Mars Long-Lived Weather Network Mission Study
Authors: Parfitt Claire , McSweeney Adam , Ball Andrew , Orgel Csilla , Svedhem Håkan , Vijendran Sanjay 
Published: July 2021

ESA&#8217;s current Mars exploration programme consists of the flying orbiters Mars Express and the ExoMars TGO, while the ExoMars rover is planned for launch in 2022. The Nov 2019 ESA Council of Ministers meeting, Space19+, has approved ESA contributions to a Mars Sample Return Campaign, led by NASA, with a launch of the sample retrieval missions planned to occur as early as 2026.The ExoMars and Mars Sample Return (MSR) missions will expand our understanding of Martian history, potential for life and environmental conditions. These missions will develop European technologies and capabilities to enable access to Mars orbit, Mars surface and shallow sub-surface as well as a round-trip journey. However, key strategic knowledge gaps will still remain for the human exploration of Mars following successful ExoMars and MSR missions. These include the understanding of the long-term behaviour of the atmosphere, wind profiles, dust properties and transport and origin of dust storms.A study was undertaken in the Concurrent Design Facility (CDF) at ESA, ESTEC in order to address this important knowledge gap through a reference mission architecture that would be the first coordinated global, regional and local network of atmospheric science and weather stations at Mars. The reference launch date for the mission is in the early-mid 2030&#8217;s.The selected mission architecture comprises several elements, including:A Low Mars Orbiter (LMO), in a high-inclination orbit;
An Areosynchronous Orbiter (ASO) situated at the same longitude as the landers
Four identical Mars landers comprising:
3 &#8220;local&#8221; landers in a triangular configuration situated 20km-150km apart
1 &#8220;regional&#8221; lander situated ~800km West of the local lander network

Two carrier spacecraft each carrying two Mars landers from Earth to Mars atmospheric entry.
The primary science objectives focus on meteorology, wind and dust transport measurements from the orbital and landed assets. In addition, the landers also contain a radio science, seismology and heat flow payload suite to address secondary science objectives. Due to the scale of the mission and large number of sizeable mission elements, the architecture was spilt into a two-launch scenario where the first launch comprises the two orbiter spacecraft, and the second launch (in the next launch window opportunity) comprises the two carrier spacecraft each carrying two landers. Due to this large scope, the CDF study focussed on the design of the four Mars landers and the Areosynchronous orbiter, the definition of the science payloads, the overall concept of operations, cost and programmatics.The study results show the technical feasibility of such a mission to be undertaken in the 2030&#8217;s at landing sites between 0&#176;N and 20&#176;N latitude whilst utilising existing European heritage in chemical propulsion Orbiters and ballistic Entry, Descent and Landing (EDL) technology. Challenges for the lander elements include the need for radioisotope heater units (RHUs), large solar arrays and energy-efficient platform and payload operations, all driven by the need to survive for multiple Mars years on the surface including science operations through potential global dust storms. Further work to refine the mission concept is planned.&#160;Figure 1: Mars Long-Lived Weather Network Mission ArchitectureFigure 2: Conceptual design of one of the four Mars landers showing the location of the science instruments