MAVEN thumbs up following checkout en route to Mars

by Chris Bergin and William Graham

NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft has provided an encouraging report card on the initial status of its array of instrumentation, as it continues its journey to Mars. The mission to study the planet’s atmosphere was launched last November, with the spacecraft having already clocked 137 million miles.


The mission is a multi-corporation/agency mission for the United States and NASA designed to study changes to the Martian atmosphere.

Z2ALaunched atop of an Atlas V rocket, MAVEN’s mission began on November 17, riding uphill from Space Launch Complex 41 (SLC-41) at Cape Canaveral Air Force Station.

The spacecraft is scheduled to enter orbit around Mars on the evening of Sept. 21, 2014 (10 p.m. EDT), ahead of its mission to determine key elements that caused the change in the Martian climate throughout the planet’s history.

With a mass of 2,454 kilograms (5,410 lb), MAVEN is expected to operate for a year once it reaches Mars. The spacecraft is carrying 1645 kilograms (3627 lb) of propellant, with a dry mass of 809 kilograms (1,784 lb).

MAVEN’s total travel distance to Mars – including its transfer orbit around the sun at a speed of 69,480 mph – is about 442 million miles, with 136,949,317 miles already covered by Tuesday.

The spacecraft is powered by a pair of two-panel solar arrays, which will generate a minimum of 1.15 kilowatts. The spacecraft also carries two lithium ion batteries with capacities of 55 amp-hours which can be recharged by the solar arrays.

Propulsion is provided by six Aerojet MR-107N liquid rocket motors, with six smaller MR-106E thrusters for maneuvering, and MR-103Ds for attitude control.

These are all monopropellant thrusters, fuelled by hydrazine propellant stored in the spacecraft’s central tank. MAVEN was manufactured by Lockheed Martin.

Z6The spacecraft has been kept busy during its transit towards Mars, undergoing a five-week commissioning phase.

One of the key objectives of the checkout task was to evaluate the status of its suite of instrumentation that will be employed during its Martian mission.

MAVEN carries eight scientific instruments, with six of these instruments collectively designated the Particles and Fields Package. The total mass of MAVEN’s instruments is 65 kilograms (143 lb).

Z9The Solar Energetic Particle experiment, or SEP, is part of the Particles and Fields Package designed to study the energies of hydrogen and helium ions emanating from solar storms which interact with Mars. Data collected will be used to help scientists characterise how these particles give energy to, and heat, the upper atmosphere of Mars.

These particles also have the effect of ionising particles in the upper atmosphere. SEP is similar to instruments previously flown on the WIND and THEMIS missions in Earth orbit, to study the interactions of solar particles with the Earth.

Led by the University of California at Berkeley, the SEP experiment utilises two sets of sensors mounted perpendicularly on the spacecraft. These consist of collectors which funnel ions through a magnetic field onto foil detectors.

The Solar Wind Ion Analyzer, or SWIA, is designed to study Mars’ interaction of the solar wind. Derived from instruments flown on the WIND, FAST and THEMIS spacecraft, SWIA will develop profiles of the temperature, velocity and density of ions in the solar wind, allowing scientists to calculate the rate at which Mars’ atmosphere is ionised by solar interactions. SWIA is part of the Particles and Fields Package.

The solar wind will also be studied by the Solar Wind Electron Analyzer (SWEA), which is another part of the Particles and Fields Package. Extended away from the body of the spacecraft by a short boom, measuring 1.7 metres in length, SWEA will study mid-energy electrons. It is designed to allow study of the distributions of energy and angular velocity amongst the electrons, helping to characterise their role in the ionisation of the upper atmosphere.

STATIC, the Suprathermal and Thermal Ion Composition experiment, is a third part of the Particles and Fields Package. It is designed to profile highly energetic charged particles in the upper atmosphere.

According to NASA it will study the velocities of the ionic forms of hydrogen, helium, oxygen and carbon dioxide. STATIC is similar to an instrument flown aboard the European Space Agency’s Cluster satellites, placed into Earth orbit by Soyuz rockets in 2000 following a failed Ariane 5 launch in June 1996.

Like SEP, the Solar Wind Ion Analyzer, Solar Wind Electron Analyzer and Suprathermal and Thermal Ion Composition experiments will be led by the University of California.

Z11Langmuir Probes and Waves (LPW) is another part of the Particles and Fields Package. Consisting of two sensors deployed away from the spacecraft on seven-metre (23-foot) booms, LPW will be used to conduct studies of Mars’ ionosphere.

An extreme ultraviolet imager is mounted on the body of the spacecraft for comparative observations. It is hoped that the experiment will better characterise the density of Mars’ ionosphere, and establish its boundaries. The experiment is led by the University of Colorado at Boulder.

The final part of the Particles and Fields Package is a pair of magnetometers mounted on the outside edges of the spacecraft’s solar arrays. The magnetometers are based on a design which has been used on NASA missions since the Voyager programme, while the arrangement of magnetometers on the solar arrays was previously flown on the Mars Global Surveyor mission.

Z11The primary objective of the magnetometers is to provide comparative data for the other instruments. NASA’s Goddard Space Flight Center is leading this part of the investigation.

An Imaging Ultraviolet Spectrograph (IUVS) will be used to study light emitted from particles in the upper atmosphere, thereby allowing scientists to determine its chemical composition.

The spectrometer has two openings, which will be used to study light reaching the spacecraft from different angles. Spectra will be produce which can then be studied to find information on the atmospheric composition.

Although primarily aimed at studying the upper atmosphere, the instrument can also be used to measure the amount of carbon dioxide in lower regions of the atmosphere. The University of Colorado will lead this experiment.

Z8MAVEN’s final instrument is the Neutral Gas and Ion Mass Spectrometer (NGIMS). This will be used to study the composition of the upper atmosphere in terms of low-energy ions and neutral, or unionised, gasses. It is hoped that by observing variations in composition by time or location data from other missions could be better calibrated.

It can also be used to produce data on the relative abundances of isotopes of particular elements, which could be used to establish the rate at which lower-mass particles are lost to space. NGIMS will be operated by NASA’s Goddard Space Flight Center.

A ninth payload aboard MAVEN is the 22-centimetre (8.7-inch) Electra communications array.

Z6On Tuesday, NASA noted that all of MAVEN’s science instruments have completed their initial checkout, with the news all of them are working as expected.

“Successful checkout of the spacecraft and instruments is a major milestone in carrying out our mission,” noted Dr. Bruce Jakosky, MAVEN principal investigator from the University of Colorado in Boulder.

“While there are still a lot of things that have to happen properly before we get to Mars and can do the mission’s science, we are exactly where we need to be today.”

More checkout key events are on the schedule for MAVEN in the coming weeks, with additional instrument testing and spacecraft calibrations.

Z7Opening tests on the aforementioned Electra communications package – that will be used to relay data from the rovers currently on the surface of Mars – will also be conducted.

A second planned trajectory correction maneuver is also on the books.

“The performance of the spacecraft and instruments to date bears out all the hard work the team put into testing the system while it was on the ground,” added David Mitchell, MAVEN project manager at NASA’s Goddard Space Flight Center.

“The way that the operations team has performed while flying the system has been nothing short of outstanding. We have big events ahead of us before we can claim success but I am very pleased with how things have gone thus far.”

(Images via NASA and Jacques van Oene/ / L2).

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