Mars Trojans may be part of a planet that was destroyed long ago

Mars has an asteroid entourage, with nine so-called Trojans trailing in its wake. Now it seems these travelling companions all had the same violent beginning: as the innards of a mini-planet, eviscerated in a violent collision. Some remnants may even have been incorporated into the material that became Mars.

Trojans are distinct from the asteroids found in the asteroid belt, which begins about 101 million kilometres past Mars and stretches toward Jupiter. While Trojans orbit the sun, like the asteroid belt, they are trapped in gravitational sweet spots that ensure they will permanently trail or precede the planet in its trip around our star. These are known as Lagrange points.

Mars is the only rocky planet accompanied by Trojan asteroids in stable orbits. Occasionally, a passing asteroid can latch on to Earth’s gravity and temporarily trail the planet for a few thousand years, but Earth doesn’t have any permanent Trojans. They are common around Jupiter, which has about 6000. Neptune has 10.

True Trojans come from the material that was present when the planets were formed, says Apostolos Christou at the Armagh Observatory and Planetarium in the UK. “The Trojans are really a relic from the early life of the solar system, when the planets were still forming.”

Trojan Eureka

In 2013, he was studying a Mars Trojan nicknamed Eureka when he spotted a group of asteroids accompanying it. They all seemed to occupy the same area in Mars’s orbital path, which was strong circumstantial evidence that they shared a common ancestor.

Previous research on Eureka showed it is rich in a mineral called olivine, which typically forms within the mantles of large rocky bodies, such as Earth and the other terrestrial planets. This implies the asteroid was once part of a bigger object, maybe even a planet, that has long since been destroyed. But asteroids like this are quite rare.

To find out if Eureka’s fellow Trojans also contained olivine, Christou studied the spectrum of sunlight that two of them reflected and found they did. This suggests that mantle material existed near Mars when it was forming.

“These asteroids might well be samples of the original building blocks that came together to form Mars and the other terrestrial planets,” Christou and his co-authors say.

Shaved planet

It is also possible that the Trojans are pieces of Mars itself, shaved off the planet in its youth and still following in its wake, Christou says.

“If it turns out that some of the Trojans are pieces of Mars’s mantle, then presumably we can have sample return missions. You can go get a piece,” he says. “The number of Mars-related science questions you can ask, if you have a piece of its mantle in the lab, would be amazing.”

The Eureka Trojans could shed light on Mars’s past whether the asteroids originated in the planet or not, says Andrew Rivkin at Johns Hopkins University in Maryland, who studies asteroids. If they did come from Mars, their make-up would give clues about the planet’s interior and formation.

If not, they could still provide clues about where Mars might have been located in the solar system in the past; about collisions that carved out its giant craters; and about the natural history of Mars compared to that of Earth, Venus and Mercury.

“Then solar system dynamics researchers would have to look at it and say, ‘Here’s why Mars has this group of asteroids, and here’s why Earth doesn’t’,” says Rivkin. He adds that interest in Mars Trojans seems to spike every few years. “Hopefully in the next 10 years, we’ll get to have a spacecraft visit them.”

Journal reference: Monthly Notices of the Royal Astronomical Society, DOI: 10.1093/mnras/stw3075

Original article here.

NEOShield-2 Participation at ACM 2017 in Montevideo

ACM 2017 Davide Perna Line Drube

The series of conferences “Asteroids, Comets, Meteors” focuses on the research of small Solar System bodies. The series constitutes the leading international meeting in this field. The first three conferences took place in Uppsala, Sweden in the 1980’s, and afterwards they were organized every ~3 years all over the world. In the last editions, a sequence was started where the conference has been held in different continents. In 2017, ACM was held in South America, more precisely in Montevideo, Uruguay.

The conference took place from April 10 to April 14, 2017. During 5 days, scientists from all over the world shared their studies with hundreds of attendees.

On Tuesday, April 11, Davide Perna, from the Observatoire de Paris, member of the NEOShield-2 project, gave a speech about “Physical Properties of the NEA Population”, where he presented the project and also the preliminary results from spectroscopic observations at NTT in Chile.

ACM 2017 Davide Perna


During the conferences, the NEOShield-2 team also took the opportunity to have a small meeting to discuss the status and goals of the Work Package 10 (WP10 – NEO observations and data reduction/analysis) for these final months of the project.

Representatives from Obs. Paris-LESIA, Obs. Paris-IMCCE, INAF and CNRS-OCA attended the meeting to discuss about spectroscopic (LESIA), light-curve (IMCCE), photometric colour and phase curve (INAF) and thermal infrared (CNRS) data acquisition and analysis.

You can check the abstract of Davide Perna’s speech here.

Also during the ACM 2017, the International Astronautical Union (IAU) announced who this year had an asteroid named after them. There was about 200 asteroids named this year and one of them was named after Dr. Line Drube, from the German Aerospace Center (DLR), also member of the NEOShield-2 project, in recognition of her work on this matter. More information about the asteroid can be found here.

ACM 2017 Line Drube

You can check the full list of named asteroids here.

More information:

ACM 2017
ACM 2014
ACM 2012
ACM 2008
ACM 2005
ACM 2002


Asteroid 2014 JO25 to Fly Safely Past Earth on April 19, 2017

2014 JO25, a relatively large near-Earth asteroid discovered nearly three years ago will fly safely past Earth on April 19, 2017 at a distance of about 1.1 million miles (1.8 million kilometers), or about 4.6 times the distance from Earth to the moon. Although there is no possibility for the asteroid to collide with our planet, this will be a very close approach for an asteroid of this size.

2014 JO25 April 19

2014 JO25 Orbit Diagram. Credits: NASA/JPL.

The asteroid, known as 2014 JO25, was discovered in May 2014 by astronomers at the Catalina Sky Survey near Tucson, Arizona — a project of NASA’s NEO Observations Program in collaboration with the University of Arizona. (An NEO is a near-Earth object). Contemporary measurements by NASA’s NEOWISE mission indicate that the asteroid is roughly 2,000 feet (650 meters) in size, and that its surface is about twice as reflective as that of the moon. At this time very little else is known about the object’s physical properties, even though its trajectory is well known.

The asteroid will approach Earth from the direction of the sun and will become visible in the night sky after April 19. It is predicted to brighten to about magnitude 11, when it could be visible in small optical telescopes for one or two nights before it fades as the distance from Earth rapidly increases.

Video credits: NASA/JPL-Caltech

Small asteroids pass within this distance of Earth several times each week, but this upcoming close approach is the closest by any known asteroid of this size, or larger, since asteroid Toutatis, a 3.1-mile (five-kilometer) asteroid, which approached within about four lunar distances in September 2004. The next known encounter of an asteroid of comparable size will occur in 2027 when the half-mile-wide (800-meter-wide) asteroid 1999 AN10 will fly by at one lunar distance, about 236,000 miles (380,000 kilometers).

The April 19 encounter provides an outstanding opportunity to study this asteroid, and astronomers plan to observe it with telescopes around the world to learn as much about it as possible. Radar observations are planned at NASA’s Goldstone Solar System Radar in California and the National Science Foundation’s Arecibo Observatory in Puerto Rico, and the resulting radar images could reveal surface details as small as a few meters.

The encounter on April 19 is the closest this asteroid has come to Earth for at least the last 400 years and will be its closest approach for at least the next 500 years.

Source: NASA

Original article here.

Is a Colorado earthquake related to dinosaurs extinction impact?

by Seismological Society of America

Researchers have found signs of fault displacement at well-known rock outcrops in Colorado that mark the end-Cretaceous asteroid impact that may have hurried the extinction of the dinosaurs. They will present their results in a poster at the 2017 Seismological Society of America’s (SSA) Annual Meeting.

Norm Sleep of Stanford University and colleagues suggest that the impact, which occurred near the Yucatán Peninsula of Mexico, could have generated massive seismic waves that triggered earthquakes as far away as Colorado, in the center of a tectonic plate where no previous fault had existed.

colorado earthquake dinosaur impact

Credits: NASA; Google

Sleep and his colleagues found evidence for the fault in two areas in Colorado’s Trinidad Lakes State Park, where a layer of iridium generated by the asteroid impact clearly marks the boundary between Cretaceous and Tertiary-age rocks, at the time of the dinosaurs’ extinction about 65 million years ago. At the Long’s Canyon and Madrid Canyon roadcuts, “there is a fault that slipped about a meter at the time of the impact,” Sleep said. “It offset the material below the impact layer but not above, but it’s not something that would be obvious to the casual observer.”

The researchers suggest that the Colorado earthquake may have been as large as magnitude 6. Very strong seismic waves from the impact–much larger than would be generated by a regular earthquake, Sleep said–would be necessary to trigger an earthquake in this location, in the middle of a tectonic plate with no previous faults.

The end-Cretaceous asteroid strike, however, could have generated ground velocities of a meter or two per second, Sleep said. “The ground would be moving up and down and sideways like a ship in a strong storm.”

At the time of the earthquake, the area in Colorado was a swampy, delta-like environment, crossed by large braided streams that ran from the young Rocky Mountains. Sleep and his colleagues saw signs that the earthquake had diverted a small stream in the area.

This summer, the researchers will be checking in New Mexico near the Raton Basin for further signs of intraplate quakes that may have been triggered by the asteroid strike.

More information: “Induced Intraplate Earthquakes in Colorado from Extreme Seismic Waves from the End-Cretaceous Asteroid Impact” will be presented at the SSA Annual Meeting on Tuesday, April 18. All presentation abstracts for the 2017 SSA Annual Meeting can be accessed at