An Impact Crater Origin for the InSight Landing Site at Homestead Hollow, Mars: Implications for Near Surface Stratigraphy, Surface Processes, and Erosion Rates

Warner, N.; Grant, J. A.; Wilson, Sharon A.; Golombek, M.; DeMott, A.; Charalambous, Constantinos; Hauber, Ernst; Ansan, V.; Weitz, C. M.; Pike, Tom; Williams, Nathan; Banks, M. Â. E.; Calef, F.; Baker, Mariah; Kopp, M.; Deahn, M.; Lethcoe, H.; Berger, Lauren

doi:10.1029/2019je006333

Cited by 26 publications

(143 citation statements)

References 75 publications

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“…A 110 m‐diameter Class 5 crater ~280 m northwest of Homestead hollow is slightly younger than the hollow and likely formed ~400 Myr ago (Sweeney et al, ; Warner, Grant, Wilson, Golombek, DeMott, Hauber, et al, ; Warner, Grant, Wilson, Golombek, DeMott, Charalambous, et al, ). Although the crater is too far away to have emplaced rocks associated with its continuous or discontinuous ejecta deposit, it is possible that a ray from the crater could have reached the hollow.…”

Section: Origin Of Rocky Fieldmentioning

confidence: 99%

“…Finally, a degraded (Class 6, see Figure and Warner, Grant, Wilson, Golombek, DeMott, Hauber, et al, ; Warner, Grant, Wilson, Golombek, DeMott, Charalambous, et al, ) ~100 m‐diameter impact structure approximately 100 m northwest of Homestead hollow is an example of a rocky ejecta crater that is surrounded by numerous m‐scale rocks excavated from more competent material below the bulk of the regolith (Warner et al, ) and is likely younger than the hollow. The crater has a probable retention age of ~0.4–0.6 Ga (Warner, Grant, Wilson, Golombek, DeMott, Hauber, et al, ; Warner, Grant, Wilson, Golombek, DeMott, Charalambous, et al, ) and, although it is relatively well‐preserved compared to the hollow, comparable amounts of degradation at both could result in the more degraded appearance of the hollow. Hence, Homestead hollow could be on order of ~0.1 Ga older than the crater to the northwest (Warner, Grant, Wilson, Golombek, DeMott, Hauber, et al, ; Warner, Grant, Wilson, Golombek, DeMott, Charalambous, et al, ).…”

Section: Origin Of Rocky Fieldmentioning

confidence: 99%

“…The crater has a probable retention age of ~0.4–0.6 Ga (Warner, Grant, Wilson, Golombek, DeMott, Hauber, et al, ; Warner, Grant, Wilson, Golombek, DeMott, Charalambous, et al, ) and, although it is relatively well‐preserved compared to the hollow, comparable amounts of degradation at both could result in the more degraded appearance of the hollow. Hence, Homestead hollow could be on order of ~0.1 Ga older than the crater to the northwest (Warner, Grant, Wilson, Golombek, DeMott, Hauber, et al, ; Warner, Grant, Wilson, Golombek, DeMott, Charalambous, et al, ).…”

Section: Origin Of Rocky Fieldmentioning

confidence: 99%

“…Occurrence of likely duricrust within the uppermost fill of Homestead hollow (Golombek et al, , ) highlights the relative stability of the interior surface at advanced stages of degradation and when the surface properties and profile are near or in equilibrium with respect to local geomorphic thresholds. Degradation rates and retention times are adopted from Warner, Grant, Wilson, Golombek, DeMott, Hauber, et al () Warner, Grant, Wilson, Golombek, DeMott, Charalambous, et al ().…”

Section: Timing Of Degradationmentioning

confidence: 99%

“…Finally, the presence of rare, possible ventifacts within the hollow (e.g., Turtle rock and Ace of Spades rock, Figure ) and occurrence of duricrust material in the uppermost fill (Golombek et al, , ) supports long‐term stability of the present hollow surface and/or potential net bypassing of most sediment since it was established. Based on local crater retention studies (Sweeney et al, ; Warner, Grant, Wilson, Golombek, DeMott, Hauber, et al, ; Warner, Grant, Wilson, Golombek, DeMott, Charalambous, et al, ), the transition from a pristine impact to more degraded Class 5 and most hollow infilling likely occurred within the first ~0.1 Ga of crater formation (Figure , Warner, Grant, Wilson, Golombek, DeMott, Hauber, et al, ; Warner, Grant, Wilson, Golombek, DeMott, Charalambous, et al, ) consistent with the contention that most hollow degradation occurred over a relatively short period following impact formation.…”

Section: Timing Of Degradationmentioning

confidence: 99%

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Degradation of Homestead Hollow at the InSight Landing Site Based on the Distribution and Properties of Local Deposits

et al. 2020

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The InSight mission landed its scientific payload in Homestead hollow, a quasi-circular depression interpreted to be a highly degraded impact crater that is 27 m in diameter. The original pristine crater formed in a preexisting impact-generated regolith averaging~3 m thick and the surrounding ejecta deposit, consisting of coarse and mostly fine fragments, was in disequilibrium with local geomorphic thresholds. As a result, early, relatively rapid degradation by mostly eolian, and lesser impact processes and mass-wasting, stripped the rim and mostly infilled the hollow where sediments were sequestered. Early, faster degradation during the first~0.1 Ga was followed by much slower degradation over the bulk of the 0.4-0.7 Ga history of the crater. Pulses of much lesser degradation are attributed to impacts in and nearby the hollow, which emplaced some rocks as ejecta and provided small inventories of fine sediments for limited additional infilling. Even lesser sediments were derived from the very slow production of fines via weathering of resistant basaltic rocks. Nevertheless, indurated regolith caps the sediment fill within the hollow and creates a relatively stable present-day surface that further sequesters infilling sediments from remobilization. The degradation sequence at Homestead hollow is like that established at the Spirit rover landing site in Gusev crater and points to the importance of eolian, and lesser impact and mass-wasting processes, in degrading volcanic surfaces on Mars over the past~1 Ga.Plain Language Summary The InSight mission landed in a highly degraded impact crater dubbed Homestead hollow in Elysium Planitia on Mars. The hollow interior is quite flat and smooth, and mostly infilled by fine-grained sediments. Rocks are 2-3 times more numerous on the western side dubbed Rocky Field. The hollow lacks a raised rim but is marked by an increase in larger rocks. The distribution of windblown and impact materials within, around, and local to the hollow indicate degradation was mostly by wind stripping of fines from the rim and depositing them inside the hollow, with lesser contributions from impact and mass wasting processes. Rocky Field was likely formed by emplacement of ejecta during a nearby impact event occurring relatively soon after Homestead hollow formed. Most degradation occurred during the first~0.1 Ga after hollow formation. Limited modification over most of hollow history was associated with small pulses of infilling and rock emplacement during/following nearby impact events and very slow weathering of basaltic rocks. Degradation at Homestead hollow is similar to the modification of small craters at the Spirit landing site in Gusev crater, which shows common geomorphic processes occurred on comparable surfaces in different places on Mars during the last~1 Ga.

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Section: Origin Of Rocky Fieldmentioning

confidence: 99%

Section: Origin Of Rocky Fieldmentioning

confidence: 99%

Section: Origin Of Rocky Fieldmentioning

confidence: 99%

Section: Timing Of Degradationmentioning

confidence: 99%

Section: Timing Of Degradationmentioning

confidence: 99%

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Degradation of Homestead Hollow at the InSight Landing Site Based on the Distribution and Properties of Local Deposits

et al. 2020

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The InSight HP3 Penetrator (Mole) on Mars: Soil Properties Derived from the Penetration Attempts and Related Activities

et al. 2022

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The NASA InSight Lander on Mars includes the Heat Flow and Physical Properties Package HP3 to measure the surface heat flow of the planet. The package uses temperature sensors that would have been brought to the target depth of 3–5 m by a small penetrator, nicknamed the mole. The mole requiring friction on its hull to balance remaining recoil from its hammer mechanism did not penetrate to the targeted depth. Instead, by precessing about a point midway along its hull, it carved a 7 cm deep and 5–6 cm wide pit and reached a depth of initially 31 cm. The root cause of the failure – as was determined through an extensive, almost two years long campaign – was a lack of friction in an unexpectedly thick cohesive duricrust. During the campaign – described in detail in this paper – the mole penetrated further aided by friction applied using the scoop at the end of the robotic Instrument Deployment Arm and by direct support by the latter. The mole tip finally reached a depth of about 37 cm, bringing the mole back-end 1–2 cm below the surface. It reversed its downward motion twice during attempts to provide friction through pressure on the regolith instead of directly with the scoop to the mole hull. The penetration record of the mole was used to infer mechanical soil parameters such as the penetration resistance of the duricrust of 0.3–0.7 MPa and a penetration resistance of a deeper layer ($>30~\text{cm}$ > 30 cm depth) of $4.9\pm0.4~\text{MPa}$ 4.9 ± 0.4 MPa . Using the mole’s thermal sensors, thermal conductivity and diffusivity were measured. Applying cone penetration theory, the resistance of the duricrust was used to estimate a cohesion of the latter of 2–15 kPa depending on the internal friction angle of the duricrust. Pushing the scoop with its blade into the surface and chopping off a piece of duricrust provided another estimate of the cohesion of 5.8 kPa. The hammerings of the mole were recorded by the seismometer SEIS and the signals were used to derive P-wave and S-wave velocities representative of the topmost tens of cm of the regolith. Together with the density provided by a thermal conductivity and diffusivity measurement using the mole’s thermal sensors, the elastic moduli were calculated from the seismic velocities. Using empirical correlations from terrestrial soil studies between the shear modulus and cohesion, the previous cohesion estimates were found to be consistent with the elastic moduli. The combined data were used to derive a model of the regolith that has an about 20 cm thick duricrust underneath a 1 cm thick unconsolidated layer of sand mixed with dust and above another 10 cm of unconsolidated sand. Underneath the latter, a layer more resistant to penetration and possibly containing debris from a small impact crater is inferred. The thermal conductivity increases from 14 mW/m K to 34 mW/m K through the 1 cm sand/dust layer, keeps the latter value in the duricrust and the sand layer underneath and then increases to 64 mW/m K in the sand/gravel layer below.

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Results from InSight Robotic Arm Activities

et al. 2023

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The InSight lander carried an Instrument Deployment System (IDS) that included an Instrument Deployment Arm (IDA), scoop, five finger “claw” grapple, forearm-mounted Instrument Deployment Camera (IDC) requiring arm motion to image a target, and lander-mounted Instrument Context Camera (ICC), designed to image the workspace, and to place the instruments onto the surface. As originally proposed, the IDS included a previously built arm and flight spare black and white cameras and had no science objectives or requirements, or expectation to be used after instrument deployment (90 sols). During project development the detectors were upgraded to color, and it was recognized that the arm could be used to carry out a wide variety of activities that would enable both geology and physical properties investigations. During surface operations for two martian years, the IDA was used during major campaigns to image the surface around the lander, to deploy the instruments, to assist the mole in penetrating beneath the surface, to bury a portion of the seismometer tether, to clean dust from the solar arrays to increase power, and to conduct a surface geology investigation including soil mechanics and physical properties experiments. No other surface mission has engaged in such a sustained and varied campaign of arm and scoop activities directed at such a diverse suite of objectives. Images close to the surface and continuous meteorology measurements provided important constraints on the threshold friction wind speed needed to initiate aeolian saltation and surface creep. The IDA was used extensively for almost 22 months to assist the mole in penetrating into the subsurface. Soil was scraped into piles and dumped onto the seismometer tether six times in an attempt to bury the tether and $\sim30\%$ ∼ 30 % was entrained in the wind and dispersed downwind 1-2 m, darkening the surface. Seven solar array cleaning experiments were conducted by dumping scoops of soil from 35 cm above the lander deck during periods of high wind that dispersed the sand onto the panels that kicked dust off of the panels into suspension in the atmosphere, thereby increasing the power by ∼15% during this period. Final IDA activities included an indentation experiment that used the IDA scoop to push on the ground to measure the plastic deformation of the soil that complemented soil mechanics measurements from scoop interactions with the surface, and two experiments in which SEIS measured the tilt from the arm pressing on the ground to derive near surface elastic properties.

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An Impact Crater Origin for the InSight Landing Site at Homestead Hollow, Mars: Implications for Near Surface Stratigraphy, Surface Processes, and Erosion Rates

Cited by 26 publications

References 75 publications

Degradation of Homestead Hollow at the InSight Landing Site Based on the Distribution and Properties of Local Deposits

Degradation of Homestead Hollow at the InSight Landing Site Based on the Distribution and Properties of Local Deposits

The InSight HP3 Penetrator (Mole) on Mars: Soil Properties Derived from the Penetration Attempts and Related Activities

Results from InSight Robotic Arm Activities

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