Falling Diamonds From A Long-Lost Planet

Our ancient Solar System was a violent place, where primordial objects crashed into one another, blasting each other into a multitude of fragments. This chaotic, turbulent mess of primordial crashes, occurring between rampaging objects, has inspired some planetary scientists to refer to our ancient, still-forming Solar System as a “cosmic shooting gallery”. Indeed, some of these invading objects wreaked havoc when they crashed into the newborn Earth, often contributing more and more of their material to our still-forming planet. Planetary formation models show that the solid, terrestrial inner planets of our Sun’s familiar family–Mercury, Venus, Earth and Mars–were born as a result of the accretion of tens of Moon-to-Mars-sized planetary embryos through raging, energetic giant impacts. In April 2018, a team of astronomers published their new findings suggesting that a space rock that fell to Earth may have come from a long-lost proto-planet from the early Solar System–and that tiny bits of iron and sulfur embedded in diamonds within this meteorite likely were created under high pressures found only deep within planets the size of Mercury or Mars.Alas, tattle-tale relics of these large, lost proto-planets have been difficult to find. Ureilites are one of the major families of achondritic meteorites and their parent body is thought to have been catastrophically blasted to pieces by an impact during the first 10 million years of our 4.56 billion-year-old Solar System. Achondrites lack chondrules and originate in differentiated bodies–such as planets. A chondrule is a spheroidal mineral grain, that is present in large numbers, within some stony meteorites. In the April 17, 2018 issue of Nature Communications, a team of planetary scientists published their report announcing that they had studied a chunk of the Almahata Sitta ureilite using transmission electron microscopy. The scientists found, scattered within this chunk, large diamonds that could only have formed at high pressure deep within a parent body. The team of researchers detected chromite, phosphate, and (Fe,Ni)-sulfide (iron, nickel, sulfide) inclusions embedded in diamond, and they reported that the composition and morphology of the inclusions can only be explained if the formation pressure was greater than 20 GPa. These pressures indicate that the ureilite parent-body was a Mercury-to-Mars-sized planetary embryo.Sulfide inclusions in diamonds are the most common of all inclusions, and they contain important information about the timing and physical/chemical conditions prevailing during diamond formation.The story of the Almahata Sitta ureilite began when an asteroid, designated as Asteroid 2008 TC3, crashed down in the Nubian desert in Sudan in 2008, and its recovered batch of meteorites, called Almahata Sitta, are mostly composed of ureilites with a variety of chondrites. Ureilite fragments are coarse-grained rocks that are primarily made up of olivine and pyroxene that originated from the mantle of the ureilite parent body (UPB), that has experienced a disruption resulting from a catastrophic impact that occurred early in our Solar System’s existence. High concentrations of carbon distinguishes ureilites from all other achondrite meteorites, with graphite and diamond nestled between grains of silicate.


Cosmic Shooting GalleryWhen our Solar System was first forming, strange things were occurring. Primordial planetary building blocks, called planetesimals, traveled away from where they had been born, and violently crashed into one another as a result. Sometimes these wandering planetsimals merged, but quite frequently they collided, leaving only the wreckage of both bodies behind to tell the tragic story of their ancient, deadly collision.The history of our Solar System is one of turmoil, and this is also the case with distant planetary systems around other stars beyond our Sun. Stars are born surrounded by a whirling disk made up of gas and dust, termed a protoplanetary accretion disk. These swirling disks form at about the same time that the baby star, called a protostar, is born within its blanketing, obscuring natal cloud.Protoplanetary accretion disks contain large quantities of gas and dust that feed growing, voracious protoplanets. Our own Solar System, as well as other planetary systems, form when a relatively small and very dense blob, embedded within the billowing, undulating swirls of a cold, dark, giant molecular cloud, collapses under the merciless influence of its own gravity. Floating throughout our Milky Way Galaxy in huge numbers, these phantom-like, beautiful clouds, serve as the bizarre nurseries of fiery baby stars. These gigantic, frigid clouds are mostly composed of gas, but they also harbor smaller quantities of very fine dust. Although it seems counterintuitive, things have to get cold in order for a hot baby star to be born.Most of the collapsing blob collects at the center, and ultimately ignites with a brilliant stellar fire as a result of the process of nuclear fusion–thus forming a new stellar infant (protostar). The remaining gas and dust eventually evolves into the protoplanetary accretion disk from which planets, their moons, and other smaller objects are born. In its earliest stages, a protoplanetary accretion disk is both very massive and searing-hot–and it can circle its host star for as long as ten million years.By the time a brilliant star, that is about the same mass as our Sun, reaches what is termed the T Tauri phase of its development, the very hot, massive surrounding accretion disk has become considerably cooler–and thinner. A T Tauri is a stellar tot–a very young, variable star that is similar to our Sun, and is quite active at the age of a mere 10 million years. These fiery stellar toddlers sport large diameters that are several times greater than that of our own Star at present. However, T Tauris are still in the process of shrinking. Unlike human babies, Sun-like stellar tots shrink as they grow up. By the time the stellar toddler has reached this stage, less volatile materials have started to condense close to the center of the surrounding accretion disk, thus creating very fine and extremely sticky motes of dust. The delicate dust particles carry within them crystalline silicates.The dust motes collide and then merge within the very dense environment of the accretion disk. As a result, they continue to grow in size, from dust-particle size, to boulder size, to mountain size, to moon size, to planet size. These growing bodies become the primordial planetesimals, and they can reach impressive sizes of 1 kilometer across–or greater. These planetary building blocks represent an abundant population within the ancient accretion disk, and they can linger around their star long enough for some of them to still be around billions of years after a mature planetary system has emerged. In our own Solar System, comets are the frozen, dusty, icy relics of the planetesimals that contributed to the formation of the quartet of outer gaseous giant planets–Jupiter, Saturn, Uranus, and Neptune. On the other hand, the asteroids are the leftover rocky and metallic planetesimals that served as the “seeds” of the inner solid planets–Mercury, Venus, Earth, and Mars.A Tattle-Tale Chunk From A Vanished Ancient WorldThe paper published in the April 17, 2018 issue of Nature Communications suggests that the chunk of the Almahata Sitta ureilite being studied is probably a piece of a Mars-sized protoplanet–one of the first planets to exist in our Solar System. Alas, this ancient planet has long since disappeared. The authors of the paper, who are of the Ecole Polytechnique Federale de Lausanne (EPFL) in Lausanne, Switzerland, analyzed very tiny pieces of the Almahata Sitta meteorites. These particular meteorites are famous because they came from the first-ever asteroid to be tracked from its orbit to the ground–as it was in the process of crashing down to the Nubian desert. These ureilites possess compositions that are different from those of the known solid, inner planets of our Sun’s family, and contain 100-micrometer diamonds. This means that the diamonds are too large to have formed in the shock of two asteroids blasting into one another. Diamonds this large, however, could form within asteroids that are at least 1,000 kilometers in diameter, because pressures within these bodies would be sufficient to compress carbon.During their study, the researchers–that include Dr. Phillippe Gillet, Dr. Farhang Nabiel, and their colleagues from the EPFL–discovered something strange that made them doubt that these tiny diamonds formed within any asteroid at all. This is because the gems had grown around even tinier crystals of iron and sulfur, which normally repel each other–and will not mix in a way that has been likened to that of water and oil. Those crystals could only remain stable at extreme pressures of 20 gigapascals–equivalent to almost 200,000 times the atmospheric pressure at sea level on our own planet. This means that they could only have formed in the center of a major planet, approximately the same size as Mercury, about 4,900 kilometers wide, or in the core-mantle boundary of a world as large as the planet Mars. Mars is approximately 6,800 kilometers wide.


Such long-lost planets likely dwelled in the primordial Solar System about 4 billion years ago. However, there are only a handful of survivors left from that violent, turbulent time–the quartet of solid inner planets that currently circle close to the warmth and light of our Sun. Supercomputer simulations indicate that most of these ancient planets blasted into one another and were destroyed. This ancient planetary smash-up probably occurred during the first 100 million years of our Solar System’s existence.Basically, there are three mechanisms that could explain diamond formation in ureilites: (i) growth under static high-pressure within the UPB; (ii) a shock-driven metamorphosis of graphite into diamond as a result of a high-energy impact; (iii) growth by chemical vapor deposition (CVD) of a heavily carbon-laden gas floating around within the solar nebula.Recent studies of the chunk of the Almahata Sitta ureilite show clusters of diamond single crystals that have almost identical crystallographic orientation, and are separated by bands of graphite. This means that individual, large diamond single crystals are present in the sample, and that these have later segmented through graphitization. The formation of such large single-crystal diamond grains along with the zoning seen in diamond segments cannot occur during a dynamic event. This is because of its brief duration (up to only a few seconds) and–even more importantly–by CVD mechanisms. This means that static high-pressure growth is the only possible origin of the single-crystal diamonds.Diamonds frequently encapsulate and imprison minerals and melts that are present in their original environment in the form of inclusions. This is because of the gem’s stability, melting temperature, and mechanical strength. In the case of the diamonds found on Earth, this feature has enabled scientists to estimate the depth of diamond formation, as well as to identify the composition and petrology of phases sampled at that depth. This indicates that diamonds formed inside the ureilite parent body can potentially solve the mystery surrounding the size and composition of the long-since-vanished ancient world.This new study confirms the existence of lost primordial Solar System planets. However, in itself, the probability that these vanished worlds once existed long ago isn’t especially surprising. The new findings are important because, for the first time, it has provided direct meteoritic evidence for the existence of a large, vanished protoplanet inhabiting our ancient Solar System.

BIM Process Risks for MEP Design Service and How to Mitigate Them

Global construction practice has seen substantial changes over recent years, with the arrival of BIM being a key factor. Building Information Modelling, known as BIM, is a process that involves the creation of 3D models, which enables designers and engineers to create accurate construction scheduling, estimate costs and adapt intelligently to design changes. Accurate building information models and precise building designs are created from the outset, which benefits all stakeholders in the construction process, particularly MEP (mechanical, electrical and plumbing) designers. MEP (M&E) designers or engineers design MEP services, while MEP contractors are then responsible for spatial coordination, detailed design, fabrication and installation. Though BIM drives an effective process for MEP (M&E) design services, there are some risks involved. We look at how these risks can be mitigated.

Firstly, it is useful to understand exactly what the BIM process contributes to MEP engineering design. A BIM model helps visualise spatial MEP requirements. Detailed views are created for analysis, and any clashes of spatial requirements are identified and can be resolved at an early stage. Designs can be altered to mitigate any clashes, and these changes can be seen in the model.

The progress of the MEP design and coordination workflow process has been supported and driven by technological advancements. BIM technology has played an important role in making this possible, especially the use of 3D models through Autodesk’s BIM 360 tool. BIM 360 is a cloud-based software platform developed primarily for construction, which employs checklists, equipment tracking and the monitoring of tasks to improve quality and on-site safety. Within BIM 360, models can be utilised for 2D construction documentation and the 3D coordination of trades. BIM 360 permits the control of processes by project managers, subcontractors, designers and architects at all design stages. It enables the sharing of vast amounts of information between stakeholders and easy communication.

MEP designers can utilise architectural, structural and trade models to plan in detail from the onset of a project by designing in 3D. In general, the process involves MEP design and installation workflows that will streamline planning, designing, coordination, fabrication, installation and construction of a project. Following architectural design, the MEP design engineer develops building services design elements, such as lighting, cooling, heating, drainage, waste, fire prevention and protection services. In most cases, the design engineer is not involved with the detailed spatial design of building services. Usually, it is the MEP, or trade, contractor who carries out the detailed spatial design and installation. It falls to the MEP contractor to convert the consultant’s design into an installation-ready MEP format and provide MEP shop drawing services. At times, fabricators creating ductwork or pipework elements, electrical ladders or sprinklers in a module also contribute.

The BIM process brings all stakeholders on to the same platform at every design stage.

Therefore, an effective collaboration tool would be required to:

  • Enable access to MEP designers, architects, structural designers, MEP contractors
  • Host various formats for files and documents
  • Ease communication
  • Permit designers and shareholders to work on the same models and share design data

BIM 360 Team with Collaboration for Revit (C4R) offers this. It integrates stakeholders and project information into a single cloud-based platform and improves quality while reducing rework. Checklists can monitor safety on site, equipment can be tracked and asset data can be collated. Any problems can be resolved early in the design process, minimising delay, cost and rework.

BIM Process Risks for MEP

Communication

If architects, modellers and designers do not communicate properly, designs may not be properly integrated and the occurrence of errors in the MEP model will increase.

Building Code Understanding

Client needs and local code requirements are of paramount importance and must be clearly understood. If misunderstandings of building codes and client requirements occur the MEP design will be negatively impacted.

Coordination

Stakeholders must coordinate effectively. Any modification executed by any MEP service should be communicated to all other trades. Failure to do so can create hazards at the project implementation stage.

Cost Estimation

The BIM process can help determine overall costs and take off quantities. MEP resources, labour and prices are considered, but materials availability and costs may vary over the duration of the design and implementation, affecting cost estimation.

Technical Knowhow

Effective BIM usage requires in-depth knowledge of BIM technology and Revit, Navisworks, etc. to develop precise MEP designs. Errors could prove costly.

Incomplete BIM Use

In common practice, BIM is used for a specific MEP objective rather than for each and every part of the design process. These include:

  • Remodelling or renovation
  • Material takeoffs and estimation
  • Design models by contractors
  • Detailed models of MEP components

Unless the BIM scope and output are accurately defined, the intended use of the BIM model may not occur.

BIM Model Not Shared with Construction Team

When 2D documents are printed from the model, some of the 3D data may not be transferred. The construction team may need to design a new 3D model, leading to unexpected changes. Designers may not share models with contractors because they are incomplete or do not tally with the construction documents, creating errors and tensions.

Not Possible to Model Everything

Creating models is time consuming. Many details, such as size, shape, location, quantity, and orientation with detailing, fabrication, assembly and installation information, can be included. It may not be possible to create models for every portion of the design, resulting in an incomplete overall picture.

MEP Design Handoff

Contractors traditionally received 2D line diagrams, schedules and specifications of the design from MEP designers. Currently, an increasing number of MEP design engineers create models, raising confusion about who is responsible for duct placement, equipment placement and coordination responsibility – designers or contractors. Models created by MEP designers may not be spatially accurate enough during the early stages.

However, there are several ways to mitigate these shortfalls, such as:

  • Early BIM Adoption (During Design Stage)

All project stakeholders should be encouraged to use BIM from the design stage, with clear guidelines for its use. If BIM is adopted at a later stage without clear specification of its purpose, the results could be confusion, wastage of time and increasing costs.

  • Defined Roles within the BIM Process

Design and modelling roles must be clearly defined before beginning design. If MEP subcontractors need to provide MEP BIM, with accurate routing, attachment details and equipment connections, they must be clearly informed of this and it should be part of the contractual obligations. They will not be able to rely on MEP consultant models in such a case.

  • Improved Coordination Skills

MEP design in BIM currently utilises improved spatial coordination skills during the design phase. This could be a result of employing more technically qualified professionals for these services, and as a consequence, contractors are presented with more accurate models to work with.

  • Accountability for Coordination

Internal coordination is necessary for a viable BIM model, much like a 2D drawing set used to be. Revisions, modifications and file versions must be coordinated as well. Since 3D models are complex, coordination must be monitored and controlled to prevent expensive and unnecessary rework. Even though files can be hosted in the cloud, it is advisable to maintain backups.

It is a certainty that precise, effective design with fewer errors is possible using BIM but there may be challenges in achieving those designs. Specifying the role of BIM, its usage, the stakeholders involved and the challenges to be expected can help optimise the benefits of using BIM and minimise its risks. The positive impact of building information modelling will be felt for some time. Analysing and mitigating the risks involved in its use can only benefit the industry and its players.