Exploring Mars' Atmosphere with MAVEN
Right on schedule on Sept. 21 at 9:50 p.m. Eastern Daylight Time, the MAVEN spacecraft fired its main engines for thirty-three minutes and twenty-six seconds in order to slow down the spacecraft from 16,000 mph (25,750 km/h) so that it could inject itself into Mars orbit. But the technical team responsible for the craft knew nothing about it for twelve minutes. Mars is currently about twelve light-minutes away from us, meaning that signals to or from the craft take twelve minutes to travel there and another twelve minutes to travel back to Earth.
Maven, at 37.4 feet (11 meters) long and weighing in at 5,410 pounds (2,454 kilograms) is our latest, greatest hope for studying Mars’ upper atmosphere and ionosphere as it interacts with the Sun and Solar Wind. It has never been studied with this level of scrutiny before. It is not expected to land or send probes to the surface, but on five specific occasions it will be sampling gases from orbits as low as 125km (78 miles), over its operational lifetime. Its normal, highly elliptical, orbit will carry it from 150km (93 miles) to 6200km (3900 miles) and back again on a regular basis. These “Deep Dips” are designed to go to the depth of the atmosphere where the Thermosphere and Mesosphere meet.
At 10:24 p.m. EDT Sunday, Sept. 21, 2014 it entered the orbit of Mars, ending its ten month journey from Earth, which it left in late 2013, to our second closest planetary neighbor. Since 2/3 of recent exploration missions to the red planet have ended in crashes or spacecraft loss, the technical team greeted the success with applause and celebrations twelve minutes after the event. The orbit was initially over thirty-five hours per circuit, but this will be reduced to about four and a half hours over the next six weeks. But even before that happens, it is going to be put to work gathering once-in-a-lifetime data. “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.”
David Brain of the University of Colorado’s LASP (Laboratory for Atmosphere and Space Physics) couldn’t be happier. Although MAVEN is still going through diagnostics and powering up its systems, a process that could last more than a month, at least it is on site and available to observe the comet Siding Spring which is due to pass quite closely to Mars at a distance of 132,000 kilometers away in less than one month’s time. MAVEN will turn all three of its instrument suites onto the comet to look for atmospheric interactions.
Most people are unaware of the sheer size of a comet’s atmosphere, but it can exceed 1.5 million kilometers. Since it will pass Mars at a distance considerably less than this, there is a distinct possibility of atmospheric collisions between the two. As the comet sheds gases they could cause changes in the upper atmosphere, which is precisely what MAVEN was designed to observe. We could be the beneficiaries in a grand cosmic experiment just by being in the right place at the right time.
Brain is hopeful that we’ll see interactions that might include Aurorae around Mars’ localized magnetic phenomena. Mars’ internal dynamo ceased to be powerful enough to generate a magnetosphere to protect Mars from solar erosion of its atmosphere, but it does have many magnetic nodes scattered about its surface. With luck, they’ll light up like Christmas trees!
There are additional possibilities, since comet Siding Spring will also be flinging out typical cometary debris (rocky material) at a speed of 56km/second (35 miles per second). Upon hitting the Martian atmosphere these bits will burn up, adding heat. This additional heat could also be quite revealing about the way the atmosphere works.
Why the name “MAVEN”?
The name Maven is borrowed from the Yiddish language and it means someone that gathers knowledge. That seems highly appropriate for this explorer. The name is a pseudo acronym that means Mars Atmosphere and Volatile EvolutioN spacecraft.
What sort of instruments does MAVEN have?
MAVEN carries three instrument suites: the Particles and Fields Package, the Remote Sensing Package, and the Neutral Gas and Ion Mass Spectrometer. MAVEN also brought along a new UHF radio to act as a back-up relay for the data-gathering robots on the surface of Mars, increasing the available information bandwidth to Earth by 100 to 1000 times. Lockheed Martin built the MAVEN spacecraft and provides OPS for the mission. JPL (Jet Propulsion Laboratory) was the one that got it to Mars successfully and will continue to provide navigation for the duration. As mentioned above, LASP will be responsible for the science operations.
The PFP (Particles and Fields Package) has six instruments that characterize the solar wind and the ionosphere. The RSP (Remote Sensing Package) contains the IUVS (Imaging Ultraviolet Spectrometer) and will analyse characteristics of the upper atmosphere and ionosphere. Finally, the NG&IMS (Neutral Gas and Ion Mass Spectrometer) will measure the composition and isotopes of neutral ions.
The PFP contains:
- SWEA, the Solar Wind Electron Analyzer
- SWIA, the Solar Wind Ion Analyzer
- STATIC, the SupraThermal And Thermal Ion Composition analyser
- SEP, the Solar Energetic Particle analyser
- LPW/EUV, the Langmuir Probe and Waves analyser and Extreme Ultra Violet analyser
- MAG, the Solar Wind and Planetary Magnetic Field analyser
MAVEN data will help us to determine the how and why of Mars’ atmospheric loss, and give us insight into Mars’ atmospheric, climactic, and hydrological history.
What do we know now?
Highly energetic particles from the sun (particularly protons, but electrons to a lesser degree) reach Mars on the Solar Wind. Unlike on Earth, where most of it is deflected by our magnetosphere, these smack into gas particles in the Martian upper atmosphere and can ionize them (giving them a net positive charge) and as the upper atmosphere becomes more ionized (hence more positively charged) atoms repel each other and can reach escape velocity, consequently migrating out of the atmosphere and into space.
Another factor is that as the Sun’s magnetic field grazes the upper atmosphere of Mars, the electrically charged (ionized) particles spin around the field and get carried off by that method. In addition, the Sun fires some ions right back into Mars’ atmosphere, but now traveling at over 2 million miles per hour (3,219,000 km/h) like shooting a bag of marbles with a shotgun – they’re going to go everywhere, and some, right out of the atmosphere. So the mechanisms of atmospheric loss are complex and messy.
Interestingly, just because Mars has no magnetosphere does not give the Sun free rein to bombard Mars itself. The stream of solar particles actually produces a magnetic moment (almost an induced magnetosphere) that acts as if Mars was properly protected. So the lack of a magnetosphere does not equate to atmospheric erosion except for the very highest regions greater than 1.5 diameters of Mars from the surface. For comparison, look at Venus, also with no magnetosphere, and its closeness to the sun where such erosion would be much more energetic – its atmosphere is one hundred times as thick as Earth’s and not eroding significantly. This is the sort of thing MAVEN will study, and bring us some answers to understand what is going on.
"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 LASP “I'm delighted to be here safely and successfully, and looking forward to starting our science mission." The project cost $485 million for R & D, building and completion, with another $187 million for launch services.
How does it end?
The Primary science phase of MAVEN’s mission will conclude in one year (an Earth-length year, since Mars’ is twice as long as ours). After that, it will spend 120% of a Martian-length year (29 months) in a nominal science orbit making additional studies and observations. Finally, the periapse (the lowest point in MAVEN’s orbit) will be raised to slow the decay of its orbit and try to keep it going for another six years of study and research, while acting as an informational relay for any remaining rovers on the surface. Ultimately, the orbit will decay and the satellite will burn up and crash on the Martian surface.
NASA | MAVEN: NASA's Next Mission to Mars
At some point in the future, maybe as soon as the 2030s, we may have actual people on Mars if NASA’s current plans come to fruition. By then our Martian research may have taught us whether life originated on Mars and was transferred to Earth during the Late Heavy Bombardment of 3.9 billion years ago, or whether early Martian bio-development was unique and unrelated to the life that eventually arose on Earth. Did we arrive on a meteoric lifeboat from Mars as bacteria and grow up to what we are now?
Either way, we may know that life is likely to be common in the Universe, arising wherever it finds a hospitable place, or that we Martians that moved to Earth so long ago have finally come home. Let’s pay attention to this most interesting subject and find out!
Latest News about MAVEN from NASA
- MAVEN | NASA
The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission, scheduled for launch in late 2013, will be the first mission devoted to understanding the Martian upper atmosphere.
© 2014 Doug West