Spacecraft in solar orbit regains contact with Earth

August 24, 2016 Leave a comment
STEREO image of whole sun, Feb. 2, 2011 - courtesy NASA

This image shows our sun’s far side. It was obtained by the STEREO probes on Feb. 2, 2011 at 23:56 UT. Image courtesy NASA.

A probe launched by NASA in 2006 has resumed communication with the agency after nearly 23 months of silence.

The STEREO-B spacecraft, which orbits the sun, lost contact with Earth on Oct. 1, 2014.

The Deep Space Network reestablished the link with STEREO-B at 6:21 pm EDT on Sunday.

The long interruption in communication with the spacecraft was most likely the result of a series of events that began with a test of its command loss timer. The device is a kind of automated switch that allows the spacecraft to recover after a hardware failure. It functions by re-setting the hardware if no commands are received for a certain period of time. In STEREO-B’s case, that re-set time was three days.

NASA explained a likely scenario for the communications failure at a website posted shortly after the loss of contact event and still available here. An animated film that provides one possible model for the probe’s communication failure is also available.

STEREO-B’s navigation system probably failed because it was unable to detect guide stars. This caused the probe’s high gain antenna to be pointed away from Earth, which meant that it could not receive a signal.  The breakdown in the star tracking system was likely the result of a failed laser.

“Basically, we made a mistake in not accounting for one of those individual lasers failing,” Dr. Joseph Gurman, the STEREO project scientist at NASA’s Goddard Space Flight Center, said. “The data still looked good coming out of the unit as a whole even though one laser was bad. That got us into a situation where the spacecraft was getting bad navigational information.”

STEREO-B remains in an uncontrolled spin, a problem for which there is not currently enough power available to correct. The spacecraft obtains energy by means of solar arrays that extend out from its main section.

Gurman explained that NASA scientists are not sure how much power the probe’s batteries can produce or whether they can be fully re-charged.

“We don’t know if the batteries are damaged,” he said. “We know they can take some charge.”

Whether the spacecraft’s instrumentation is still functional is also unknown.

“I would say that we know nothing about the state of the instruments at this point,” Gurman said.

NASA will proceed cautiously to investigate the STEREO-B probe’s status. What Gurman and his colleagues want to avoid is any command that would return STEREO-B to an uncontrolled spin.

“We have an inertial problem that is giving bad information to the control system on the spacecraft,” he said. “We have to proceed in a step-by-step method.”

The first step will be to figure out the extent to which the probe has, to put it metaphorically, any gas in its tank.

“We have to heat up the probably frozen fuel in the fuel tank,” Gurman explained. “We can proceed from there to use the thrusters to right our attitude by using the autonomy software.”

Gurman is optimistic, though, about the prospects for obtaining more data about the sun from STEREO-B. NASA’s prior experience with another spacecraft that experienced a communication failure – the Solar and Heliospheric Observatory – indicates that instruments can survive with little or no damage, even in the cold of space, for quite some time.

“On SOHO, there were 12 principal investigator experiments,” Gurman said. “Only one mechanism in one telescope was damaged in such a way that we really couldn’t use the instrument. There was one instrument that suffered some degradation. That’s about it. We’re cautiously optimistic that we’ll be able to regain most of the scientific capability, if not all, that we had before.”

In any case, the STEREO mission formally ended eight years ago, so any data obtained from STEREO-B is beyond what was expected at the time of launch.

“Anything we get is gravy, to say the least,” Gurman said.

The probe’s twin, STEREO-A, also revolves around our closest star.

STEREO is an acronym that shortens the twin probes’ formal name – Solar Terrestrial Relations Observatories.

 

New report says world’s largest primate is on fast track to extinction

June 22, 2016 Leave a comment
Grauer's gorilla infant

An infant Grauer’s gorilla is carried on the back of an adult. Photo courtesy Wildlife Conservation Society, photo by A.J. Plumptre.

The eastern lowland gorilla, Earth’s largest primate, is in rapid decline and has seen its population decline by nearly 80 percent since the late 1990s. There are now fewer than 4,000 individuals of the subspecies remaining in the wild.

Such is the bleak conclusion of a report released in April.

Persistent war in the animal’s home range, which is limited to a forested region in eastern Democratic Republic of Congo, is the leading culprit for the rapid extermination of the great ape species.

“Since 1996, the entire range of Grauer’s gorilla has been consumed in conflict,” the report said. “This has resulted in an almost complete breakdown in government control, including wildlife protection activities.”

Grauer's gorilla - courtesy FFI, photo by Stuart Nixon

Image of adult Grauer’s gorilla courtesy Fauna & Flora International, photo by Stuart Nixon.

The civil war in DRC began in in the aftermath of the 1994 genocide event in Rwanda. Hundreds of thousands of refugees streamed into DRC. Upon arrival, they engaged in deforestation in the eastern region of the country. The inflow of Rwandans refugees also helped set off a conflict that killed millions of people between 1996-2003.

Although the war is over, the militias who participated in it have not disappeared. They control areas in the eastern DRC that are the only habitat for Grauer’s gorillas and, in that territory, they tolerate mining and engage in bushmeat hunting.

The mining, which is done on a small scale and often illegally, is aimed at extracting minerals used in the production of elecronic devices such as cellular phones, laptop computers, and gaming consoles.

Grauer’s gorillas, as well as chimpanzees, are hunted by the militia soldiers to feed the miners, which fund them, and themselves. Although protected by law, the large size of a Grauer’s gorilla means it can provide enough meat to feed multiple humans. Because the animal moves in a troop through its forested habitat, hunters can take multiple gorillas and feed even more humans.

Disarming the militias and imposing legal controls on the small-scale mining within Grauer’s gorilla habitat is a crucial step toward assuring the subspecies’ survival, said the report’s authors.

“Significantly greater efforts must be made for the government to regain control of this region of DRC,” Andrew Plumptre, a wildlife biologist with Wildlife Conservation Society and the lead author of the report, said. “In particular, the government needs to quickly establish Reserve des Gorilles de Punia and the Itombwe Preserve, and reinforce Kahuzi-Biega National Park efforts, which have community support, and to establish strong communication between [Institut Congolais pour la Conservation de la Nature] and the DRC military to tackle armed militias that control mining camps in Grauer’s gorilla heartland.”

The report also concluded that agriculture, poaching for body parts, and “socio-economic depression from over a decade of civil war” are contributing to the rapid decline of Grauer’s gorilla and other plant and animal species.

Stuart Nixon, a wildlife biologist at the United Kingdom’s Chester Zoo and a co-author of the report, emphasized that a speedy government response to these stressors is vital.

“Unless greater investment and effort is made, we face the very real threat that this incredible primate will disappear from many parts of its range in the next five years,” he said.

The most recent prior population survey of Gorilla beringei graueri occurred during the mid-1990s. Researchers concluded that a population of about 17,000 individuals remained at that time.

The current conflict is not the first occasion in which Grauer’s gorillas have suffered extensive losses at the hands of humans.

During the 1960s and 1970s many individuals were killed as grassland areas of their range were converted to agriculture and farmers used shotguns provided by the government of Zaire to kill the gorillas.

Gorilla beringei graueri is one of four gorilla subspecies. Like individuals of the other three subspecies, Grauer’s gorillas live in groups. They are thought to organize themselves into harem-like assemblages that include two males. A female matures at about eight years of age, while a male reaches full development after about 12 years.

A full-grown male Grauer’s gorilla can weigh up to 400 pounds.

Both females and males leave the group at maturity, with male Grauer’s gorillas staying together until each can attract females and form new groups. Females join a group or ally themselves with a single adult male.

Also known as the eastern lowland gorilla, Grauer’s gorilla is closely related to the smaller western lowland gorilla (Gorilla gorilla gorilla) that is endemic to central African forests.

The report’s authors recommend that the status of Gorilla beringei graueri be downgraded from endangered to critically endangered by the International Union for the Conservation of Nature.

A species listed as “critically endangered” is just one step, on the IUCN hierarchy of classification, from extinction in the wild.

The report was published by the Wildlife Conservation Society, Flora and Fauna International and the Congolese Institute for the Conservation of Nature.

 

Look up tonight to see first summer solstice strawberry moon since 1967

June 20, 2016 Leave a comment
June full moon

A June full moon is also called a “honey moon” because it appears amber-colored through Earth’s atmosphere.

Today’s summer solstice in the northern hemisphere does not bring only the longest day of the year. Night sky watchers also have the opportunity to see, for the first time in 49 years, a full moon on the first day of summer.

The full moon occurs about once each month. The lunar year – the amount of time it takes for the moon to cycle through 12 lunar cycles – is 354 days; the lunar cycle averages 29.53 days.

A full moon occurs when the sun, Earth, and the moon are nearly aligned. During most  full moons we see nearly all of one of the Moon’s hemispheres from our planet. We do not see all of that hemisphere during a typical full moon because, if we did, the sun, Earth, and moon would be so aligned as to result in a lunar eclipse.

The other hemisphere of the moon is never visible from Earth because the moon’s rate of  rotation is equal to the amount of time it takes to orbit our planet.

Because tonight’s full moon occurs in June, it is colloquially known as a “strawberry moon.” According to the 1918 book The American Boy’s Book of Signs, Signals and Symbols, the nickname originated with native Americans of the northeastern United States because June is the month in which strawberries were harvested.

According to a 2012 National Geographic article, “Europeans have dubbed [a June full moon] the rose moon, while other cultures named it the hot moon for the beginning of the summer heat.”

The summer solstice in the northern hemisphere is the one day of the year on which the sun will be directly overhead at noon at the Tropic of Cancer. The sun is never directly overhead at a latitude north of the Tropic of Cancer or south of the Tropic of Capricorn.

In Colorado and the rest of the Mountain Time Zone of North America, the sun will get to its annual highest point in the sky at 4:34 pm.

Earth at summer solstice

This graphic shows Earth’s northern hemisphere at the summer solstice. Graphic courtesy Space.com.

The sun is directly overhead at high noon above the Tropic of Capricorn on the winter solstice in the northern hemisphere.

The southern hemisphere experiences its summer solstice on that day and its winter solstice when the sun is directly overhead at the Tropic of Cancer.

CORRECTION, June 20, 2016, 5:24 pm MDT: This article originally stated that the last summer solstice full moon occurred in 1949, 67 years ago. That is not an accurate statement and the article has been edited to correct the error.

Asian fossil discovery may help explain how tyrannosaurs became dominant predators

June 17, 2016 Leave a comment
Timurlengia euotica - March 2016 - courtesy

This artist’s conception shows the tyrannosaur Timurlengia euotica in its environment 90 million years ago, accompanied by two flying reptiles (Azhdarcho longicollis). The fossilized remains of a the horse-sized dinosaur help explain how Tyrannosaurus rex and its close relatives became top predators. The paper describing the discovery was published in March in the Proceedings of the National Academy of Sciences. Illustration by Todd Marshall.

Researchers have discovered 90 million-year old fossils of an early tyrannosaur that may help improve scientists’ understanding of how that group of dinosaurs evolved into the predatory giants that later roamed North America.

The horse-sized animal, which would have likely weighed about 250 kilograms, apparently had impressive hearing ability. Its capacity to hear low frequency sounds can be deduced from an elongated cochlear duct.

Named Timurlengia euotica, the newly-identified tyrannosaur helps fill a gap in knowledge about how the relatively small theropods, which had to compete with larger allosaurs, evolved into some of the largest land predators ever known.

The discovery indicates that the tyrannosaur clade probably gained the sensory tools needed to become apex predators before late Cretaceous enormity took hold.

“Tyrannosaurs had to get smart before they got big,” Dr. Stephen L. Brusatte, a paleontologist at the University of Edinburgh in the United Kingdom and lead author of the paper describing the discovery, said.

Enormity on the scale so obviously presented by later tyrannosaurs like Tyrannosaurus rex, which stood about five meters tall and about 12 meters long and weighed about 3,600 kilograms, evolved during the last 20 million years of the dinosaurs’ dominance of Earth.

Researchers found a brain case, which they then subjected to a computed microtomography (CT) scan. That scan revealed not only the animal’s inner ear structure, but also likely similarities between T. euotica‘s brain and the brain of Tyrannosaurus rex.

Brusatte wrote in The Conversation that these features likely helped T. euotica become a very skilled tracker of prey.

“Their intelligence and sharp senses made tyrannosaurs perfectly equipped to swoop into the top-predator role,” he wrote.

As the tyrannosaur head became larger, it became more useful for hunting.

“Their heads became giant killing machines and their arms, now unnecessary, shrunk down to nubbins,” Brusatte wrote in The Conversation feature.

The fossilized braincase, along with a variety of other bones, had been stored in a museum for about ten years. Brusatte and his colleagues examined them in 2014.

Reconstructed T. euotica skeleton

This is a reconstructed skeleton of Timurlengia euotica with discovered fossilized bones, highlighted in red, and other bones remaining to be discovered inferred from other related species of tyrannosaurs in white. Individual scale bars for the pictured fossilized bones each equal 2 centimeters. The fossilized remains of T. euotica may reveal how Tyrannosaurus rex and its close relatives became top predators. Graphic (c) National Academy of Sciences.

“Working on Timurlengia has been one of the highlights of my career,” Brusatte said. “It gives us a glimpse of what the ancestor of T. rex was – a tyrannosaur right on the cusp of becoming huge.”

The fossils were found in the remote Kyzylkum Desert of Uzbekistan. Their significance was described in a paper published in March in Proceedings of the National Academy of Sciences.

Astronomers discover moon orbiting dwarf planet Makemake

June 17, 2016 Leave a comment
makemake's moon

This image obtained by the Hubble Space Telescope in April 2015 shows a moon – the first discovered – in orbit around the dwarf planet Makemake. The tiny satellite, located just above Makemake in this image, is barely visible because it is almost lost in the glare of the very bright dwarf planet. Image courtesy NASA, European Space Agency, Southwest Research Institute.

Makemake, a dwarf planet far beyond Pluto in the Kuiper Belt, has a moon.

Imagery obtained by the Hubble Space Telescope detected the satellite last April, according to a recently published paper.

The moon, which has been temporarily catalogued as S/2015 (136472) 1 and nicknamed MK2, is about 100 miles in diameter. It was observed orbiting Makemake from a distance of about 13,000 miles.

MK2 probably orbits Makemake in an orientation that makes it difficult for astronomers to observe the moon.

“Our preliminary estimates show that the moon’s orbit seems to be edge-on, and that means that often when you look at the system you are going to miss the moon because it gets lost in the bright glare of Makemake,” Dr. Alex H. Parker, a planetary scientist at Southwest Research Institute in Boulder, Colo., said.

Parker led the team that analyzed the Hubble image of MK2.

One implication of the Makemakean moon’s discovery is an increased ability to measure Makemake’s mass and density.

To measure the dwarf planet’s mass, scientists will need to overcome the challenges inherent in observing MK2’s orbit. If they succeed in doing so, and because the distance from Earth to Makemake is already known, it would be possible to use the orbital period and the mean distance of MK2 from Makemake to determine Makemake’s mass.

To determine Makemake’s density, scientists must know its volume, which in turn requires knowledge of the dwarf planet’s diameter. Makemake’s diameter is about 1,500 kilometers.

Once the volume is determined, density can be calculated by dividing Makemake’s mass by its volume.

makemake-artist-view

Early artist’s impression of Makemake. Courtesy NASA.

Astronomers used a camera on the Hubble Space Telescope to find MK2. That instrument, called Widefield Camera 3, is able to capture images across the radiation spectrum.

Widefield Camera 3 has a 16 megapixel capacity and can capture an image as large as 160 arcseconds by 160 arcseconds in size.

Makemake is the second-brightest object, after Pluto, in the Kuiper Belt and is, like Pluto, covered with methane ice.

The dwarf planet, which was discovered in 2005, is named for a deity that is worshiped by native people of Easter Island.

In addition to Makemake, there are four other dwarf planets in the solar system: Pluto, Eris, Haumea, and Ceres.

With the discovery of MK2, astronomers now know that all of the solar system’s dwarf planets have moons.

Southwest U.S. readies for possible record-breaking heat

June 15, 2016 Leave a comment

The southwestern United States may be facing near record-breaking summer heat during the next few days.

According to the National Weather Service, major cities in Arizona, Nevada, and even southern California will experience temperatures of at least 100 degrees Fahrenheit at the beginning of next week.

The forecast officially calls for Phoenix to hit 117 degrees on Sunday and 118 degrees on Monday. Las Vegas may hit 110 degrees on Monday and Tuesday, while Tucson’s temperature could reach 114 degrees on Sunday and 112 degrees on Monday.

Meteorologist Bob Henson, writing at the Weather Underground blog, thinks it could be warmer.

WU forecast SW June 2016

Graphic courtesy Weather Underground.

So does Ryan Maue, a meteorologist affiliated with Weatherbell Analytics. Maue predicts that the temperature in Phoenix will reach 120 degrees on Monday.

The all-time hottest temperature in Phoenix is 122 degrees, which was reached in 1990. At least one forecast map shows that the metropolis in central Arizona’s Salt River Valley might reach 120 degrees on Monday.

The Valley of the Sun has experienced four straight record-breaking warm days this month (June 3-7), as well as its earliest 115 degree day in recorded history. If Phoenix reaches 116 degrees on Sunday, it would be the hottest day ever recorded in the city prior to the summer solstice.

The heat record in Las Vegas (most recently on June 30, 2013) and Tucson (June 26, 1990) is 117 degrees, while Yuma’s all-time mark is 124 degrees (July 28, 1995).

Los Angeles could reach 101 degrees on Monday, June 20. That is not close to the city’s all-time record high temperature of 113 degrees.

Southwest temperatures

This graphic shows the forecasted high temperatures on June 20, 2016. Graphic courtesy Weatherbell Analytics, National Weather Service.

Records maintained by the National Centers for Environmental Information, an agency of the National Oceanic & Atmospheric Administration, show that record high temperatures are much more common in the U.S. this year than are record low temperatures.

South Pole reaches 400 ppm of carbon dioxide

June 15, 2016 Leave a comment
South Pole carbon dioxide record - courtesy NOAA

This graphic shows the rise in daily average carbon dioxide levels at the South Pole to 400 parts per million on May 23. It’s the first time this has happened in at least four million years. Data for 2014-present recorded NOAA’s greenhouse gas monitoring network. Graphic courtesy NOAA.

The concentration of carbon dioxide in the atmosphere above our planet’s South Pole reached the worrisome threshold of 400 parts per million.

At least four million years have past since the last time carbon dioxide was so plentiful in the air above the South Pole, according to a statement announcing the milestone released Wednesday by the National Oceanic & Atmospheric Administration.

No region of Earth remains below the 400 ppm threshold.

“The far southern hemisphere was the last place on earth where CO2 had not yet reached this mark,” Pieter Tans, the lead scientist of NOAA’s Global Greenhouse Gas Reference Network, said. “Global CO2 levels will not return to values below 400 ppm in our lifetimes, and almost certainly for much longer.”

The South Pole is slower to demonstrate increases in atmospheric greenhouse gas concentrations driven by human combustion of fossil fuels because that region is so remote from the populated, and economically developed, areas of Earth.

Another federal government entity, the National Center for Atmospheric Research in Boulder, Colo., recently warned that the South Pole would soon cross the 400 ppm threshold.

Atmospheric co2 ppm - graphic courtesy Scripps Institution of Oceanography, graphic by Eric Morgan

This graphic illustrates the atmospheric concentration of carbon dioxide near Antarctica in January, just as air masses over the Southern Ocean began to exceed 400 parts per million of CO2. Graphic courtesy Scripps Institution of Oceanography, illustration by Eric Morgan.

“Throughout humanity, we have lived in an era with CO2 levels below 400 ppm,” Ralph Keeling, director of the CO2 Program at the Scripps Institution of Oceanography, said in an NCAR statement released May 12 . “With these data, we see that era drawing to a close, as the curtain of higher CO2 spreads into the Southern hemisphere from the north. There is no sharp climate threshold at 400 ppm, but this milestone is symbolically and psychologically important.”

NOAA data obtained at the South Pole indicates that the atmospheric concentration of carbon dioxide there was about 336 ppm in 1980 and has generally been rising since that time.

 

Evolutionary Biology

No foresight, no way back

Why? Because Science.

Combating Stupidity Since 2012

Empirical SCOTUS

Viewing the Supreme Court in an entirely new light

Discover

A daily selection of the best content published on WordPress, collected for you by humans who love to read.

The Evolving Paleontologist

Digital Home of Dr. Matthew F. Bonnan, Ph.D.

The Library's Blog

News from the Thomas Tredway Library at Augustana College

Mad4science's Blog

Just another WordPress.com weblog

Aiming Higher

Navigating Air, Space, & Science - a Blog by Casey Stedman

Lofty Ambitions Blog

Space, Science, Aviation, and Writing as a Couple

Wayne Hale's Blog

space > exploration > leadership

The Jaguar

And its Allies

Follow

Get every new post delivered to your Inbox.

Join 1,404 other followers