Preparing for Comet Siding Spring (C/2013 A1)

This artist's concept shows NASA's Mars orbiters lining up behind the Red Planet for their "duck and cover" maneuver to shield them from comet dust that may result from the close flyby of comet Siding Spring (C/2013 A1) on October 19, 2014.

The comet's nucleus will miss Mars by about 87,000 miles (139,500 kilometers), shedding material as it hurtles by at about 126,000 miles per hour miles (56 kilometers per second), relative to Mars and Mars-orbiting spacecraft.

NASA is taking steps to protect its Mars orbiters, while preserving opportunities to gather valuable scientific data. The NASA orbiters at Mars are Mars Reconnaissance Orbiter, Mars Odyssey and MAVEN.

Image credit: NASA/JPL-Caltech

Note: For more information, see PIA18612: View of Comet Siding Spring from Southern Hemisphere (Artist's Concept) and NASA Prepares its Science Fleet for October 19 Mars Comet Encounter.

MAVEN Enters Orbit Around Mars

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

NASA's Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft successfully entered Mars' orbit at 7:24 p.m. PDT (10:24 p.m. EDT) Sunday, September 21, where it now will prepare to study the Red Planet's upper atmosphere as never done before. MAVEN is the first spacecraft dedicated to exploring the tenuous upper atmosphere of Mars.

"As the first orbiter dedicated to studying Mars' upper atmosphere, MAVEN will greatly improve our understanding of the history of the Martian atmosphere, how the climate has changed over time, and how that has influenced the evolution of the surface and the potential habitability of the planet," said NASA Administrator Charles Bolden. "It also will better inform a future mission to send humans to the Red Planet in the 2030s."

After a 10-month journey, confirmation of successful orbit insertion was received from MAVEN data observed at the Lockheed Martin operations center in Littleton, Colorado, as well as from tracking data monitored at NASA's Jet Propulsion Laboratory navigation facility in Pasadena, California. The telemetry and tracking data were received by NASA's Deep Space Network antenna station in Canberra, Australia.

"NASA has a long history of scientific discovery at Mars and the safe arrival of MAVEN opens another chapter," said John Grunsfeld, astronaut and associate administrator of the NASA Science Mission Directorate at the agency's Headquarters in Washington. "Maven will complement NASA's other Martian robotic explorers-and those of our partners around the globe-to answer some fundamental questions about Mars and life beyond Earth."

Following orbit insertion, MAVEN will begin a six-week commissioning phase that includes maneuvering into its final science orbit and testing the instruments and science-mapping commands. MAVEN then will begin its one Earth-year primary mission, taking measurements of the composition, structure and escape of gases in Mars' upper atmosphere and its interaction with the sun and solar wind.

"It's taken 11 years from the original concept for MAVEN to now having a spacecraft in orbit at Mars," said Bruce Jakosky, MAVEN principal investigator with the Laboratory for Atmospheric and Space Physics at the University of Colorado, Boulder (CU/LASP). "I'm delighted to be here safely and successfully, and looking forward to starting our science mission."

The primary mission includes five "deep-dip" campaigns, in which MAVEN's periapsis, or lowest orbit altitude, will be lowered from 93 miles (150 kilometers) to about 77 miles (125 kilometers). These measurements will provide information down to where the upper and lower atmospheres meet, giving scientists a full profile of the upper tier.

"This was a very big day for MAVEN," said David Mitchell, MAVEN project manager from NASA's Goddard Space Flight Center, Greenbelt, Maryland. "We're very excited to join the constellation of spacecraft in orbit at Mars and on the surface of the Red Planet. The commissioning phase will keep the operations team busy for the next six weeks, and then we'll begin, at last, the science phase of the mission. Congratulations to the team for a job well done today."

MAVEN launched November 18, 2013, from Cape Canaveral Air Force Station in Florida, carrying three instrument packages. The Particles and Fields Package, built by the University of California at Berkeley with support from CU/LASP and Goddard, contains six instruments that will characterize the solar wind and the ionosphere of the planet. The Remote Sensing Package, built by CU/LASP, will identify characteristics present throughout the upper atmosphere and ionosphere. The Neutral Gas and Ion Mass Spectrometer, provided by Goddard, will measure the composition and isotopes of atomic particles.

The spacecraft's principal investigator is based at CU/LASP. The university provided two science instruments and leads science operations, as well as education and public outreach, for the mission.

NASA Goddard Space Flight Center manages the project and also provided two science instruments for the mission. Lockheed Martin built the spacecraft and is responsible for mission operations. The Space Sciences Laboratory at the University of California at Berkeley provided four science instruments for MAVEN. JPL provides navigation and Deep Space Network support, and Electra telecommunications relay hardware and operations. JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Program for NASA.

Image credit: NASA/Goddard Space Flight Center

Note: For more information, see NASA Mars Spacecraft Ready for Sept. 21 Orbit Insertion and NASA's MAVEN Spacecraft Reaches Mars.

Colliding Atmospheres: Mars vs Comet Siding Spring

On October 19, 2014, Comet Siding Spring will pass by Mars only 132,000 km away--which would be like a comet passing about 1/3 of the distance between Earth and the Moon.

The nucleus of the comet won't hit Mars, but there could be a different kind of collision.

"We hope to witness two atmospheres colliding," explains David Brain of the University of Colorado's Laboratory for Atmospheric and Space Physics (LASP). "This is a once in a lifetime event!"

Everyone knows that planets have atmospheres. Lesser known is that comets do, too. The atmosphere of a comet, called its "coma," is made of gas and dust that spew out of the sun-warmed nucleus. The atmosphere of a typical comet is wider than Jupiter.

"It is possible," says Brain, "that the atmosphere of the comet will interact with the atmosphere of Mars. This could lead to some remarkable effects — including Martian auroras."

The timing could scarcely be better. Just last year, NASA launched a spacecraft named MAVEN to study the upper atmosphere of Mars, and it will be arriving in September 2014 barely a month before the comet.

MAVEN is on a mission to solve a longstanding mystery: What happened to the atmosphere of Mars? Billions of years ago, Mars had a substantial atmosphere that blanketed the planet, keeping Mars warm and sustaining liquid water on its surface. Today, only a wispy shroud of CO2 remains, and the planet below is colder and dryer than any desert on Earth. Theories for this planetary catastrophe center on erosion of the atmosphere by solar wind.

"The goal of the MAVEN mission is to understand how external stimuli affect the atmosphere of Mars," says Bruce Jakosky of LASP, MAVEN's principal investigator. "Of course, when we planned the mission, we were thinking about the sun and the solar wind. But Comet Siding Spring represents an opportunity to observe a natural experiment, in which a perturbation is applied and we can see the response."

Brain, who is a member of the MAVEN science team, thinks the comet could spark Martian auroras. Unlike Earth, which has a global magnetic field that shields our entire planet, Mars has a patchwork of "magnetic umbrellas" that sprout out of the surface in hundreds of places all around the planet. If Martian auroras occur, they would appear in the canopies of these magnetic umbrellas.

"That is one thing that we will be looking for with both MAVEN and Hubble Space Telescope," says Brain. "Any auroras we see will not only be neat, but also very useful as a diagnostic tool for how the comet and the Martian atmosphere have interacted."

The atmosphere of the comet includes not only streamers of gas, but also dust and other debris blowing off the nucleus at 56 kilometers per second relative to Mars. At that velocity, even particles as small as half a millimeter across could damage spacecraft. NASA's fleet of Mars orbiters including MAVEN, Mars Odyssey and Mars Reconnaissance Orbiter will maneuver to put the body of Mars between themselves and the comet’s debris during the dustiest part of the encounter.

"It's not yet clear whether any significant dust or gas will hit the Mars atmosphere," cautions Jakosky. "But if it does, it would have the greatest effects on the upper atmosphere."

Meteoroids disintegrating would deposit heat and temporarily alter the chemistry of upper air layers. The mixing of cometary and Martian gases could have further unpredictable effects. Although MAVEN, having just arrived at Mars, will still be in a commissioning phase, it will use its full suite of instruments to monitor the Martian atmosphere for changes.

"By observing both before and after, we hope to determine what effects the comet dust and gas have on Mars, if any," says Jakosky.

Whatever happens, MAVEN will have a ringside seat.

Video credit: NASA

MAVEN: What Happened to Mars?

Billions of years ago when the planets of our solar system were still young, Mars was a very different world. Liquid water flowed in long rivers that emptied into lakes and shallow seas. A thick atmosphere blanketed the planet and kept it warm. In this cozy environment, living microbes might have found a home, starting Mars down the path toward becoming a second life-filled planet next door to our own.

But that's not how things turned out.

Today, Mars is bitter cold and desiccated. The planet's thin, wispy atmosphere provides scant cover for a surface marked by dry riverbeds and empty lakes. If Martian microbes still exist, they're probably eking out a meager existence somewhere beneath the dusty Martian soil.

What happened? This haunting question has long puzzled scientists. To find the answer, NASA is sending a new orbiter to Mars called MAVEN (Mars Atmosphere and Volatile Evolution).

"The goal of MAVEN is to figure out what processes were responsible for those changes in Martian climate," says Bruce Jakosky, Principal Investigator for MAVEN at the University of Colorado at Boulder.

Scheduled for launch in November 2013, and due to arrive in September 2014, MAVEN is bristling with instruments to study Mars’ upper atmosphere. That's where many researchers believe the answer lies.

The only way Mars could have been wet and warm 4 billion years ago, is if it also had a thick atmosphere. CO2 in the Martian atmosphere is a greenhouse gas, just as it is in our own atmosphere. A thick blanket of CO2 and other greenhouse gases would have provided the warmer temperatures and greater atmospheric pressure required to keep liquid water from freezing solid or boiling away.

Something caused Mars to lose that blanket. One possibility is the solar wind. Unlike Earth, Mars is not protected by a global magnetic field. Instead, it has “magnetic umbrellas” scattered around the planet that shelter only part of the atmosphere. Erosion of exposed areas by solar wind might have slowly stripped the atmosphere away over billions of years. Recent measurements of isotopes in the Martian atmosphere by Mars rover Curiosity support this idea: light isotopes of hydrogen and argon are depleted compared to their heavier counterparts, suggesting that they have floated away into space.

Scientists have also speculated that the planet's surface might have absorbed the CO2 and locked it up in minerals such as carbonate. However, this theory has faded in recent years as Mars rovers and orbiters have failed to find enough carbonate to account for the missing gas.

MAVEN will be the first mission to Mars specifically designed to help scientists understand the ongoing escape of CO2 and other gases into space. The probe will orbit Mars for at least one Earth-year. At the elliptical orbit's low point, MAVEN will be 125 km above the surface; its high point will take it more than 6000 km out into space. MAVEN's instruments will track ions and molecules in this broad cross-section of the Martian atmosphere, thoroughly documenting the flow of CO2 and other molecules into space for the first time.

Once Jakosky and his colleagues know how quickly Mars is losing CO2 right now, they can extrapolate backward in time to estimate the total amount lost during the last four billion years. "MAVEN will determine if loss to space was the most important player in driving Martian climate change," Jakosky says.

In the grand scheme of the Solar System, Earth orbits alongside a world that began with as much promise for life as our own … yet turned out so differently. After all these years, MAVEN could write the final chapter in a haunting planetary mystery.

Video credit: NASA

MAVEN

This artist's concept depicts NASA's Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft near Mars. MAVEN is in development for launch in 2013 and will be the first mission devoted to understanding the Martian upper atmosphere. The mission's principal investigator is Bruce Jakosky from the Laboratory for Atmospheric and Space Physics at the University of Colorado.

The goal of MAVEN is to determine the role that loss of atmospheric gas to space played in changing the Martian climate through time. MAVEN will determine how much of the Martian atmosphere has been lost over time by measuring the current rate of escape to space and gathering enough information about the relevant processes to allow extrapolation backward in time.

Illustration credit: NASA