Lockheed Martin is entering the final assembly, test and launch phase of the Maven spacecraft, which will be launched in November on a mission to investigate what caused the disappearance of most of the Martian atmosphere.

The Mars Atmosphere And Volatile Evolution (Maven) spacecraft is being built at Lockheed Martin’s Space Systems Waterton site near Denver, and will be shipped to Cape Canaveral in August for payload integration. Lockheed Martin successfully completed deployment tests of the spacecraft’s solar panels in March and says testing is on track to meet the start of the launch window, which opens on Nov. 18.

Due to planetary alignment, the program is targeting an optimal 20-day launch window that closes on Dec. 7, 2013. Meeting the target is vital because the next time the planets will be favorably aligned for a Mars mission will be in early 2016. Following launch, the spacecraft should enter orbit around Mars in late September 2014 and collect data for at least one year.

The vehicle will fly a highly elliptical orbit around the planet, enabling it to travel through the upper reaches of the Martian atmosphere, gathering data that should help scientists reconstruct a climatic history of the planet. To achieve this, the craft will be configured with three main suites of instruments. The first of these, the NASA Goodard-made Neutral Gas and Ion Mass Spectrometer, will measure the atmosphere’s composition. A Remote Sensing Package built by the University of Colorado’s Laboratory for Atmospheric and Space Physics will determine the characteristics of the planet’s upper atmosphere.

The final suite is a Particles and Fields Package, which consists of six instruments designed to measure properties of Mars’ upper atmosphere, solar wind and solar energetic particles, magnetic fields, and solar extreme ultraviolet radiation. The University of California Berkeley Space Sciences Laboratory is building the Particles Package, with support from NASA Goddard and the University of Colorado.

Other contributors to the program include NASA’s Jet Propulsion Laboratory, which will provide program management well as navigation support; the Deep Space Network; and an Electra telecommunications relay hardware package.

As NASA prepares to investigate the upper atmosphere of Mars, new data from the planet’s surface collected by the agency’s Mars rover Curiosity reveals strong evidence that the planet lost much of its original atmosphere by a process of gas escaping from the top of the atmosphere. Curiosity team scientists, reporting their findings at the European Geosciences Union 2013 General Assembly, in Vienna, found the atmosphere has four times as much of a lighter stable isotope (argon-36) compared to a heavier one (argon-38).

Scientists say the imbalance indicated by this data, collected last week by Curiosity’s Sample Analysis at Mars (SAM) instrument, confirms a substantial portion — possibly up to 95% — of the planet’s original atmosphere has escaped into space.