Earth – The Space Reporter

Asteroid-bound spacecraft slingshots past Earth

Gravity assist will alter its trajectory while saving fuel.

Traveling through space at 19,000 miles (30,000 km) per hour, NASA’s Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) spacecraft is flying by Earth on Friday, September 22, using the planet’s gravity to redirect its path to the asteroid Bennu.

Launched a year ago from Cape Canaveral on an Atlas V rocket, the spacecraft will arrive at Bennu in November 2018. It will orbit the asteroid, identify ideal surface locations for collecting samples, then use a robotic arm to reach into the surface to take the samples and store them inside a special collection device.

In 2021, OSIRIS-REx will head back toward Earth where, two years later, it will return the samples by parachuting a canister containing them into Utah.

From there, they will be taken to NASA’s Johnson Space Center in Houston, where scientists will analyze them for organic molecules and materials that make up the building blocks of life.

An Earth flyby is necessary to propel OSIRIS-REx to its target because a direct flight would have required additional fuel that would have mandated it launch on a larger rocket.

“It was a way to substantially save on resources, either on the spacecraft or on the launch vehicle, or both,” said mission principal investigator Dante Lauretta of the University of Arizona.

The flyby, which takes the probe within about 11,000 miles (17,000 km) of Earth’s surface, will increase its velocity by 8,400 miles per hour.

NASA will be out of contact with the probe for about an hour during closest approach while it flies over Antarctica.

“OSIRIS-REx uses the Deep Space Network to communicate with Earth, and the spacecraft will be too low relative to the southern horizon to be in view with either the Deep Space tracking station at Canberra, Australia, or Goldstone, California,” explained Mike Moreau, NASA Goddard Space Flight Center flight dynamics system lead.

The spacecraft will photograph the Earth and Moon with its three imaging cameras for as long as 10 days after the flyby.

Earth data will be collected by its thermal emission spectrometer and visible and infrared spectrometer for instrument calibration purposes.

Members of the mission team plan to release photographs collected by the probe on Tuesday, September 26.

Asteroid that will fly close to Earth on Thursday poses no danger

Astronomers will have opportunity to observe a complete rotation of the object in just one night.

An asteroid discovered five years ago will come within 31,000 miles (50,000 km) of Earth on Thursday, October 12, but poses no impact danger to our planet.

Just a week after its discovery by Hawaii’s Pan-STARRS, asteroid 2012 TC4 passed within 58,900 miles (94,800 km) of Earth, and observation over time indicates it has made many such approaches in the past.

Approximately the size of the meteor that hit Chelyabinsk, Russia, in 2013, with a diameter ranging from 26 to 85 feet (8 to 26 meters), 2012 TC4 has an elongated shape, rotates at a high speed, and orbits the Sun every 1.67 years. Its distance from the Sun is around 1.4 AU or astronomical units, with one AU equal to the average Earth-Sun distance or 93 million miles.

“There is no hazard in its upcoming pass or anytime in the near future,” said Alan Harris, formerly a researcher at NASA’s Jet Propulsion Laboratory (JPL).

Early calculations conducted this summer by JPL led scientists to believe 2012 TC4 could come as close as 4,200 miles (6,800 km). Because these calculations were based on just seven days of tracking the asteroid, later studies by the European Space Agency’s (ESA) Oliver Hainaut, Detlef Koschny, and Marco Micheli using the European Southern Observatory (ESO) concluded its approach would not be that close.

According to JPL, “The new calculations indicate that TC4 will fly safely past our planet on Oct. 12, at a distance of about 43,500 km (27,000 miles) above the surface, or about one-eighth of the distance to the Moon.”

Astronomers around the world will be able to observe the asteroid, which will have a brightness of approximately magnitude 14, when it makes its close approach at 5:41 UTC (1:41 AM EDT) on Thursday.

Because 2012 TC4 has such a fast rotation rate, observers should be able to watch a full rotation in just one night, Harris said.

The International Asteroid Warning Network, a UN-sanctioned organization that focuses on collecting data on asteroids that pose potential threats to Earth, will also be following it.

While there is no chance of 2012 TC4 hitting the Earth, even if it did impact, it is too small to cause major damage and would likely land harmlessly over one of Earth’s oceans, Harris noted.

Arecibo Observatory damaged by Hurricane Maria

Officials have yet to assess damage, as roads to the site remain impassable.

Puerto Rico’s Arecibo Observatory, home of the world’s second largest radio telescope, used for research in radio astronomy and study of Earth’s atmosphere, sustained damage when Hurricane Maria battered the island last week.

The telescope’s 1,000-foot (300-meter) dish reflector was pierced several times by a 96-foot (29-meter) line feed antenna that tumbled from a height of more than 328 feet (100 meters), where it had been suspended.

That particular line feed was used largely for atmospheric research. It transmitted and received radio waves at 430 MHz.

Arecibo’s weather station measured 78 mile (126 km) per hour winds on Wednesday, September 20, and gusts up to 108 miles (174 km) per hour.

Also destroyed was a 39-foot (12 meter) dish that served as a phase reference for Very Long Baseline Interferometry (VLBI).

VLBI is a technique in which many separate radio telescopes are linked together in a network to function as a single, more powerful telescope.

In preparation for the storm, observatory staff had secured all facilities and equipment. Similar preparations had been made two weeks earlier in expectation of Hurricane Irma, but that storm took a different trajectory and did not hit Puerto Rico directly.

Staff members who remained at the facility during the hurricane are all safe. The Universities Space Research Association (USRA), one of several organizations that manage Arecibo Observatory for the National Science Foundation, is attempting to contact employees who rode out the storm in their homes or in shelters to make sure they are unharmed.

Because the island has no power, the observatory’s phone and Internet are out. All communication to and from the site is being conducted via shortwave radio.

Transportation for those not on site remains impossible because the area’s roads are filled with debris.

“We will need a full assessment of the damage, repairs that are needed, and when the observatory can resume operations,” said USRA senior vice president for science Nicholas White.

Built in the 1960s, Arecibo has been used to study a wide range of astronomical objects, from black holes and dark matter to pulsars, galaxies, planets, and asteroids.

It has sent signals into space to search for intelligent alien life and also monitored incoming signals in an attempt to determine whether any might be coming from extraterrestrial civilizations.

Arecibo’s visitor center will be closed at least through Wednesday, September 27.

New NASA satellite will track ice melt on Earth

ICESat-2 will study seasonal changes using lasers to measure ice height worldwide.

NASA is launching a new laser satellite that will study Earth’s ice sheets and changes they undergo over the next three years.

Titled the Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2), the satellite will measure and track changes in ice levels across the globe from one season to another. It will be capable of detecting thickness changes as small as one-fifth of an inch.

Two previous NASA probes, the original ICESat, launched in 2003 and Operation IceBridge, begun in 2009, previously monitored changes in ice thickness worldwide.

ICESat measured ice thickness by bouncing a single laser off the surface of ice in each area it studied. Operation IceBridge, which used an airplane rather than a satellite, focused on specific regions of ice deemed crucial and was largely a stopgap mission until the current satellite was ready for launch.

Unlike the previous missions, ICESat-2 will measure the world’s ice in 3D.

“The areas that we’re talking about are vast–think the size of the continental US or larger–and the changes that are occurring over them can be very small,” explained NASA scientist Tom Wagner at an August 22 press conference. “They benefit from an instrument that can make repeat measurements in a very precise way over a large area and that’s why satellites are an ideal way to study them.”

The first ICESat mission confirmed the planet’s sea ice is becoming thinner, Wagner said. “We’ve probably lost over two-thirds of the ice that used to be there back in the ’80s.”

Capable of monitoring ice levels on both land and sea, ICESat-2 will orbit 300 miles (500 km) above Earth’s surface. Its Advanced Topographic Laser Altimeter System (ATLAS) will emit single laser beams of green light, each of which will be split into six separate beams, which will be bounced off ice surfaces in a grid-like pattern. The satellite will then measure the exact time it takes for these photons to bounce off the ice and return to ATLAS. Only a small number of the photons will return.

Mission scientists will use the amount of time the photons take to return to calculate the height of the surface from which the laser was bounced.

In order for ICESat-2 to observe the same locations during each season, “The orbit is designed so that after 91 days, which is 1,387 individual orbits of the Earth, it exactly repeats itself. This allows the mission to look at the same piece of Earth in each of the four seasons,” said ICESat-2 project manager Doug McLennan.

Launch of ICESat-2 from Vandenberg Air Force Base in California is scheduled for September 15.

ESA launches satellite that will map Earth’s winds

Data the satellite returns will fill gaps in scientists’ knowledge of wind movement on Earth.

The European Space Agency (ESA) just launched the first satellite that will map Earth’s winds on a global scale, appropriately named Aeolus after the wind guardian in Greek mythology.

Aeolus is one component of a larger collaboration between the European Union (EU) and the ESA known as the Copernicus project. Its goal is to track environmental damage worldwide and assist in disaster relief operations.

Equipped with an advanced laser system known as Doppler wind lidar, which is capable of measuring wind patterns on Earth from space, the satellite launched from the Guiana Space Center in French Guiana on Wednesday, August 22, at 9:20 PM UT (5:20 PM ET), following a 24-hour delay due to poor weather.

The fifth of ESA’s Earth Explorer missions, Aeolus will be placed 200 miles (320 km) above the planet’s surface in a pole-to-pole Sun-synchronous orbit. This means it will pass over the same parts of Earth at the same time every day and always keep the same orientation in relation to the Sun.

“This mission will provide much-needed data to improve the quality of weather forecasting as well as contributing to long-term climate research,” Arianespace, the manufacturer of the Vega rocket on which Aeolus launched, stated on its website.

Scientists expect the satellite to be especially useful in measuring tropical winds, which are rarely observed directly and therefore not well mapped.

Aeolus will measure Earth’s winds by beaming short pulses of ultraviolet radiation through Earth’s atmosphere, then detecting back scatter from dust, gases, and water. The direction, speed, and distance winds traveled will be revealed by the delay between the outgoing pulses and the back scattered signal.

Data will be downloaded to a ground station in Svalbard, Norway, once every orbit.

“The Aelous mission will be a wonderful addition to our fleet of satellites that continually observe Earth, bringing us incredible insights into our planet, in particular into the complex world of atmospheric dynamics and climate processes–systems that not only affect our everyday lives but also have huge consequences for our future,” said Paolo Ferri, ESA head of mission operations, in a public statement released last month.

The mission is planned to operate for three years.

Earth’s oldest rocks came from asteroids, study reports

A new study suggests that the oldest rocks on Earth came from ancient meteorite impacts.

A group of researchers from the Curtin University have found evidence that Earth’s oldest rocks once came from meteors traveling through space, according to a new study published in the journal Nature Geoscience.

The theory — which argues that a meteorite bombardment created the ancient stones — states such an event is the only way to explain the temperature and pressure conditions that formed the oldest rocks on our world.

“We believe that these rocks may be the only surviving remnants of a barrage of extraterrestrial impacts which characterized the first 600 million years of Earth’s history,” said lead study author Tim Johnson, a geologist at Curtin University, according to Space.com.

To make the findings, scientists analyzed a 4-billion-year-old rock type — known as Idiwhaa gneiss — in northwest Canada. They looked at the chemical composition of the rocks and then modeled how they first formed. That revealed they came about through low pressures and temperatures that reached 1,650 degrees Fahrenheit.

Those conditions almost never happen under normal circumstances. When temperatures hit those levels, pressures need to be much higher. To explain that, the team turned to meteorites.

They found that in the early days of Earth impacts from space rocks would have been able to raise temperatures enough to melt rocks at the top of the crust without increasing pressure. Though most of the rocks created during that time fell back into Earth’s interior, the Idiwhaa rocks are still around to give insight into that ancient time.

“The idea of making felsic melts by large or giant impacts seems plausible considering the high-energy nature of these events and the pockmarked ancient surfaces of other inner Solar System planets and moons,” said Balz Kamber, a researcher from Trinity College Dublin who was not involved in the research, according to Phys.org.

Satellite data shows acceleration of Arctic carbon cycle

Region is behaving more like a boreal forest than a tundra.

Satellite data collected under NASA’s Arctic Boreal Vulnerability Experiment (ABoVE) confirms the Arctic carbon cycle is speeding up due to warming temperatures, causing the region to act more like a North American boreal forest than like icy tundra.

Boreal forests are those found in regions south of the Arctic, specifically cold, temperate regions.

A NASA research team analyzed over 40 years of carbon dioxide surface measurements acquired by the National Oceanic and Atmospheric Administration’s (NOAA) observatory in Barrow, Alaska, using a standard computer model geared toward ecosystem carbon balance in a study to determine the rate at which carbon is moving into and out of Alaska’s North Slope.

While computer models used in earlier studies indicated an acceleration in the region’s carbon cycle, satellite data, along with information collected from the area’s air and surface, show that acceleration to be greater than any of the models predicted.

Carbon in the North Slope’s tundra regions now spends 13 percent less time trapped in frozen soil than it did four decades ago, the researchers determined.

“Warming temperatures mean that essentially we have one ecosystem–the tundra–developing some of the characteristics of a different ecosystem–a boreal forest,” said Anthony Bloom of NASA’s Jet Propulsion Laboratory (JPL) in California. “While various factors regulate how fast this transformation will continue to occur, studies using Landsat and MODIS satellite imagery with field measurements over the past decades have observed a northward migration of shrubs and trees.”

Landsat is a joint program between NASA and the United States Geological Survey (USGS) of Earth-observing satellites that provide the longest continuous space-based Earth observations. The Moderate Resolution Imaging Spectroradiometer (MODIS) is a satellite that observes every point on Earth in discrete spectral bands every one to two days.

The Arctic carbon cycle involves the release of carbon dioxide during Arctic summers, when warmer temperatures melt the top layers of permafrost, allowing microbes to break down organic matter that had been frozen in colder weather. This triggers plant growth, with plants removing the carbon dioxide as they conduct photosynthesis.

Overall warmer temperatures mean the carbon dioxide spends less time frozen in the soil and more time in the atmosphere, a phenomenon that could have global consequences.

“The balance between these two dynamics will determine whether Arctic ecosystems will ultimately remove or add atmospheric carbon dioxide in the future climate. Our study finds the latter is more likely. We anticipate that residence time of Arctic carbon will lead to faster and more pronounced seasonal and long-term changes in global atmospheric carbon dioxide,” said former JPL researcher Sujong Jeong of Seoul National University.

A paper on the study has been published in the journal Science Advances.

“Green” comet makes closest approach to Earth

Originating from the Oort Cloud, comet is on its first trip to the inner solar system.

A green-colored comet is making its closest approach to Earth on Tuesday, August 7, as it travels on its first ever journey through the inner solar system.

Discovered with the PanSTARRS telescopes in Haleakala, Hawaii, on September 23, 2017, and designated C/2017 S3, the comet has undergone two recent outbursts, one on June 30, and the other two weeks later.

Many comets experience outbursts in which they brighten. For this unusually large comet, which came from the Oort Cloud, a reservoir of comets in the outer solar system beyond the Kuiper Belt, these outbursts give it a greenish tinge. Its second eruption produced a large gas cloud surrounding the comet that swelled to 161,000 miles (260,000 km) in diameter.

C2017 S3’s green color is the result of the ionization of its carbon and cyanide molecules due to warming from the Sun. Ionization involves the separation of electrons and protons, which produces the trademark green glow, as explained by Brian Koberlein of the Rochester Institute of Technology (RIT) in New York.

At closest approach, the comet will come within 70 million miles (112 million km) of the Earth, then head toward the Sun. It will swing around the Sun on August 16 and then head back to the distant Oort Cloud.

While C2017/S3 is currently too close to the Sun to be visible, observers will get the chance to see it after it begins heading back toward the outer solar system later this month, noted Paul Chodas, manager of the Jet Propulsion Laboratory’s (JPL) Center for Near-Earth Object Studies (CNEOS).

Regular outbursts by comets were long thought to be caused by surface heating and pressure buildup that produce explosions on their surfaces as they head toward the Sun. However, this theory was called into question by the Rosetta spacecraft’s close observations of Comet 67P/Churyumov-Gerasimenko, whose data pointed to dust kicked up and out into space by landslides on the comet’s surface as the outbursts’ cause.

The comet’s close approach involves no threat to Earth.

A 3D interactive visualization of the comet produced by JPL is available for public viewing.

Hurricane relief efforts impacted by solar flares

Better prediction is needed for space weather events.

Solar flares caused radio blackouts that disrupted hurricane relief efforts in September 2017, when three separate Atlantic Ocean storms posed a threat to land, according to a new study published in the American Geophysical Union’s (AGU) journal Space Weather.

As category 5 Hurricane Irma made landfall in Barbuda, Tropical Storm Katia intensified in the Gulf of Mexico, and Tropical Storm Jose headed toward the open ocean on September 6, two major solar flares erupted on the Sun’s surface.

Both tropical storms were upgraded to hurricanes later that day. Both solar storms were of the most intense X-class, with the first an X-2.2 and the second an X-9.3.

As warned by the National Oceanic and Atmospheric Administration’s (NOAA) Space Weather Prediction Center, radio communications went down for several hours during the morning and afternoon, as reported by amateur radio operators helping with emergency communications to the islands affected by Hurricane Irma.

Several days later, NOAA confirmed that high-frequency radio, used by emergency bands, did not operate for as long as eight hours on September 6.

Another X-class flare that erupted on the Sun on September 10 took radio communication down for three hours, just as Hurricane Jose battered the Bahamas and Leeward Islands, and Hurricane Irma bore down on Cuba.

A group of licensed amateur radio operators known as the Hurricane Watch Net confirmed the solar flares disrupted radio communications over several critical hours.

“You can hear a solar flare on the air as it’s taking place,” said Hurricane Watch Net manager Bobby Graves of Jackson, Mississippi. “It’s like hearing bacon fry in a pan; it just all of a sudden gets real staticky and then it’s like someone just turns the light completely off, you don’t hear anything. And that’s what happened this last year on two occasions. We had to wait ’til the power of those solar flares weakened, so that our signals could actually bounce back off the atmosphere. It was a helpless situation.”

The coinciding of both space and Earth weather aggravated an already tense situation, confirmed study lead author Rob Redmon, space scientist with NOAA’s National Centers for Environmental Information (NCEI) in Boulder, Colorado.

During hurricanes and tropical storms, amateur radio operators transmit crucial information regarding people who need rescue.

The study provides suggestions on improving the prediction of space weather and discusses safeguards that can be put in place to better deal with a joint recurrence of Earth and space weather. It also acknowledges that some protections that already were in place did alleviate the situation.

“Safeguards put in place to prevent dangerous disruption to GPS from solar events worked. In many ways, we were ready. Some things that could have caused big problems didn’t, but shortwave radio is always tricky to use during solar events. But good radio operators are aware of the events and will work hard to overcome problems,” stated Mike Hapgood, head of space weather at Rutherford Appleton Laboratory in the United Kingdom.