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

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 cm depth) of 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.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s11214-022-00941-z.

Clinical outcome and quality of life after gracilis muscle transposition for fistula closure over a 10-year period

PURPOSE

Gracilis muscle transposition (GMT) is an established surgical technique in the treatment of anorectal fistulas and fistulas to the vagina and the urinary system when previous closure options have failed. There is little evidence on the success rate of this procedure in the long term.

METHODS

This is a follow-up study on all patients undergoing GMT over a 10-year period at a tertiary referral center for complex fistulas. Postoperative function and quality of life were evaluated by standardized questionnaires (Wexner score, Fecal Incontinence Quality of Life Score (FIQL), SF-12 and a brief questionnaire designed for this study). Sexual function was evaluated by the Female Sexual Function Index (FSFI) and the International Index of Erectile Function.

RESULTS

Forty-seven gracilis muscle transpositions (GMT) in 46 patients were performed. Most treated patients had (neo-)-rectovaginal fistulas (n = 29). An overall fistula closure was achieved in 34 of 46 patients (74%): in 25 cases primarily by GMT (53%) and in nine patients with persistent or recurrent fistula by additional surgical procedures. A clinically apparent relapse occurred on average 276 days (median: 180 days) after GMT (mean follow-up 73.4 months).

CONCLUSION

GMT in our hands has a primary closure rate of 53%, and after further procedures, this rises to 74%. Fecal continence is impaired in patients having undergone GMT. The overall quality of life in patients after GMT is only slightly impaired, and sexual function is severely impaired in female patients.

Images from the surface of asteroid Ryugu show rocks similar to carbonaceous chondrite meteorites

The near-Earth asteroid (162173) Ryugu is a 900-m-diameter dark object expected to contain primordial material from the solar nebula. The Mobile Asteroid Surface Scout (MASCOT) landed on Ryugu's surface on 3 October 2018. We present images from the MASCOT camera (MASCam) taken during the descent and while on the surface. The surface is covered by decimeter- to meter-sized rocks, with no deposits of fine-grained material. Rocks appear either bright, with smooth faces and sharp edges, or dark, with a cauliflower-like, crumbly surface. Close-up images of a rock of the latter type reveal a dark matrix with small, bright, spectrally different inclusions, implying that it did not experience extensive aqueous alteration. The inclusions appear similar to those in carbonaceous chondrite meteorites.

Resection enterostomy versus Hartmann's procedure for emergency colonic resections

BACKGROUND

If a primary anastomosis is considered too risky after emergency colon resection either a resection enterostomy or an end stoma with closure of the distal bowel (Hartmann's procedure) is possible. This study analyzes the rate of restoration of intestinal continuity and other surgical outcomes after resection enterostomy placement versus Hartmann's procedure for emergency colon resections.

METHODS

All patients who underwent emergency colorectal resections between August 2009 and June 2014 at the University Medical Center Mannheim were reviewed in regard to therapeutic approach, rate of restoration of bowel continuity, and surgical morbidity after the primary operation and after reversal surgery.

RESULTS

Fifty-five patients in whom both studied interventions would have been technically feasible were further analyzed. The rate of revisional surgery was significantly higher in the resection enterostomy cohort after the primary operation. There were no significant differences regarding morbidity, mortality, and the rate of restoration of intestinal continuity. Overall, bowel continuity could be restored in 63% (29/46) of the surviving patients. The median time of surgery of the initial as well as of the reversal surgery was significantly longer in the Hartmann's group. Five of 13 patients underwent protective ileostomy placement in the Hartmann's group at the time of the reversal (vs. none in the resection enterostomy group).

CONCLUSIONS

The bowel continuity can be restored in the majority of patients after emergency colonic resection. Conclusive evidence which surgical option should be preferred when a primary anastomosis is considered too risky-Hartmann's procedure or resection enterostomy-is still lacking.

COMETARY SCIENCE. Thermal and mechanical properties of the near-surface layers of comet 67P/Churyumov-Gerasimenko

Thermal and mechanical material properties determine comet evolution and even solar system formation because comets are considered remnant volatile-rich planetesimals. Using data from the Multipurpose Sensors for Surface and Sub-Surface Science (MUPUS) instrument package gathered at the Philae landing site Abydos on comet 67P/Churyumov-Gerasimenko, we found the diurnal temperature to vary between 90 and 130 K. The surface emissivity was 0.97, and the local thermal inertia was 85 ± 35 J m(-2) K(-1)s(-1/2). The MUPUS thermal probe did not fully penetrate the near-surface layers, suggesting a local resistance of the ground to penetration of >4 megapascals, equivalent to >2 megapascal uniaxial compressive strength. A sintered near-surface microporous dust-ice layer with a porosity of 30 to 65% is consistent with the data.

Mixed anxiety-depression in a primary-care clinic

To determine the prevalence and clinical significance of a mixed anxiety-depressive (MAD) syndrome in primary care, a two-stage sampling design was applied to 796 consecutive clinic attendees without known psychiatric illness. Among 78 systematically interviewed subjects, 10.3% (n = 8) had a depressive disorder alone, 12.8% (n = 10) had an anxiety disorder alone, 19.2% (n = 15) had a comorbid anxiety and depressive disorder and 12.8% (n = 10) had a combination of subsyndromal anxiety and depressive features that fulfilled either ICD-10 or our own operational criteria for MAD. Patients with MAD rated their disability as being comparable to that of patients with anxiety or depressive disorders. These findings lend support to the notion that there is a sizeable subgroup of patients in primary care who appear to be suffering from a psychiatric syndrome with an admixture of subsyndromal depressive and anxiety features. Questions about the temporal stability of MAD and preferred approaches to treatment have yet to be answered.