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MetNet

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MetNet

MetNet
MetNet impactor concept
Mission type Technology
Atmospheric science
Operator Finnish Meteorological Institute
Website .php/index.fi.fmimetnet
Spacecraft properties
Landing mass entry mass: 22.2 kg per unit[1]
Payload mass 4 kg allocation
Dimensions Impactor: 1.8 m diameter[2]
Power 0.6 W [1]
Start of mission
Launch date Proposed: 2015—2016 launch window[1]
Rocket Zenit-2M or Volna
Mars impactor

MetNet is an atmospheric science mission to Mars, initiated and defined by the Finnish Meteorological Institute (FMI).[1] The mission includes deploying at least 16 MetNet impact landers on the Martian surface. The objective is to establish a widespread surface observation network on Mars to investigate the planet's atmospheric structure, physics and meteorology. A precursory 'demonstration mission' consisting of one lander is proposed to launch in the 2015—2016 launch window.[1]

History

The basic concepts of MetNet were cast by the Finnish Meteorological Institute team in late 1980s. The concept was matured over a decade, and eventually the MetNet development work started in the year 2000.[3][4] MetNet may be considered as a successor of the NetLander, Russian Mars 96 and the earlier ESA Marsnet and InterMarsnet mission concepts.[5]

The scope of the MetNet mission is eventually to deploy several tens of impact landers on the Martian surface by 2018. MetNet is being developed by a consortium consisting of the Finnish Meteorological Institute (Mission Lead), the Russian Space Research Institute (IKI) (in cooperation with Lavochkin Association), and Instituto Nacional de Técnica Aeroespacial (INTA) from Spain. By 2013, all qualification activities had been completed and the payload and flight model components were being manufactured.[6]

Current status

The precursory demonstrator is proposed for the launch windows starting from 2015. The precursory mission would consist of one lander and is intended as a technology and science demonstration mission. If successful and if funded, more landers are proposed to be deployed in the following launch windows extending up to 2019.[7]

By September 2013, two flight-capable entry, descent and landing systems (EDLS) had been manufactured and tested with acceptance levels.[8] one of those articles is being used for further environment tests, while a second is currently considered flight-worthy. The tests covered resistance to vibration, heat, and mechanical impact shock, and are ongoing as of April 2015. The test EDLS unit may later be refurbished for flight.[9]

Objectives

Detailed characterization of the Martian circulation patterns, boundary layer phenomena, and climatological cycles requires simultaneous in situ meteorological measurements from networks of stations on the Martian surface.[5] The purpose of the MetNet precursor mission is to confirm the concept of deployment for the mini-meteorological stations onto the Martian surface, to obtain atmospheric data during the descent phase, and to obtain information about the meteorology and surface structure at the landing site during one Martian year or longer.[10] Specifically, the scientific objectives of the lander are to study:[11]

  • Atmospheric dynamics and circulation
  • Surface to atmosphere interactions and planetary boundary layer
  • Dust raising mechanisms
  • Cycles of CO2, H2O and dust
  • Evolution of the Martian climate

Lander concept

Artist's rendering of a MetNet impactor entering the Martian atmosphere. Lower module: inflatable heat shield; upper module: 1.8 m inflatable decelerator

Each MetNet lander, or impactor probe, will use inflatable entry and descent system instead of rigid heat shields and parachutes as earlier semi-hard landing devices have used.[12] This way the ratio of the payload mass to the overall mass is optimized, and more mass and volume resources are spared for the science payload. The MetNet lander's atmospheric descent process can be partitioned into two phases: the primary aerodynamic or the 'Inflatable Braking Unit' deceleration phase, and the secondary aerodynamic or the 'Additional Inflatable Braking Unit' deceleration phase. The probes will have a final landing speed of 44.6 to 57.6 m/s.[2] The operational lifetime of a lander on the Martian surface will be seven years.[13]

The fact that both meteorology in particular and climatology in general vary both temporally and spatially means that the most effective means of monitoring these is to make simultaneous measurements at multiple locations and over a sufficiently long period of time. Bearing this in mind, MetNet includes both a global-scale, multi-point network of surface probes supplemented by a supporting satellite in orbit, for a projected duration of two Martian years. Somewhere in the range of ten to twenty observation points is seen as a minimum to get a good picture of atmospheric phenomena on a planet-wide scale.[14]

Orbiter concept

As the requirements for a transfer vehicle are not very extensive, the MetNet impact landers could be launched with any mission going to Mars. The landers could piggyback on a Martian orbiter from ESA, NASA, Russia or China or an add-on to larger Martian landers like ExoMars.[1] Also a dedicated launch with several units from low Earth orbit is under study.[1] Most of the MetNet landers would be deployed to Mars separately a few weeks prior to the arrival to Mars to decrease the amount of required fuel for deceleration maneuvers. The satellite platform would then be inserted to an orbit around Mars and the last few MetNet impact landers would be deployed to the Martian surface form the orbit around Mars to be able to land on any selected areas of the Martian surface in a latitude range of +/- 30 degrees for optimal solar panel efficiency.[1][5] A sounder on board the orbiter would perform continuous atmospheric soundings, thus complementing the in situ observations. The orbiter will also serve as the primary data relay between the impact landers and the Earth.[1][5]

Precursory mission

For the earlier launch window, two delivery concepts were being considered:[15]

  1. Piggyback to the Russian Phobos Grunt Sample Return mission.
  2. Dedicated launch using the Russian Volna — a converted Submarine/Sea-Launched Ballistic Missile (SLBM).

The FMI originally planned to launch the demonstration lander on board the Phobos Grunt mission on 2011. However, the MetNet lander was later dropped from the Phobos-Grunt mission due to weight constraints on the spacecraft. Phobos-Grunt later failed to depart Earth orbit and crashed into the Pacific Ocean on January 16, 2012.[16] The precursory mission is now proposed for the 2014-2015 launch window.

Payload

The payload of the MetNet Mars Precursor Mission include the following instruments:[10][12]

  • MetBaro: pressure sensor with a 1015 hPa limit (100 g)
  • MetHumi: humidity sensor (15 g)
  • MetTemp: temperature sensor with a range from -110 °C to +30 °C (2 g)
  • Panoramic camera with four lenses mounted at 90° intervals (100 g)
  • MetSIS: a solar radiance sensor to measure its daily and seasonal variations (115 g)
  • Dust Sensor: can measure 10 particles/cm3 of airborne dust on the Martian surface (42 g)
  • MOURA: a magnetometer to determine mineral composition (80 g)

Power

The impact landers are equipped with flexible solar panels, located on the upper side of the inflatable braking unit, that will provide approximately 0.6 W during the day.[1] As the provided power output is insufficient to operate all instruments simultaneously, they are activated sequentially according to the different environmental constraints.[12]

References

  1. ^ a b c d e f g h i j
  2. ^ a b
  3. ^
  4. ^ MetNet - Precursor Mission Overview
  5. ^ a b c d
  6. ^
  7. ^
  8. ^
  9. ^ http://adsabs.harvard.edu/abs/2015EGUGA..1713336H
  10. ^ a b
  11. ^
  12. ^ a b c
  13. ^
  14. ^
  15. ^
  16. ^

External links

  • MetNet Mission Poster (2012) PDF
  • Animation video (58 seconds) of the hard landing sequence: [1]
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