell, principal investigator for the Dawn mission, based at the University of California, Los Angeles. “Ceres, unlike Vesta, has no meteorites linked to it to help reveal its secrets. All we can predict with confidence is that we will be surprised.”

The two planetary bodies are thought to be different in a few important ways. Ceres may have formed later than Vesta, and with a cooler interior. Current evidence suggests that Vesta only retained a small amount of water because it formed earlier, when radioactive material was more abundant, which would have produced more heat. Ceres, in contrast, has a thick ice mantle and may even have an ocean beneath its icy crust.

Ceres, with an average diameter of 590 miles (950 kilometers), is also the largest body in the asteroid belt, the strip of solar system real estate between Mars and Jupiter. By comparison, Vesta has an average diameter of 326 miles (525 kilometers), and is the second most massive body in the belt.

The spacecraft uses ion propulsion to traverse space far more efficiently than if it used chemical propulsion. In an ion propulsion engine, an electrical charge is applied to xenon gas, and charged metal grids accelerate the xenon particles out of the thruster. These particles push back on the thruster as they exit, creating a reaction force that propels the spacecraft. Dawn has now completed five years of accumulated thrust time, far more than any other spacecraft.

“Orbiting both Vesta and Ceres would be truly impossible with conventional propulsion. Thanks to ion propulsion, we’re about to make history as the first spaceship ever to orbit two unexplored alien worlds,” said Marc Rayman, Dawn’s chief engineer and mission director, based at NASA’s Jet Propulsion Laboratory in Pasadena, California.

The next couple of months promise continually improving views of Ceres, prior to Dawn’s arrival. By the end of January, the spacecraft’s images and other data will be the best ever taken of the dwarf planet.

The Dawn mission to Vesta and Ceres is managed by JPL, a division of the California Institute of Technology in Pasadena, for NASA’s Science Mission Directorate, Washington. UCLA is responsible for overall Dawn mission science.

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Elizabeth Landau
Jet Propulsion Laboratory, Pasadena, Calif.