Category Archives: NASA

Two New Moons?

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Could the data from the Voyager spacecraft still be providing discoveries?  Yes indeed!

Credits: NASA/Erich Karkoschka (Univ. Arizona)

From NASA:

NASA’s Voyager 2 spacecraft flew by Uranus 30 years ago, but researchers are still making discoveries from the data it gathered then. A new study led by University of Idaho researchers suggests there could be two tiny, previously undiscovered moonlets orbiting near two of the planet’s rings.

Rob Chancia, a University of Idaho doctoral student, spotted key patterns in the rings while examining decades-old images of Uranus’ icy rings taken by Voyager 2 in 1986. He noticed the amount of ring material on the edge of the alpha ring — one of the brightest of Uranus’ multiple rings — varied periodically. A similar, even more promising pattern occurred in the same part of the neighboring beta ring.

“When you look at this pattern in different places around the ring, the wavelength is different — that points to something changing as you go around the ring. There’s something breaking the symmetry,” said Matt Hedman, an assistant professor of physics at the University of Idaho, who worked with Chancia to investigate the finding. Their results will be published in The Astronomical Journal and have been posted to the pre-press site arXiv.

Chancia and Hedman are well-versed in the physics of planetary rings: both study Saturn’s rings using data from NASA’s Cassini spacecraft, which is currently orbiting Saturn. Data from Cassini have yielded new ideas about how rings behave, and a grant from NASA allowed Chancia and Hedman to examine Uranus data gathered by Voyager 2 in a new light. Specifically, they analyzed radio occultations — made when Voyager 2 sent radio waves through the rings to be detected back on Earth — and stellar occultations, made when the spacecraft measured the light of background stars shining through the rings, which helps reveal how much material they contain.

They found the pattern in Uranus’ rings was similar to moon-related structures in Saturn’s rings called moonlet wakes.

The researchers estimate the hypothesized moonlets in Uranus’ rings would be 2 to 9 miles (4 to 14 kilometers) in diameter — as small as some identified moons of Saturn, but smaller than any of Uranus’ known moons. Uranian moons are especially hard to spot because their surfaces are covered in dark material.

“We haven’t seen the moons yet, but the idea is the size of the moons needed to make these features is quite small, and they could have easily been missed,” Hedman said. “The Voyager images weren’t sensitive enough to easily see these moons.”

Hedman said their findings could help explain some characteristics of Uranus’ rings, which are strangely narrow compared to Saturn’s. The moonlets, if they exist, may be acting as “shepherd” moons, helping to keep the rings from spreading out. Two of Uranus’ 27 known moons, Ophelia and Cordelia, act as shepherds to Uranus’ epsilon ring.

“The problem of keeping rings narrow has been around since the discovery of the Uranian ring system in 1977 and has been worked on by many dynamicists over the years,” Chancia said. “I would be very pleased if these proposed moonlets turn out to be real and we can use them to approach a solution.”

Confirming whether or not the moonlets actually exist using telescope or spacecraft images will be left to other researchers, Chancia and Hedman said. They will continue examining patterns and structures in Uranus’ rings, helping uncover more of the planet’s many secrets.

“It’s exciting to see Voyager 2’s historic Uranus exploration still contributing new knowledge about the planets,” said Ed Stone, project scientist for Voyager, based at Caltech, Pasadena, California.

Voyager 2 and its twin, Voyager 1, were launched 16 days apart in 1977. Both spacecraft flew by Jupiter and Saturn, and Voyager 2 also flew by Uranus and Neptune. Voyager 2 is the longest continuously operated spacecraft. It is expected to enter interstellar space in a few years, joining Voyager 1, which crossed over in 2012. Though far past the planets, the mission continues to send back unprecedented observations of the space environment in the solar system, providing crucial information on the environment our spacecraft travel through as we explore farther and farther from home.

NASA’s Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, built the twin Voyager spacecraft and operates them for the Heliophysics Division within NASA’s Science Mission Directorate in Washington.

Super Guppy Delivers

The Super Guppy, an aptly named NASA cargo plane might look unwieldy but don’t let looks fool you; this plane can deliver large items.

The image here for example shows the cargo bay of the plane and a new heat shield being unloaded at Kennedy Space Center (Photo credit: NASA/Dimitri Gerondidakis).

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The heat shield will protect the new Orion spacecraft from the intense heat of re-entry. The heat-shield, built by Lockheed Martin in Colorado will withstand temperatures of 2,760 C / 5,000 F. The 5 meter / 16.5 ft diameter heat-shield plus crating fits easily inside the Guppy.

Here’s a video of the Super Guppy in action.

Earth 50 Years Ago

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50 years ago today the Lunar Orbiter 1 took the first picture of Earth from the moon. Lunar Orbiter 1 was launched on 10 August 1966 and returned 42 high-resolution and 187 medium-resolution frames were taken and transmitted to Earth covering over 5 million square kilometers of the Moon’s surface. This image was taken on 23 August 1966 at 16:35 GMT.

More about Lunar Orbiter 1

Image: NASA via Wikimedia

RS-25 Testing Continues

On 18 August an upgraded shuttle engine was tested at NASA’s Stennis Space Center.

This particular firing, in addition to the pressure and temperature conditions, tested a new engine controller which monitors engine status and communicates between the rocket and the engine.

This is the third in a series of six tests for the RS-25 working towards a 2018 test flight. The engines will eventually will be a package of four and will provide the power to put space travelers on course to Mars.

This Week At NASA

An especially good episode this week. Very interesting bit on the atmosphere of the Jupiter moon Io, the sulfur dioxide atmosphere freezes onto the moons surface during the period where Jupiter shades the moon and then is restored as the shading goes away.

Video

The Heart of the Crab

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This image is a composite of separate exposures acquired by the ACS/WFC instrument using several filters. Coloration results from assigning different hues (colors) to the grayscale image associated with an individual filter.The assigned colors represent not only changes in different filters, but also the same filters taken on different exposure dates to highlight features that change over time.

Credit: ESA / NASA Acknowledgment: J. Hester (ASU) and M. Weisskopf (NASA/GSFC)

From Hubblesite:
At the center of the Crab Nebula, located in the constellation Taurus, lies a celestial “beating heart” that is an example of extreme physics in space. The tiny object blasts out blistering pulses of radiation 30 times a second with unbelievable clock-like precision. Astronomers soon figured out that it was the crushed core of an exploded star, called a neutron star, which wildly spins like a blender on puree. The burned-out stellar core can do this without flying apart because it is 10 billion times stronger than steel. This incredible density means that the mass of 1.4 suns has been crushed into a solid ball of neutrons no bigger than the width of a large city. This Hubble image captures the region around the neutron star. It is unleashing copious amounts of energy that are pushing on the expanding cloud of debris from the supernova explosion — like an animal rattling its cage. This includes wave-like tsunamis of charged particles embedded in deadly magnetic fields.

On July 4, 1054, Chinese astronomers recorded the supernova that formed the Crab Nebula. The ultimate celestial firework, this “guest star” was visible during the daytime for 23 days, shining six times brighter than the planet Venus. The supernova was also recorded by Japanese, Arabic, and Native American stargazers. While searching for a comet that was predicted to return in 1758, French astronomer Charles Messier discovered a hazy nebula in the direction of the long-vanished supernova. He would later add it to his celestial catalog as “Messier 1.” Because M1 didn’t move across the sky like a comet, Messier simply ignored it other than just marking it as a “fake comet.” Nearly a century later the British astronomer William Parsons sketched the nebula. Its resemblance to a crustacean led to M1’s other name, the Crab Nebula. In 1928 Edwin Hubble first proposed associating the Crab Nebula to the Chinese “guest star” of 1054.