Friday 31 May 2024

Potentially Hazardous Asteroid 2024 HP passes the Earth.

Asteroid 2024 HP passed by the Earth at a distance of about 592 000 km (15.4 times the average distance between the Earth and the Moon, or 3.96% of the distance between the Earth and the Sun), with a relative velocity of about 7.67 km per second, slightly before 5.00 pm GMT on Thursday 23 May 2024. There was no danger of the asteroid hitting us, though were it to do so it would have presented a significant threat. 2024 HP has an estimated equivalent diameter of 160-350 m (i.e. it is estimated that a spherical object with the same volume would be 160-350 m in diameter), and an object of this size would be expected to penetrate the Earth's atmosphere and impact  the Earth's surface, causing an explosion with an equivalent energy release to between 1.5 and  12.8 megatons of TNT. An impact at the lower end of this range would be expected to flatten forests and man-made structures over a significant distance, while one at the upper end of the range could cause a crater 2.87 km in diameter and global climatic effects which would persist for decades if not centuries.

300 second image of 2024 JN16 taken with the Celestron 14"-F8/8.4 (356/3000 mm) Schmidt-Cassegrain Telescope at Ceccano in Italy on 28 May 2024, when the asteroid was 6.8 million km from the Earth, and moving away. The asteroid is the small point at the centre of the image, indicated by the white arrow, the longer lines are stars, their elongation being caused by the telescope tracking the asteroid over the length of the exposure. Gianluca Masi/Virtual Telescope Project.

2024 HP was discovered on 17 April 2024 (36 days before its closest approach to the Earth) by the University of Arizona's Mt. Lemmon Survey at the Steward Observatory on Mount Lemmon in the Catalina Mountains north of Tucson. The designation 2024 HP implies that the asteroid was the fifteenth object (asteroid P - in numbering asteroids the letters A-Z, excluding I, are assigned numbers from 1 to 25, with a number added to the end each time the alphabet is ended, so that A = 1, A1 = 26, A2 = 51, etc., which means that P = 15) discovered in the second half of April 2024 (period 2024 H - the year being split into 24 half-months represented by the letters A-Y, with I being excluded).

The relative positions of 2024 HP and the Earth at 5.00 pm on Thursday 23 May 2024. JPL Small Body Database.

2024 HP is calculated to have a 983 day (2.69 year) orbital period, with an elliptical orbit tilted at an angle of 6.53° to the plain of the Solar System which takes in to 1.01 AU from the Sun (101% of the average distance at which the Earth orbits the Sun) and out to 2.85 AU (2.85 times the distance at which the Earth orbits the Sun, almost twice the distance at which the planet Mars orbits). 

The positions and orbits of 2024 HP and the planets of the Inner Solar System at 5.00 pm on Thursday 23 May 2024. JPL Small Body Database.

2024 HP is therefore classed as an Apollo Group Asteroid, which is an asteroid that is on average further from the Sun than the Earth, but which does get closer (1.01 AU from the Sun would appear to be further from the Sun than the Earth, which is, on average 1.00 AU from the Sun, but at aphelion, which happens in July each year, the Earth reaches almost 1.02 AU from the Sun). As an asteroid possibly larger than 150 m in diameter that occasionally comes within 0.05 AU of the Earth, 2024 HP is also classified as a Potentially Hazardous Asteroid.

2024 HP is calculated to have fairly regular close encounters with the Earth, with the last thought to have happened in April 2016 and the next predicted for August 2032.

See also...

Thursday 30 May 2024

English museum aquires Bronze Age Hoard.

The Dorset Museum and Art Gallery in southern England has raised £17 000 needed to acquire a Bronze Age hoard discovered by a metal detectorist in 2020. The hoard, which comprises a sword, and axe head, and a bracelet, was found by metal detectorist John Belgrave during an organised event at a farm in the village of Stalbridge, near Sherborne in Dorset, during an organised event, when he became separated from the group and climbed a hill outside the planned area of the survey, where he made the discovery. The £17 000 will be divided between Belgrave and the owner of the land where the discovery was made.

Middle Bronze Age rapier, a bangle and palstave axe head. Portable Antiquities Scheme/British Museum/Surry County Council.

The sword from the Stalbridge Middle Bronze Age Hoard is a bronze rapier with a blade 535 mm in length, cast in one piece, but apparently deliberately broken into the sections, one of which is still attached to the hilt, before being buried. The hilt of the sword is made from a copper alloy, and has been cast in the form of the wooden sword hilts typical of the time. The blade is cross shaped in profile, 60 mm wide and 7.5 mm thick at the hilt. The longer of the two blade fragments is bent, and weighs 188 g, the smaller weighs 23.34 g. The hilt is 113 mm long, with an ovel pommel measuring 46.2 mm by 41.6 mm. The guard is c-shaped, with the bade of the blade still attached by four dome-headed rivets. Swords of this type have been referred to as Wandsworth-type rapiers, and are associated with the Middle Bronze Age Taunton Phase, between about 1400 and 1275 BC.

Metal detectorist John Belgrave with the sword he found in Stalbridge, Dorset, in 2020. Max Willcock/Bournemouth News & Picture Service.

The bronze axe-head is of a type called a South-western palstave, also associated with the Taunton Phase. These have a side-loop, a mid-rib, and side-flanges which would have been used to support a forked wooden handle. It is made from a copper-alloy, and is 159 mm in length with a maximum thickness of 31.5 mm. The cutting edge of the axe flares to give a rounded cutting edge, 51.7 mm wide.

A palstave axe-head found in Dorset in 2020. Portable Antiquities Scheme/British Museum/Surry County Council.

The bracelet is a copper-alloy ring-shaped bangle, of a type known as a Liss Bracelet, again associated with the Taunton Phase. It has an outer diameter of 75.6 mm, an inner diameter of 61.5 mm, a width of 16.3 mm, and a width that varies between 6.1 and 6.8mm. Its outer surface has an incised or engraved panels which with complex geometric decoration, which appears to be centred on a thickened lobe on one side. Liss Bracelets are known only from the Taunton Phase of the English Bronze Age, with most known examples coming from Hampshire, Wiltshire, Dorset, and West Sussex, though they have also been found in Norfolk and Suffolk. 

A Liss Bracelet from the Stalbridge Middle Bronze Age Hoard. Portable Antiquities Scheme/British Museum/Surry County Council.

See also...

Town of Grindavik evacuated again as new eruption begins on the Reykjanes Peninsula, Iceland.

Eruptive activity on the Reykjanes Peninsula, Iceland began again on 29 May 2024, according to the Icelandic Met Office, the first such eruption since activity on a fissure which opened in March petered out three weeks ago. The activity is thought to have started when magma flowing from the magma reservoir beneath Svartsengi into the area beneath the Sundhn├║kur crater row. At about 4.00 pm on 29 May the magma encountered groundwater penetrating through a fissure from a previous eruption, leading to a phreatic explosion as a large volume of the water was turned into steam instantly. This led to the formation of a new fissure running southwest to northeast (parallel to previous fissures on the peninsula) for about 2.4 km. This fissure has produced lava fountains up to 50 m high, and is extruding lava at a rate of about 1500-2000 m³ per second. The eruption has prompted the evacuation of the town of Grindavik, and the nearby Blue Lagoon Geothermal Spa. The fissure is further from the town than the eruption in January which saw lava entering the streets of the settlement and several buildings destroyed, but is also significantly larger, and is evolving significant amounts of toxic gasses.

A volcanic fssure on the Reykjanes Peninsula, Iceland, which opened on 29 May 2024. Marco Di Marco/AP.

Although dramatic, lava flows are not usually considered particularly dangerous, as their advancing fronts are quite slow and can quickly be outpaced by an able-bodied Human being. The more deadly volcanic events are pyroclastic flows, such as the one which engulphed the Roman town of Pompeii, in which clouds of superheated gas and ash move downhill at high speeds in an avalanche-like motion, and phreatic explosions, caused by bodies of lava encountering bodies of water, which evaporate almost instantly, causing huge explosions.

The size and position of the new fissure on the Reykjanes Peninsula, Iceland. Icelandic Met Office/BBC.

Iceland lies directly upon the Mid-Atlantic Ridge, a chain of (mostly) submerged volcanoes running the length of the Atlantic Ocean along which the ocean is splitting apart, with new material forming at the fringes of the North American and European Plates beneath the sea (or, in Iceland, above it). The Atlantic is spreading at an average rate of 25 mm per year, with new seafloor being produced along the rift volcanically, i.e. by basaltic magma erupting from below. The ridge itself takes the form of a chain of volcanic mountains running the length of the ocean, fed by the upwelling of magma beneath the diverging plates. In places this produces volcanic activity above the waves, in the Azores, on Iceland and on Jan Mayen Island. All of this results in considerable Earth-movement beneath Iceland, where Earthquakes are a frequent event.

The passage of the Mid-Atlantic Ridge beneath Iceland. NOAA National Geophysical Data Center.

See also...

Wednesday 29 May 2024

A potential major lithium source from the Devonian Marcellus Shale of Pennsylvania.

Lithium for use in batteries is a major requirement for a transition to electric vehicles, and as such a potential limiting factor in such a transition. In the US, the Infrastructure Investment and Jobs Act requires that all of the materials used in the production of batteries for electric vehicles be sourced within the country by 2030, making the identification of viable sources of lithium a priority for the industry. Recent research has shown that the saline fluids produced as a biproduct of gas and petroleum extraction are often rich in lithium, presenting a potential solution to this problem. 

This appears to be particularly true for Palaeozoic groundwaters from the Appalachian region. One such promising source is the Middle Devonian Marcellus Shale Formation. The Marcellus Shale is currently worked as an 'unconventional' natural gas field, in which methane is extracted from the shale by means of hydraulic fracturing (fracking), a process by which water, sand and chemicals are forced into buried sediments in order to shock them into releasing trapped hydrocarbons, which can then be extracted for commercial use.

This process has also resulted in the extraction of large amounts of hypersaline groundwater being brought to the surface, for which there is little current use, with the effect that 95% of this is pumped back into the ground in further fracking operations. The total dissolved solids present in the Marcellus Shale groundwater exceed 100 000 mg/L, leading to a requirement for it to be treated before re-injection of the water into the ground can be carried out. A significant proportion of this dissolved material is lithium, derived from layers of volcanic ash within the shale. This high proportion of lithium makes the Marcellus Shale groundwater a potential target for lithium extraction. 

Current extraction infrastructure targeting the Marcellus Shale is concentrated around two hotspots for methane production, one in the northeast of Pennsylvania and one in the southwest of the state. The Marcellus Shale is known to vary in composition over its extent, leading to quite different groundwater chemistry in the two areas. Several previous studies have highlighted the possibility of extracting lithium from Palaeozoic brines, but to date none have considered geochemical variation within these sources, which could have a significant impact on the viability of such projects.

In a paper published in the journal Scientific Reports on 16 April 2024, Justin Mackey of the National Energy Technology Laboratory and the University of PittsburghDaniel Bain, also of the University of Pittsburgh, and Greg Lackey, James Gardiner, Djuna Gulliver, and Barbara Kutchko, also of the National Energy Technology Laboratory, present the results of a study which used chemical and production compliance data reported to the Pennsylvania Department of Environmental Protection to predict the potential yields of lithium from Marcellus Shale groundwaters in the two areas of Pennsylvania where the Shale is currently accessed.

Map of study area showing the Marcellus shale extent, well locations using in decline curve analysis, Water samples used in this study, and previous USGS sample locations. Lithium concentration data was calculated using new data from the study and existing data from the USGS National Produced Waters Database. Mackey et al. (2024).

The proportions of lithium and magnesium in groundwater vary between locations within the Marcellus Shale, leading to differences in the maximum likely estimation of lithium yields in different areas. The proportion of lithium in the water is more variable at wells in the northeastern sector of the Shale, varying between 139 and 267 mg/L. In the southwestern area the proportion of lithium is more constant, varying between 112 and 140 mg/L. Although the lithium is more concentrated in the northeast, more water is produced in the southwest, leading to a higher overall lithium yield. Mackay et al. estimate that a well in the southwest portion of the field could produce between 2.80 and 2,99 tonnes of lithium over ten years, while in the same time a well in the northeast could produce between 1.86 and 2.07 tonnes.

Histogram plot of Monte Carlo simulation results (25 000 simulations) of estimated ultimate lithium mass yield from a single Marcellus Shale gas well over 10-years of assumed continuous production. Regional estimates on lithium yields from a southwest Pennsylvania (SW) well is marginally more (approximately 33%) than its northeast Pennsylvania (NE) counterpart. Mackey et al. (2024).

The proportion of magnesium in the water is far higher in the southwest, averaging 2300 mg/L, compared to an average of 1000 mg/L in the northeast. Thus wells in the southwest will produce between 14.3 and 20.7 times as much magnesium as they do lithium, while wells in the northeast will produce between 2.66 and 7.26 times as much magnesium as lithium. 

Lithium extracted from pore waters from the Marcellus Shale in Pennsylvania could go a significant way towards meeting the US's need for the metal, although the extraction of the lithium would presumably have an impact on the way the industry works (currently salt rich water is pumped back into wells to produce more methane, with more water produced as a biproduct, which is then re-injected). 

The US currently uses about 3000 metric tonnes of lithium per year, and the Marcellus Shale Pore Waters could potentially provide 38-40% of this need, if all the dissolved lithium in the extracted water was recovered. However, about 95% of the water currently extracted from wells targeting the Marcellus Shale in Pennsylvania is reinjected, so if the pore water was diverted for lithium extraction, water from a different source would need to be used for this purpose. This would also involve considerable reorganization of the infrastructure surrounding the wells, and reconsideration of the associated the associated environmental and social impacts. Pore water is currently shipped from wells via a pipeline, then redistributed to other wells for re-injection with minimal treatment. Adding lithium-extraction to this process would require a substantial increase in the infrastructure needed, and subsequently the environmental footprint of the operation, although the value of the lithium would probably more than offset the financial cost of this.

The regional variation in the proportion of lithium in the water in the different areas is likely to have an impact on both the method used to extract lithium from the water, and the ultimate lithium yield. The southwestern portion of the Shale appears likely to produce more lithium overall, as well as having a slower decline in productivity. However, this difference is not huge, with southwestern wells probably producing only 26-38% more lithium than northeastern wells over their lifetime. Mackey et al. also note that it is less efficient and more expensive to extract lithium from water with higher magnesium contents, as is the case in southwestern Pennsylvania. The pore water extracted in the northeast of Pennsylvania has a magnesium/lithium ratio similar to that found in the salar Atacama brines of Chile, from which lithium is currently extracted via a combination of evaporation and distillation, demonstrating the economic viability of the process. Extracting lithium from pore water obtained from the southwestern part of the Marcellus Shale may prove to be a more expensive process, due to the need for additional treatment.

The rate at which lithium production from the Marcellus Shale will decline also needs to be taken into consideration. A typical well in the are suffers an 80% decline in water production over two years. This means that to achieve sustainable production of lithium, new wells would have to be brought into production more-or-less continuously, to replace wells where production had fallen below the point of viability. It is possible that improvements in technology will lead to the lives of wells being extended if the main target of the operation becomes lithium rather than shale gas; Mackey et al.'s production estimates are based entirely upon current extraction methods.

Mackey et al.'s study demonstrates that the Marcellus Shale has the potential to make a significant contribution towards the US's lithium needs, based upon a reasonably conservative set of assumptions. Even allowing for significant over-estimation of potential yields, it is likely that the Shale could produce 30% of curent US lithium demands. Current estimates suggest that the Marcellus Shale hosts about 2.7 billion cubic metres of undiscovered methane gas, suggesting that well-drilling activity here is likely to persist for several decades, and expand into other parts of the deposits, such as north-central Pennsylvania. Thus, even if lithium remains a biproduct of shale gas production, there is a potential for this to continue for decades to come.

See also...

Monday 27 May 2024

Rancher and 34 Cattle killed by lightning in Colorado.

A rancher and 34 Cattle have been killed by a lightning strike in Jackson County, Colorado. Mike Morgan (51) was unloading bales of hay from a trailer, when the vehicle was hit by the lightning bolt, at about 2.00 pm local time on Saturday 25 May 2024. The incident was witnessed by Morgan's wife and father-in-law, who reported that the strike knocked over about a hundred Cattle that were surrounding the trailer at the time of the incident, the majority of these got back up almost immediately, but 34 were found to have died, along with Mr Morgan.

Cattle killed by a lightning strike in Jackson County, Colorado, on 25 May 2024. Shannon Lukens/Denver Visitor.

The Earth's surface is struck by lightning about 40 million times each year, but it is extremely rare for people to be hit. The average Human has a roughly one in 15 000 chance of being hit by lightning during their lifetime, with 90% of those who are hit surviving.

Thunderstorms occur when warm, moist bodies of air encounter cooler, drier air packages. The warm air rises over the cooler air until it rises above its dew point (the point where it cools too far to retain its water content as vapor), and the water precipitates out, falling as rain, sleet, or hail.

Warm moist air passing over the surface of the Earth acts as an electrical generator, creating a negative charge in the cloud tops and a positive charge at the ground (or occasionally in a second cloud layer). The atmosphere acts as an electrical insulator, allowing this potential to build up, until water begins to precipitate out. This allows a channel of ionized air to form, carrying a current between the clouds and the ground, which we perceive as lightning.

See also...