Mars Pathfinder

Mars Pathfinder was highly successful, combining technological and scientific goals, and lander and rover elements, to become the first Martian surface mission since the Viking Landers. For more details see the Case Study, Chapter 24 (Figures 17.6 and 17.7).

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

Technological: demonstrating the feasibility of low-cost landings on and exploration of the Martian surface

Scientific: atmospheric entry science, geological characterization of the landing site, meteorology, and long-range and close-up surface imaging, with the general objective being to characterize the Martian environment for further exploration

ETR, Delta 2

04/12/1996

04/07/1997

27/09/1997

Entry mass 585.3 kg. Landed mass 410kg (incl. 99kg airbag system, 264 kg lander + 10.5 kg rover)

Sagan Memorial Station:

• IMP Imager for Mars Pathfinder (Smith, Keller)

• ASI/MET atmospheric structure instrument/meteorology package (Seiff)

• Windsock investigation (Sullivan)

• Magnetic properties investigation (Knudsen)

• Celestial mechanics radio science (Folkner)

The Project Scientist was Matthew Golombek

Sojourner:

• Rover imaging cameras

• APXS alpha-proton-X-ray spectrometer (Rieder)

• WAE wheel abrasion experiment (Ferguson)

• MAE materials adherance experiment (Landis)

• Surface material properties (Moore)

Delivery architecture Thermal aspects

Power aspects

Communications architecture

EDL architecture

Landing speed(s)

Active operations (deployments, etc.)

Key references

Separation from cruise stage on approach

Lander: all sensitive electronics in thermally-isolated box (foam insulation) (no RHUs). Rover: electronics box aerogel insulated plus 3 RHUs

Lander: 2.5 m2, —177 W solar array, 27 V 50 A-hr Ag-Zn secondary battery

Rover: 16.5 W GaAs/Ge solar array plus 150 W-hr lithium thionyl chloride (LiS0Cl2) primary battery

X-band two-way DTE at 6 kbits s-1 to 70 m DSN via high-gain antenna. Also low-gain antennas. Sojourner-Lander: UHF at 9.6 kbits s-1

Entry at 7.26 km s-1 (inertial) or 7.48 km s-1 (relative), with a flight path angle of -13.6° 2.65 m diameter, 70° blunt half cone, ablative SLA-561 aeroshell. Spin-stabilised. Max. deceleration: 16 g. Parachute deployment at 7.9 km altitude. Lander lowered from back shell and airbags inflated (each face of the tetrahedral lander having six 1.8 m diameter spherical lobes on a 1 m 'billiard rack' grid). Radar-altimeter triggered braking rockets at 98 m. Bridle cut, with motion continuing for 2 min after initial impact. Airbags deflated / retracted and petals opened

Initial impact at 14 ms-1

EDL aspects including airbag retraction and petal opening. Deployment of camera mast, met boom, HGA and rover deployment ramps

J. Geophys. Res. 102(E2), 1997, and 104(E4), 1997; Science 278(5344), 1997; Shirley, 1998; Mishkin, 2004; Spencer et al., 1999; http://mars.jpl.nasa.gov/

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