ExoMars

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ExoMars
Operator ESA & Russian Federal Space Agency
Major contractors Orbiter: Thales Alenia Space
Rover: Astrium
Mission type Orbiter, 2 landers and rover
Launch date 2016 and 2018
Launch vehicle Two Proton rockets
Mission duration Schiaparelli EDM lander: 4 sols
Rover: ≥6 months
Orbiter: several years
Orbital insertion date 2017 and 2019
Homepage ExoMars programme
Mass

TGO: 3,130 kg[1]
Schiaparelli EDM lander: 600 kg[2]
Russian lander: ~1800 kg [3]

Rover: ~300 kg[4]
Power

TGO: Solar power
Schiaparelli EDM lander: electric battery

Rover: Solar power
Russian lander: TBD

ExoMars (Exobiology on Mars) is a large Mars mission to search for biosignatures of Martian life, past or present. This astrobiology mission is currently under development by the European Space Agency (ESA) in collaboration with the Russian Federal Space Agency (Roscosmos).[5] The programme includes several spacecraft elements to be sent to Mars on two launches. The ExoMars Trace Gas Orbiter (TGO) and an EDM stationary lander called 'Schiaparelli' are planned for 2016. The TGO would deliver the ESA-built stationary lander and then proceed to map the sources of methane on Mars and other gases, and in doing so, help select the landing site for the ExoMars rover[6] to be launched on 2018 on a Russian heavy lift Proton launch vehicle. The TGO will feature four instruments and will also act as the communication relay satellite for the follow up rover. In 2018 a Roscosmos-built lander is to deliver the ESA-built rover to the martian surface.[4][5][7] The rover will also include some Roscomos built instruments.

History[edit]

Since its inception, ExoMars has gone through several phases of planning with various proposals for landers, orbiters, launch vehicles, and international cooperation planning,[8] such as the defunct 2009 Mars Exploration Joint Initiative (MEJI) with the United States.[9][10] Originally, the ExoMars concept consisted of a large robotic rover being part of ESA's Aurora programme as a Flagship mission and was approved by the European Space Agency ministers in December 2005. Originally conceived as a rover with a stationary ground station, ExoMars was planned to launch in 2011 aboard a Russian Soyuz Fregat rocket.[11]

In 2007, Canadian-based technology firm MacDonald Dettwiler and Associates Ltd. (MDA) was selected for a one-million-euro contract with EADS Astrium of Britain to design and build a prototype Mars rover chassis for the European Space Agency. Astrium was also contracted to design the final rover.[12]

On July 2009 NASA and ESA signed the Mars Exploration Joint Initiative, which proposed to utilize an Atlas rocket launcher instead of a Soyuz, which significantly altered the technical and financial setting of the ExoMars mission. On June 19, when the rover was still planned to piggyback the Mars Trace Gas Orbiter, it was reported that a prospective agreement would require that ExoMars lose enough weight to fit aboard the Atlas launch vehicle with a NASA orbiter.[13]

Then the mission was combined with other projects to a multi-spacecraft programme divided over two Atlas V-launches:[2][14][15] the ExoMars Trace Gas Orbiter (TGO) was merged into the project, piggybacking a stationary meteorological lander slated for launch in January 2016. It was also proposed to include a second rover, the MAX-C.

In August 2009 it was announced that the Russian Federal Space Agency (Roscosmos) and ESA had signed a contract that included cooperation on two Mars exploration projects: Russia's Fobos-Grunt project and ESA's ExoMars. Specifically, ESA secured a Russian Proton rocket as a "backup launcher" for the ExoMars rover, which would include Russian-made parts.[16][17]

On December 17, 2009, the ESA governments gave their final approval to a two-part Mars exploration programme to be conducted with NASA, confirming their commitment to spend €850 million ($1.23 billion) on missions in 2016 and 2018.[18]

In April 2011, because of a budgeting crisis, a proposal was announced to cancel the accompanying MAX-C rover, and fly only one rover in 2018 that would be larger than either of the vehicles in the paired concept.[19] One suggestion was that the new vehicle would be built in Europe and carry a mix of European and U.S. instruments. NASA would provide the rocket to deliver it to Mars and provide the sky crane landing system. Despite the proposed reorganisation, the goals of the 2018 mission opportunity would have stayed broadly the same.[19]

Under the FY2013 Budget President Obama released on February 13, 2012, NASA terminated its participation in ExoMars due to budgetary cuts in order to pay for the cost overruns of the James Webb Space Telescope.[20][21] With NASA's funding for this project completely cancelled, most of these plans had to be restructured.[10][22]

On March 14, 2013, representatives of the ESA and the Russian space agency (Roscosmos), signed a deal in which Russia becomes a full partner. Roscosmos will supply both missions with Proton launch vehicles with Briz-M upper stages and launch services,[23] as well as an additional entry, descent and landing module for the rover mission in 2018.[5] Under the agreement, Roscosmos was granted three asking conditions:[24]

  1. Roscosmos will contribute two Proton launch vehicles as payment for the partnership.
  2. The Trace Gas Orbiter payload shall include two Russian instruments that were originally developed for Fobos-Grunt.[3][5][25]
  3. All scientific results must be intellectual property of the European Space Agency and the Russian Academy of Sciences (i.e. Roscosmos will have full access to research data[26]).

Current status[edit]

While the 2016 segment appears secure, the financial situation of the 2018 mission remains unclear.[27][28][29] Italy is the largest contributor to ExoMars, and the UK is the mission's second-largest financial backer.[30] Russia's financing of ExoMars could be partially covered by insurance payments of 1.2 billion rubles ($40.7 million USD) for the loss of Fobos-Grunt,[24] and reassigning funds for a possible coordination between the Mars-NET and ExoMars projects.[31][32] On 25 January 2013, Roscosmos fully funded the development of the scientific instruments to be flown on the first launch, the Trace Gas Orbiter (TGO).[33]

ESA had originally cost-capped the ExoMars projects at €1 billion, (USD 1.3 billion) but the withdrawal of the U.S. space agency (NASA) and the consequent reorganisation of the ventures will probably add several hundred million euros to the sum so far raised.[4] So on March 2012, member states instructed the agency's executive to look at how this shortfall could be made up.[34] One possibility is that other science activities within ESA may have to step back to make ExoMars a priority.[4][35] On September 2012 it was announced that new ESA members, Poland and Romania will be contributing up to €70 million to the ExoMars programme.[36] ESA has not ruled out a possible partial return of NASA to the 2018 portion of ExoMars, albeit in a relatively minor role.[4][7][37]

As of March 2014, the lead builder the ExoMars rover, the British division of Airbus Defence and Space, has started procuring critical components.[30] The 2018 rover mission is still short by more than 100 million euros, or $138 million.[30] The wheels and suspension system are paid by the Canadian Space Agency and are being manufactured by MDA Corporation in Canada.[30]

Mission objectives[edit]

The scientific objectives, in order of priority, are:[38]

  • to search for possible biosignatures of Martian life, past or present.
  • to characterize the water and geochemical distribution as a function of depth in the shallow subsurface.
  • to study the surface environment and identify hazards to future manned missions to Mars.
  • to investigate the planet's subsurface and deep interior to better understand the evolution and habitability of Mars.
  • achieve incremental steps ultimately culminating in a sample return flight.

The technological objectives to develop are:

  • landing of large payloads on Mars.
  • to exploit solar electric power on the surface of Mars.
  • to access the subsurface with a drill able to collect samples down to a depth of 2 metres (6.6 ft)
  • to develop surface exploration capability using a rover.

Mission profile[edit]

ExoMars is a two-mission project that is considered as a single programme at ESA. According to current plans, the ExoMars project will comprise four spacecraft: two stationary landers, one orbiter and one rover. All mission elements will be sent in two launches using two heavy-lift Proton rockets.[4][7][39]

Contributing agency First launch in 2016 Second launch in 2018
Roscosmos logo ru.svg Proton rocket Proton rocket
Most instruments for the TGO
Russian landing system & some rover instruments
ESA logo.svg ExoMars Trace Gas Orbiter ExoMars rover
Schiaparelli EDM lander

The two landing modules and the rover will be sterilised in order not to pollute the planet with Earth life forms. Cleaning will require a combination of sterilising methods, including ionizing radiation, UV radiation, and chemicals such as ethyl and isopropyl alcohol.[23][40] (See: Planetary protection.)

First launch (2016)[edit]

Trace Gas Orbiter[edit]

The Trace Gas Orbiter (TGO) will be a Mars telecommunications orbiter and atmospheric gas analyzer mission for launch on January 2016. The spacecraft will arrive in the Martian orbit in October 2016. It will deliver the ExoMars Schiaparelli EDM lander and then proceed to map the sources of methane on Mars and other gases, and in doing so, help select the landing site for the ExoMars rover to be launched in 2018.[41] The presence of methane in Mars' atmosphere is intriguing because its likely origin is either present-day life or geological activity. Upon the arrival of the rover in 2018/2019, the orbiter would be transferred into a lower orbit where it would be able to perform analytical science activities as well as provide the Schiaparelli EDM lander and ExoMars rover with telecommunication relay. NASA will provide an Electra telecommunications relay and navigation instrument to ensure communications between probes and rovers on the surface of Mars and controllers on Earth.[5][42] The TGO would continue serving as a telecommunication relay satellite for future landed missions until 2022.[43]

Schiaparelli EDM lander[edit]

Diameter 2.4 m (7.9 ft)[8]
Height 1.8 m (5.9 ft)
Mass 600 kg (1,300 lb)
Heat shield material Norcoat Liege
Structure Aluminium sandwich with carbon fiber
reinforced polymer skins
Parachute Disk-Gap-Band canopy
12 m diameter
Propulsion 3 clusters of 3 hydrazine pulse engines
(400 N each)[44]
Power Batteries
Communications UHF link with the
ExoMars Trace Gas Orbiter

The Entry, Descent and Landing Demonstrator Module (EDM) called 'Schiaparelli',[45] will provide ESA with the technology for landing on the surface of Mars with a controlled landing orientation and touchdown velocity; key technologies for the 2018 mission.[44] After entering the Martian atmosphere, the module will deploy two parachutes and will complete its landing by using a closed-loop guidance, navigation and control system based on a Radar Doppler Altimeter sensor and on-board Inertial Measurement Units. The final stages of the landing will be performed using pulse-firing liquid-fuel engines. About a metre above ground, the engines will turn off. The platform will land on a crushable structure, designed to deform and absorb the final touchdown impact.[44][46] Throughout the descent, the Entry and Descent Science Team will perform investigations using various sensors to record a number of atmospheric parameters.[46]

The landing will take place on Meridiani Planum[44] during the dust storm season, which will provide a unique chance to characterize a dust-loaded atmosphere during entry and descent, and to conduct surface measurements associated with a dust-rich environment.[47] Once on the surface, it will measure the wind speed and direction, humidity, pressure and surface temperature, and determine the transparency of the atmosphere.[47] It will also make the first measurements of electrical fields at the planet's surface. A descent camera is included in the payload.

Initially, Roscosmos offered to contribute a 100 watt radioisotope thermoelectric generator (RTG) power source for the EDM lander to allow it to monitor the local surface environment for a full Martian year,[4][20] but because of Russian export control procedures, it later opted for the use of a regular electric battery with enough power for four sols.[48]

The lander's name refers to 19th century astronomer Giovanni Schiaparelli, best known for describing the surface features of Mars. He was also the first astronomer to determine the relationship between comet debris and yearly meteor showers.[45]

Surface payload[edit]

The ExoMars 'Entry, Descent and Landing Demonstrator Module' (EDM), called 'Schiaparelli', is a stationary lander originally planned to carry a group of eleven instruments collectively called the "Humboldt payload",[49] that would be dedicated to investigating the geophysics of the deep interior. But a payload confirmation review in the first quarter of 2009 resulted in a severe descope of the lander instruments, and the Humboldt suite was cancelled entirely.[50]

The latest EDM surface payload, based on the proposed meteorological DREAMS (Dust Characterization, Risk Assessment, and Environment Analyser on the Martian Surface) package, consists of a suite of sensors to measure the wind speed and direction (MetWind), humidity (MetHumi), pressure (MetBaro), surface temperature (MarsTem), the transparency of the atmosphere (Optical Depth Sensor; ODS), and atmospheric electrification (Atmospheric Radiation and Electricity Sensor; MicroARES).[51]

The DREAMS payload will function for 2 or 3 days as an environmental station for the duration of the EDM surface mission after landing.[44][46] DREAMS will provide the first measurements of electric fields on the surface of Mars (with MicroARES). Combined with measurements (from ODS) of the concentration of atmospheric dust, DREAMS will provide new insights into the role of electric forces on dust lifting, the mechanism that initiates dust storms. In addition, the MetHumi sensor will complement MicroARES measurements with critical data about humidity; this will enable scientists to better understand the dust electrification process.[51]

In addition to the surface payload, a camera called DECA (Entry and Descent Module Descent Camera) on the EDM will deliver additional scientific data and exact location data in the form of images.[52] DECA is a reflight of the Visual Monitoring Camera VMC of the Herschel/Planck mission.

Second launch (2018)[edit]

Russian landing system[edit]

The second mission, scheduled for launch in May 2018, will have an 1800 kg Russian-buillt landing system derived from the 2016 Schiaparelli EDM lander, to place the ExoMars rover on the surface of Mars.[3][53] This lander module will be built 80% by Russian company Lavochkin, and 20% by ESA.[7] Lavochkin will produce most of the landing system's hardware, while ESA will handle elements such as the guidance, radar and navigation systems.[4] The Russians plan to equip a meteorological station on the rover's lander that will be powered by a radioisotope thermoelectric generator. This will give the weather sensors long-term power.[53]

Lavochkin's current strategy is to use two parachutes; one will open while the module is still moving at supersonic speed, and another will deploy once the probe has been slowed down to subsonic velocity. The heat shield will eventually fall away from the entry capsule to allow the ExoMars rover, riding its retro-rocket-equipped lander, to come for a soft landing on legs or struts. The lander will then deploy ramps for the rover to drive down.[53]

Critics have stated that while Russian expertise may be sufficient to provide a launch vehicle, it does not currently extend to the critical requirement of a landing system for Mars.[53][54][55]

Rover[edit]

Main article: ExoMars rover
An early design ExoMars rover test model at the ILA 2006 in Berlin
Another early test model of the rover from the Paris Air Show 2007

The ExoMars rover will land on January 2019 and is designed to navigate autonomously across the Martian surface.[56][57][58]

Instrumentation will consist of the exobiology laboratory suite, known as "Pasteur analytical laboratory" to look for signs of biomolecules and biosignatures from past or present life.[4][49][59][60] Among other instruments, the rover will also carry a 2-metre (6.6 ft) sub-surface core drill to pull up samples for its on-board laboratory.[61] The rover will have a mass of about 207 kg (456 lb).

Landing site selection[edit]

Mawrth Vallis with its potential clues on the history of water on Mars is a landing site-candidate

A primary goal when selecting the rover's landing site is to identify a particular geologic environment, or set of environments, that would support —now or in the past— microbial life. The scientists prefer a landing site with both morphologic and mineralogical evidence for past water. Furthermore, a site with spectra indicating multiple hydrated minerals such as clay minerals is preferred, but it will come down to a balance between engineering constraints and scientific goals.[62]

Engineering constraints call for a flat landing site in a latitude band straddling the equator that is only 30° latitude from top to bottom because the rover is solar-powered and will need best sunlight exposure.[62] The landing module carrying the rover will have a landing ellipse that measures about 105 km by 15 km.[63] Scientific requirements include landing in an area with 3.6 billion years old sedimentary rocks that are a record of the past wet habitable environment.[62][64] The year before launch, the European Space Agency will make the final decision.[62] As of March 2014, the long list was:[63]

Following additional review by an ESA-appointed panel, four sites, all of which are located relatively near the equator, were formally recommended in October 2014 for further detailed analysis:[65][66]

See also[edit]

References[edit]

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External links[edit]