Assessing the Martian atmosphere: MAVEN prepares for launch

by Chris Gebhardt

With less than 18 days to go before the beginning of NASA’s next scheduled mission to Mars, engineers and vehicle processing personnel at the Cape Canaveral Air Force Station, Florida, are hard at work preparing MAVEN and its Atlas V rocket for launch on 18 November.


MAVEN – A multi-year/corporation endeavor:

The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission is a multi-corporation/agency mission for the United States and NASA designed to study changes to the Martian atmosphere.

Birthed from the now-discontinued Mars Scout Program – a program that also saw the creation, implementation, and flight of the Mars Phoenix lander last decade – MAVEN successfully survived challenges from 20 other mission proposals to gain funding for a 2013 scout mission to the red planet.

Formally announced on 15 September 2008, MAVEN was constructed in a joint effort by Lockheed Martin; the University of Colorado, Boulder; the University of California, Berkley; and NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

Like numerous other Mars missions, construction, mission implementation, and pre-flight preparations were designed and carefully choreographed to meet the short, three (3) week 2013 launch window to Mars – a launch window constrained based on mission orbital parameters, planetary alignment, and the sun’s solar cycle (which needs to be “not at minimum” for optimal mission success).

Earlier in assembly, Lockheed MartinFollowing mission acceptance, MAVEN was built in Colorado at the Lockheed Martin facility in Denver and was based partly on the designs of the Mars Reconnaissance Orbiter and the Mars Odyssey spacecraft.

MAVEN itself is 11.43 meters in length, carries a dry mass of 903 kilograms, a wet mass of 2,550 kilograms, and is capable of producing 1,135 watts (in orbit of Mars) from its photovoltaic solar arrays.

After five years of construction and testing, MAVEN was flown to and arrived at the Kennedy Space Center, FL on 2 August 2013 to begin final mission and launch preparations.

MAVEN at Lockheed MartinIn August 2013, MAVEN underwent several tests and procedures crucial to its pending mid-November launch.

These activities included work and testing on MAVEN’s Power Performance, Power Subsystem, Payload Regression, Reaction Wheel Assembly Regression, Powered Magnetics, and self-test program.

August work also included updating the craft’s Remote Sensing and Neutral Gas and Ion Mass Spectrometer software, cleaning and inspecting MAVEN’s solar cells, and installing Flight Software Build 6.

Launch-site processing continued throughout the month of September with the delivery of several pieces of equipment to support final internal propellant loading to MAVEN.

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Moreover, at SLC-41, build-up of the Atlas V launch vehicle commenced following the successful 18 September 2013 launch of the AEHF-3 mission.

Despite the great progress made by the ground teams, and the maintenance of the contingency processing time for the 18 Nov. launch, all work on MAVEN ground to a halt on Tuesday, 1 Oct. 2013 because of an inability of the U.S. Congress to pass a budget to fund the federal government and its ancillary agencies.

Surviving the U.S. government shutdown:

Beginning at midnight on 1 Oct. 2013, all work deemed non-essential in the eyes of the U.S. federal government stopped because of a lack of funding due a budgetary impasse within the U.S. Congress – an impasses that led to a lapse in federal appropriations.

For NASA, this meant that there was no money to continue processing MAVEN or to pay NASA employees.

Z4Furthermore, without direct federal approval, it was illegal for United Launch Alliance contract workers and NASA personnel to access the facilities on the Cape Canaveral Air Force Station or in any government-owned building where MAVEN and its launch components were located.

For three days, workers sat idly by while precious processing and contingency time passed.

The real possibility began to present itself: If the government shutdown persisted for a prolonged period, it could become impossible for MAVEN to complete its final processing milestones in time to make the three (3) week launch window.

If this happened, and MAVEN missed the 2013 launch window, the processing and science teams would have to wait 26 months, until January 2016, for the next launch window (based on Earth-Mars planetary alignments).

Behind the scene negotiations finally yielded what to many was a surprise (but a highly welcomed surprise): On 3 October, the U.S. federal government classified MAVEN as an “essential” operation. Therefore, all activities necessary to ensure a launch within the 2013 window would proceed despite the government shutdown.

Z14However, all NASA personnel involved in processing MAVEN now had to work without pay or compensation for the duration of the federal government shutdown.

And they worked, at first, without the promise of back-pay after the end of the shutdown – since only authorization by Congress for back-pay (which was not granted at the time of MAVEN’s “essential” classification) can result in federal workers receiving their earned or usual wages during a government shutdown.

Eventually, Congress did authorize back-pay for all federal workers.

While processing resumed, it quickly became clear that MAVEN’s “essential” classification was, as many would have hoped, not because of the probe’s scientific mission. It also had nothing to due with the high cost to NASA and the federal government that would have amounted had MAVEN missed the launch window and had to wait until 2016.

Instead, it had everything to do with probe’s communication function: Providing upgraded and continued communication links for NASA with the operational Mars rovers Opportunity and Curiosity.

Final processing:

Since work on MAVEN proceeded through the U.S. federal government shutdown, MAVEN will now have the entirety of the three (3) week launch window (18 Nov. – 7 Dec.) available to it.

The only possible constraint within that three week window is a pending-range-approval 22 November launch of a Falcon 9 rocket from Cape Canaveral with the SES 8 spacecraft.

That mission has already been delayed multiple times since July, and at last word, had requested but not yet received approval for a 22 November launch attempt.

The only other active mission listed on the Eastern Range launch table with a potential launch within MAVEN’s window is a Delta IV mission with GPS 2F-S; however, that mission’s launch date is currently TBD pending completion of an investigation into an RL10 engine anomaly during a Delta IV mission in 2012.

Z3On 29 Oct., ULA rolled MAVEN’s launch vehicle, an Atlas V rocket, out to SLC-41 for a wet countdown dress rehearsal.

The Atlas V rocket sailed through this rehearsal with no issues reported. It was then returned to the VIF (Vertical Integration Facility) nearby its sea-side launch pad for final process and preps for spacecraft arrival and mating.

Meanwhile, MAVEN spent the final few days of October undergoing dry spin before being lifted into its dolly stand.

MAVEN was then loaded with its flight fuel between 23 and 25 October, a process that culminated with the pressurization of its flight fuel tanks.

Launch:

If the schedule holds, MAVEN is set to launch from the Cape Canaveral Air Force Station, FL, from SLC-41 atop an Atlas V rocket on 18 Nov. 2013 in a launch window that extends from 1347-1547 EST.

Z12For MAVEN’s launch, the Atlas V will fly in its 401 configuration with a four-meter payload fairing, no solid rocket boosters, and a single-engine Centaur upper stage.

Atlas Vehicle 038 (AV-038) will be used for the flight – which will be the 41st flight of the Atlas V.

The Atlas V is currently the United States’ most-trustworthy and reliable in-service rocket with a 100% mission success rate as determined by payload customer satisfaction with vehicle performance.

Following launch, MAVEN will perform a 10 month, 4 day cruise to planet Mars.

Arrival and mission at Mars:

Assuming a launch on the opening day of the window, MAVEN will perform an orbital insertion maneuver and be inserted into Mars orbit on 22 September 2014.

Orbit insertion will result in a highly elliptical orbit with an apoapsis of 6,200 km and a periapsis of 150 km. MAVEN’s orbit will be inclined 75 degrees to the Martian equator and carry a nominal orbital period of 4.5 hours.

Z6Following successful orbital insertion, MAVEN will be tasked with gathering detailed data on Mars’ atmosphere with a specific eye toward explaining what caused water in Mars’ atmosphere to be lost to space over the billions of years of the planet’s evolution.

Formations on the Martian surface and the discovery on the surface of certain minerals that form in the presence of water suggest that Mars’ atmosphere, at one time, had to be much thicker than it currently is.

This means that Mars, over the course of the last few millions of years, has lost nearly 99% of its atmosphere to space.

Scientists think this is because of planetary core cooling which in turned caused the collapse of Mars’ protective magnetic field (like the one the protects Earth’s atmosphere).

Z8Without the presence of this protective magnetic field, Mars’ atmosphere was slowly stripped away by the solar wind.

MAVEN will help answer the question of how this has and is happening.

Over the course of its one Earth year primary mission, MAVEN will take detailed measurements of Mars’ upper atmosphere to determine the rate at which the Martian atmosphere is currently escaping into space.

These readings will be coupled with similar readings taken by the Curiosity rover on the surface of Mars for data comparison.

In all, MAVEN has four primary mission objectives. To (1) determine the role that loss of volatiles to space from the Mars atmosphere has played through time; (2) determine the current state of the upper atmosphere, ionosphere, and interactions with the solar wind; (3) determine the current rates of escape of neutral gases and ions to space and the processes controlling them; and (4) determine the ratios of stable isotopes in the Martian atmosphere.

Z9To accomplish these objectives, MAVEN will carry three instrument suites, including the Particles and Fields Package (PFP), the Remote Sensing Package (RSP), and the Neutral Gas and Ion Mass Spectrometer (NGIMS).

The PFP was designed and built by the University of California at Berkeley Space Sciences Laboratory and contains six instruments that characterize the solar wind and the ionosphere of the planet.

Of these six instruments, four were built by the University of California at Berkeley Space Sciences Laboratory, one was built jointly with the University of Colorado at Boulder Laboratory for Atmospheric and Space Physics, and one was built by NASA’s Goddard Space Flight Center.

Z11The six instruments of the PFP are the Solar Energetic Particle (SEP) experiment, the Solar Wind Ion Analyzer (SWIA), the Solar Wind Electron Analyzer (SWEA), the SupraThermal and Thermal Ion Composition (STATIC) experiment, the Langmuir Probe and Waves (LPW) experiment, and the Magnetometer (MAG).

The RSP was build by the University of Colorado at Boulder Laboratory for Atmospheric and Space Physics and will determine global characteristics of the upper atmosphere and ionosphere of Mars.

The NGIMS was built by NASA Goddard and will measure the composition and isotopes of neutrals and ions in the Martian atmosphere.

(Images via Lockheed Martin, ULA and NASA).

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