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Tag Archives: asteroid

Anthony Lydgate, editor of Elements, newyorker.com’s science-and-tech blog provides details of the September 8 launch and goals of the OSIRIS-REx mission, to collect and return about 60 g of material from the asteroid Bennu. Read the full New Yorker article here.

(Note: newyorker.com restricts how many articles non-subscribers may read each month.)

av_orex_l2

Credit: United Launch Alliance

Links: OSIRIS-REx mission homepage.

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Adapted from an article in the LA Times (July 15, 2016):

A layer of soot deposited after the K/T extinction event may explain why dinosaurs but not everything else died. (See The Cosmos, A Closer Look 8.5, p. 220.)

Researchers from Japan argue that the 6-mile-wide asteroid slammed into an oil field in the present day Yucatán Peninsula and triggered an inferno that launched a massive cloud of smoke into the sky. The resulting layer of soot that enveloped the globe would have been just the right thing to kill the dinosaurs and most other land-dwelling creatures.

Previous theories have postulated that the asteroid sparked the mass extinction by releasing high levels of sulfuric acid particles in the atmosphere. The particles would have caused complete darkness, near-freezing temperatures and acid rain. However, sulfuric acid particles don’t hang around for very long — and if they did, the results would have been catastrophic for many species besides dinosaurs. Instead, soot from the immense fire caused by the Chicxulub impact was a prime candidate.

The scientists collected soot samples from the thin band of rock that marks the timing of the extinction of dinosaurs and found the same composition from locations around the world. They hypothesize that soot was slowly deposited on land in the five years following the massive collision. The powdery substance is primarily made of black carbon that results from incineration of organic matter.

The tiny particles are about a million times more light-absorbing than carbon dioxide. They would have blocked about 85% of sunlight from reaching Earth and cut rainfall by nearly 80%, creating near-drought conditions, as well as causing temperatures to plummet. In this post-asteroid wasteland, plants began to die off, cutting off the food supply to creatures higher up the food chain — such as the dinosaurs — while allowing smaller mammals, birds and aquatic creatures to survive.

Link: the LA Times article

From a JAXA press release, December 3, 2014:

Mitsubishi Heavy Industries, Ltd. and the Japan Aerospace Exploration Agency (JAXA) successfully launched the H-IIA Launch Vehicle No. 26 with the Asteroid Explorer “Hayabusa2” on board at 1:22 p.m. on December 3, 2014 (Japan Standard Time) from the Tanegashima Space Center. The launch vehicle flew as planned, and at approximately one hour, 47 minutes and 21 seconds after liftoff, the separation of the Hayabusa2 to Earth-escape trajectory was confirmed.

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Credit: JAXA

The asteroid explorer “Hayabusa2” is a successor to the “Hayabusa”, which verified various new exploration technologies and returned to Earth in June 2010. “Hayabusa2” is setting out on a journey to clarify the origin and evolution of the Solar System as well as search for organic matter.

Links: JAXA press release, including detailed flight sequence.

Abridged from a New Scientist article by Rebecca Boyle, September 30, 2014:

A newly discovered asteroid called 2014 OL339 is the latest quasi-satellite of Earth – a space rock that orbits the Sun but is close enough to Earth to look like a companion. The asteroid has been hanging out near Earth for about 775 years, but its orbit is unstable – it will probably move on about 165 years from now.

Credit: NASA

Credit: NASA

Quasi-satellites orbit in resonance with Earth, allowing our planet’s gravity to shift the rock’s position. The asteroid orbits the Sun every 365 days, as Earth does, but Earth’s gravity guides it into an eccentric wobble, which causes the rock to appear to circle backward around the planet.

The asteroid, which is between 90 and 200 metres in diameter, is among several different categories of space rock in Earth’s retinue besides our one satellite, the Moon. Rocks that hang out at a gravitational middle ground known as a Lagrange point, where they follow or lead Earth in its orbit, are called Trojans.

Links: The full New Scientist article; NASA’s Near-Earth Object program.

Adapted from an ESA press release, August 6, 2014:
After a decade-long journey chasing its target, ESA’s Rosetta has today become the first spacecraft to rendezvous with a comet, opening a new chapter in Solar System exploration. Comet 67P/Churyumov–Gerasimenko and Rosetta now lie 405 million kilometers from Earth, about half way between the orbits of Jupiter and Mars, rushing towards the inner Solar System at nearly 55,000 kilometers per hour.

Comet 67P/Churyumov-Gerasimenko on August 3, 2014

Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

The comet is in an elliptical 6.5-year orbit that takes it from beyond Jupiter at its furthest point, to between the orbits of Mars and Earth at its closest to the Sun. Rosetta will accompany it for over a year as they swing around the Sun and back out towards Jupiter again.
The journey to the comet was not straightforward, however. Since its launch in 2004, Rosetta had to make three gravity-assist flybys of Earth and one of Mars to help it on course to its rendezvous with the comet. It has traveled for ten years, five months and four days, clocking up 6.4 billion kilometers. Its complex course also allowed Rosetta to pass by asteroids Šteins and Lutetia, obtaining unprecedented views and scientific data on these two objects.

August 6 saw the last of a series of ten rendezvous manoeuvres that began in May to adjust Rosetta’s speed and trajectory gradually to match those of the comet. If any of these manoeuvres had failed, the mission would have been lost, and the spacecraft would simply have flown by the comet.

Links: the ESA press release, including further images; Rosetta fact-sheet.

Our Solar System seems like a neat and orderly place, with small, rocky worlds near the Sun and big, gaseous worlds farther out, all eight planets following orbital paths unchanged since they formed. However, the true history of the Solar System is far more riotous. Giant planets migrated in and out, tossing interplanetary flotsam and jetsam far and wide.

New clues to this tumultuous past come from the asteroid belt. Millions of asteroids circle the Sun between the orbits of Mars and Jupiter, in a region known as the main asteroid belt. Traditionally, they were viewed as the pieces of a failed planet that was prevented from forming by the influence of Jupiter’s powerful gravity. Their compositions seemed to vary methodically from drier to wetter, due to the drop in temperature as you move away from the Sun.

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Credit: David A. Aguilar (CfA)

This traditional view has changed, as astronomers have recognized that the current residents of the main asteroid belt weren’t all there from the start. In the early history of the Solar System the giant planets ran amok, migrating inward and outward substantially. Jupiter may have moved as close to the Sun as Mars is now. In the process, it swept the asteroid belt nearly clean, leaving only a tenth of one percent of its original population. As the planets migrated, they stirred the contents of the Solar System. Objects from as close to the Sun as Mercury, and as far out as Neptune, all collected in the main asteroid belt.

Using data from the Sloan Digital Sky Survey, astronomers have examined the compositions of thousands of asteroids within the main belt. They found that the asteroid belt is more diverse than previously realized, especially when you look at the smaller asteroids. This finding has interesting implications for the history of Earth. Astronomers have theorized that long-ago asteroid impacts delivered much of the water now filling Earth’s oceans. If true, the stirring provided by migrating planets may have been essential to bringing those asteroids.

This raises the question of whether an Earth-like exoplanet would also require a rain of asteroids to bring water and make it habitable. If so, then Earth-like worlds might be rarer than we thought.  The paper describing these findings appears in the January 30, 2014 issue of Nature.

Links: Harvard-Smithsonian Center for Astrophysics press release; Nature article.

NASA has just released new photos and video animations depicting the agency’s planned initiative to find, capture, redirect, and study a near-Earth asteroid. The images depict crew operations including the Orion spacecraft’s trip to and rendezvous with the relocated asteroid, as well as astronauts maneuvering through a spacewalk to collect samples from the asteroid.

Part of President Obama’s FY 2014 budget request for NASA, the asteroid initiative capitalizes on activities across the agency’s human exploration, space technology, and science programs. NASA is enhancing its ongoing efforts to identify and characterize near-Earth objects for scientific investigation, and to find potentially hazardous asteroids and targets appropriate for capture and exploration.

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Credit: NASA

The mission is still just at the concept stage, but it is expected to employ advanced solar electric propulsion technology as a power source for its Orion spacecraft.

Read  the full press release here, or link straight to the images and video.