The MAVEN spacecraft used an orbital insertion burn just 11 seconds longer than nominal when slipping into Mars orbit last night. That's a fantastically short correction to end a 711 million kilometer, 10-month journey, and a perfect kickoff to its mission investigating the structure and evolution of the planet's upper atmosphere.
Top image: MAVEN is downright sexy in this artist's concept, skimming above the Martian atmosphere. Credit: NASA/GSFC
The journey to Mars has been downright perfect for MAVEN. Launched on November 18, 2013 by United Launch Alliance, the Atlas V rocket that boosted it into space gave it such a good start that the craft only underwent two trajectory corrections prior to the orbital insertion.
This Atlas V rocket gave MAVEN an excellent start to its journey. Image credit: ULA
After a pair of trajectory correction manoeuvres a month after launch in December 2013, and again in February 2014, the team has been hands-off watching the craft go exactly where it needed to be. The scheduled July correction burn was cancelled, as was one originally scheduled for earlier this month on September 12th, both deemed unnecessary as MAVEN was right on target.
Principal Investigator Bruce Jakosky was easily the happiest man on Earth after the successful insertion of MAVEN into orbit around Mars. Image credit: NASA
The team had two final possibilities for fine-tuning the approach, with windows for preemptive burns 24 hours and 6 hours prior to the big show last night. Again, they were skipped. When the moment of truth finally arrived, the burn lasted just 11 seconds longer than theoretically ideal. Or, as NASA Social participant Daniel Wein succinctly quoted NASA Goddard project manager David Mitchell during the press briefing:
Now it's at Mars, what's MAVEN going to do? The short version is: figure out what happened to the Martian atmosphere. Read on for the long version.
Project scientists from the Laboratory for Atmosphere and Space Physics at Univeristy of Colorado, Boulder celebrate the probe's arrival along with their friends and families. Image credit: Glenn Asakawa/University of Colorado
MAVEN is only a slightly-forced acronym, spelled out as Mars Atmosphere and Volatile EvolutioN. The mission is exactly what it says, investigating the upper atmosphere of Mars in an effort to understand how it evolved and changed over time, from its former thick glory to its current wispy existence.
MAVEN is loaded with tools to track gas escaping from the upper atmosphere, measuring the rate of loss so that researchers can backtrack to how that may have impacted the planet's climate history. It will also be tracking what processes impact gas loss rates over time, and poking around what exactly the structure of the upper atmosphere is, anyway. Finally, the spacecraft will run communications duty, relaying messages from the surface rovers to us back at home.
Now Maven is comfortably circling Mars, the next stage will be to tighten up into an elliptical orbit just 4.5 hours long. Image credit: MAVEN
In the next five weeks, the craft will get into its scientific orbit, and test out its sensor suite one more time. The orbit is an unusual one: it will swoop in elliptical loops, dipping down to just 150 kilometers above the surface at closest approach, and soaring up to an astonishing 6,000 kilometers altitude. This will take it directly through the upper atmosphere, while also regularly placing it high enough for full-planet imaging. Later, it will execute deep dips, diving to an even lower 124 kilometers to enable sampling of a full profile of the atmosphere from the well-mixed lower levels up through the wispy upper limits.
Concept art of MAVEN dancing in the skies above Mars. Animation credit: NASA/Goddard/Ryan Zuber
The eight instruments dedicated to investigating the atmosphere during this dramatic dance are in three packages: the Remote Sensing Package, the Neutral Gas and Ion Mass Spectrometer, and the Particles and Fields Package.
One spacecraft, three packages, eight instruments: a recipe for investigating the evolution of a Martian atmosphere. Image credit: NASA
The Remote Sensing Package
The Remote Sensing Package is just one instrument. It will determine global characteristics of the atmosphere and ionosphere by using the Imaging Ultraviolet Spectrometer (IUVS) during full-planet imaging at orbital apices.
The Imaging Ultraviolet Spectrometer. Image credit: NASA
The instrument works through detecting atomic absorption. This is a bit like identifying a critter by its shadow: the detector will be looking for the absence of particular wavelengths of light. As ultraviolet light from the sun passes through the Martian atmosphere, certain elements and molecules will absorb specific frequencies of light. So, if particular wavelengths are missing, that means those compounds are present in the atmosphere.
The UV spectrometer was getting turned on the same night as the insertion, so soon we might get even more excited scientist-squealing.
The Neutral Gas and Ion Mass Spectrometer Package
The Neutral Gas and Ion Mass Spectrometer Package is again, just one instrument, but this time it shares the same name. The Neutral Gas and Ion Mass Spectrometer (NGIMS)will be used to precisely identify the composition of the atmosphere from direct sampling, or by taking advantage of stellar occultations.
Preparation for integration of the Neutral Gas and Ion Mass Spectrometer into the MAVEN spacecraft. Image credit: NASA/GSFC
MAVEN will nab samples of the atmosphere, allowing point observations of its composition. Those samples will be fed into the mass spectrometer for identification.The spectrometer identifies gases by zapping molecules with an electron beam, then applying high-frequency electric fields to sort component fragments by mass and electric charge.
By catching the sun backlighting the atmosphere, this instrument will also be able to take vertical profiles of carbon dioxide, measuring all the way down to the lower atmosphere.
MAVEN is anticipating six stellar occultations to survey carbon dioxide in the lower atmosphere. Image credit: NASA/GSFC
The first time this particular spectrometer flipped on was part of an interplanetary hat trick last December as one of a trifecta of mass spectrometers functioning at different locations in the solar system all on the same day.
Particles and Fields Package
The Particles and Fields Package contains six instruments to characterize the solar wind and ionosphere of Mars. MAVEN is arriving at Mars just after a solar maximum, which is important because this package is all about how the Martian atmosphere reacts with space weather.
Predicted solar activity cycle at the time of the MAVEN launch. Image credit: Hathaway/NASA/MSFC
The instruments are a magnetometer, a Langmuir probe and waves, an imaging ultraviolet spectrometer, a solar wind electron analyzer, a solar wind ion analyzer, a solar energetic particles detector, and a suprathermal and thermal ion composition detector.
The Magnetometer (MAG) will detect magnetic fields, measuring the interplanetary solar wind and ionospheric magnetic fields.
The Magnetometer squeezes a lot of science into a small package. Image credit: NASA/GSFC
Specifically, it will be able to observe the vector magnetic field unperturbed by solar wind to within 3 nT, the magnetosheath, a dynamic transition region, to within 10 to 50 nT, and even the crustal magnetosphere to within 3,000 nT, resolving crustal magnetic crusts to within horizontal length scales of 100 kilometers.
The Magnetometer has a fabled heritage: it's the same style that was used by MGS, Voyager, AMPTE, GIOTTO, CLUSTER, Lunar Prospector, MESSENGER , STEREO, Juno, and Van Allen Probes.
I admit to being quietly giddy about the potential for measuring the crustal magnetic structure. When I was but a proto-geophysicist, the tantalizingly striped magnetic field on Mars utterly captivated me, and learning more just deepened the mystery. Mapping out the planet's magnetic field will be neat, but providing data for better maps of the crustal field will tickle that still-unsatisfied curiosity spawned a decade ago.
The Langmuir Probe and Waves (LPW) are a pair of sensors dangling on booms used to measure thermal electron density and temperature. This will be used to characterize the basic state of the ionosphere, including its structure, variability, and thermal properties. It also carries an Extreme Ultraviolet (EUV) monitor to detect variation in sunlight at wavelengths important for ionization, dissociation, and heating of the upper atmosphere
The Solar Wind Electron Analyzer (SWEA) will be used to measure electron energy and angle distributions, solar wind and ionosphere photoelectron distribution, and auroral electron populations. While these measurements sound downright mystical, their function is to allow researchers to determine the rate at which electrons ionize, evaluate the plasma environment, and even determine the magneto-plasma topology from electron spectra and pitch angle distributions.
Just which drivers, reservoirs, and escape rates are important in the evolution of Mars' atmosphere? Image credit: MAVEN
The Solar Wind Ion Analyzer (SWIA) will characterize the solar wind and magnetosheath ions, tracking density, temperature, and velocity. The instrument can track the velocity of plasma flow from interacting with solar wind speeds (350 to 1,000 km/s) slowing all the way down to stagnating magnetosheath speeds (10s of km/s) of the upper atmosphere, and the pickup acceleration of newly-formed ions, determining how much energy is coming into the upper atmosphere. It will also allow for analysis of charge exchange rates, tracking the ionization of neutral particles as a potential process influencing the atmospheric loss, measurement of the structure and variability of the magnetosphere. Of course, the most romantic bit is tucked away under a list of "basic space plasma phenomena." Along with detecting flux ropes, plasmoids, bulk plasma escape, and boundary instabilities, SWIA will be able to detect auroral processes, answering a question I never knew I had: Did the Phoenix lander fall asleep under the dancing light of aurora?
The Solar Energetic Particles (SEP) is a pair of dual-ended telescopes, used to characterized solar particles. The time resolution of the instruments is less than an hour, which should be short enough to allow it to capture distinct events.
SEP is a pair of double-ended telescopes for measuring the impact of solar wind. Image credit: UCB/SSL
The telescopes are optimized for parallel and perpendicular Parker Spiral viewing, and will be used to determine the input of solar energetic particles as a function of altitude, how those particles heat, ionize, and sputter, and identify the highest energy pickup ions.
The SupraThermal And Thermal Ion Composition (STATIC) does more of the same, yet different. It will track escaping ions and the related processes. By specifically measuring ionospheric ions (0.1-10 eV), superthermal ions (5-100 eV), pickup ions (100-20,000 eV), along with key atmospheric ions (H+, O+, O2+, CO2+), STATIC will add on observations of yet more processes that may be key drivers of atmospheric loss.
Is STATIC a delicate scientific instrument, or stylish robot? Image credit: NASA/SSL
The instrument will be able to measure source ion populations near periapsis, those heated ions that reach escape velocity, and the pickup acceleration of these ions in the magnetosheath and solar wind. It will also allow for separate measurements of the shocked solar wind and planetary ions in the sheath plasma.
Artist's concept of MAVEN swooping high above Mars for a full-planet view. Image credit: NASA/GSFC
Last, but certainly not least, MAVEN is taking over communications duties, relaying word from our robotic rovers on the surface. As it shifts into its science orbit and puts its instruments through their paces, MAVEN will also engage in an end-to-end communications relay test with Curiosity.
Congratulations to everyone involved with the MAVEN project: you did an absolutely flawless job, and I'm looking forward to seeing what this probe tells us about the red planet! Or, in the eloquent artistic stylings of planetary astronomer Alex Parker: