Collecting Soil Samples
Viking Lander 1 Primary Mission
Below is a plan view of the VL1 sample site at the end of the Primary Mission. The map shows the spacecraft and its orientation, locations of sample sites, locations of selected rocks, and surface disturbances relevant to the physical properties experiment. The area highlighted in red indicates the Sandy Flats site from which the three Primary Mission biology samples were taken.
VL1 sample site at end of Primary Mission. Click on figure to enlarge. (Moore et al., 1987)
Sol 8, First Biology Sample (Sandy Flats)
The sample was taken from drift material at Sandy Flats, located to the left of the lander, by extending the boom to deploy the collector head into the drift material and then retracting. The trench was 4.0-4.5 cm deep, 8.0 cm wide, and about 45 cm long from tip to rim crest of tailings; small lumps in and around trench were chiefly clods. The material was very fine grained as evidenced by materials rubbed and tamped by surface sampler parts being smooth and reflective. This sample was used in VL1 cycles 1 and 2.
Sol 36, Second Biology Sample (Sandy Flats)
The second biology sample was again taken by extending the boom into drift material of Sandy Flats then retracting. This trench was 4.0-5.0 cm deep, 7.0-8.0 cm wide, and 46 cm long from tip to rim crest of tailings; The new ttrench transects tailings of the previous Sol 8 trenches. The Sol 36 trench was partly obscured by the spacecraft which precluded mapping of entire trench. This sample was used for VL1 cycle 3.
VL1 Extended Mission
Below is a plan view of the VL1 sample site at the end of the Extended Mission. The map shows the spacecraft and its orientation, locations of sample sites, locations of selected rocks, and surface disturbances relevant to the physical properties experiment. The area highlighted in red indicates the Deep Hole site from which the one extended mission biology sample was taken (fourth biology sample). Note that the third biology sample acquired early in the Extended Mission was used for the LR experiment.
VL1 sample site at end of Extended Mission. Click on figure to enlarge. (Moore et al., 1987)
Sol 91, Third Biology Sample (Sandy Flats)
The third biology sample was also collected from Sandy Flats next to the two previous biology samples. The trench for the third sample was about 5 cm deep, 9 cm wide, and 47 cm long from tip to rim crest of the tailings. The trench transects the tailings of the Sol 14 trench. The sample was collected on Sol and stored in the Biology hopper in the dark, open to the Mars atmosphere, and at temperatures between 10° and 26°C until analysis started on Sol 230. The original intent was to collect a fresh sample, but concerns by the surface sampler team about possible damage to the sampler arm changed the scenario. This sample was used for VL1 cycle 4.
VL2 Primary Mission
Below is a plan view of the VL2 sample site at the end of the Primary Mission. The map shows the spacecraft and its orientation, locations of sample sites, locations of selected rocks, and surface disturbances relevant to the physical properties experiment. The area highlighted in red indicates the Beta site from which the first and second Primary Mission biology samples were taken. The area highlighted in blue indicates the Notch Rock site from which the third biology sample was taken.
VL2 sample site at end of Primary Mission. Click on figure to enlarge. (Moore et al., 1987)
Sol 8, First Biology Sample (Beta site)
The sample was taken from the Beta site by extending the boom into crusty to cloddy material after surface contact by the collector head. The trench is about 3.5 cm deep, 7.6 cm wide, and 41 cm long from tip to rim crest of tailings. The sample was delivered to biology processor. The coarse fraction was purged over the XRFS funnel but no sample was received. Small lumps in and around trench are probably clods. The collector head tip reached about 5 cm below surface. Surface temperature during acquisition was approximately -23°C. The sample had a residence time of 3 sols before LR nutrient injection. This sample was used for VL2 cycle 1.
Sol 28, Second Biology Sample (Beta site)
The sample was also taken from the Beta site, adjacent to the first biology sample, by extending the boom into crusty to cloddy material after surface contact. This trench was about 2.5-3.0 cm deep, 8-9 cm wide, and 45 cm long from tip to rim crest of tailings. The sample was delivered to biology processor and was used for VL2 cycle 2.
Biology Sampling Under Notch Rock
To test the possibility that ultraviolet exposure might cause a soil sample to give a positive LR response, a sample from under a rock that had been shielded from sunlight was collected. Notch rock was selected as the primary target based upon its size, location, and shape (the notch offered a good place to position the collector head). To assure the feasibility of a push, Notch Rock was first nudged a few centimeters on Sol 45. Since the nudge was successful, the push sequence was carried through on Sol 51, exposing the surface previously under the rock. Directly following the push, the third biology sample was taken from the newly exposed surface to preclude any ultraviolet exposure.
Sol 45, Notch Rock Nudge
Notch rock was nudged by pushing with the collector head on the left side of the rock. Notch rock rotated in horizontal plane about an axis on right side of rock; the left edge of rock was displaced about 3.8 cm.
Sol 51, Notch Rock Push
Notch rock was pushed by extending the boom after contact with the rock. The rock rotated about 47° counterclockwise in horizontal plane; translated about 24 cm from original position by plowing and sliding away from surface sampler.
Sol 51, Third Biology Sample, from under Notch Rock
The sample from under Notch rock was taken by retracting the collector head to clear away possible contaminating debris, elevating. The boom was then extended and de-elevated to make surface contact. It was then extended into material originally under rock. The backhoe trench is about 7.6 cm wide. The sample trench is about 2.5 cm deep, 9 cm wide, and 42 cm long from tip to rim crest of tailings. The sample was then delivered to the biology processor (Moore et al., 1987).
The rock pushing and sample acquisition event was conducted approximately 1 hour after sunrise. The soil sample was exposed to low angle sunlight for approximately 37 minutes prior to placement in the biology processor. It is estimated that this sample contained at least 90 percent of material from under the rock and thus had been protected from ultraviolet light for a long period of time (Levin and Straat, 1976b). Surface temperature during acquisition was approximately -66°C. The sample had a residence time of 2 sols before LR nutrient injection. This sample was used for VL2 cycle 3.
VL2 Extended Mission
Below is a plan views of the VL2 sample site at the end of the Extended Mission. The map shows the spacecraft and its orientation, locations of sample sites, locations of selected rocks, and surface disturbances relevant to the physical properties experiment. The area highlighted in red indicates the Beta site from which the fourth biology sample was taken.
VL2 sample site at end of Extended Mission. Click on figure to enlarge. (Moore et al., 1987)
Sol 145, Fourth Biology Sample (Beta Site)
The sample was taken by extending the boom to move the collector head into crusty to cloddy material and tailings from the Sol 28 Biology trench. The new trench was 3.5 cm deep and 10 cm wide near the tip. The collector head tip probably reached depth of 4.5-5.0 cm. No stereoscopic image coverage of tailings was made, but the trench is about 40 cm long. The sample was delivered to biology processor. It was used for VL2 cycles 4 and 5.
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