It’s International Asteroid Day, and today we’re talking about everything asteroids! Although there are no known threats for the next 100 years, our Planetary Defense experts are constantly finding, tracking, and monitoring near-Earth objects to protect our home planet.

Asteroids are rocky remnants from the beginning of our solar system, and as of today, 26,110 near-Earth asteroids have been discovered!

So how do we spot these near-Earth objects? Let’s watch and see:

In addition to tracking and monitoring asteroids, we are also launching several missions to study these rocky relics. By studying asteroids, we can better understand the formation of our solar system. Here are some exciting missions you can look forward to:

OSIRIS-REx: Returning a Sample from Asteroid Bennu

Last year, our OSIRIS-REx mission successfully captured a sample of asteroid Bennu, a 4.5-billion-year-old asteroid the size of the empire state building.

Currently, OSISRIS-REx is making its long journey home carrying this sample as it returns to Earth in 2023.

Psyche: A Journey to a Metal World

Our Psyche mission will journey to a unique metal asteroid orbiting the Sun between Jupiter and Mars.

What makes the asteroid Psyche unique is that it appears to be the exposed nickel-iron core of an early planet, one of the building blocks of our solar system. Deep within rocky, terrestrial planets - including Earth - scientists infer the presence of metallic cores, but these lie unreachably far below the planets’ rocky mantles and crusts. Because we cannot see or measure Earth’s core directly, Psyche offers a unique window into the violent history of collisions and accretion that created terrestrial planets.

Lucy: Studying the Trojan Asteroids

Launching this year, our Lucy mission will be the first mission to study the Trojans, a group of asteroids that share Jupiter’s orbit around the Sun. Time capsules from the birth of our Solar System more than 4 billion years ago, the swarms of Trojan asteroids associated with Jupiter are thought to be remnants of the primordial material that formed the outer planets.

The mission takes its name from the fossilized human ancestor (called “Lucy” by her discoverers) whose skeleton provided unique insight into humanity’s evolution. Likewise, the Lucy mission will revolutionize our knowledge of planetary origins and the formation of the solar system.

DART: Double Asteroid Redirection Test

Launching this year, our DART mission is a planetary defense driven test of technologies and will be the first demonstration of a technique to change the motion of an asteroid in space.

The destination of this mission is the small asteroid Dimorphos, which orbits slowly around its larger companion Didymos. Dimorphos is referred to as a moonlet since it orbits a larger asteroid.

The DART spacecraft will achieve the kinetic impact deflection by deliberately crashing itself into the moonlet. The collision will change the speed of the moonlet in its orbit around the main body by a fraction of one percent, but this will change the orbital period of the moonlet by several minutes - enough to be observed and measured using telescopes on Earth.

At NASA, every day is asteroid day, as we have missions exploring these time capsules of our solar system and surveying the sky daily to find potential hazards. We, along with our partners are watching the skies 24/7/365, so rest assured! We’re always looking up.

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Our solar system is littered with asteroids and comets, and sometimes they get a little close to Earth. But no need to worry! This happens all the time. When an asteroid or comet could come close to our planet, it’s known as a near-Earth object – aka NEO.

But how close is “close”?

A near-Earth object is defined as an object that could pass by our Earth within 30 million miles. We begin to keep close watch on objects that could pass within 5 million miles of our planet.

To put that into perspective, our Moon is only 238,900 miles away.

However unlikely an impact is, we want to know about all near-Earth objects. Our Planetary Defense Coordination Office maintains watch for asteroids and comets coming close to Earth. Along with our partners, we discover, catalog and characterize these bodies.

But what if one of these objects posed a threat?

We want to be prepared. That is why we are working on several deflection techniques and technologies to help protect our planet.

So next time that you hear of an asteroid passing “close” to Earth, know that it’s just one of many that we are tracking.

Here are 10 more things you should know about Planetary Defense.

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On October 20^th, our OSIRIS-REx mission will make its first attempt to collect and retrieve a sample of asteroid Bennu, a near-Earth asteroid. On sample collection day, Bennu will be over 200 million miles away from Earth.  

Asteroids are the building blocks of our solar system. A sample of this ancient material can tell us about the history of our planet and the origins of life. Science results published from the mission on October 8^th confirm that Bennu contains carbon in a form often found in biology or in compounds associated with biology.

To collect a sample, OSIRIS-REx will attempt a method NASA has never used before – called Touch-And-Go (TAG).  First, the spacecraft extends its robotic sampling arm, the Touch-And-Go Sample Acquisition Mechanism (TAGSAM) – from its folded storage position. The spacecraft’s two solar panels then move into a “Y-wing” configuration over the spacecraft’s body, which positions them safely up and away from the asteroid’s surface during touch down. This configuration also places the spacecraft’s center of gravity directly over the TAGSAM collector head, which is the only part of the spacecraft that will contact Bennu’s surface.

Finding a safe sample collection site on Bennu’s rocky landscape was a challenge. During the sampling event, the spacecraft, which is the size of a large van, will attempt to touch down in an area that is only the size of a few parking spaces, and just a few steps away from enormous boulders.

The spacecraft will only make contact with Bennu for a matter of seconds - just long enough to blow nitrogen gas onto the surface to roil up dust and small pebbles, which will then be captured for a return to Earth.

We need to conduct a few tests before we can confirm we collected a large enough sample (about 2 oz). First, OSIRIS-REx will take images of the collector head to see if it contains rocks and dust. Second, the spacecraft will spin with the TAGSAM extended to determine the mass of collected material. If these measures show a successful collection, we will stow the sample for return to Earth. If sufficient sample has not been collected, the spacecraft has onboard nitrogen charges for two more attempts. The next TAG attempt would be made no earlier than January 2021.

Despite the many challenges, the OSIRIS-REx team is ready. They’ve practiced and prepared for this moment.

Join in with #ToBennuAndBack and tune in on October 20^th.

Learn more about the OSIRIS-REx countdown to TAG HERE.

Learn more about the OSIRIS-REx mission HERE, or follow the mission on Facebook, Twitter and Instagram.

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This week, we’re at one of the biggest science conferences in the country, where our scientists are presenting new results from our missions and projects. It’s called the American Geophysical Union’s Fall Meeting.

Here are a few of the things we shared this week…

The Sun

A few months into its seven-year mission, Parker Solar Probe has already flown far closer to the Sun than any spacecraft has ever gone. The data from this visit to the Sun has just started to come back to Earth, and scientists are hard at work on their analysis.

Parker Solar Probe sent us this new view of the Sun’s outer atmosphere, the corona. The image was taken by the mission’s WISPR instrument on Nov. 8, 2018, and shows a coronal streamer seen over the east limb of the Sun. Coronal streamers are structures of solar material within the Sun’s atmosphere, the corona, that usually overlie regions of increased solar activity. The fine structure of the streamer is very clear, with at least two rays visible. Parker Solar Probe was about 16.9 million miles from the Sun’s surface when this image was taken. The bright object near the center of the image is Mercury, and the dark spots are a result of background correction.

Hurricane Maria

Using a satellite view of human lights, our scientists watched the lights go out in Puerto Rico after Hurricane Maria. They could see the slow return of electricity to the island, and track how rural and mountainous regions took longer to regain power.

In the spring, a team of scientists flew a plane over Puerto Rico’s forests, using a laser instrument to measure how trees were damaged and how the overall structure of the forests had changed.

Earth’s Ice

Our scientists who study Antarctica saw some surprising changes to East Antarctica. Until now, most of the continent’s melting has been on the peninsula and West Antarctica, but our scientists have seen glaciers in East Antarctica lose lots of ice in the last few years.

Our ICESat-2 team showed some of their brand new data. From the changing height of Antarctic ice to lagoons off the coast of Mexico, the little satellite has spent its first few months measuring our planet in 3D. The laser pulses even see individual ocean waves, in this graph.

Scientists are using our satellite data to track Adélie penguin populations, by using an unusual proxy – pictures of their poop! Penguins are too small to be seen by satellites, but they can see large amounts of their poop (which is pink!) and use that as a proxy for penguin populations.

Asteroid Bennu

Our OSIRIS-REx mission recently arrived at its destination, asteroid Bennu. On approach, data from the spacecraft’s spectrometers revealed chemical signatures of water trapped in clay minerals.  While Bennu itself is too small to have ever hosted liquid water, the finding indicates that liquid water was present at some time on Bennu’s parent body, a much larger asteroid.

We also released a new, detailed shape model of Bennu, which is very similar to our ground-based observations of Bennu’s shape. This is a boon to ground-based radar astronomy since this is our first validation of the accuracy of the method for an asteroid! One change from the original shape model is the size of the large boulder near Bennu’s south pole, nicknamed “Benben.” The boulder is much bigger than we thought and overall, the quantity of boulders on the surface is higher than expected. Now the team will make further observations at closer ranges to more accurately assess where a sample can be taken on Bennu to later be returned to Earth.

Jupiter

The Juno mission celebrated it’s 16th science pass of #Jupiter, marking the halfway point in data collection of the prime mission. Over the second half of the prime mission — science flybys 17 through 32 — the spacecraft will split the difference, flying exactly halfway between each previous orbit. This will provide coverage of the planet every 11.25 degrees of longitude, providing a more detailed picture of what makes the whole of Jupiter tick.

Mars

The Mars 2020 team had a workshop to discuss the newly announced landing site for our next rover on the Red Planet. The landing site…Jezero Crater! The goal of Mars 2020 is to learn whether life ever existed on Mars. It’s too cold and dry for life to exist on the Martian surface today. But after Jezero Crater formed billions of years ago, water filled it to form a deep lake about the same size as Lake Tahoe. Eventually, as Mars’ climate changed, Lake Jezero dried up. And surface water disappeared from the planet.

Interstellar Space

Humanity now has two interstellar ambassadors. On Nov. 5, 2018, our Voyager 2 spacecraft left the heliosphere — the bubble of the Sun’s magnetic influence formed by the solar wind. It’s only the second-ever human-made object to enter interstellar space, following its twin, Voyager 1, that left the heliosphere in 2012.

Scientists are especially excited to keep receiving data from Voyager 2, because — unlike Voyager 1 — its plasma science instrument is still working. That means we’ll learn brand-new information about what fills the space between the stars.

Learn more about NASA Science at science.nasa.gov. 

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