PASSING BY

With a small telescope and our sky charts, you can watch a very sizable near-Earth asteroid race across winter's constellations on the night of January 26–27.

Asteroids that buzz close by Earth make the news either by being especially close or especially large. The one that's going to miss us on the night of January 26-27 is especially large as near-Earth objects go, and it will become bright enough to follow with a 3- or 4-inch telescope as it moves among the stars.


When closest to Earth on January 26th, the asteroid 2004 BL86 will be 1.2 million km (745,000 miles) from Earth.


While most known Earth-grazers are just meters across, this one is roughly a half kilometer wide. As a result it should become as bright as magnitude 9.2 (maybe a bit brighter) shortly after it passes us at a very safe distance of 1.2 million km (745,000 miles). That's three times as far away as the Moon — and while this might not seem terribly close, remember that by comparison Mars never comes closer to us than 145 lunar distances.

The asteroid has been designated 2004 BL86, and it was discovered 10 years ago by the LINEAR project hunting for near Earth objects. Its well-defined orbit has earned it an asteroid number: 357439, perhaps making it the highest-numbered asteroid you've ever had a chance to see.

(Interestingly, once an asteroid is assigned number, it's eligible for naming — but Herbert Viggh of MIT's Lincoln Laboratory, which ran LINEAR, says no name has been submitted yet.)

"Monday, January 26th, will be the closest asteroid 2004 BL86 will get to Earth for at least the next 200 years," said Don Yeomans in a press release from NASA's Near Earth Object Program Office. Moreover, this flyby will be the closest by any known space rock this large until asteroid 1999 AN10 flies past Earth in 2027.

Planetary radar networks have imaged many near-Earth asteroids that have come this close, and both NASA's Goldstone tracking station in California and Arecibo Observatory in Puerto Rico will be used to map 2004 BL86 with 2- to 4-meter resolution.

-

 

Asteroid that flew past Earth has moon
Scientists have released the first radar images of asteroid 2004 BL86, which made its closest approach January 26.


Asteroid 2004 BL86
NASA
Scientists working with NASA's 230-foot-wide (70 meters) Deep Space Network antenna at Goldstone, California, have released the first radar images of asteroid 2004 BL86. The images show the asteroid, which made its closest approach January 26, 2015, at 11:19 a.m. EST, at a distance of about 745,000 miles (1.2 million kilometers), has its own small moon.

The 20 individual images used in the movie were generated from data collected at Goldstone on January 26. They show the primary body is approximately 1,100 feet (325 meters) across and has a small moon approximately 230 feet (70 meters) across. In the near-Earth population, about 16 percent of asteroids that are about 655 feet (200m) or larger are a binary — the primary asteroid with a smaller asteroid moon orbiting it — or even triple systems — two moons. The resolution on the radar images is 13 feet (4m) per pixel.

The trajectory of asteroid 2004 BL86 is well understood. Monday's flyby was the closest approach the asteroid will make to Earth for at least the next two centuries. It is also the closest a known asteroid this size will come to Earth until asteroid 1999 AN10 flies past our planet in 2027.

Asteroid 2004 BL86 was discovered January 30, 2004, by the Lincoln Near-Earth Asteroid Research (LINEAR) survey in White Sands, New Mexico.

Radar is a powerful technique for studying an asteroid's size, shape, rotation state, surface features and surface roughness, and for improving the calculation of asteroid orbits. Radar measurements of asteroid distances and velocities often enable computation of asteroid orbits much further into the future than if radar observations weren't available.

 

New Horizons begins first stages of Pluto encounter
The “optical navigation” campaign that starts January 25 will mark the first time pictures from the spacecraft will be used to help pinpoint Pluto’s location.


Artist’s concept of NASA’s New Horizons spacecraft as it passes Pluto and Pluto’s largest moon, Charon, in July 2015.
NASA/JHU APL/SwRI/Steve Gribben
NASA’s New Horizons spacecraft has begun its long-awaited historic encounter with Pluto, entering the first of several approach phases that will culminate with the first close-up flyby of the Pluto system six months from now.

“NASA’s 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 from NASA Headquarters in Washington, D.C. “The New Horizons team worked very hard to prepare for this first phase, and they did it flawlessly.”

New Horizons launched in January 2006 and, after a voyage of more than 3 billion miles (5 billion kilometers), will soar close to Pluto, inside the orbits of its five known moons, this July 14. The fastest spacecraft ever launched, New Horizons awoke from its final hibernation period in early December. Since then, the mission’s science, engineering, and spacecraft operations teams have configured the piano-sized probe for distant observations of the Pluto system, starting with a long-range photo shoot that begins January 25.

Snapped by New Horizons’ telescopic Long-Range Reconnaissance Imager (LORRI), those pictures will give mission scientists a continually improving look at the dynamics of those moons. And they’ll play a critical role in navigating the spacecraft as it covers the remaining 135 million miles (220 million km) to Pluto.

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

Over the next few months, LORRI will take hundreds of pictures of Pluto against star fields to refine the team’s estimates of New Horizons’ distance to Pluto. Though the Pluto system will resemble little more than bright dots in the camera’s view until May, mission navigators will use those data to design course-correction maneuvers that aim the spacecraft toward its flyby 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 from Johns Hopkins University Applied Physics Laboratory 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.

This first approach phase, which lasts until spring, also includes a significant degree of other science. New Horizons will take essentially continuous data on the interplanetary environment where the Pluto system orbits, with its two charged-particle sensors measuring the high-energy particles streaming from the Sun, and its dust counter tallying dust-particle concentrations in the inner reaches of the Kuiper Belt — the unexplored outer region of the solar system that includes Pluto and potentially thousands of similar icy, rocky small planets.

More intensive Pluto studies begin in the spring when the cameras and spectrometers aboard New Horizons can provide resolutions better than the most powerful telescopes on Earth. Eventually, New Horizons will obtain images good enough to map Pluto and its moons better than has ever been achieved by any previous first planetary reconnaissance mission.

 

Rosetta swoops in for a close encounter
The February 14 flyby will allow the spacecraft to sample the innermost parts of Comet 67P/Churyumov-Gerasimenko’s atmosphere.




The European Space Agency’s (ESA) Rosetta probe is preparing to make a close encounter with its comet on February 14, passing just 4 miles (6 kilometers) from the surface.

Yesterday was Rosetta’s last day at 16 miles (26km) from Comet 67P/Churyumov–Gerasimenko, marking the end of the current orbiting period and the start of a new phase for the rest of this year.

Today, Rosetta is moving into a new path ahead of a close encounter next week. First, it will move out to a distance of roughly 87 miles (140km) from the comet by February 7, before swooping in for the close encounter at 12:41 GMT (13:41 CET) February 14. The closest pass occurs over the comet’s larger lobe, above the Imhotep region.

“The upcoming close flyby will allow unique scientific observations, providing us with high-resolution measurements of the surface over a range of wavelengths and giving us the opportunity to sample — taste or sniff — the very innermost parts of the comet’s atmosphere,” said Matt Taylor from ESA.

The flyby will take Rosetta over the most active regions of the comet, helping scientists understand the connection between the source of the observed activity and the atmosphere, or coma.

In particular, they will be looking for zones where the outflowing gas and dust accelerates from the surface and how these constituents evolve at larger distances from the comet.

The comet’s surface is already known to be very dark, reflecting just 6 percent of the light that falls on it. During the close flyby, Rosetta will pass over the comet with the Sun directly behind, allowing shadow-free images to be collected. By studying the reflectivity of the nucleus as it varies with the angle of the sunlight falling on it, scientists hope to gain a more detailed insight into the dust grains on the surface.

“After this close flyby, a new phase will begin when Rosetta will execute sets of flybys past the comet at a range of distances between about 15km [9 miles] and 100km [60 miles],” said Sylvain Lodiot from ESA.

It was always planned to change from “bound orbits” to flyby trajectories at this point in the mission, based on predictions of increasing cometary activity. The range of flyby distances also balances the various needs of Rosetta’s 11 instruments in order to optimize the mission’s scientific return.

During some of the close flybys, Rosetta will encounter the comet almost in step with the rotation, allowing the instruments to monitor a single point on the surface as it passes by.

Meanwhile, the more distant flybys will provide the broader context of a wide-angle view of the nucleus and its growing coma.

“We’re in the main science phase of the mission now, so throughout the year we’ll be continuing with high-resolution mapping of the comet,” said Taylor.

“We’ll sample the gas, dust, and plasma from a range of distances as the comet’s activity increases and then subsides again later in the year.”

Perihelion, closest approach to the Sun, occurs August 13 when the comet and Rosetta will be 116 million miles (186 million km) from the Sun, between the orbits of Earth and Mars.

In the month before perihelion, as activity is reaching a peak, the team is planning to study one of the comet’s jets in greater detail than ever before.

“We hope to target one of these regions for a fly-through, to really get a taste of the outflow of the comet,” said Taylor.

After perihelion and once the comet’s activity begins to subside, the mission team will determine if and when to return to a bound orbit around the comet and how long Rosetta might be able to operate beyond the end of 2015.

 

Good morning Armandll my friend that was very informative and interesting and thank you for the post

 

Curiosity analyzing sample of martian mountain
Preliminary results suggest the area had acidic ancient conditions
By NASA/JPL | Published: Friday, February 06, 2015





The second bite of a martian mountain taken by NASA's Curiosity Mars rover hints at long-ago effects of water that was more acidic than any evidenced in the rover's first taste of Mount Sharp, a layered rock record of ancient martian environments.

The rover used a new, low-percussion-level drilling technique to collect sample powder last week from a rock target called "Mojave 2."

Curiosity reached the base of Mount Sharp five months ago after two years of examining other sites inside Gale Crater and driving toward the mountain at the crater's center. The first sample of the mountain's base layer came from a target called "Confidence Hills," which was drilled in September.

A preliminary check of the minerals in the Mojave 2 sample comes from analyzing it with the Chemistry and Mineralogy (CheMin) instrument inside Curiosity. The still-partial analysis shows a significant amount of jarosite, an oxidized mineral containing iron and sulfur that forms in acidic environments.

"Our initial assessment of the newest sample indicates that it has much more jarosite than Confidence Hills," said David Vaniman of the Planetary Science Institute in Tucson, Arizona. The minerals in Confidence Hills indicate less acidic conditions of formation.

Open questions include whether the more acidic water evident at Mojave 2 was part of environmental conditions when sediments building the mountain were first deposited, or fluid that soaked the site later.

Both target sites lie in an outcrop called "Pahrump Hills," an exposure of the Murray formation that is the basal geological unit of Mount Sharp. The Curiosity mission team already has proposed a hypothesis that this mountain, the size of Mount Rainier in Washington, began as sediments deposited in a series of lakes filling and drying.

In the months between Curiosity's drilling of these two targets, the rover team based at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, directed the vehicle through an intensive campaign at Pahrump Hills. The 1-ton roving laboratory zigzagged up and down the outcrop's slope, using cameras and spectrometer instruments to study features of interest at increasing levels of detail. One goal was to select which targets, if any, to drill for samples to be delivered into the rover's internal analytical instruments.

The team chose a target called "Mojave," largely due to an abundance of slender features, slightly smaller than rice grains, visible on the rock surface. Researchers sought to determine whether these are salt-mineral crystals, such as those that could result from evaporation of a drying lake, or if they have some other composition. In a preparatory drilling test of the Mojave target, the rock broke. This ruled out sample-collection drilling at that spot, but produced chunks with freshly exposed surfaces to be examined.

Mojave 2, an alternative drilling target selected at the Mojave site, has the same type of crystal-shaped features. The preliminary look at CheMin data from the drilled sample material did not identify a clear candidate mineral for these features. Possibly, minerals that originally formed the crystals may have been replaced by other minerals during later periods of wet environmental conditions.

The drilling to collect Mojave 2 sample material might not have succeeded if the rover team had not recently expanded its options for operating the drill.

"This was our first use of low-percussion drilling on Mars, designed to reduce the energy we impart to the rock," said John Michael Morookian from JPL, the team's surface science and sampling activity lead for the Pahrump Hills campaign. "Curiosity's drill is essentially a hammer and chisel, and this gives us a way not to hammer as hard."

Extensive tests on Earth validated the technique after the team became concerned about fragility of some finely layered rocks near the base of Mount Sharp.

The rover's drill has six percussion-level settings ranging nearly 20-fold in energy, from tapping gently to banging vigorously, all at 30 times per second. The drill monitors how rapidly or slowly it is penetrating the rock and autonomously adjusts its percussion level. At the four targets before Mojave 2, including three before Curiosity reached Mount Sharp, sample-collection drilling began at level four and used an algorithm that tended to remain at that level. The new algorithm starts at level one, then shifts to a higher level only if drilling progress is too slow. The Mojave 2 rock is so soft, the drill reached its full depth of about 2.6 inches (6.5 centimeters) in 10 minutes using just levels one and two of percussion energy.

Curiosity also has delivered Mojave 2 powder to the internal Sample Analysis at Mars (SAM) suite of instruments for chemical analysis. The rover may drive to one or more additional sampling sites at Pahrump Hills before heading higher on Mount Sharp.