The Cassini mission

An assessment study of a Saturn-Orbiter plus Titan-probe mission was made. The NASA Solar System Exploration Committee (SSEC) had recommended two separate missions to the Saturn system, in keeping with its charter to design low-cost, dedicated planetary missions. These were a Titan probe, to be carried by a small spacecraft that would include some type of radar mapping device, and a Saturn Orbiter that would be a more sophisticated spacecraft, to be launched separately. A Saturn orbiter and a Titan probe are combined in a single mission that would be carried out in collaboration with NASA. It is this proposal, called the Cassini Project, which was approved by NASA and ESA for an assessment study to be carried out over the next year and a half. Details of the Cassini mission are discussed

A possible deuterium anomaly: Implications of the CH3D/CH4 mixing ratios in the atmospheres of Jupiter, Saturn, and Uranus

Observations of CH3D in the atmospheres of the outer planets provide a test of the theory of deuterium fractionation equilibrium in the formation and evolution of these planets. Recent measurements of the CH3D/CH4 mixing ratios made for Saturn and Uranus are presented and intercompared with current values of Jupiter, illustrating large differences between the planets. Their implied D/H ratios are compared to D/H ratios derived from measurements of HD/H2; and, in the cases of Jupiter and Saturn, they may be incompatible. Implications of these comparisons are discussed in terms of the deuterium fractionation chemistry and possible enrichments of deuterium in the core ices of the planets

Spectroscopic Observations of the Planets

During the period under review, the main effort of the research supported by this grant was concentrated on Titan, Iapetus, and two comets, Comet Hyakutake and Comet Hale-Bopp. Significant discoveries were made in each case as summarized in the report

Titan

The following topics are discussed with respect to Titan: observations of the atmosphere; laboratory simulations and theoretical models of Titan's atmosphere; endpoints of atmospheric chemistry - aerosols and oceans; exobiology; and the next steps in understanding Titan

Galileo Probe Mass Spectrometer

During the past year, the Principal Investigator's research carried out under this contract has focused on an analysis of the implications of Galileo Probe Mass Spectrometer (GPMS) results for the origin of Jupiter's atmosphere and the origin of the ice and other possible volatiles on the Galilean satellites

Outer Solar System Nomenclature

The Principal Investigator's responsibilities on this grant fell into two categories according to his participation. In the nomenclature work of the International Astronomical Union (IAU). Owen is chair of the Task Group for the Outer Solar System. He is also a member of the IAU's Working Group on Planetary and Satellite Nomenclature (WGPSN) which is composed of the chairs of the several Task Groups plus the presidents of two IAU Commissions and several outside consultants. The WGPSN is presided over by its President, Professor Kaare Aksnes from the Rosseland Institute for Theoretical Astrophysics in Oslo, Norway

The presence and influence of glacier surging around the Geladandong ice caps, North East Tibetan Plateau

This study was supported by the Strategic Priority Research Program of Chinese Academy of Sciences (XDA20100300).Many glaciers and ice caps on the Tibetan Plateau have retreated and lost mass in recent years in response to temperature increases, providing clear evidence of the impact of climate change on the region. There is increasing evidence that many of the glaciers on the Tibetan Plateau have also shown periodically dynamic behaviour in the form of glacier surging and some even catastrophic collapse events. In this study, we examine the prevalence of glacier surging at the Geladandong ice caps, North East Tibetan Plateau, to better understand the role of surge events in the evolution of glacier mass loss budgets. Using glacier surface elevation change data over the period 1969–2018 and glacier surface velocity data from the ITS_LIVE dataset, we find that 19 outlet glaciers of the ice caps are of surge-type. Our multi-temporal measurements of glacier mass balance show that surge-type glacier mass budgets vary depending on the portion of the surge-cycle captured by geodetic data. At the regional level, pre- and post-surge glacier mass loss variability does not bias regional mass budget estimates, but enhanced, or suppressed, mass loss estimates are likely when small groups of glaciers are examined. Our results emphasise the importance of accurate surge-type glacier inventories and the need to maximise geodetic data coverage over glacierised regions known to contain surge-type glaciers.Publisher PDFPeer reviewe

Update on the Cognitive Presentations of iNPH for Clinicians

This mini-review focuses on cognitive impairment in iNPH. This symptom is one of the characteristic triad of symptoms in a condition long considered to be the only treatable dementia. We present an update on recent developments in clinical, neuropsychological, neuroimaging and biomarker aspects. Significant advances in our understanding have been made, notably regarding biomarkers, but iNPH remains a difficult diagnosis. Stronger evidence for permanent surgical treatment is emerging but selection for treatment remains challenging, particularly with regards to cognitive presentations. Encouragingly, there has been increasing interest in iNPH, but more research is required to better define the underlying pathology and delineate it from overlapping conditions, in order to inform best practise for the clinician managing the cognitively impaired patient. In the meantime, we strongly encourage a multidisciplinary approach and a structured service pathway to maximise patient benefit

Glaciological and climatological drivers of heterogeneous glacier mass loss in the Tanggula Shan (Central-Eastern Tibetan Plateau), since the 1960s

This study was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (grant no. XDA20100300), the Swiss National Science Foundation (200021E_177652/1) within the framework of the DFG Research Unit GlobalCDA (FOR2630) and the Dragon 5 program supported by ESA and NRSCC (4000136930/22/I-NB). A. B. acknowledges research funding (grant no. CRG/2021/002450) received from Science & Engineering Research Board (SERB), Department of Science & Technology (DST), India.Despite their extreme elevation, glaciers on the Tibetan Plateau are losing mass in response to atmospheric warming, the pattern of which purportedly reflects regional contrasts in climate. Here we examine the evolution of glaciers along ~500 km of the Tanggula Shan, Central-Eastern Tibetan Plateau. Using remotely sensed datasets, we quantified changes in glacier mass, area and surface velocity, and compared these results to time series of meteorological observations, in order to disentangle drivers of glacier mass loss since the 1960s. Glacier mass loss has increased (from −0.21 ± 0.12 m w.e. a−1 in 1960s–2000s, to −0.52 ± 0.18 m w.e. a−1 in 2000s–2015/18) in association with pervasive positive temperature anomalies (up to 1.85°C), which are pronounced at the end of the now lengthened ablation season. However, glacier mass budget perturbations do not mirror the magnitude of temperature anomalies in sub-regions, thus additional factors have heightened glacier recession. We show how proglacial lake expansion and glacier surging have compounded glacier recession over decadal/multi-decadal time periods, and exert similar influence on glacier mass budgets as temperature changes. Our results demonstrate the importance of ice loss mechanisms not often incorporated into broad-scale glacier projections, which need to be better considered to refine future glacier runoff estimates.Publisher PDFPeer reviewe

Contrasting surface velocities between lake- and land-terminating glaciers in the Himalayan region

This research has been supported by the Swiss National Science Foundation (grant no. IZLCZ2_169979/1) and the Strategic Priority Research Program of Chinese Academy of Sciences (grant no. XDA20100300). Bert Wouters has been supported by NWO VIDI (grant no. 016.Vidi.171.063).Meltwater from Himalayan glaciers sustains the flow of rivers such as the Ganges and Brahmaputra on which over half a billion people depend for day-to-day needs. Upstream areas are likely to be affected substantially by climate change, and changes in the magnitude and timing of meltwater supply are expected to occur in coming decades. About 10 % of the Himalayan glacier population terminates into proglacial lakes, and such lake-terminating glaciers are known to exhibit higher-than-average total mass losses. However, relatively little is known about the mechanisms driving exacerbated ice loss from lake-terminating glaciers in the Himalaya. Here we examine a composite (2017–2019) glacier surface velocity dataset, derived from Sentinel 2 imagery, covering central and eastern Himalayan glaciers larger than 3 km2. We find that centre flow line velocities of lake-terminating glaciers (N = 70; umedian: 18.83 m yr−1; IQR – interquartile range – uncertainty estimate: 18.55–19.06 m yr−1) are on average more than double those of land-terminating glaciers (N = 249; umedian: 8.24 m yr−1; IQR uncertainty estimate: 8.17–8.35 m yr−1) and show substantially more heterogeneity than land-terminating glaciers around glacier termini. We attribute this large heterogeneity to the varying influence of lakes on glacier dynamics, resulting in differential rates of dynamic thinning, which causes about half of the lake-terminating glacier population to accelerate towards the glacier termini. Numerical ice-flow model experiments show that changes in the force balance at the glacier termini are likely to play a key role in accelerating the glacier flow at the front, with variations in basal friction only being of modest importance. The expansion of current glacial lakes and the formation of new meltwater bodies will influence the dynamics of an increasing number of Himalayan glaciers in the future, and these factors should be carefully considered in regional projections.Publisher PDFPeer reviewe