Deposition occurs when small pieces of Earth are moved by erosion and deposited elsewhere, often close to their source such as when rivers deposit silt onto the land they flow over.
Frost formation can also happen far away, such as when water vapour in freezing cold air suddenly converts directly to ice without first becoming liquid – this is what happens when frost forms on window panes.
Cave Formations
As water seeps into caves and dissolves rock, it deposits minerals that create spectacular speleothem formations known as speleothems – most famously seen as stalactites and stalagmites that protrude from ceilings or rise from floors of these underground landscapes.
Water falling onto a cave’s ceiling re-deposits calcium carbonate in the form of stalactites, creating decorative columns. Stalagmites rise from below stalactites and when they eventually meet they create decorative columns. Other formations include rimstone dams, soda straws and draperies with twisty shapes reflecting their rate of evaporation and composition of minerals found within.
Caves can form both above and below the water table, with primary caves being formed when their surrounding rock material solidifies, while solutional caves form when acidic groundwater percolates up through them and dissolve soluble rock layers that had previously formed primary caves. Speleothems form on cave walls, ceilings and floors and come in an assortment of sizes and shapes – providing ample opportunities for speleothems formation!
Semiconductor Manufacturing
Deposition science plays a critical role in creating microchips – which provide power for your laptop, smartphone and game console – but manufacturing these miniscule pieces of technology is no easy feat.
Initial wafer preparation begins with photoresist application to a thin silicon substrate, followed by exposure to ultraviolet light for chemical changes that transform these areas into areas suitable for etching and deposition.
Metal (conducting) and dielectric (insulating) layers are deposited to form an internal circuitry using methods such as physical vapor deposition, plasma-enhanced CVD and atomic layer deposition (ALD).
Domestic semiconductor manufacturing is essential to strengthening our defense industrial base, supporting economic growth and increasing supply chain security. However, manufacturing such tiny devices requires specialized equipment and chemicals of high purity; many are flammable or toxic; all must be managed carefully to ensure they only react with their intended targets.
Climate Change
Earth’s climate is evolving at an alarmingly fast rate, and most scientists agree this change is caused by human activities such as fossil fuel combustion, land-use changes and deforestation that release heat-trapping greenhouse gases into the atmosphere that trap heat-generating energy that causes temperatures to increase globally.
Deposition in chemistry refers to the process by which gases change directly to solids without passing through an intermediate liquid state, for instance when water vapor in the air encounters cold surfaces such as window panes it undergoes deposition to form frost.
Metal coatings, widely found in industries like aerospace and manufacturing, also utilize this process. Researchers from Joint Global Change Research Institute and University of Illinois recently released a paper discussing how climate and emissions changes may alter dry/wet NOy deposition patterns.
Space Exploration
Since the dawn of civilization, people have marvelled at the night sky and wondered what lies beyond. The allure of space exploration has long served as an incentive for states, individuals, companies and non-governmental organizations alike – both governments as well as individual researchers – to pursue space research & development efforts as part of scientific advancement or technological innovation initiatives.
Space exploration not only offers novel solutions to global challenges, but it has also inspired generations of young people to pursue education and careers in science, technology, engineering and mathematics (STEM). Such initiatives foster international cooperation and strengthen global unity.
Humans could one day discover evidence of extraterrestrial life on another planet, whether that means finding evidence that other organisms exist or even something more significant such as losing Earth’s dominant species or experiencing major environmental disaster. We could do much to increase space exploration efforts so as not to let such discoveries slip by without action being taken now; this Special Feature investigates how expanding activities in space can drive economic growth on Earth during times of slow growth or environmental degeneration.