NASA MAVEN: Studying the passing of comet C/2013 A1 Siding Spring and its effects

This image shows an artist concept of NASA's Mars Atmosphere and Volatile Evolution (MAVEN) mission. 

Image Credit: NASA/GSFC

NASA's newest orbiter at Mars, MAVEN, took precautions to avoid harm from a dust-spewing comet that flew near Mars today and is studying the flyby's effects on the Red Planet's atmosphere.

The MAVEN spacecraft reported back to Earth in good health after about three hours of precautions against a possible collision with high-velocity dust particles released by comet C/2013 A1 Siding Spring.

"We're glad the spacecraft came through, we're excited to complete our observations of how the comet affects Mars, and we're eager to get to our primary science phase," said MAVEN Principal Investigator Bruce Jakosky of the University of Colorado, Boulder.

MAVEN began orbiting Mars on Sept. 21. The opportunity to study this rare near-miss of a planet by a comet comes during the project's commissioning phase.

A few weeks of instrument calibration and orbit fine-tuning remain before the start of the primary science phase. The mission will study the upper atmosphere of Mars and its interaction with the solar wind.

Comet Siding Spring hurtled past Mars today at about 125,000 mph (56 kilometers per second), coming within about 87,000 miles (139,500 kilometers) of the planet.

That is equivalent to about one-third of the distance between Earth and Earth's moon. The closest approach by the comet's nucleus came at about 11:27 a.m. PDT (2:27 p.m. EDT).

The period when dust from the comet was most likely to reach Mars and the orbits of spacecraft around Mars peaked about 100 minutes later.

From about 10:45 a.m. to 2 p.m. PDT (1:45 p.m. to 5:00 p.m. EDT) MAVEN kept in a defensive posture to reduce its profile relative to the direction from which the comet's high-velocity dust particles would come.

In that "hunkered down" orientation, its main antenna was not facing the right way for transmitting to Earth, so communications were maintained at low data rate via a secondary antenna.

Also, the mission performed a maneuver on Oct. 2 that set its orbit timing so that the spacecraft was behind Mars, relative to the possible dust flow, from about 12:53 p.m. to 1:23 p.m. PDT (3:53 p.m. to 4:23 p.m. EDT).

Downlink of data has begun from MAVEN observations of the comet and Mars' atmosphere. Some observations are designed to provide information about the composition of the gases and dust being released by the comet.

Others are investigating possible interaction between material from the comet and the atmosphere of Mars.

Three NASA Mars orbiters (MAVEN, Mars Reconnaisance Orbiter and Odyssey Orbiter), two Mars rovers (Curiosity and Opportunity) and other assets on Earth and in space are studying comet Siding Spring.

This comet is making its first visit this close to the sun from the outer solar system's Oort Cloud, so the concerted campaign of observations may yield fresh clues to our solar system's earliest days more than 4 billion years ago.

MAVEN's principal investigator is based at the University of Colorado's Laboratory for Atmospheric and Space Physics.

The university provided two science instruments and leads science operations, as well as education and public outreach, for the mission.

Possible meteor shower May 23-24 as Earth passes through dust trail of 209P/LINEAR

Composite photo of Lyrid meteor shower and non-Lyrids taken with a NASA all-sky camera April 21-23, 2012. 

A new meteor shower emanating from Camelopardalids near the North Star is expected to light up the skies the morning May 24 around 2 a.m. CDT (7 UT). 

Credit: NASA /MSFC /Danielle Moser

On Friday night/early Saturday May 23-24 skywatchers across the U.S. and southern Canada may witness the birth of a brand new meteor shower.

If predictions hold true, Earth will pass through multiple tendrils of dust and pebbly bits left behind by comet 209P/LINEAR, firing up a celestial display on par with the strongest showers of the year. Or better.

Earlier predictions called for a zenithal hourly rate or ZHR of 1,000 per hour, pushing this shower into the 'storm' category.

ZHR is an idealized number based on the shower radiant located at the zenith under ideal skies.

The actual number is lower depending on how far the radiant is removed from the zenith and how much light pollution or moonlight is present.

Peter Jenniskens

Meteor expert Peter Jenniskens of NASA's SETI Institute and Finland's Esko Lyytinen first saw the possibility of a comet-spawned meteor storm and presented their results in Jenniskens' 2006 book Meteor Showers and Their Parent Comets.

Esko Lyytinen

Quanzhi Ye and Paul Wiegert (University of Western Ontario) predict a weaker shower because of a decline in the comet's dust production rate based on observations made during its last return in 2009. They estimate a rate of ~200 per hour.

On the bright side, their simulations show that the comet sheds larger particles than usual, which could mean a shower rich in fireballs. Other researchers predict rates between 200 and 40o per hour.

At the very least, the Camelopardalids – the constellation from which the meteors will appear to originate – promise to rival the Perseids and Geminids, the year's richest showers.

Approximate location of the radiant (blue) of the 209P/LINEAR shower at the peak of the brief maximum around 2 a.m. CDT May 24. 

Between 100-400 meteors may radiate from the dim constellation of Camelopardalids near the North Star. 

This map shows the sky from the central U.S. 

Created with Stellarium

Comet 209P/LINEAR, discovered in Feb. 2004 by the automated Lincoln Laboratory Near-Earth Asteroid Research (LINEAR) sky survey, orbits the sun every 5.04 years with an aphelion (most distant point from the sun) near Jupiter.

The OSIRIS-REx spacecraft with its sample-collecting arm resembles a standing heron and inspired Michael Toler Puzio’s inventive name for the asteroid that the OSIRIS-REx space mission will visit. 

Credit: NASA/Goddard Flight Center/University of Arizona.

In 2012, during a relatively close pass of that planet, Jupiter perturbed its orbit, bringing it to within 280,000 miles (450,000 km) of Earth's orbit.

That set up a remarkably close encounter with our planet on May 29 when 209P/LINEAR will cruise just 5 million miles (8 million km) from Earth to become the 9th closest comet ever observed.

Multiple debris trails shed by the comet as long ago as the 18th century will intersect our planet's path 5 days earlier, providing the material for the upcoming meteor shower/storm.

Read the full article here