Category Archives: Asteroids & Comets

Asteroids & Comets, Space Science

NASA DART and ESA Hera to study deflecting asteroids via spacecraft impact

ESA and NASA are testing defenses against an asteroid threat:

Earth’s first mission to a binary asteroid,
for planetary defence

Hera is the European contribution to an ESA-NASA double-spacecraft mission intended to test whether a kinetic deflection technique can be used to shift the orbit of an asteroid. Target of the mission is a double asteroid system, called Didymos, which will come a comparatively close 11 million km to Earth in 2022. The 800-m diameter main body is orbited by a 170-m moon, informally called ‘Didymoon’. In 2022 NASA will first perform a kinetic impact on the smaller of the two bodies, then Hera will follow-up with a detailed post-impact survey that will turn this grand-scale experiment into a well-understood and repeatable planetary defence technique.

25 June 2018: Planning for humankind’s first mission to a binary asteroid system has entered its next engineering phase. ESA’s proposed Hera mission would also be Europe’s contribution to an ambitious planetary defence experiment.

Named for the Greek goddess of marriage, Hera would fly to the Didymos pair of Near-Earth asteroids: the 780 m-diameter mountain-sized main body is orbited by a 160 m moon, informally called ‘Didymoon’, about the same size as the Great Pyramid of Giza.

“Such a binary asteroid system is the perfect testbed for a planetary defence experiment but is also an entirely new environment for asteroid investigations. Although binaries make up 15% of all known asteroids, they have never been explored before, and we anticipate many surprises,”

explains Hera manager Ian Carnelli.

“The extremely low-gravity environment also presents new challenges to the guidance and navigation systems. Fortunately we can count on the unique experience of ESA’s Rosetta operations team which is an incredible asset for the Hera mission.”

The smaller Didymoon is Hera’s main focus: the spacecraft would perform high-resolution visual, laser and radio science mapping of the moon, which will be the smallest asteroid visited so far, to build detailed maps of its surface and interior structure.

By the time Hera reaches Didymos, in 2026, Didymoon will have achieved historic significance: the first object in the Solar System to have its orbit shifted by human effort in a measurable way.

A NASA mission called the Double Asteroid Redirection Test, or DART, is due to collide with it in October 2022. The impact will lead to a change in the duration of Didymoon’s orbit around the main body. Ground observatories all around the world will view the collision, but from a minimum distance of 11 million km away.

“Essential information will be missing following the DART impact – which is where Hera comes in,” adds Ian. “Hera’s close-up survey will give us the mass of Didymoon, the shape of the crater, as well as physical and dynamical properties of Didymoon.

“This key data gathered by Hera will turn a grand but one-off experiment into a well-understood planetary defence technique: one that could in principle be repeated if we ever need to stop an incoming asteroid.”

The traditional method of estimating the mass of a planetary body is to measure its gravitational pull on a spacecraft. That is not workable within the Didymos system: Didymoon’s gravitational field would be swamped by that of its larger partner.

Hera uses infrared to scan impact crater.

Instead, Hera imagery will be used to track key landmarks on the surface on the bigger body, ‘Didymain’, such as boulders or craters. By measuring the ‘wobble’ Didymoon causes its parent, relative to the common centre of gravity of the overall two-body system, its mass could be determined with an accuracy over 90%.

Hera will also measure the crater left by DART to a resolution of 10 cm, accomplished through a series of daring flybys, giving insight into the surface characteristics and internal composition of the asteroid.

“Hera benefits from more than five years of work put into ESA’s former Asteroid Impact Mission,” comments Ian. “Its main instrument is a replica of an asteroid imager already flying in space – the Framing Camera used by NASA’s Dawn mission as it surveys Ceres, which is provided by the German Aerospace Center, DLR.

“It would also carry a ‘laser radar’ lidar for surface ranging, as well as a hyperspectral imager to characterise surface properties. In addition, Hera will deploy Europe’s first deep space CubeSats to gather additional science as well as test advanced multi-spacecraft intersatellite links.”

NASA’s DART mission meanwhile has passed its preliminary design review and is about to enter its ‘Phase C’ detailed design stage.

In 2022, NASA’s Double Asteroid Redirection Test (DART) collides with the smaller body of the Didymos binary asteroid system in an attempt to measurably shift its orbit. ESA’s Hera mission, now under study, will examine the aftermath of this impact to help determine whether humans can deflect threatening asteroids.

=====

 

Asteroids & Comets, Events, Space participation

Asteroid Day – June 30, 2018

Saturday June 30th is Asteroid Day: 

Asteroid Day is a global awareness campaign where people from around the world come together to learn about asteroids, the impact hazard they may pose, and what we can do to protect our planet, families, communities, and future generations from future asteroid impacts. Asteroid Day is held each year on the anniversary of the largest impact in recent history, the 1908 Tunguska event in Siberia. 

In this brief video, Neil deGrasse Tyson tells the story behind Asteroid Day.

Here is a list and map of Asteroid Day events around the world: Plan your Event | Asteroid Day.

All around the globe, regionally organised events are held on Asteroid Day. These events range from live concerts and community events, to lectures and other educational programmes, to raise public awareness of the need for increased detection and mapping of asteroids.

Check out the set of resources including infographics, class lesson plans, paper models, etc : Asteroid Day Resources.

Submit a question to the Asteroid Day Expert Panel:

The Asteroid Day Expert Panel is chaired by Physicist Dr. Mark Boslough (left) and consists of 16 world–class asteroid experts. They oversee the scientific information Asteroid Day is publicising to guarantee accuracy.  They are always happy to answer any asteroid related questions you may have.

Get updates at

Here is the movie 51 Degrees North which

 inspired Asteroid Day. It was directed by co-founder Grigorij Richters and the music was composed by Dr. Brian May. We are proud to present to you this alternate version of the film, by Discovery Science. As an event organiser you can have access to download both the full length film (88 minutes) or the 45 minute (Discovery Science) version. Event organizers must fill out this form to download the movie.


51 Degrees North – Full movie, free. from Asteroid Day on Vimeo.

====

Asteroids & Comets, Astronomy, fireballs

Videos: Boulder-sized asteroid discovered in space shortly before causing fireball over South Africa

A two meter wide meteoroid was tracked in space last Saturday and later that day he created a fireball over South Africa. This video shows the “Meteor 2018 LA (ZLAF9B2) [as] seen from farm between Ottosdal and Hartebeesfontein North West South Africa”:

This NASA JPL article describes the

Tiny Asteroid Discovered Saturday
Disintegrates Hours Later Over Southern Africa 

A boulder-sized asteroid designated 2018 LA was discovered Saturday morning, June 2, and was determined to be on a collision course with Earth, with impact just hours away. Because it was very faint, the asteroid was estimated to be only about 6 feet (2 meters) across, which is small enough that it was expected to safely disintegrate in Earth’s atmosphere. Saturday’s asteroid was first discovered by the NASA-funded Catalina Sky Survey, located near Tucson and operated by the University of Arizona.

Although there was not enough tracking data to make precise predictions ahead of time, a swath of possible locations was calculated stretching from Southern Africa, across the Indian Ocean, and onto New Guinea. Reports of a bright fireball above Botswana, Africa, early Saturday evening match up with the predicted trajectory for the asteroid. The asteroid entered Earth’s atmosphere at the high speed of 10 miles per second (38,000 mph, or 17 kilometers per second) at about 16:44 UTC (9:44 a.m. PDT, 12:44 p.m. EDT,6:44 p.m. local Botswana time) and disintegrated several miles above the surface, creating a bright fireball that lit up the evening sky. The event was witnessed by a number of observers and was caught on webcam video [see above].

When it was first detected, the asteroid was nearly as far away as the Moon’s orbit, although that was not initially known. The asteroid appeared as a streak in the series of time-exposure images taken by the Catalina telescope. As is the case for all asteroid-hunting projects, the data were quickly sent to the Minor Planet Center in Cambridge, Massachusetts, which calculated a preliminary trajectory indicating the possibility of an Earth impact. The data were in turn sent to the Center for Near-Earth Object Studies (CNEOS) at NASA’s Jet Propulsion Laboratory in Pasadena, California, where the automated Scout system also found a high probability that the asteroid was on an impact trajectory. Automated alerts were sent out to the community of asteroid observers to obtain further observations, and to the Planetary Defense Coordination Office at NASA Headquarters in Washington. However, since the asteroid was determined to be so small and therefore harmless, no further impact alerts were issued by NASA.

“This was a much smaller object than we are tasked to detect and warn about,” said Lindley Johnson, Planetary Defense Officer at NASA Headquarters. “However, this real-world event allows us to exercise our capabilities and gives some confidence our impact prediction models are adequate to respond to the potential impact of a larger object.”

The ATLAS asteroid survey obtained two additional observations hours before impact, which were used by Scout to confirm the impact would occur, and narrowed down the predicted location to southern Africa. Infrasound data collected just after the impact clearly detected the event from one of the listening stations deployed as part of the International Monitoring System of the Comprehensive Nuclear-Test-Ban Treaty. The signal is consistent with an atmospheric impact over Botswana.

“The discovery of asteroid 2018 LA is only the third time that an asteroid has been discovered to be on an impact trajectory, said Paul Chodas, manager of the Center for Near-Earth Object Studies (CNEOS) at JPL. “It is also only the second time that the high probability of an impact was predicted well ahead of the event itself.”

The first event of this kind was the impact of asteroid 2008 TC3, which lit up the predawn sky above Northern Sudan on October 7, 2008. That was a slightly larger asteroid (about 13 feet, or 4 meters in size), and it was discovered a full 19 hours before impact, allowing for a large number of follow-up observations and a very precise trajectory to be calculated. The second predicted impact event was for asteroid 2014 AA, which was discovered only a few hours before impact on Jan. 1, 2014, in the Atlantic Ocean, leaving too little time for follow-up observations. The Catalina Sky Survey has been responsible for discovering all three of these small asteroids on impact trajectories, and all on the watch of the same observer, Richard Kowalski.

NASA’s Planetary Defense Coordination Office is responsible for finding, tracking and characterizing potentially hazardous asteroids and comets coming near Earth, issuing warnings about possible impacts, and assisting coordination of U.S. government response planning, should there be an actual impact threat. JPL hosts the Center for Near-Earth Object Studies for NASA’s Near-Earth Object Observations Program, an element of the Planetary Defense Coordination Office within the agency’s Science Mission Directorate.

For more information about NASA’s Planetary Defense Coordination Office, visit: https://www.nasa.gov/planetarydefense

More information about asteroids and near-Earth objects can be found at:

For asteroid and comet news and updates, follow AsteroidWatch on Twitter. twitter.com/AsteroidWatch

====

Asteroids & Comets, Astronomy

ESO: “Exiled Asteroid Discovered in Outer Reaches of Solar System”

The latest news from ESO (European Southern Observatory):

Exiled Asteroid Discovered in Outer Reaches of Solar System

This artist’s impression shows the exiled asteroid 2004 EW95, the first carbon-rich asteroid confirmed to exist in the Kuiper Belt and a relic of the primordial Solar System. This curious object likely formed in the asteroid belt between Mars and Jupiter and must have been transported billions of kilometres from its origin to its current home in the Kuiper Belt. [Larger images]
An international team of astronomers has used ESO telescopes to investigate a relic of the primordial Solar System. The team found that the unusual Kuiper Belt Object 2004 EW95 is a carbon-rich asteroid, the first of its kind to be confirmed in the cold outer reaches of the Solar System. This curious object likely formed in the asteroid belt between Mars and Jupiter and has been flung billions of kilometres from its origin to its current home in the Kuiper Belt.

The early days of our Solar System were a tempestuous time. Theoretical models of this period predict that after the gas giants formed they rampaged through the Solar System, ejecting small rocky bodies from the inner Solar System to far-flung orbits at great distances from the Sun [1]. In particular, these models suggest that the Kuiper Belt — a cold region beyond the orbit of Neptune — should contain a small fraction of rocky bodies from the inner Solar System, such as carbon-rich asteroids, referred to as carbonaceous asteroids [2].

Now, a recent paper has presented evidence for the first reliably-observed carbonaceous asteroid in the Kuiper Belt, providing strong support for these theoretical models of our Solar System’s troubled youth. After painstaking measurements from multiple instruments at ESO’s Very Large Telescope (VLT), a small team of astronomers led by Tom Seccull of Queen’s University Belfast in the UK was able to measure the composition of the anomalous Kuiper Belt Object 2004 EW95, and thus determine that it is a carbonaceous asteroid. This suggests that it originally formed in the inner Solar System and must have since migrated outwards [3].

An international team of astronomers has used ESO telescopes to investigate a relic of the primordial Solar System. The team found that the unusual Kuiper Belt Object 2004 EW95 is a carbon-rich asteroid, the first of its kind to be confirmed in the cold outer reaches of the Solar System. The red line in this image shows the orbit of 2004 EW95, with the orbits of other Solar System bodies shown in green for comparison. [Larger images]
The peculiar nature of 2004 EW95 first came to light during routine observations with the NASA/ESA Hubble Space Telescope by Wesley Fraser, an astronomer from Queen’s University Belfast who was also a member of the team behind this discovery. The asteroid’s reflectance spectrum — the specific pattern of wavelengths of light reflected from an object — was different to that of similar small Kuiper Belt Objects (KBOs), which typically have uninteresting, featureless spectra that reveal little information about their composition.

“The reflectance spectrum of 2004 EW95 was clearly distinct from the other observed outer Solar System objects,” explains lead author Seccull. “It looked enough of a weirdo for us to take a closer look.”

The team observed 2004 EW95 with the X-Shooter and FORS2 instruments on the VLT. The sensitivity of these spectrographs allowed the team to obtain more detailed measurements of the pattern of light reflected from the asteroid and thus infer its composition.

However, even with the impressive light-collecting power of the VLT, 2004 EW95 was still difficult to observe. Though the object is 300 kilometres across, it is currently a colossal four billion kilometres from Earth, making gathering data from its dark, carbon-rich surface a demanding scientific challenge.

“It’s like observing a giant mountain of coal against the pitch-black canvas of the night sky,”

says co-author Thomas Puzia from the Pontificia Universidad Católica de Chile.

“Not only is 2004 EW95 moving, it’s also very faint,” adds Seccull. “We had to use a pretty advanced data processing technique to get as much out of the data as possible.”

Two features of the object’s spectra were particularly eye-catching and corresponded to the presence of ferric oxides and phyllosilicates. The presence of these materials had never before been confirmed in a KBO, and they strongly suggest that 2004 EW95 formed in the inner Solar System.

Seccull concludes:

“Given 2004 EW95’s  present-day abode in the icy outer reaches of the Solar System, this implies that it has been flung out into its present orbit by a migratory planet in the early days of the Solar System.”

[ Olivier Hainaut, an ESO astronomer who was not part of the team, comments, ]

“While there have been previous reports of other ‘atypical’ Kuiper Belt Object spectra, none were confirmed to this level of quality,” … “The discovery of a carbonaceous asteroid in the Kuiper Belt is a key verification of one of the fundamental predictions of dynamical models of the early Solar System.”

Notes

[1] Current dynamical models of the evolution of the early Solar System, such as the grand tack hypothesis and the Nice model, predict that the giant planets migrated first inward and then outward, disrupting and scattering objects from the inner Solar System. As a consequence, a small percentage of rocky asteroids are expected to have been ejected into orbits in the Oort Cloud and Kuiper belt.

[2] Carbonaceous asteroids are those containing the element carbon or its various compounds. Carbonaceous — or C-type — asteroids can be identified by their dark surfaces, caused by the presence of carbon molecules.

[3] Other inner Solar System objects have previously been detected in the outer reaches of the Solar System, but this is the first carbonaceous asteroid to be found far from home in the Kuiper Belt.

=====

Asteroids & Comets, Astronomy, Education

Video: Rubble Piles in the Sky – The Science, Exploration, and Danger of Near-Earth Asteroids

Dr. Michael Busch of the SETI Institute recently gave the following talk in the Silicon Valley Astronomy Lecture Series sponsored by the Astronomical Society of the Pacific:  Rubble Piles in the Sky: The Science, Exploration, and Danger of Near-Earth Asteroids –

Near-Earth asteroids are a population of small bodies whose orbits around the Sun cross or come near our planet’s orbit. They turn out to be unusual physical environments: essentially rubble piles. They represent a natural hazard we ignore at our peril, because some of these bodies have the potential to impact Earth. Dr. Busch reviews the near-Earth population, programs to track and characterize near-Earth asteroids, and current efforts to address the danger of asteroid impacts.

====