Category: Solar System

OSIRIS-REx captures first image of its target asteroid Bennu

Probe that will return asteroid surface samples to Earth will arrive at its target in three months.

NASA’s OSIRIS-REx spacecraft has taken its first image of asteroid Bennu, from which it will retrieve soil samples that will be sent back to Earth for analysis.

Launched in September 2016, NASA’s first probe to a near-Earth asteroid has traveled approximately 1.1 billion miles. It will arrive at Bennu in December of this year and fly by the asteroid’s poles and equator before entering orbit.

From a distance of 1.4 millon miles, the spacecraft’s PolyCam camera photographed its target on August 17.

“Right now, Bennu just looks like a star, a point source. That will change in November, when we begin detailed observations, and we’ll start seeing craters and boulders. You could say that’s when our asteroid will transition from being an astronomical object to an actual geological object,” said OSIRIS-REx working group lead and University of Arizona Lunar and Planetary Laboratory (LPL) staff scientist Carl Hergenrother.

Between now and the probe’s arrival date, its science instruments, which include a thermal spectrometer, a visible and infrared spectrometer, a laser altimeter, and an X-ray spectrometer, will gather data about Bennu.

Early flybys will occur at distances ranging from 4.4 to 11.8 miles above the asteroid’s surface, a challenging maneuver because Bennu is so small and has very weak gravity.

Based on the spacecraft’s studies of Bennu, the mission team will select two possible sample collection sites. Collection will occur in July 2020, followed by a return to Earth. The samples will be placed in a Sample Return Capsule, which the probe will eject to land in the Utah desert in September 2023.

“The story of this asteroid is the story of our solar system. When we understand Bennu, we will understand something fundamental about our solar system,” stated OSIRIS-REx Camera Suite (OCAMS) instrument scientist Bashar Rizk.

PolyCam, one of three cameras on the spacecraft,  is designed to function as both a long-range acquisition camera that will photograph Bennu on approach, and as a reconnaissance camera, which will take detailed images of Bennu once OSIRIS-REx arrives at its target.

After conducting a slingshot or gravity assist maneuver around the Earth last December to raise it to Bennu’s orbital plane, OSIRIS-REx has been traveling close to 32,000 miles per hour on its way to Bennu.

“Now that OSIRIS-REx is close enough to observe Bennu, the mission team will spend the next few months learning as much as possible about Bennu’s size, shape, surface features, and surroundings before the spacecraft arrives at the asteroid,” explained OSIRIS-REx principal investigator Dante Lauretta of the University of Arizona.

“After spending so long planning for this moment, I can’t wait to see what Bennu reveals to us.”

JAXA proposes possible Hayabusa 2 landing sites on asteroid Ryugu

Asteroid’s terrain and structure make site selection more difficult than anticipated.

The Japan Aerospace Exploration Agency (JAXA) has selected possible landing sites for its Hayabusa 2 probe on the asteroid Ryugu, from which it will gather samples that will be returned to Earth for analysis.

Selection of the sites required modeling and analyzing the shape of the 9,843-foot- (3,000-meter-) wide asteroid, identifying temperatures at various locations, and determining the density of boulders on its surface.

“We learned that that asteroid is not friendly to us, so [landing is] not as easy as we had supposed when we were planning the mission,” said Masaki Fujimoto, director of solar system exploration at JAXA’s Institute of Space and Astronautical Science.

During a day-long conference last week, JAXA officials announced a site designated L08 as its ideal landing location, with backup sites designated as L07 and M04. Additional, separate landing sites were given for Hayabusa 2’s MASCOT suite of science instruments and MINERVA-II-1, which holds two rovers that will be placed on Ryugu’s surface.

MASCOT carries an infrared spectrometer, a magnetometer, a radiometer, and a camera. The latter will image the distribution, structure, and texture of surface material.

All of the selected sites are flat regions located within 656 feet (200 meters) of the asteroid’s equator, have slopes less than 30 degrees, have flat regions with 328-foot (100-meter) diameters, contain boulders no higher than 20 inches (50 cm), and have temperatures below 206 degrees Fahrenheit (97 degrees Celsius).

These conditions are considered ideal for the size of Hayabusa 2’s sample device, its best operating temperature, and the direction of its solar panels.

Touchdown rehearsals for the 1,300-pound probe will be conducted on September 12 and in mid-October. Actual landing is currently planned for late October.

MINERVA-II-1 is scheduled to begin operations on September 20-21, followed by MASCOT on October 2-4.

After landing, the spacecraft will drill into Ryugu’s surface and collect subsurface samples in a capsule.

Studying Ryugu is valuable because the asteroid contains both water and the organic molecules that made up the building blocks of Earth.

Samples collected will be returned to Earth in late 2020.

InSight lander is now halfway to Mars

Tests indicate all its science instruments are healthy.

NASA’s Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) lander passed the halfway point between Earth and Mars on August 6, and tests of its science instruments indicate all are healthy and fully functional.

Launched on May 5 of this year, the lander is scheduled to touch down in Mars’s Elysium Planitia on November 26.

Mission scientists and engineers are testing software important for landing and surface operations. InSight’s highly sensitive science instruments will probe the planet’s deep interior.

Some of the instruments’ technology s being reused from NASA’s Phoenix Mars lander, which touched down on the Red Planet’s north polar region in 2008.

The lander is equipped with a seismometer, the Seismic Experiment for Interior Structure (SEIS), which will explore Mars’s internal activity by measuring ground motions in a broad range of frequencies.

Another instrument, the Heat Flow and Physical Properties Package (HP3), will burrow 10 to 16 feet (3 to 5 meters) to measure the amount of heat escaping from the planet. It will drill into the surface using a self-hammering mechanical mole connected to sensors via a science tether that will run from the mole to the surface.

To assure HP3 operates successfully, mission team members tested its main electronics, its sensors, its internal heaters, and its electronic settings.

A third science instrument, the Rotation and Interior Structure Experiment (RISE), will study changes in Mars’s rotation axis through InSight’s radio connection with Earth. This will provide scientists with important data about the composition of Mars’s core.

Mars’s rotation axis is believed to be less stable and more changeable than Earth’s because the Red Planet does not have a large moon to act as a stabilizer.

InSight’s cameras were found to be functioning well after taking a “selfie” of the spacecraft’s interior.

“If you are an engineer on InSight, that first glimpse of the heat shield blanket, harness tie-downs, and cover bolts is a very reassuring sight, as it tells us our Instrument Context Camera is operating perfectly. The next picture we plan to take with this camera will be the surface of Mars,” said InSight Project Manager Tom Hoffman of NASA’s Jet Propulsion Laboratory (JPL).

Current plans call for the cameras to photograph Elysium Planitia within minutes after landing.

Data returned by InSight is expected to help scientists better understand the processes that shaped the solar system’s rocky planets over four billion years ago.

Probe fails to detect water on asteroid Ryugu

Asteroid belongs to category of objects known to contain moisture in surface boulders.

The Japanese Aerospace Exploration Agency’s (JAXA) Hayabusa2 spacecraft has not detected any evidence of water on the asteroid Ryugu.

Since arriving at the asteroid in June of this year, the probe has studied 54,000 spots on its surface. Among the data the spacecraft returned are close up images of surface boulders and ridges.

Ryugu is classed as a C-type asteroid, a category of asteroids that contain high levels of carbon and often have moisture in the boulders on their surfaces. Scientists would like to find evidence of such moisture on Ryugu, as the presence of water could make the asteroid habitable for microbial life.

Located 186.4 million miles (300 million km) from Earth, Ryugu, which rotates on its axis once every 7.5 hours and takes 474 days to orbit the Sun, is too small and distant for observers on Earth to see its surface details.

Mission scientists are not giving up on the possibility that evidence of water might still be found on Ryugu. The probe will continue studying the near-Earth asteroid for a year and a half, during which time it will drop four small rovers on Ryugu’s surface.

After identifying an ideal landing site, the spacecraft will touch down on the surface this fall, then create a hole in that surface for sample collection by firing a metal fragment into it.

Hayabusa2 is a sample return mission, meaning the probe will collect samples from the asteroid’s surface and subsurface and return them to Earth for analysis. It will leave Ryugu in December 2019 and arrive back on Earth with the samples a year later.

“There is a possibility that water  might be discovered after an artificial crater is created on its surface next spring,” said JAXA project member Kohei Kitazato, a professor of Earth and planetary science astronomy at the University of Aizu.

Even if no evidence of water is found on Ryugu, that does not mean it never had water. It is possible that surface water once was present but subsequently evaporated, possibly through interaction with light from the Sun.

 

 

New Horizons spots ‘hydrogen wall’ at edge of solar system

For the first time in history scientists believe they may be able to view the mysterious “hydrogen wall” that sits at the edge of our solar system.

For the first time in history astronomers believe they may be able to see the so-called “hydrogen wall” at the distant edge of our solar system, according to a new study in the journal Geophysical Research Letters.

The hydrogen wall is a boundary that sits at the edge of our home system. It is where the sun’s bubble of solar wind ends and where a mass of interstellar matter that is too small to break through that wind builds up. That then creates a visible boundary that has the last remains of solar wind on one side and interstellar matter on the other.

While scientists have never been able to view the odd phenomenon before, they believe that is about to change.

New Horizons, the craft that moved past Pluto in 2015, is able to see extra ultraviolet light out at the space where the wall should be. In addition, it also appears to be the same light that NASA’s probes first detected back in 1992.

While such observations are promising, they do not necessarily show that New Horizons can view the hydrogen wall. That is because the ultraviolet light detected by the probes could easily come from another source.

However, the team is still hopeful because Alice — the instrument on board New Horizons that detected the light — is much more sensitive than anything the Voyagers had on board.

“If the ultraviolet light drops off at some point, then New Horizons may have left the wall in its rearview mirror,” wrote the researchers, according to Live Science. “But if the light never fades, then its source could be farther ahead — coming from somewhere deeper in space.”

The finding holds a lot of promise. To follow up on it, New Horizons will scan the cosmos for ultraviolet light twice a year and then report any findings back down to Earth. If anything unusual pops up again, astronomers will instantly know.

“It’s really exciting if these data are able to distinguish the hydrogen wall,” said David McComas, a researcher at Princeton University who was not involved in the new work, in a statement.

Last year’s solar eclipse viewed by record number of Americans

People continued to seek information for months after the eclipse.

The August 21, 2017, “Great American Eclipse” was observed by 216 million or 88 percent of American adults over 18 either in person or online, according to a survey conducted by Jon Miller, director of the International Center for Advancement of Scientific Literacy at the University of Michigan’s (U-M) Institute for Social Research.

Following the event, Americans continued to seek information about it through library visits, online searches, and conversations with their friends, Miller found in his national study, which is available for viewing online.

Miller polled people on the evening of August 21 and continued doing so for the following week. He followed up by surveying some of the same people and some new ones at the end of 2017 and again in February-March of this year.

“What we found was there was a substantial amount of people going online, going to libraries, talking to their friends, trying to figure out what was going to happen with the eclipse before and after the event. To a large extent, scholars have watched what people do before a scientific event but not what they do after. The event can be a stimulus that causes people to look for more information,” he said.

The number of Americans who viewed the total solar eclipse, either directly or electronically, is among the largest to view any public event, including sporting events and entertainment productions.

Of the 21 million adults who traveled to locations in or near the narrow path of totality, respondents engaged in an average of 24 activities seeking information about the eclipse in the two months leading up to the event.

Several months after the eclipse, many people continued to seek information about it and about space-related issues, Miller found in his year-end poll.

Information sought prior to the eclipse most frequently involved searches for safe methods of viewing it, including eclipse glasses and pinhole projectors.

Just three percent of those who observed the eclipse did so as part of an organized group. The majority viewed it with family members, friends, or co-workers.

“This level of public interest and information seeking about a science-oriented event is unparalleled,” Miller emphasized. “It suggests that groups and organizations interested in fostering increased adult interest in science should think about post-event programming to provide resources and a forum for these discussions.”

Last year’s spectacle was the first total solar eclipse visible in the mainland United States since 1979.

Mars orbiters studying global dust storm

Scientists hope to learn why some annual local dust storms become global events.

NASA’s Mars orbiters have been taking advantage of the rare dust storm that has engulfed the Red Planet for weeks to study its  effects on the Martian atmosphere and surface.

Dust storms that envelop the entire planet occur approximately once every three to four Martian years, or every six to eight Earth years.

In this case, a small, localized dust storm that formed on May 30 began a series of runaway storms that by June 20 created a dust cloud surrounding the entire planet.

On the ground, NASA’s Opportunity rover, which requires sunlight to recharge its batteries, went dormant and stopped communicating with Earth. However, the dust covering the rover acts as insulation, preventing its temperatures from dropping too low.

NASA’s Curiosity rover, which is nuclear-powered, can operate without sunlight and is studying the storm from its surface vantage point.

The majority of data on the storm is being collected by NASA’s Mars Reconnaissance Orbiter (MRO), Mars Odyssey, and Mars Atmosphere and Volatile EvolutioN (MAVEN).

Two MRO science instruments, the Mars Color Imager (MARCI) and the Mars Climate Sounder (MCS) are actively studying the storm. MARCI is tracing the storm’s evolution by mapping the planet during Martian afternoons while MCS is measuring changes in atmospheric temperatures at various altitudes.

When dust in the Martian atmosphere is heated by the Sun, wind patterns across the planet and even circulation of the entire atmosphere are altered. These temperature changes affect the storm by altering wind directions and carrying more surface dust into the atmosphere.

“The very fact that you can start with something that’s a local storm, no bigger than a small [U.S.] state, and then trigger something that raises more dust and produces a haze that covers almost the entire planet is remarkable,” said MRO project scientist Rich Zurek of NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California.

Through its Thermal Emission Imaging System (THEMIS), Mars Odyssey is tracking Mars’s surface and atmospheric temperatures and measuring atmospheric dust levels, all of which help scientists learn how such storms grow, evolve, and dissipate.

“This is one of the largest weather events we’ve seen on Mars. Having another example of a dust storm really helps us to understand what’s going on,” emphasized Michael Smith of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who works on THEMIS.

MRO has increased its atmospheric observations from every 10 days to twice a week since the storm began.

Instead of studying the storm, MAVEN is focusing on how it impacts Mars’s upper atmosphere approximately 62 miles (100 km) above the surface. This orbiter’s primary goal is to determine the fate of ancient Mars’s atmosphere, and its findings suggest that atmosphere was stripped by the solar wind between 3.5 and four billion years ago.

MAVEN scientists hope to learn whether atmospheric escape is altered when dust traps heat from the Sun. A warmer atmosphere may have caused ancient water vapor to rise to a position where it was broken up by sunlight, causing its hydrogen atoms to escape into space.

 

Passing star may have perturbed outer solar system

Orbits of outer solar system objects are warped and distorted.

A star that passed close to our solar system several billion years ago may have perturbed outer solar system objects, according to a new study based on computer simulations led by Susanne Pfalzner of the Max Planck Institute for Radio Astronomy in Bonn, Germany.

Many dwarf planets and smaller Trans-Neptunian Objects (TNOs) beyond the orbit of Pluto have extremely inclined, eccentric orbits, which scientists are hard pressed to explain. For example, dwarf planet Sedna takes 11,400 years to complete a single orbit around the Sun.

Additionally, the outer solar system is emptier than researchers think it should be.

Although Neptune orbits further from the Sun than Uranus, it is more massive, posing yet another puzzle.

These anomalies led researchers to propose a rogue star passed close to the solar system in its early days, in the process scattering thousands of distant, icy worlds into unusual positions and orbits.

“You could well have a hybrid scenario, where the movement of the planets is responsible for the things we find in the inner solar system, like the low mass of Mars, and a flyby [is responsible] for the properties of the outer solar system,” Pfalzner said.

Using data on the behavior of young stars, the researchers conducted a computer simulation of a stellar flyby to determine whether the passage of a rogue star could have caused the current arrangement of the outer solar system.

According to the simulation, the chances of a star having done this over a period of one billion years are approximately one in four, meaning this likely occurred at some point in the solar system’s early years.

Specifically, the simulation determined that a star with a mass similar to that of our Sun could have created the dynamics seen in the outer solar system if it passed within 80 to 100 astronomical units (AU, with one AU equal to the average Earth-Sun distance or 93 million miles) while the system was still forming.

During its passage, the star could have flung thousands of tiny, icy worlds beyond Pluto into interstellar space, leaving the outer solar system with the empty regions it has today.

The researchers plan to further test their theory by adding more detail to their computer simulations.

A paper on their findings has been accepted for publication in the Astrophysical Journal.

 

Hayabusa2 captures closeup image of asteroid Ryugu

Boulders and dust photographed following free fall experiment.

Japan’s Hayabusa2, a spacecraft on a mission to return an asteroid sample to Earth, captured a closeup image of its target revealing surface features just a few feet in diameter.

The Japan Aerospace Exploration Agency’s (JAXA) Hayabusa2 probe entered orbit around asteroid 162173 Ryugu on June 27 of this year. In practice for its eventual landing on the asteroid, it descended from a height of 12.5 miles (20 km) to a distance of just 2,792 feet (851 meters) above the surface after spending 21 hours in free fall.

From a distance of just 0.6 miles (one km), Hayabusa2 trained its Optical Navigation Camera–Wide Angle on Ryugu’s surface, revealing large rocks and dust.

Mission controllers conducted the descent on August 6 for the purpose of gaining a better understanding of the asteroid’s gravity.

“By monitoring the exact movement of the Hayabusa2, we can see how strong the gravitational attraction is from Ryugu,” a JAXA statement explained.

Several images of Ryugu were taken as the spacecraft fell toward the asteroid.

Although Ryugu occasionally crosses Earth’s orbit and is classified as a potentially hazardous asteroid, it poses no threat to our planet. However, by studying its composition, scientists will likely gain valuable insight into appropriate methods of deflecting or destroying any similar asteroids that may one day pose such threats.

Studying Ryugu’s composition will also provide researchers with important information about the history of the solar system.

In 2010, JAXA’s first asteroid sample return mission, Hayabusa, successfully brought back samples of asteroid 25143 Itokawa to Earth.

The Hayabusa2 spacecraft, launched in December 2014, was built with improved ion engines, navigation technology, guidance technology, antennas, and attitude control systems. It will drop a lander and three rovers onto Ryugu’s surface and use an explosive device to obtain samples of its subsurface.

After collecting samples multiple times, Hayabusa2 will leave Ryugu in December 2019 and return home a year later.

Following its successful closeups of the asteroid, Hayabusa2 fired its thrusters and returned to an altitude of approximately 3.1 miles (five km) above its target’s surface.

Perseid meteor shower to peak this weekend

Lack of visible Moon will make this the year’s best meteor shower.

Skywatchers will have ideal viewing conditions to watch the annual Perseid meteor shower, which will peak this weekend, between August 10 and 13.

Named for the Perseus constellation from which it originates, this meteor shower is visible every year in August when Earth passes through debris from the comet Swift-Tuttle. A short-period comet, Swift-Tuttle takes 133 years to circle the Sun. Each time it makes its closest approach, the Sun’s heat and tidal forces cause pieces of it to break off, leaving behind a debris field.

The Perseids will be especially bright this year because the meteor shower occurs at the new Moon, when the Moon will not be present to brighten the sky and obscure the meteors. Night skies without a Moon are darker and provide the best opportunities for meteor viewing.

“This year, the Moon will be near new Moon; it will be a crescent, which means it will set before the Perseid show gets underway after midnight. The Moon is very favorable for the Perseids this year, and that’ll make the Perseids probably the best shower of 2018 for people who want to go out and view it,” NASA meteor specialist Bill Cooke told the website Space.com.

On Saturday night August 11, viewers with dark skies should be able to see between 60 and 70 meteors per hour. An online map of areas across the country with the least light pollution, created by a research team at the Cooperative Institute for Research in Environmental Sciences (CIRES) and Chris Elvidge of the National Oceanic and Atmospheric Administration (NOAA) is available to guide viewers to the best locations.

Both the brightness of meteor showers and the number of meteors visible are determined by several factors, including the density of the debris field, the debris field’s relative speed in relation to Earth, the distance between Earth and the debris field, and the degree of light pollution at a viewing site.

Observers should allow approximately 30 minutes for their eyes to adapt to the dark.

While the shower peaks this weekend, Perseid meteors can be seen any clear night between July 17 and August 24.