| Operator | ESA, NASA |
|---|---|
| Major contractors | Thales Alenia Space and Astrium |
| Mission type | Orbiter, lander and rover |
| Orbital insertion date | 2017 and 2019 |
| Launch date | 2016 and 2018 from Cape Canaveral, Florida, USA |
| Launch vehicle | Two Atlas V rockets.[1] |
| Mission duration | Few days for the static lander;[2] 6 months for the rover; several years for the orbiter |
| Homepage | ExoMars programme |
| Mass | TGO: 3,130 kg;[3] Lander: 600 kg;[4] ExoMars rover: 270 kg;[5] |
| Power | Solar power / Batteries |
ExoMars (Exobiology on Mars) is a European-led robotic mission to Mars currently under development by the European Space Agency (ESA) with collaboration by NASA. Since its inception it has gone through several phases of planning with various proposals for landers, orbiters, launch vehicles, and international cooperation planning, such as the 2009 Mars Exploration Joint Initiative (MEJI) with the United States. As of 2011[update], an ExoMars orbiter examining trace gases and a short-life static lander test is planned for 2016, and one rover—ExoMars rover—for 2018.
Originally conceived as a rover with a static ground station, ExoMars was planned to launch in 2011 aboard a Soyuz Fregat rocket.[6] Within the framework of the new Mars Joint Exploration Initiative signed by NASA and ESA in July 2009, the drastically delayed ExoMars mission was combined with other projects to a multi-spacecraft programme divided over two Atlas V-launches:[4] the ExoMars Trace Gas Orbiter (TGO) was merged into the project, piggybacking a static meteorological lander being slated for launch in 2016. The accompanying NASA MAX-C rover was cancelled in 2011 in favor of one joint ExoMars rover.[7]
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Since its beginnings in the early 2000s, ExoMars was subject to massive political and financial strife. Originally, the ExoMars concept consisted of one single, large robotic rover being part of ESA's Aurora programme as a Flagship mission and was approved by Europe's space ministers in December 2005. Initially planned to launch in 2011, Italy, a leading nation on the ExoMars mission, decided to limit its financial contribution, causing the first of three delays.
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.[8]
In July 2009 NASA and ESA signed the Mars Joint Exploration Initiative, which significantly altered the technical and financial setting of the ExoMars mission. On June 19, when the rover was still planned to piggyback on the Mars Trace Gas Orbiter, it was reported that a prospective agreement would require that ExoMars lose enough weight to fit aboard the Atlas vehicle with NASA's orbiter.[9]
In August 2009 it was announced that the Russian Space Agency Roscosmos and ESA had signed a collaboration agreement 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 should also include Russian-made parts.[10][11]
In October 2009 it was reported that under the agreed Mars Joint Exploration Initiative, the project would consist of two separate launches: a lander/orbiter mission in 2016 and a rover mission in 2018, each with a significant NASA role, including the use of two Atlas V rockets.[1][12] This initiative would apparently reconcile technological and science goals with available budgets.[12]
In 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. Another €150 million needed for operating the mission will be solicited during a meeting of ESA government ministers in late 2011 or early 2012. Unlike some ESA programmes, the ExoMars financing will not include a 20% margin for cost overruns, however.[13]
A group of scientists will be testing instruments being developed for the ExoMars missions in Morocco, chosen by reason of its arid and varied landscape.[14] One of the first tests scheduled for 2011 will be the Entry, Descent and Landing Demonstrator Module (EDM).[15]
In April 2011, because of a budgeting crisis, a proposal was announced to fly only one rover in 2018 that would be larger than either of the vehicles in the paired concept - ExoMars (ESA) and Max-C (NASA).[16] One suggestion is that the new vehicle would be built in Europe and take a mix of European and U.S. instruments. NASA would provide the rocket to get it into Mars and the 'Sky Crane' landing system. Despite the proposed reorganisation, the goals of the 2018 mission opportunity would stay broadly the same. These would be to look for signs of past or present life by drilling down into the soil, and packaging or caching rocks that can be picked up and despatched to Earth laboratories by a subsequent mission.[16] In April 2011 MAX-C was canceled.[7]
The ExoMars mission's scientific objectives, in order of priority, are:[17]
The technological objectives to develop are:
According to current plans,[4][19][20] the ExoMars mission will comprise three spacecraft elements sent in two launches, both from Florida:
| Contributing agency | First launch in 2016 | Second launch in 2018 |
|---|---|---|
| Launch vehicle: Atlas V 411 | Launch vehicle: Atlas V 551 | |
| 4 unspecified instruments for TGO | Landing system: Sky-crane | |
| Trace Gas Orbiter | 270 kg ExoMars rover | |
| 600 kg static meteorological lander | ||
| Entry, descent and landing system (EDL) |
The Trace Gas Orbiter (TGO), to be launched on January 2016,[18] will deliver the ExoMars 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 on 2018. 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 EDM lander and ExoMars rover with telecommunication relay. The TGO would continue serving as a relay satellite for future landed missions until 2022.[21]
The ExoMars 'Entry, Descent and Landing Demonstrator Module' (EDM) is a static lander originally planned to carry a group of eleven instruments collectively called the "Humboldt payload"[22] that would be dedicated to investigate 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.[23] The ESA-NASA collaboration (Mars Exploration Joint Initiative) concluded to launch all mission elements with two rockets, which generated new payload reviews, so it was decided to first demonstrate ESA's new descent and landing system technology on the EDM lander, so its payload and operation time will be very limited.[2]
The Entry, Descent and Landing Demonstrator Module (EDM) will provide Europe with the technology for landing on the surface of Mars with a controlled landing orientation and touchdown velocity. After entering the Martian atmosphere, the module will deploy a parachute 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 latter will guide a liquid propulsion system which will produce a semi-soft touchdown on the surface of Mars by the actuation of clusters of thrusters to be operated in pulsed on-off mode.[24]
The EDM will be landing during the dust storm season, this will provide a unique chance to characterise a dust-loaded atmosphere during entry and descent, and to conduct surface measurements associated with a dust-rich environment.[25] Once on the surface, it will measure the wind speed and direction, humidity, pressure and surface temperature, and determine the transparency of the atmosphere.[25] It will also make the first measurements of electrical fields at the planet's surface. A color camera system is included in the payload. The EDM lander is expected to operate on the surface of Mars for a short time (about 8 sols) by using the excess energy capacity of its batteries.[24] Its proposed landing site is the Meridiani Planum because it is almost flat and without too many rocks, ideal for its airbag landing system.[2]
Plans call for the use of NASA's sky crane entry, descent and landing (EDL) system to deliver the rover on the surface of Mars.[7][18]
The ExoMars rover is a highly autonomous six-wheeled terrain vehicle and will weigh 295 kg, ca. 100 kg more than NASA's Mars Exploration Rovers Spirit and Opportunity.[5] Temporary plans considered a downsized version with a reduced weight of 207 kg.[26] Instrumentation will consist of the 10 kg 'Pasteur Payload' containing, among other instruments, a 2 meter sub-surface drill.[27]
The carrier module will deliver the descent module to Mars from a hyperbolic approach trajectory after which the Sky-crane landing system will ensure a soft landing with high accuracy. Once safely landed on the Martian surface the solar powered rover would begin a 218-sol mission. To counter the difficulty of remote control due to communication lag, ExoMars will have autonomous software for visual terrain navigation using compressed stereo images from mast mounted panoramic and infrared cameras and independent maintenance. For this purpose it creates digital maps from navigation stereo pair cameras and autonomously finds the adequate trajectory. Close-up collision avoidance cameras are used to ensure safety enabling the vehicle to navigate and safely travel approximately 100 meters per day. After the lander has been released and landed on the surface of Mars, the Mars Trace Gas Orbiter will operate as the rover's data-relay satellite.[19]
It had been proposed that ESA ExoMars rover would be deployed together with a smaller NASA rover, the Mars Astrobiology Explorer-Cacher (MAX-C).[28][29][30][31] However, this was canceled in April 2011 in favor of a single larger joint ESA-NASA rover and for budget cuts.[7][32]
It was thought two rovers active at the same location could lead to synergies, such as bistatic radar surveys between the two rovers. The MAX-C rover would collect, analyze, and cache the most valuable samples in a manner suitable for return to Earth by a future mission. When the idea of the two rovers delivered to the same location on Mars was active, their science objectives and instruments was to be complementary in order to minimize duplication. Advantages of operating two rovers in the same area are: rover to rover imaging, cross analysis of similar geological targets, a low-frequency ground-penetrating radar on MAX-C and listen with ExoMars, and the MAX-C could receive and cache some of the most valuable subsurface samples collected by ExoMars for a later sample retrieval mission.[18]
Under the agreed collaboration, NASA will provide two Atlas V rockets, as it was decided to divide the weight of the ExoMars system in two launches.[20][33][34]
ESA has already worked out a framework agreement with the Russian Space Agency that would allow it to cooperate on ExoMars, including provision of backup launch services and a payload contribution, along with mission support.[34] The backup launcher is the Proton rocket,[11] which is a four-stage rocket that was previously used to launch the Salyut 6, Salyut 7, Mir and some International Space Station components.
If the collaboration with NASA takes place as proposed, it would be possible to implement NASA's new skycrane entry and descent system to be used on the Mars Science Laboratory rover.[35]
As of November 2007, the potential landing sites are:[36]
However, the 2009 discovery of methane sources on the planet makes them a high value target for exploration.[1] The presence of methane is intriguing because its likely origin is either present-day life or geological activity; confirmation of either would be a major discovery. Methane occurres in extended plumes, and the profiles imply that the methane was released from discrete regions. The profiles suggest that there may be two local source regions, the first centered near 30° N, 260° W and the second near 0°, 310° W.[37] To determine the optimal landing site and secure telecommunications, it was decided to include the Mars Trace Gas Mission orbiter in the 2016 launch in order to map beforehand what appears to be seasonal methane production.[38] The rover could then investigate the methane sources identified by the orbiter.
The present environment on Mars is exceedingly hostile for the widespread proliferation of surface life: it is too cold and dry and receives large doses of solar UV radiation as well as cosmic radiation. Notwithstanding these hazards, basic microorganisms may still flourish in protected places underground or within rock cracks and inclusions.[38] The science package in the ExoMars rover will hold a variety of instruments to study the environment for past or present habitability and possible biosignatures on Mars. The first instrument proposal (2004) is as follows:[39]
The Panoramic Camera System (PanCam) has been designed to perform digital terrain mapping for the rover and to search for morphological signatures of past biological activity preserved on the texture of surface rocks. The PanCam assembly includes two wide angle cameras for multi-spectral stereoscopic panoramic imaging, and a high resolution camera for high-resolution colour imaging.[40][41] The PanCam will also support the scientific measurements of other instruments by taking high-resolution images of locations that are difficult to access, such as craters or rock walls, and by supporting the selection of the best sites to carry out exobiology studies.
The ExoMars core drill is devised to acquire soil samples down to a maximum depth of 2 metres, in a variety of soil types. The drill will acquire a core sample (1 cm in diameter x 3 cm in length), extract it and deliver it to the inlet port of the Rover Payload Module, where the sample will be distributed, processed and analyzed. The ExoMars Drill embeds the Mars Multispectral Imager for Subsurface Studies (Ma-Miss) which is a miniaturised IR spectrometer devoted to the borehole exploration. The system will complete experiment cycles and at least 2 vertical surveys down to 2 metres (with four sample acquisitions each). This means that a minimum number of 17 samples shall be acquired and delivered by the drill for subsequent analysis.[42]
These instruments are placed internally and used to study collected samples:[43]
The ExoMars Rover is designed to navigate autonomously across the surface. A pair of stereo cameras allow the rover to build up a 3D map of the terrain, which the navigation software then uses to assess terrain around it so that it avoids obstacles and find the most efficient route.[53]
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