OrbitalHub

Wikipedia dixit:

“The Cassini–Huygens (commonly called Cassini) mission was a collaboration between NASA, the European Space Agency (ESA), and the Italian Space Agency (ASI) to send a probe to study the planet Saturn and its system, including its rings and natural satellites. The Flagship-class unmanned robotic spacecraft comprised both NASA’s Cassini probe, and ESA’s Huygens lander which would be landed on Saturn’s largest moon, Titan. Cassini was the fourth space probe to visit Saturn and the first to enter its orbit. The craft were named after astronomers Giovanni Cassini and Christiaan Huygens.

Launched aboard a Titan IVB/Centaur on October 15, 1997, Cassini was active in space for more than 19 years, with 13 years spent orbiting Saturn, studying the planet and its system after entering orbit on July 1, 2004. The voyage to Saturn included flybys of Venus (April 1998 and July 1999), Earth (August 1999), the asteroid 2685 Masursky, and Jupiter (December 2000). Its mission ended on September 15, 2017, when Cassini was commanded to fly into Saturn’s upper atmosphere and burn up in order to prevent any risk of contaminating Saturn’s moons, which may offer habitable environments to stowaway terrestrial microbes on the spacecraft. (At that point Cassini lacked sufficient impulse to leave the Saturn system, so it could only be left in orbit, where it might collide with a moon, or be destroyed.) The mission is widely perceived to have been successful beyond expectation. Cassini-Huygens has been described by NASA’s Planetary Science Division Director as a “mission of firsts”, that has revolutionized human understanding of the Saturn system, including its moons and rings, and our understanding of where life might be found in the Solar System.

Cassini’s original mission was planned to last for four years, from June 2004 to May 2008. The mission was extended for another two years until September 2010, branded the Cassini Equinox Mission. The mission was extended a second and final time with the Cassini Solstice Mission, lasting another seven years until September 15, 2017, on which date Cassini was de-orbited to burn up in Saturn’s upper atmosphere.

The Huygens module traveled with Cassini until its separation from the probe on December 25, 2004; it was successfully landed by parachute on Titan on January 14, 2005. It successfully returned data to Earth for around 90 minutes, using the orbiter as a relay. This was the first landing ever accomplished in the outer Solar System and the first landing on a moon other than our own. Cassini continued to study the Saturn system in the following years.

At the end of its mission, the Cassini spacecraft executed the “Grand Finale” of its mission: a number of risky passes through the gaps between Saturn and Saturn’s inner rings. The purpose of this phase was to maximize Cassini’s scientific outcome before the spacecraft was destroyed. The atmospheric entry of Cassini effectively ended the mission.”

Video credit: NASA

NASA dixit:

“The SpaceX/Dragon cargo craft departed the International Space Station September 17, one month after delivering more than three tons of supplies and scientific experiments for the station’s residents. Expedition 53 Flight Engineer Paolo Nespoli of the European Space Agency and station Commander Randy Bresnik used the Canadarm2 robotic arm to release Dragon after it was detached from the Earth-facing port of the Harmony module. Dragon was scheduled to move to a safe distance away from the station for its engine to conduct a deorbit burn, enabling it to drop out of orbit for a parachute-assisted splashdown in the Pacific southwest of Long Beach, California. Dragon was launched on a SpaceX Falcon 9 rocket from the Kennedy Space Center on August 14, arriving at the orbital outpost August 16.”

Video credit: NASA

NASA dixit:

“After launching in their Soyuz MS-06 spacecraft from the Baikonur Cosmodrome in Kazakhstan, Expedition 53-54 Soyuz Commander Alexander Misurkin of Roscosmos and flight engineers Mark Vande Hei and Joe Acaba of NASA arrived at the International Space Station. The trio docked their Soyuz to the Poisk module on the Russian segment of the complex, to complete their six-hour journey to the station.”

Video credit: Roscosmos / NASA

NASA dixit:

“NASA’s Cassini spacecraft has explored the Saturn system since 2004, re-writing our understanding of the giant planet, its rings, moons and magnetosphere. For 13 years the spacecraft’s incredible, truly otherworldly images have revealed the wonder of Saturn in surprising, often awe-inspiring ways. Cassini is planetary exploration at its finest, proving that to truly reveal the grandeur of a world, there is no substitute for actually going there.”

Video credit: NASA Jet Propulsion Laboratory

NASA dixit:

“NASA’s Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) mission has released its third year of survey data, with the spacecraft discovering 97 previously unknown celestial objects in the last year. Of those, 28 were near-Earth objects, 64 were main belt asteroids and five were comets. The spacecraft has now characterized a total of 693 near-Earth objects since the mission was re-started in December 2013. Of these, 114 are new. The NEOWISE team has released an animation depicting this solar system survey’s discoveries and characterizations for its third year of operations.

“NEOWISE is not only discovering previously uncharted asteroids and comets, but it is providing excellent data on many of those already in our catalog,” said Amy Mainzer, NEOWISE principal investigator from NASA’s Jet Propulsion Laboratory in Pasadena, California. “It is also proving to be an invaluable tool in in the refining and perfecting of techniques for near-Earth object discovery and characterization by a space-based infrared observatory.”

Near-Earth objects (NEOs) are comets and asteroids that have been nudged by the gravitational attraction of the planets in our solar system into orbits that allow them to enter Earth’s neighborhood. Ten of the objects discovered by NEOWISE in the past year have been classified as potentially hazardous asteroids, based on their size and their orbits. More than 2.6 million infrared images of the sky were collected in the third year of operations by NEOWISE. These data are combined with the Year 1 and 2 NEOWISE data into a single archive that contains approximately 7.7 million sets of images and a database of more than 57.7 billion source detections extracted from those images. The NEOWISE images also contain glimpses of rare objects, like comet C/2010 L5 WISE. A new technique of modeling comet behavior called tail-fitting showed that this particular comet experienced a brief outburst as it swept through the inner-solar system.

“Comets that have abrupt outbursts are not commonly found, but this may be due more to the sudden nature of the activity rather than their inherent rarity,” said Emily Kramer, a NASA Postdoctoral Program Fellow at JPL and lead author of paper on the NEOWISE study. “It is great for astronomers to view and collect cometary data when they find an outburst, but since the activity is so short-lived, we may simply miss them most of the time.”

The tail-fitting technique identifies the size and quantity of dust particles in the vicinity of the comet, and when they were ejected from the comet’s nucleus, revealing the history of the comet’s activity. With tail-fitting, future all-sky surveys may be able to find and collect data on more cometary outburst activity when it happens. A paper detailing the tail-fitting technique and other results of the study was published in the March 20 volume of the Astrophysical Journal.

Originally called the Wide-field Infrared Survey Explorer (WISE), the spacecraft was launched in December 2009. It was placed in hibernation in 2011 after its primary astrophysics mission was completed. In September 2013, it was reactivated, renamed NEOWISE and assigned a new mission: to assist NASA’s efforts to identify the population of potentially hazardous near-Earth objects. NEOWISE also is characterizing more distant populations of asteroids and comets to provide information about their sizes and compositions.

NASA’s Jet Propulsion Laboratory in Pasadena, California, manages the NEOWISE mission for NASA’s Planetary Defense Coordination Office within the Science Mission Directorate in Washington. The Space Dynamics Laboratory in Logan, Utah, built the science instrument. Ball Aerospace & Technologies Corp. of Boulder, Colorado, built the spacecraft. Science operations and data processing take place at the Infrared Processing and Analysis Center at Caltech in Pasadena. Caltech manages JPL for NASA.”

Video credit: NASA Jet Propulsion Laboratory

NASA dixit:

“Scientists using data from NASA’s Lunar Reconnaissance Orbiter, or LRO, have identified bright areas in craters near the moon’s south pole that are cold enough to have frost present on the surface. The new evidence comes from an analysis that combined surface temperatures with information about how much light is reflected off the moon’s surface.

“We found that the coldest places near the moon’s south pole are also the brightest places—brighter than we would expect from soil alone—and that might indicate the presence of surface frost,” said Elizabeth Fisher, the lead author of the study, published in Icarus. Fisher carried out the data analysis while doing research at the University of Hawai‘i at Manoa after earning her undergraduate degree. She is now a graduate student at Brown University.

The icy deposits appear to be patchy and thin, and it’s possible that they are mixed in with the surface layer of soil, dust and small rocks called the regolith. The researchers say they are not seeing expanses of ice similar to a frozen pond or skating rink. Instead, they are seeing signs of surface frost. The frost was found in cold traps close to the moon’s south pole. Cold traps are permanently dark areas—located either on the floor of a deep crater or along a section of crater wall that doesn’t receive direct sunlight—where temperatures remain below minus 260 degrees Fahrenheit (minus 163 degrees Celsius). Under these conditions, water ice can persist for millions or billions of years.

More than a half-century ago, scientists suggested that lunar cold traps could store water ice, but confirming that hypothesis turned out to be challenging. Observations made by NASA’s Lunar Prospector orbiter in the late 1990s identified hydrogen-rich areas near the moon’s poles but could not determine whether that hydrogen was bound up in water or was present in some other form. Understanding the nature of these deposits has been one of the driving goals of LRO, which has been orbiting the moon since 2009.

Fisher and her colleagues found evidence of lunar frost by comparing temperature readings from LRO’s Diviner instrument with brightness measurements from the spacecraft’s Lunar Orbiter Laser Altimeter, or LOLA. In these comparisons, the coldest areas near the south pole also were very bright, indicating the presence of ice or other highly reflective materials. The researchers looked at the peak surface temperatures, because water ice won’t last if the temperature creeps above the crucial threshold.”

Video credit: NASA Goddard