Published: 2014-09-20 08:50:00
Updated: 2014-09-21 17:07:52
Posted September 20, 2014
Updated September 21, 2014
By Tony Rice
When Elizabeth Gardner interviewed Dr. Jim Garver, chief scientist at NASA’s Goddard Spaceflight Center, Friday morning, MAVEN was a little less than half a million miles from Mars. I last saw MAVEN 10 months and 442 million miles ago as it left Space Launch Complex 41 at Cape Canaveral.
That launch day began early with conversations with the science team from the University of Colorado Boulder, representatives from Lockheed Martin that built the spacecraft, the team from the United Launch Alliance responsible for the vehicle and an optimistic weather briefing from the launch weather office from the U,S. Air Force’s 45th Weather Squadron at Cape Canaveral ahead.
After a tour of refurbishment Space Shuttle launch pads and firing rooms for the upcoming Orion program, I gathered with teachers, meteorologists from the Weather Channel and just plain space fans along the Banana River to watch MAVEN leave Earth in a plume of smoke and scattering of birds.
This Sunday, at 9:38:24 p.m. EDT (plus another 12 minutes for signals to travel the 138 million miles back to Earth, according to the latest flight plan), MAVEN will fire its engine to reduce speed sufficiently to be captured by Mars gravity, placing it in a highly elliptical orbit. The spacecraft will remain in orbit during a yearlong primary science mission where it will taste and smell what remains of Martian air. It will also measure of the rest of near-Mars space with a suite of instruments seeking an answer to the question “What happened to Mars atmosphere?”
A lot of the blame is placed on the sun. Impacts from energetic particles can knock atoms in the upper atmosphere away in a process called “sputtering.” The sun also provides a 1-2 punch when energetic particles knock loose electronics creating vulnerable ions which are then attracted to and stripped away by magnetic fields carried by the solar wind. With only about one-third the gravity of Earth, it doesn’t take much velocity to overcome Mars’ hold on its atmosphere.
MAVEN’s highly elliptical path takes it out more than six times the diameter of the planet at the apoapsis (farthest point). The spacecraft will then fly down through the ionosphere to just 93 miles above the surface at the periapsis of its orbit (closest point). Instead of flat solar panels seen on most other spacecraft, MAVEN’s are angled inward like feathers on a badminton shuttlecock to help aerodynamically stabilize the spacecraft as passes through the atmosphere. In late December and another four times throughout its primary mission, MAVEN will take a “deep dip” an additional 17 miles closer to the surface, where the atmosphere is 30 times denser. All this goes on as Mars rotates beneath the spacecraft for our most complete view of the atmosphere of another planet.
This unique orbit also provides a view of near-Mars space, including the magnetic boundaries formed around the planet by solar wind. Scientists will use this data for many years to help put together a comprehensive picture of atmospheric loss. That data will be extrapolated back hundreds of millions of years. This combined with evidence of past flowing water discovered by the Curiosity rover last year will help scientists better understand if and when Mars may have been more Earth like.
You can follow along with MAVEN’s arrival Sunday night live on NASA TV. JPL’s Eyes on the Solar System, a free download available for PC, Mac and Linux, also offers live simulations of what the spacecraft is doing based on real data flowing through NASA’s Deep Space Network.
Tony Rice is a volunteer in the NASA/JPL Solar System Ambassador program and software engineer at Cisco Systems. You can follow him on twitter @rtphokie.