Earth Has An Asteroid Buddy

In 2016 planetary astronomers at the University of Arizona Lunar and Planetary Laboratory discovered a small ( 100 meter ) object moving with Earth around the Sun. Dubbed 2016 OR3, initial science speculation wondered if it might be a piece of space junk, perhaps a rogue rocket booster caught in wobbly orbit occasionally intersecting Earth orbit.

Last week at the annual Division For Planetary Sciences  meeting in Provo, Utah Vishnu Reddy from University of Arizona laid speculation to rest, identifying 2016 OR3 as an asteroid, stating in part –

“2016 HO3 is a small near-Earth object (NEO) measuring no more than 100 meters (330 feet) across that, while orbiting the sun, also appears to circle around the Earth as a quasi-satellite. Only five quasi-satellites have been discovered so far, but 2016 HO3 is the most stable of them. The provenance of this object is unknown. On timescales of a few centuries, 2016 HO3 remains within 38 to 100 lunar-distances from us.”

“One way to visualize HO3’s orbit is by picturing a hula hoop dancer — the sun in this analogy — twirling two hoops around the hips at the same time, ever so slightly out of sync. While it orbits the sun, the object makes yearly loops around the Earth.

As a result, the object appears to orbit the Earth, but it is not gravitationally bound to our planet.”

2016 HO3 is seen at the top left corner of this animation made of ten 2mn long exposures in I band using MODS1 on the left side of LBT – The telescope is tracking the moving asteroid, so background stars (and even a couple of galaxies) are trailed. Image via LBTO.

Asteroid 2016 OR3 is hardly a harbinger of doom – orbiting politely at 38 – 100 lunar distance from Earth, it is a cosmic companion which now bears official designation of quasi-satellite. NASA Jet Propulsion Laboratory said –

The asteroid’s orbit also undergoes a slow, back-and-forth twist over multiple decades. “The asteroid’s loops around Earth drift a little ahead or behind from year to year, but when they drift too far forward or backward, Earth’s gravity is just strong enough to reverse the drift and hold onto the asteroid so that it never wanders farther away than about 100 times the distance of the moon,” said Chodas. “The same effect also prevents the asteroid from approaching much closer than about 38 times the distance of the moon. In effect, this small asteroid is caught in a little dance with Earth.”

“Caught in a little dance with Earth” makes me smile. Not for knowing Earth has an asteroid buddy, but for affirmation everything in our universe is caught in a little dance.

Titan Touchdown

On January 11, 2017 NASA’s Jet Propulsion Laboratory ( JPL ) released “Titan Touchdown”, a short video of stoic little probe Huygens landing on Saturn’s moon Titan. A video marking the 12th anniversary of January 14, 2005, the day Huygens bravely marched into history as the furthest ever landing from Earth. The day Huygens met fate in a blaze of glory, making the most of precious minutes until Titan claimed it for eternity.

The Cassini-Huygens mission holds a place in my heart – RIP Huygens, your sacrifice won’t be forgotten.

Encounter With 2013 TX68

October 6, 2013 scientists at Catalina Sky Survey noticed an anomaly approaching Earth on the night side of our planet. For three days asteroid 2013 TX68 basked in feverish observation. Barely time to estimate diameter of 38 meters, woefully short of establishing accurate orbital projections. Three days after raising eyebrows, tracking ground to a halt when 2013 TX68 passed into Earth’s daytime sky.

A few days ago NASA’s Jet Propulsion Laboratory announced March 5, 2016 dawns with a return engagement – a fly-by of indeterminate distance. Uncertain trajectory, the result of brief observation comes with assurances TX68 won’t raise a ruckus. Closest estimates place TX68 at 17,000 kilometers, well within orbital distance of many communication satellites. A far cry from the high range of 14 million kilometers. Blood pressure needn’t rise, science assures we have nothing to worry about – at least not this visit. On September 28, 2017 TX68 returns with an “elevated” dash of concern. As of today, no chance on this lap increases to a 1 in 250 million gamble in 2017 – about the same probability of being killed by a falling coconut,


Cassini’s Curtain Call

NASA’s unassuming civil servant Cassini has a thing or two to prove. Before graciously accepting an inevitable and long overdue retirement -Cassini   obligingly agreed to traipse through daunting plumes of ice and water vapor, allowing mankind unprecedented insight into ice plumes erupting from the south pole of Saturn’s moon Enceladus.

Eighteen years after launch, seven years en-route to Saturn, eleven years exploring Saturn and her moons, two mission extensions beyond wildest expectations – Cassini has nothing to lose. On October 28 this sentiment meant taking a dive at 31,000 kph to within 45 Km of Enceladus at the south pole, directly into erupting “plumes” of icy vapor.

Below – seven facts about Cassini/Enceladus from earthsky (linked above)

1. Early in its mission, Cassini discovered Enceladus has remarkable geologic activity, including a towering plume of ice, water vapor and organic molecules spraying from its south polar region. Cassini later determined the moon has a global ocean and likely hydrothermal activity, meaning it could have the ingredients needed to support simple life.

2. The flyby will be Cassini’s deepest-ever dive through the Enceladus plume, which is thought to come from the ocean below. The spacecraft has flown closer to the surface of Enceladus before, but never this low directly through the active plume.

3. The flyby is not intended to detect life, but it will provide powerful new insights about how habitable the ocean environment is within Enceladus.

4. Cassini scientists are hopeful the flyby will provide insights about how much hydrothermal activity – that is, chemistry involving rock and hot water – is occurring within Enceladus. This activity could have important implications for the potential habitability of the ocean for simple forms of life. The critical measurement for these questions is the detection of molecular hydrogen by the spacecraft.

5. Scientists also expect to better understand the chemistry of the plume as a result of the flyby. The low altitude of the encounter is, in part, intended to afford Cassini greater sensitivity to heavier, more massive molecules, including organics, than the spacecraft has observed during previous, higher-altitude passes through the plume.

6. The flyby will help solve the mystery of whether the plume is composed of column-like, individual jets, or sinuous, icy curtain eruptions — or a combination of both. The answer would make clearer how material is getting to the surface from the ocean below.

7. Researchers are not sure how much icy material the plumes are actually spraying into space. The amount of activity has major implications for how long Enceladus might have been active.

Linked below, NASA’s Jet Propulsion Laboratory definitive guide to Cassini.

Ponder the exquisite magnificence of Cassini’s accomplishments.

Comet Hitchhiker

Masahiro Ono of NASA’s Jet Propulsion Laboratory had a “aha” moment – design a spacecraft capable of landing on multiple comets and asteroids. Equip a craft with harpoons and tethers for landing, then cast off for the next destination using kinetic energy.

This week Ono submitted his Hitchhikers Guide to the Galaxy based research at the American Institute of Aeronautics and Astronautics SPACE conference. Included were solutions to initial concerns over harpoon and tether strength. Exhaustive analysis and computer simulation arrived at a solution dubbed the Space Hitchhike Equation. The equation led to Ono’s conclusion – materials exist (Zylon and Kelvar) capable of withstanding changes in velocity necessary for safe landing. (velocity change of 1.5 Km/second – imagine Los Angeles to San Fransisco in under 7 minutes). The next phase will include harpoon tests at targets mimicking asteroids and comets.

You go Masahiro – imaginations like yours are the future of cosmic exploration and discovery.

While closely flying by the target, a spacecraft would first cast an extendable tether toward the asteroid or comet and attach itself using a harpoon attached to the tether. Next, the spacecraft would reel out the tether while applying a brake that harvests energy while the spacecraft accelerates.

This technique is analogous to fishing on Earth. Imagine you’re on a boat on a lake with a fishing pole, and want to catch a big fish. Once the fish bites, you would release more of the line with a moderate tension, rather than holding it tightly. With a long enough line, the boat will eventually catch up with the fish.

Once the spacecraft matches its velocity to the ‘fish’ – the comet or asteroid, in this case – it is ready to land by simply reeling in the tether and descending gently.

When it’s time to move on to another celestial target, the spacecraft would use the harvested energy to quickly retrieve the tether, which accelerates the spacecraft away from the body.

This artist concept shows Comet Hitchhiker, an idea for traveling between asteroids and comets using a harpoon and tether system. Image credit: NASA/JPL-Caltech/Cornelius Dammrich

This artist concept shows Comet Hitchhiker, an idea for traveling between asteroids and comets using a harpoon and tether system. Image via NASA/JPL-Caltech/Cornelius Dammrich

A description of Comet Hitchhiker by Masahiro Ono –

Fly Around Ceres

Ponder Ceres, largest resident of the asteroid belt between Mars and Jupiter. Discovered in 1801 by Giuseppe Piazzi, early astronomers considered it a planet. With a diameter of 598 miles, planet is a stretch. Officially, this 33rd largest object in our solar system is a dwarf planet. Large enough to be rounded by its own gravity, yet much too small for planetary respect.

Fortunately, size doesn’t matter to science. In 2007 NASA’s Jet Propulsion Laboratory launched the Dawn probe. Dawn’s mission – study “protoplanets” Vesta and Ceres in the asteroid belt to advance understanding of how solar systems form. In July of 2011 Dawn began a 14 month orbit of Vesta (Ceres rocky little sister with a diameter of 325 miles), March of this year found Dawn entering orbit around Ceres. On June 8, 2015 NASA released this video compilation, flying around Ceres – Taken from Dawn’s first orbital mapping and navigational images.

Remarkable as it is, the video hasn’t solved one of Ceres greatest mysteries, a curious surface anomaly dubbed the double bright spot. Over the next few months NASA is asking our opinion – vote volcano, geyser, rock, ice, salt deposit or other at the link below.

Image – NASA