Mars Surveyor landers

These legged Mars landers arose from the US 'Mars Surveyor' programme in the wake of the success of Mars Pathfinder. At that stage the programme envisaged launching one Surveyor lander and one Surveyor orbiter with each Mars launch window, starting in '98/'99 with the Mars Surveyor '98 lander (later renamed Mars Polar Lander), launched a few weeks after Mars Climate Orbiter (which was in part reflying payload lost with Mars Observer in 1993). Mars Polar Lander also carried the second New Millennium technology mission, the Deep Space 2 Mars Microprobes. Before the failure of both these missions on arrival at Mars, the plan was to launch a Mars Surveyor '01 lander in the same launch window as the Mars Surveyor '01 orbiter (launched as planned as Mars Odyssey). Further

Parts The Viking Lander
Figure 18.12 Viking Lander.

Target Objectives

Prime contractor Launch site, vehicle Launch date Arrival date Landing site co-ordinates End(s) of mission(s)

Mass(es)

Payload experiments

Mars

Study high-latitude Martian surface environment; search for H2O and CO2 in soil; monitor weather. More specifically, to:

• Record local meteorological conditions near the Martian south pole, including temperature, pressure, humidity, wind, surface frost, ground ice evolution, ice fogs, haze, and suspended dust

• Analyse samples of the polar deposits for volatiles, particularly H2O and CO2

• Dig trenches and image the interior to look for seasonal layers and analyse soil samples for water, ice, hydrates, and other aqueously deposited minerals

• Image the regional and immediate landing site surroundings for evidence of climate changes and seasonal cycles

• Obtain multi-spectral images of local regolith to determine soil types and composition

Lockeed Martin Astronautics

ETR, Delta II (Delta 7425)

03/01/1999 03/12/1999

Mission expected to end after — 3 months when batteries freeze as days get shorter in late summer. Contact lost prior to entry - never regained

Launch mass 583 kg, incl. 64 kg cruise/descent propellent, 82kg cruise stage, 140kg aeroshell and two 3.6kg DS-2 Mars Microprobes. Landed dry mass 290 kg

• MVACS Mars Volatiles and Climate Surveyor (Paige)

• SSI surface stereo imager (Smith, Keller) (clone of Pathfinder camera, dual lenses focusing onto single CCD chip, with filters between 0.4 and 1.1 mm for mineralogy and atmospheric science.)

• RA robotic arm (2 m long, to insert temperature probe, perform soil mechanics analyses, and to deliver surface samples to TEGA), carrying the RAC robotic arm camera (Keller)

• MET meteorological package (1.2m mast with windspeed/ direction sensor, temperature sensors, and TDL absorption cells to measure water vapour content and carbon dioxide and water isotope ratios. Pressure sensors mounted on spacecraft. Secondary 0.9 m submast for saltation layer windspeed and temperature measurements. RAATS robotic arm atmospheric temperature sensor, and STP soil temperature probe, also on the arm) (Crisp, May, Harri)

• TEGA thermal & evolved gas analyser (set of 8 one-shot ovens for differential scanning calorimetry (DSC) of surface samples, coupled to oxygen detector and TDL H2O/CO2 absorption cell to determine ice concentration, adsorbed volatiles and volatile-bearing minerals) (Boynton)

• MARDI Mars descent imager (nested downlooking images 1.25 mrad per pixel. 1000 X 1000 pixels, panchromatic electronically shuttered CCD. 9 km at start of descent (7.5 m resolution) to 9 m at end (9 mm)) (Malin)

• LIDAR (light detection and ranging) (400 nJ, 100 ns pulses at 2.5 kHz, 0.88 mm GaAlAs diode to probe lowest ^3 km for dust and ice haze) (Linkin)

• Mars microphone (Friedman)

• Mars magnetic properties experiment (Knudsen)

• Cruise stage also carried the DS-2 Mars Microprobes (Section 19.2 and Chapter 25)

The Project Scientist was Richard Zurek.

Separation from cruise stage on approach

Delivery architecture Thermal aspects

Power aspects

Communications architecture

EDL architecture

Landing speed(s) Active operations (deployments, etc.) Key references

Thermally regulated interior component deck (min. —30 °C) Very cold ambient environment

16 A h NiH secondary batteries + 2.9 m2 GaAs solar arrays. Nominal power 200 W Via UHF antenna: two-way relay via Mars Climate Orbiter, or one-way relay (Mars-to-orbit) via Mars Global Surveyor (128 kbits s—Two-way DTE via articulated X-band medium gain antenna (2.1-12.6kbits s—or low-gain antenna Entry at 6.9kms—l. 2.4 m diameter, 70° blunt half cone, ablative SLA-561 aeroshell. Active attitude control, using thrusters to minimise angle of attack. Max. deceleration 12 g. Parachute deployment at 8.8 km altitude, 430 ms— \ Heatshield separation at 7.5 km altitude, 250 ms—l. Landing legs deployed 70-100 s before landing. Back shell/parachute jettisoned and descent engines fired, controlled using four-beam Doppler radar. Final 40 m of descent controlled using gyros and accelerometers. Cruise/ descent propulsion system: 64 kg hydrazine in 2 diaphragm tanks; regulated He pressurization; 12 266 N descent engines (3 groups of 4) Nominally 2.4 ms— 1 under thruster control for last 12 m of descent Deployment of solar arrays, camera boom and meteorology masts. Sample acquisition via robotic arm and scoop. Articulated medium-gain antenna J. Geophys. Res. 106(E8), 2001; Casani et al., 2000; Warwick, 2003; Backes et al., 2000. See also Mars Polar Lander/Deep Space 2 Press Kit, NASA, 1999.

Figure 18.13 Mars Polar Lander.

Mars Surveyor landers were planned for at least 2003 and 2005, with greater international participation (e.g. from Italy), in parallel with a series of smaller 'Mars Micromissions'.

However, following the MPL failure, work was stopped on the '01 lander and it was put into storage. Already at an advanced stage of construction, it was eventually resurrected as the 2007 Phoenix lander, with a modified payload that drew upon elements from both MPL and the original '01 lander. Phoenix is the first 'Mars Scout' mission (i.e. a competitively selected Pi-led mission, like the Discovery series of missions; in this instance the mission is led by Peter Smith of the University of Arizona). The planned 2003 Surveyor lander was dropped in favour of the twin Mars Exploration Rovers (drawing significant heritage from Pathfinder's successful EDL system and, indeed, from the experience gained with operations of Sojourner), with the 2005 opportunity being used to send the Mars Reconnaissance Orbiter. The 2009 surface mission is planned to be a large rover, the Mars Science Laboratory, which evolved from the initial concept of a 'Mars Smart Lander' and 'LongRange Science Rover'. Further Scout missions are planned for 2011, with sample return at some later date.

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