exomars mission and spacecraft design

Paper number

IAC-08.A3.3.A3

Author

Mr. carlo cassi, Thales Alenia Space Italia, Italy

Year

2008

Abstract

introduction
exomars is the first mission of the esa exploration programme - aurora. the mission will demonstrate the feasibility of several key technologies that are necessary to support the european ambitions for future human exploration:
entry and descent of a large re-entry capsule (1200 kg) and landing (edl) of a payload of about 600 kg on the mars surface
surface mobility via a rover (250 kg) having several kilometres of mobility range
access to sub-surface via a drill, mounted in the rover, to acquire samples down to 2 meters.
automatic sample preparation and distribution for analyses of scientific experiments.
two sets of scientific payloads will be brought to mars with the following objectives:
establish whether life ever existed or still exists on mars (tight control of the bio-burden
exported to mars)
characterize the mars geochemistry and water distribution
improve the knowledge of the mars environment and geophysics
identify possible surface hazards to future human exploration missions.
mission
the mission configuration, named enhanced baseline mission, foresees the launch of a spacecraft
composite (sc) by means of an ariane 5 launcher lifting from kourou. an optimal launch window
has been established from november 23  to december 13  2013.
the mission and the sc will be designed to be compatible with a back-up launcher, proton –m
from baikonur.
an alternative launch date is foreseen, in january 2016.
sc composite and dm
the sc composite is formed by a carrier module and a descent module composite, consisting of
the descent module (dm) housing the rover module (rm). the total mass at launch is about 4550 kg.
the carrier module will provide the propulsion, communications and attitude control means to
perform the cruise phase (about 10 months), to enter a 4-sols orbit around mars and stay on that
orbit until favourable conditions for landing are met.
in the 2013 launch opportunity landing will take place after another 11 months, in september 2015,
outside the global dust storm season.
once the decision to land is made, the carrier will perform a de-orbiting manoeuvre to put the
entire sc composite on a collision course with mars, approximately 24 hours before the impact.
half a hour before reaching the mars atmosphere entry point, located at 120 km above the mars
surface, the descent module composite will separate from the carrier and coast until the entry
interface point in the mars atmosphere is reached. after a six minute flight through it the lander of
the dm will touch the mars surface, cushioned by its air bags.
once the lander has safely landed on the martian surface, it will perform a series of automatic
operations, lasting approximately half a hour, that will bring to the start of the rover mission and
the exposition of the humboldt stationary instruments to the mars environment. the rover and
humboldt surface operations will last 180-sol (6 months).
the lander is fitted with two radio-isotope heater units (rhu) to enable a robust surface mission.
rover
the exomars rover is capable of moving on the mars surface with a high degree of autonomy,
using stereo vision, sun and inertial sensors for navigation control.
the locomotion is provided by six driving and steering wheels.
the electrical power is generated by solar panels. during the martian night, the heat needed to keep
the minimum survival temperature is provided by two rhu’s.
the rover communicates with the ground station both directly in the x-band for basic
telecommand and telemetry, and via the nasa data-relay orbiter for the main data flow including
scientific data.
the rover hosts a number of scientific instruments and relevant support equipment. an analytical
laboratory module inside the rover is in charge of analysing the samples of the mars terrain,
looking for organic material, trace of past or present life on mars. the samples are dug up by a
drill, installed on the rover, down to a depth of 2 meters below the surface. other instruments,
including a ground-penetrating radar, are mounted on the rover: some of them are installed on a
small, 5-degree-of-freedom robotic arm.
the nominal mission of the rover on the mars surface will last six moths. the total mass of the
rover is 250 kg.
implementation phase
the exomars implementation phase, started in february with the phase b2 which will last until the
end of this year. the challenging december 2013 launch date requires that the detail design
activities of the principal elements are kicked-off before the system pdr, presently foreseen in
november this year.
as such the prime contractor will conduct the pdr’s of the entry and descent system, landing
platform, rover vehicle, drill & spds, cm/dm main separation assembly and carrier module in
the forthcoming months.
the objective is to accelerate the design and development activities of the lower-tier subcontractors
to let them enter in their pdr process right after the system pdr.
the assembly of the sc composite stm is foreseen to start in december 2009, one year after the
system pdr. the stm test campaign will confirm the thermal and mechanical design assumptions
and qualify the main sc structures to the launch and landing loads.
on the avionics and electrical side, test benches will be developed for the main elements to
converge into two avionics verification models, one for the carrier and descent module and one
for the rover, to be set-up at the prime premises in torino. the avm test campaign will last
approximately 6 months to allow electrical and functional validation of the avionics subsystems. it
will be completed in the summer of the year 2011.
dedicated flight-like models of the rover and the descent module will be built to allow a full
environmental and functional qualification of those elements; it’s not foreseen to produce a
qualification model for the more standard carrier module. the qualification phase will start in july
2010 and last until february 2012. the phase will be closed by a system qualification review,
combined with the critical design review, in march 2012. besides all other classical objectives the
cdr will authorize the starting of the s/c composite (p)fm ait campaign.
the pfm campaign will be completed within february 2013 with the flight acceptance review
which authorises the sc shipment to korou for the starting of the launch campaign.
the flight readiness review is placed mid november 2013: the optimal 21-days launch window
will last from 23 november to 13 december 2013.

Abstract document

IAC-08.A3.3.A3.pdf

Manuscript document

IAC-08.A3.3.A3.pdf (🔒 authorized access only).

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