MAVEN

Mars Atmosphere and Volatile EvolutioN Mission (MAVEN) is a space probe developed by NASA designed to study the Martian atmosphere while orbiting Mars. Mission goals include determining how the planet's atmosphere and water, presumed to have once been substantial, were lost over time.

MAVEN was successfully launched aboard an Atlas V launch vehicle at the beginning of the first launch window on November 18, 2013. Following the first engine burn of the Centaur second stage, the vehicle coasted in low Earth orbit for 27 minutes before a second Centaur burn of five minutes to insert it into a heliocentric Mars transit orbit.

On September 22, 2014, MAVEN reached Mars and was inserted into an areocentric elliptic orbit 6200 km by 150 km above the planet's surface. The principal investigator for the spacecraft is Bruce Jakosky of the Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder.

On 5 November 2015, NASA announced that data from MAVEN shows that the erosion of Mars’ atmosphere increases significantly during solar storms. That loss of atmosphere to space likely played a key role in Mars' gradual shift from its carbon dioxide-dominated atmosphere - which had kept Mars relatively warm and allowed the planet to support liquid surface water - to the cold, arid planet we see today. This shift took place between about 4.2 to 3.7 billion years ago.

History
The mission was spawned by NASA's Mars Scout Program, which, although discontinued in 2010, yielded Phoenix, MAVEN, and numerous missions' studies. Mars Scout missions target a cost of less than US$485 million, not including launch services, which cost approximately $187 million. The total project costs up to $671 million.

On September 15, 2008, NASA announced that it had selected MAVEN to be the Mars Scout 2013 mission. There was one other finalist and eight other proposals that were competing against MAVEN. The name is a deliberate use of the word maven, "a person who has special knowledge or experience; an expert".

On August 2, 2013, the MAVEN spacecraft arrived at Kennedy Space Center Florida to begin launch preparations. NASA scheduled the launch of MAVEN from the Cape Canaveral Air Force Station on November 18, 2013, using an Atlas V 401 rocket. The probe arrived in Mars orbit in September 2014, at approximately the same time as India's Mars Orbiter Mission.

On October 1, 2013, only seven weeks before launch, a government shutdown caused suspension of work for two days and initially threatened to force a 26-month postponement of the mission. With the spacecraft nominally scheduled to launch on November 18, a delay beyond December 7 would have caused MAVEN to miss the launch window as Mars moved too far out of alignment with the Earth. However, two days later, a public announcement was made that NASA had deemed the 2013 MAVEN launch so essential to ensuring future communication with current NASA assets on Mars—the Opportunity and Curiosity rovers—that emergency funding was authorized to restart spacecraft processing in preparation for an on-time launch.

On September 22, 2014, at approximately 2:24 UTC, MAVEN spacecraft entered orbit around Mars, completing an interplanetary journey of 10 months and 442 million miles (711 million kilometers).

Objectives
Features on Mars that resemble dry riverbeds and the discovery of minerals that form in the presence of water indicate that Mars once had a dense enough atmosphere and was warm enough for liquid water to flow on the surface. However, that thick atmosphere was somehow lost to space. Scientists suspect that over millions of years, Mars lost 99% of its atmosphere as the planet’s core cooled and its magnetic field decayed, allowing the solar wind to sweep away most of the water and volatile compounds that the atmosphere once contained.

The goal of MAVEN is to determine the history of the loss of atmospheric gases to space, providing answers about Martian climate evolution. By measuring the rate with which the atmosphere is currently escaping to space and gathering enough information about the relevant processes, scientists will be able to infer how the planet's atmosphere evolved over time. The MAVEN mission has four primary scientific objectives:


 * 1) Determine the role that loss of volatiles to space from the Martian 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.
 * 4) Determine the ratios of stable isotopes in the Martian atmosphere.

MAVEN reached Mars and successfully maneuvered into orbit around the planet on September 21, 2014. The Sample Analysis at Mars (SAM) instrument suite on board the Curiosity rover was scheduled to make similar surface measurements from Gale crater by that date. The data from Curiosity will help guide the interpretation of MAVEN's upper atmosphere measurements. MAVEN's measurements will also provide additional scientific context with which to test models for current methane formation in Mars.

Spacecraft overview
MAVEN was built and tested by Lockheed Martin Space Systems. Its design is based on those of the Mars Reconnaissance Orbiter and Mars Odyssey spacecraft. The orbiter has a cubical shape of about 2.3 meters × 2.3 meters × 2 meters high, with two solar arrays that hold the magnetometers on both ends. The total length is 11.4 meters.

Relay telecommunications
NASA's Jet Propulsion Laboratory provided an Electra ultra high frequency (UHF) relay radio payload which has a data return rate of up to 2048 kbit/s. The highly elliptical orbit of the MAVEN spacecraft may limit its usefulness as a relay for operating landers on the surface, although the long view periods of MAVEN's orbit have afforded some of the largest relay data returns to date of any Mars orbiter. During the mission's first year of operations at Mars — the primary science phase — MAVEN served as a backup relay orbiter. Going forward into the extended mission for a period of up to ten years, MAVEN will provide UHF relay service for present and future Mars rovers and landers.

Scientific instruments
MAVEN will study Mars' upper atmosphere and its interactions with the solar wind. Its instruments will measure characteristics of Mars' atmospheric gases, upper atmosphere, ionosphere, and the solar wind. MAVEN will perform measurements from a highly elliptical orbit over a period of one Earth year, with five "deep dips" at 150 km minimum altitude to sample the upper atmosphere. The University of Colorado Boulder, University of California, Berkeley, and Goddard Space Flight Center each built a suite of instruments for the spacecraft, and they include:

Particles and Field (P&F) Package:
 * Built by the University of California, Berkeley Space Sciences Laboratory.


 * Solar Wind Electron Analyzer (SWEA) – measures solar wind and ionosphere electrons
 * Solar Wind Ion Analyzer (SWIA) – measures solar wind and magnetosheath ion density and velocity
 * SupraThermal And Thermal Ion Composition (STATIC) – measures thermal ions to moderate-energy escaping ions
 * Solar Energetic Particle (SEP) – determines the impact of SEPs on the upper atmosphere
 * Langmuir Probe and Waves (LPW) – determines ionosphere properties and wave heating of escaping ions and solar extreme ultraviolet (EUV) input to atmosphere
 * Magnetometer (MAG) – measures interplanetary solar wind and ionosphere magnetic fields

Remote Sensing (RS) Package:
 * Built by the University of Colorado Laboratory for Atmospheric and Space Physics.


 * Imaging Ultraviolet Spectrometer (IUVS) – measures global characteristics of the upper atmosphere and ionosphere

Neutral Gas and Ion Mass Spectrometer (NGIMS) Package:
 * Built by Goddard Space Flight Center


 * Measures the composition and isotopes of neutral gases and ions

Status
The orbiter is in Mars orbit and operational. The commissioning phase lasted until the first week of November 2014 (six weeks), and then the science phase of the mission commenced. In June 2015, the science phase was extended through September 2016. MAVEN carries enough fuel to extend its science mission for an additional two years, and then another six years to function as a telecomm orbiter at a higher, more circular orbit.

Results
On November 5, 2015, NASA scientists reported, based on results from the MAVEN orbiter circling Mars, that the solar wind is responsible for stripping away the atmosphere of Mars over the years, as the shielding effect of the global magnetic field was lost as the planet's internal dynamo cooled.