OrbitalHub

NASA dixit:

“May 16, 2013. The craters of Tethys tell the story of a violent history marked by impacts. The names of the craters also tell oft-violent stories: in this case, the Iliad and the Odyssey. Here, we see the craters Melanthius (near the center, at the day/night terminator), Dolius (above Melanthius), and Penelope (upper left almost over the limb). Penelope was the faithful and wise wife of the Greek hero Odysseus, Dolius was their loyal gardener, and Melanthius was Dolius’ son.

This view looks toward the leading side of Tethys. North on Tethys is up and rotated 32 degrees to the right. The image was taken in visible light with the Cassini spacecraft narrow-angle camera. The view was obtained at a distance of approximately 684,000 miles (1.1 million kilometers) from Tethys and at a Sun-Tethys-spacecraft, or phase, angle of 63 degrees. Image scale is 4 miles (7 kilometers) per pixel. The image has been zoomed in by a factor of 1.5.”

“After almost 20 years in space, NASA’s Cassini spacecraft begins the final chapter of its remarkable story of exploration: its Grand Finale. Between April and September 2017, Cassini will undertake a daring set of orbits that is, in many ways, like a whole new mission. Following a final close flyby of Saturn’s moon Titan, Cassini will leap over the planet’s icy rings and begin a series of 22 weekly dives between the planet and the rings.

No other mission has ever explored this unique region. What we learn from these final orbits will help to improve our understanding of how giant planets – and planetary systems everywhere – form and evolve.

On the final orbit, Cassini will plunge into Saturn’s atmosphere, sending back new and unique science to the very end. After losing contact with Earth, the spacecraft will burn up like a meteor, becoming part of the planet itself.

Cassini’s Grand Finale is about so much more than the spacecraft’s final dive into Saturn. That dramatic event is the capstone of six months of daring exploration and scientific discovery. And those six months are the thrilling final chapter in a historic 20-year journey.”

Image credit: NASA

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

NASA dixit:

“March 9, 2013. On its fourth and final targeted flyby of Rhea, the Cassini spacecraft provided this stunning view of the ancient and heavily cratered surface. Billions of years of impacts have sculpted Rhea’s surface into the form we see today. With a diameter of 949 miles (1,528 kilometers) Rhea is Saturn’s second-largest moon.

This view is centered on terrain at 33 degrees north latitude, 358 degrees west longitude. The image was taken in visible light with the Cassini spacecraft narrow-angle camera. The view was acquired at a distance of approximately 2,280 miles (3,670 kilometers) from Rhea and at a Sun-Rhea-spacecraft, or phase, angle of 92 degrees. Image scale is 72 feet (22 meters) per pixel.”

“After almost 20 years in space, NASA’s Cassini spacecraft begins the final chapter of its remarkable story of exploration: its Grand Finale. Between April and September 2017, Cassini will undertake a daring set of orbits that is, in many ways, like a whole new mission. Following a final close flyby of Saturn’s moon Titan, Cassini will leap over the planet’s icy rings and begin a series of 22 weekly dives between the planet and the rings.

No other mission has ever explored this unique region. What we learn from these final orbits will help to improve our understanding of how giant planets – and planetary systems everywhere – form and evolve.

On the final orbit, Cassini will plunge into Saturn’s atmosphere, sending back new and unique science to the very end. After losing contact with Earth, the spacecraft will burn up like a meteor, becoming part of the planet itself.

Cassini’s Grand Finale is about so much more than the spacecraft’s final dive into Saturn. That dramatic event is the capstone of six months of daring exploration and scientific discovery. And those six months are the thrilling final chapter in a historic 20-year journey.”

Image credit: NASA

NASA dixit:

“Our Cold War history is now offering scientists a chance to better understand the complex space system that surrounds us. Space weather — which can include changes in Earth’s magnetic environment — are usually triggered by the sun’s activity, but recently declassified data on high-altitude nuclear explosion tests have provided a new look at the mechanisms that set off perturbations in that magnetic system. Such information can help support NASA’s efforts to protect satellites and astronauts from the natural radiation inherent in space.”

Video credit: NASA Goddard

NASA dixit:

“This image was taken on March 09, 2013, and received on Earth March 10, 2013, by NASA’s Cassini spacecraft. The camera was pointing toward Rhea at approximately 39,072 miles (62,880 kilometers) away, and the image was taken using the CL1 and CL2 filters.”

“After almost 20 years in space, NASA’s Cassini spacecraft begins the final chapter of its remarkable story of exploration: its Grand Finale. Between April and September 2017, Cassini will undertake a daring set of orbits that is, in many ways, like a whole new mission. Following a final close flyby of Saturn’s moon Titan, Cassini will leap over the planet’s icy rings and begin a series of 22 weekly dives between the planet and the rings.

No other mission has ever explored this unique region. What we learn from these final orbits will help to improve our understanding of how giant planets – and planetary systems everywhere – form and evolve.

On the final orbit, Cassini will plunge into Saturn’s atmosphere, sending back new and unique science to the very end. After losing contact with Earth, the spacecraft will burn up like a meteor, becoming part of the planet itself.

Cassini’s Grand Finale is about so much more than the spacecraft’s final dive into Saturn. That dramatic event is the capstone of six months of daring exploration and scientific discovery. And those six months are the thrilling final chapter in a historic 20-year journey.”

Image credit: NASA

NASA dixit:

“No planet is better studied than the one we actually live on. NASA’s fleet of Earth observing spacecraft, supported by aircraft, ships and ground observations, measure aspects of the environment that touch the lives of every person around the world. They study everything from the air we breathe, to rain and snow that provide water for agriculture and communities, to natural disasters such as droughts and floods, to the oceans, which cover 70 percent of Earth’s surface and provide food for many people around the world. Satellites and instruments on the International Space Station circle the whole globe, seeing both where people live and those remote parts of deserts, mountains and the vast oceans that are difficult if not impossible to visit. With instruments in space, scientists can get data for the whole globe in detail that they can’t get anywhere else. This visualization shows the NASA fleet in 2017, from low Earth orbit all the way out to the DSCOVR satellite taking in the million-mile view.”

Music credit: The Glide, by Zubin Thakkar [SOCAN]

Video credit: NASA Goddard