Spacecraft sample collection and subsurface excavation of asteroid (101955) Bennu.

Carbonaceous asteroids, such as (101955) Bennu, preserve material from the early Solar System, including volatile compounds and organic molecules. We report spacecraft imaging and spectral data collected during and after retrieval of a sample from Bennu's surface. The sampling event mobilized rocks and dust into a debris plume, excavating a 9-meter-long elliptical crater. This exposed material is darker, spectrally redder, and more abundant in fine particulates than the original surface. The bulk density of the displaced subsurface material was 500 to 700 kilograms per cubic meter, which is about half that of the whole asteroid. Particulates that landed on instrument optics spectrally resemble aqueously altered carbonaceous meteorites. The spacecraft stored 250 ± 101 grams of material, which will be delivered to Earth in 2023.

Pebbles and sand on asteroid (162173) Ryugu: In situ observation and particles returned to Earth.

The Hayabusa2 spacecraft investigated the C-type (carbonaceous) asteroid (162173) Ryugu. The mission performed two landing operations to collect samples of surface and subsurface material, the latter exposed by an artificial impact. We present images of the second touchdown site, finding that ejecta from the impact crater was present at the sample location. Surface pebbles at both landing sites show morphological variations ranging from rugged to smooth, similar to Ryugu's boulders, and shapes from quasi-spherical to flattened. The samples were returned to Earth on 6 December 2020. We describe the morphology of >5 grams of returned pebbles and sand. Their diverse color, shape, and structure are consistent with the observed materials of Ryugu; we conclude that they are a representative sample of the asteroid.

Mid-infrared emissivity of partially dehydrated asteroid (162173) Ryugu shows strong signs of aqueous alteration.

The near-Earth asteroid (162173) Ryugu, the target of Hayabusa2 space mission, was observed via both orbiter and the lander instruments. The infrared radiometer on the MASCOT lander (MARA) is the only instrument providing spectrally resolved mid-infrared (MIR) data, which is crucial for establishing a link between the asteroid material and meteorites found on Earth. Earlier studies revealed that the single boulder investigated by the lander belongs to the most common type found on Ryugu. Here we show the spectral variation of Ryugu's emissivity using the complete set of in-situ MIR data and compare it to those of various carbonaceous chondritic meteorites, revealing similarities to the most aqueously altered ones, as well as to asteroid (101955) Bennu. The results show that Ryugu experienced strong aqueous alteration prior to any dehydration.

Sample collection from asteroid (162173) Ryugu by Hayabusa2: Implications for surface evolution.

The near-Earth asteroid (162173) Ryugu is thought to be a primitive carbonaceous object that contains hydrated minerals and organic molecules. We report sample collection from Ryugu's surface by the Hayabusa2 spacecraft on 21 February 2019. Touchdown images and global observations of surface colors are used to investigate the stratigraphy of the surface around the sample location and across Ryugu. Latitudinal color variations suggest the reddening of exposed surface material by solar heating and/or space weathering. Immediately after touchdown, Hayabusa2's thrusters disturbed dark, fine grains that originate from the redder materials. The stratigraphic relationship between identified craters and the redder material indicates that surface reddening occurred over a short period of time. We suggest that Ryugu previously experienced an orbital excursion near the Sun.

An artificial impact on the asteroid (162173) Ryugu formed a crater in the gravity-dominated regime.

The Hayabusa2 spacecraft investigated the small asteroid Ryugu, which has a rubble-pile structure. We describe an impact experiment on Ryugu using Hayabusa2's Small Carry-on Impactor. The impact produced an artificial crater with a diameter >10 meters, which has a semicircular shape, an elevated rim, and a central pit. Images of the impact and resulting ejecta were recorded by the Deployable CAMera 3 for >8 minutes, showing the growth of an ejecta curtain (the outer edge of the ejecta) and deposition of ejecta onto the surface. The ejecta curtain was asymmetric and heterogeneous and it never fully detached from the surface. The crater formed in the gravity-dominated regime; in other words, crater growth was limited by gravity not surface strength. We discuss implications for Ryugu's surface age.

The surface composition of asteroid 162173 Ryugu from Hayabusa2 near-infrared spectroscopy.

The near-Earth asteroid 162173 Ryugu, the target of the Hayabusa2 sample-return mission, is thought to be a primitive carbonaceous object. We report reflectance spectra of Ryugu's surface acquired with the Near-Infrared Spectrometer (NIRS3) on Hayabusa2, to provide direct measurements of the surface composition and geological context for the returned samples. A weak, narrow absorption feature centered at 2.72 micrometers was detected across the entire observed surface, indicating that hydroxyl (OH)-bearing minerals are ubiquitous there. The intensity of the OH feature and low albedo are similar to thermally and/or shock-metamorphosed carbonaceous chondrite meteorites. There are few variations in the OH-band position, which is consistent with Ryugu being a compositionally homogeneous rubble-pile object generated from impact fragments of an undifferentiated aqueously altered parent body.

Hayabusa2 arrives at the carbonaceous asteroid 162173 Ryugu-A spinning top-shaped rubble pile.

The Hayabusa2 spacecraft arrived at the near-Earth carbonaceous asteroid 162173 Ryugu in 2018. We present Hayabusa2 observations of Ryugu's shape, mass, and geomorphology. Ryugu has an oblate "spinning top" shape, with a prominent circular equatorial ridge. Its bulk density, 1.19 ± 0.02 grams per cubic centimeter, indicates a high-porosity (>50%) interior. Large surface boulders suggest a rubble-pile structure. Surface slope analysis shows Ryugu's shape may have been produced from having once spun at twice the current rate. Coupled with the observed global material homogeneity, this suggests that Ryugu was reshaped by centrifugally induced deformation during a period of rapid rotation. From these remote-sensing investigations, we identified a suitable sample collection site on the equatorial ridge.

The geomorphology, color, and thermal properties of Ryugu: Implications for parent-body processes.

The near-Earth carbonaceous asteroid 162173 Ryugu is thought to have been produced from a parent body that contained water ice and organic molecules. The Hayabusa2 spacecraft has obtained global multicolor images of Ryugu. Geomorphological features present include a circum-equatorial ridge, east-west dichotomy, high boulder abundances across the entire surface, and impact craters. Age estimates from the craters indicate a resurfacing age of [Formula: see text] years for the top 1-meter layer. Ryugu is among the darkest known bodies in the Solar System. The high abundance and spectral properties of boulders are consistent with moderately dehydrated materials, analogous to thermally metamorphosed meteorites found on Earth. The general uniformity in color across Ryugu's surface supports partial dehydration due to internal heating of the asteroid's parent body.

A thermal control system for long-term survival of scientific instruments on lunar surface.

A thermal control system is being developed for scientific instruments placed on the lunar surface. This thermal control system, Lunar Mission Survival Module (MSM), was designed for scientific instruments that are planned to be operated for over a year in the future Japanese lunar landing mission SELENE-2. For the long-term operations, the lunar surface is a severe environment because the soil (regolith) temperature varies widely from nighttime -200 degC to daytime 100 degC approximately in which space electronics can hardly survive. The MSM has a tent of multi-layered insulators and performs a "regolith mound". Temperature of internal devices is less variable just like in the lunar underground layers. The insulators retain heat in the regolith soil in the daylight, and it can keep the device warm in the night. We conducted the concept design of the lunar survival module, and estimated its potential by a thermal mathematical model on the assumption of using a lunar seismometer designed for SELENE-2. Thermal vacuum tests were also conducted by using a thermal evaluation model in order to estimate the validity of some thermal parameters assumed in the computed thermal model. The numerical and experimental results indicated a sufficient survivability potential of the concept of our thermal control system.

Endoscopic variceal ligation versus endoscopic injection sclerotherapy: comparison of hepatic and renal function.

OBJECTIVES: The aim of the present study was to compare the safety of endoscopic variceal ligation (EVL) and endoscopic injection sclerotherapy (EIS) in terms of liver and kidney functions in patients with liver cirrhosis. METHODS: Forty-four patients admitted to Takatsuki General Hospital between February 1991 and March 1993 with esophageal varices due to liver cirrhosis were randomly assigned to receive either EVL or EIS. Serum levels of AST, ALT, total bilirubin (T-bil), direct bilirubin (D-bil), prothrombin time (PT), hepaplastin test (HPT), antithrombin III (ATIII), creatinine (Cr), and blood urea nitrogen (BUN) were measured before and 24 h, 3 days, 7 days, and 14 days after both forms of therapy. RESULTS: Significant elevations of serum T-bil, serum D-bil, and serum ALT and AST levels were observed in the EIS group but not in the EVL group. No significant increases of serum PT, HPT, ATIII, BUN, or Cr levels were observed after treatment in either group. CONCLUSION: EVL should be considered a first choice therapy for eradicating esophageal varices.

Neuropeptide regulation of feeding in dogs.

Norepinephrine and four families of neuropeptides, namely, neuropeptide Y (NPY), opioid peptides, galanin, and growth hormone-releasing factor (GRH), have been shown to stimulate feeding after central administration. Because these studies were mainly done on laboratory rats, the present study was designed to ascertain the central stimulators of feeding in dogs. We have shown that porcine and human pancreatic polypeptides (PPs), when administered into the third cerebral ventricle (intracerebroventricularly), increased food and water intake of satiated animals but that the COOH-terminal fragments [hPP-(18-36) and hPP-(23-36)] did not do so at the same molar dose (11.9 nmol). The kappa-opioid receptor agonist dynorphin (A-(1-17) also stimulated food and water intake, whereas alpha-neoendorphin and Met-enkephalin did not. These results suggest the structural specificity of PPs and dynorphin peptides for stimulating feeding. Surprisingly, neither intracerebroventricular injections of NPY and peptide YY nor intracerebroventricular pretreatment with anti-hNPY gamma-globulin modulated feeding, stressing the species differences in the feeding response to exogenous substances and the underlying physiology. Intracerebroventricular injections of norepinephrine, GRH, galanin, and pancreastatin also failed to increase food intake, although most substances tended to or did increase water intake. These results suggest that neuropeptides play a role in a species-specific way in modulating appetite regulation.

[The effect of neuropeptide Y on the hypothalamic-pituitary-adrenal axis in the dog].

There is increasing evidence that neuropeptide Y (NPY) affects the release of pituitary hormones, including adrenocorticotropic hormone (ACTH). The present study was designed to clarify the mechanism by which NPY activates the hypothalamic-pituitary-adrenal (HPA) axis in the dog. Mongrel dogs were equipped with a chronic cannula allowing intra-third (i.t.v.) or intra-lateral (i.l.v.) cerebroventricular administration. A 1.19 nmol, i.t.v. dose of NPY produced as great an ACTH and cortisol response as did equimolar ovine corticotropin releasing factor (CRF). This action of NPY was dose-dependent and shared by peptide YY (PYY) and pancreatic polypeptide (PP), other members of the PP family peptide. Intravenously (i.v.) administered NPY (1.19-11.9 nmol) was much less potent than i.v. CRF in stimulating ACTH and cortisol secretion. However, i.v. NPY significantly increased plasma ACTH and cortisol concentrations, raising the possibility that NPY may modulate the activity of corticotrophs. We next investigated the possible relationship between NPY and CRF on the HPA axis. Pretreatment with a novel CRF antagonist, alpha-helical CRF9-41 (130.9 nmol i.t.v. or 261.5 nmol i.v.), partly but significantly attenuated the ACTH and cortisol responses to i.t.v. NPY (1.19 nmol). Furthermore, adding a subthreshold dose of i.t.v. NPY (0.119 nmol) to i.t.v. CRF (1.19 nmol) or i.v. NPY (2.38 nmol) to i.v. CRF (0.595 nmol) resulted in the potentiation of CRF-induced ACTH secretion. These results indicate that NPY may activate the HPA axis in concert with CRF probably at hypothalamic and/or pituitary levels. The present findings that NPY evokes ACTH secretion and potentiates the effectiveness of CRF as a secretagogue, together with high concentrations of NPY in the hypothalamus and pituitary portal blood, suggest the NPY is involved in the multihormonal control of ACTH release.

Brain neuropeptide Y in the control of adrenocorticotropic hormone secretion in the dog.

An immunoneutralization technique with specific antibodies was used to explore the role of endogenous neuropeptide Y (NPY) in the adrenocorticotropic hormone (ACTH) release after hypoglycemic stress in the dog. Dogs received injections of rabbit antihuman NPY gamma-globulin (anti-NPY) or normal gamma-globulin (NGG) into the third cerebral ventricle, which was followed by i.v. injection of insulin. Hypoglycemia of a 40% fall in systemic glucose levels occurred in anti-NPY-treated dogs as well as NGG-treated animals. An intraventricular administration of anti-NPY significantly inhibited the ACTH and cortisol release to hypoglycemia, but had no effect on the pancreatic polypeptide (PP) response. These findings suggest involvement by endogenous NPY in the ACTH secretion induced by hypoglycemia.

Effect of cholecystokinin octapeptide analogues on food intake in the dog.

Cholecystokinin octapeptide, administered into the third cerebral ventricle (icv), suppresses feeding in sheep, pigs, chicken, rats, and dogs. Because of the species differences in the feeding response to cholecystokinin (CCK), we studied the pharmacological characterization of this peptide on feeding in 16-h-fasted dogs. We examined the effects of CCK-(26-33)-NH2 (CCK-8) and a variety of its analogues, nonsulfated CCK-(26-33)-NH2 (desulfated CCK-8), CCK-(26-33)-OH (deamidated CCK-8), (Nle28,31)-CCK-(26-33)-NH2 [(Nle28,31)-CCK-8], succinyl-CCK-(27-33)-NH2 (Suc-CCK-7) succinyl-Thr28, Leu29, MePhe33-CCK-(27-33)-NH2 [Suc-Thr28, Leu29, MePhe33)-CCK-7], CCK-(29-33)-NH2 (CCK-5), and CCK-(30-33)-NH2 (CCK-4) on food intake after iv injection. Systemic dose-response studies appeared to reveal the following rank order of potencies: Suc-CCK-7 = Suc-(Thr28, Leu29, MePhe33)-CCK-7 greater than CCK-8 = (Nle28,31)-CCK-8 greater than desulfated CCK-8 greater than deaminated CCK-8 greater than CCK-5 = CCK-4 = 0. Smaller COOH-terminal fragments acted as antagonists to the satiety effects of CCK-8. These data demonstrate in the dog that the structural requirements for the behavioral activity of CCK-8 are the COOH-terminal amide group, the sulfate ester of the tyrosine moiety, and the conformational constraints observed in CCK-7.

[The effect of cholecystokinin antagonists on satiety induced by cholecystokinin octapeptide in dogs].

We administered two cholecystokinin antagonists to dogs intravenously (i.v.) and into the third cerebral ventricle (i.t.v.). Proglumide (3-300mg/kg/hr i.v. or 0.1-10mg/dog i.t.v.) reversed the satiety previously shown by mongrel dogs after i.t.v. CCK-8. A new glutaramic derivative, CR1409, blocked this satiety even more strongly when administered by either route. Proglumide increased proglumide levels in ventricular fluid, indicating its ability to cross the blood-brain barrier. However, i.t.v. proglumide did not appear in the blood during the observation period. These results suggest that systemic proglumide and CR1409 act as antagonists of the central CCK receptor concerning satiety in dogs; intravenously administered proglumide was found to cross the blood-brain barrier and partially but significantly reverse the satiety caused by CCK-8.

Effects of pancreastatin on insulin and pancreatic polypeptide secretion in the dog.

Porcine pancreastatin (1.19 nmol) was administered into the peripheral vein (i.v.) or the third cerebral ventricle (i.t.v.) of dogs and its effect on the secretion of insulin and pancreatic polypeptide (PP) studied. Neither means of administration had any effect on basal and glucose-induced insulin or PP secretion. However, i.v. pancreastatin did inhibit the i.v. CCK-8-induced insulin but not PP release. Pancreastatin may thus play a role in the regulation of insulin secretion in the canine pancreas.

Physiological antagonism between prostaglandin E2 and neuropeptide Y on thermoregulation in the dog.

These experiments were undertaken to determine whether neuropeptide Y (NPY) could suppress a prostaglandin hyperthermia in conscious dogs. Prostaglandin E2 (PGE2) (5 micrograms), injected into the lateral cerebral ventricle (ILV), evoked a hyperthermia of approximately 1 degrees C. Addition of ILV NPY (5 micrograms) significantly attenuated the PGE2-induced hyperthermia, whereas pancreatic polypeptide (PP), another member of the PP family peptide, did not. These results provide evidence for a role of NPY on thermoregulation in the dog.

Effects of pancreatic polypeptide on basal and meal stimulated secretion of gastrointestinal, pancreatic and adrenocortical hormones in the dog.

We have assessed the effects of intravenous infusion of bovine pancreatic polypeptide (PP) (1 microgram kg-1 h-1) on the basal and postprandial secretion of gastrointestinal, pancreatic and adrenocortical hormones in normal dogs. Bovine PP within the physiological range increased plasma cortisol levels transiently but significantly. PP elicited an inhibition of insulin response to a protein-rich meal, and tended to reduce the gastrin response. There were, however, no significant changes in basal or postprandial plasma concentrations of motilin and pancreatic glucagon during PP infusion. These results suggest that PP may have a role in controlling insulin secretion from the pancreas. The possible mechanisms are discussed mainly on the basis of vagal innervation.

Effect of neuropeptide Y on the hypothalamic-pituitary-adrenal axis in the dog.

There is increasing evidence that neuropeptide Y (NPY) affects the release of pituitary hormones, including adrenocorticotropic hormone (ACTH). The present study was designed to clarify the mechanism by which NPY activates the hypothalamic-pituitary-adrenal (HPA) axis in the dog. Mongrel dogs were equipped with a chronic cannula allowing intra-third (i.t.v.) or intra-lateral (i.l.v.) cerebroventricular administration. A 1.19 nmol, i.t.v. dose of NPY produced as great an ACTH and cortisol response as did equimolar ovine corticotropin releasing factor (CRF). This action of NPY was dose-dependent and shared by peptide YY (PYY) and pancreatic polypeptide (PP), other members of the PP family peptide. Intravenously (i.v.) administered NPY (1.19-11.9 nmol) was much less potent than i.v. CRF in stimulating ACTH and cortisol secretion. However, i.v. NPY significantly increased plasma ACTH and cortisol concentrations, raising the possibility that NPY may modulate the activity of corticotrophs. We have next investigated the possible relationship between NPY and CRF on the HPA axis. Pretreatment with a novel CRF antagonist, alpha-helical CRF9-41 (130.9 nmol i.t.v. or 261.8 nmol i.v.), partly but significantly attenuated the ACTH and cortisol responses to i.t.v. NPY (1.19 nmol). Furthermore, adding a subthreshold dose of i.t.v. NPY (0.119 nmol) to i.t.v. CRF (1.19 nmol) or i.v. NPY (2.38 nmol) to i.v. CRF (0.595 nmol) resulted in the potentiation of CRF-induced ACTH secretion. These results indicate that NPY may activate the HPA axis in concert with CRF probably at hypothalamic and/or pituitary levels. The present findings that NPY evokes ACTH secretion and potentiates the effectiveness of CRF as a secretagogue, together with high concentrations of NPY in the hypothalamus and pituitary portal blood, suggest that NPY is involved in the multihormonal control of ACTH release.