In situ
Ex situ methods, by contrast, involve the removal or displacement of materials, specimens, or processes for study, preservation, or modification in a controlled setting, often at the cost of contextual integrity.
In geology, field analysis of soil composition and rock formations provides direct insights into Earth's processes.
Biological field research observes organisms in their natural habitats, revealing behaviors and ecological interactions that cannot be replicated in a laboratory.
In chemistry and experimental physics, in situ techniques allow scientists to observe substances and reactions as they occur, capturing dynamic processes in real time.
In the aerospace industry, on-site inspection protocols and monitoring systems assess operational performance without disrupting functionality.
Space exploration relies on in situ research methods to conduct direct observational studies and data collection on celestial bodies, eliminating the challenges of sample-return missions.
Archaeology maintains the spatial relationships and environmental conditions of artifacts at excavation sites, allowing for more accurate historical interpretation.
The Oxford English Dictionary cites its first appearance in 1648 in the writings of William Molins, author of the anatomical text Myskotomia.
[1] The usage of the term in scientific literature expanded steadily from the late 19th century, primarily in medicine and engineering, including geological surveys and petroleum extraction.
For instance, an example of biomedical engineering in situ involves the procedures to directly create an implant from a patient's own tissue within the confines of the Operating Room.
[8] In aerospace structural health monitoring, in situ inspection involves diagnostic techniques that assess components within their operational environments, eliminating the need for disassembly or service interruptions.
The nondestructive testing (NDT) methods commonly used for in situ damage detection include infrared thermography, which measures thermal emissions to identify structural anomalies but is less effective on low-emissivity materials;[9] speckle shearing interferometry (shearography), which analyzes surface deformation patterns but requires carefully controlled environmental conditions;[10] and ultrasonic testing, which uses sound waves to detect internal defects in composite materials but can be time-intensive for large structures.
The differences in the soil properties for supporting building loads, accepting underground utilities, and infiltrating water persist indefinitely.
A use of the term in situ that appears in computer science focuses primarily on the use of technology and user interfaces to provide continuous access to situationally relevant information in various locations and contexts.
[14][15] Examples include athletes viewing biometric data on smartwatches to improve their performance,[16] a presenter looking at tips on a smart glass to reduce their speaking rate during a speech,[17] or technicians receiving online and stepwise instructions for repairing an engine.
In materials science, in situ describes the study of a sample maintained in a steady-state[b] condition within a controlled environment, where specific parameters such as temperature or pressure are regulated.
Examples include a sample held at a fixed temperature inside a cryostat, an electrode material operating within an electric battery, or a specimen enclosed within a sealed container to protect it from external influences.
External stimuli in in situ TEM/STEM experiments include mechanical loading and pressure, temperature changes, electrical currents (biasing), radiation, and environmental factors—such as exposure to gas, liquid, and magnetic field—or any combination of these.
[22][23] CIS is a critical term in early cancer diagnosis, as it signifies a non-invasive stage, allowing for more targeted interventions before potential progression.
[26] In archaeology, the term in situ refers to artifacts and other materials that remain in their original depositional context, undisturbed since their initial placement.
Recording the exact spatial coordinates, stratigraphic position, and surrounding matrix of in situ materials is crucial for reconstructing past human activities and historical processes.
While artifacts are often removed for analysis, certain archaeological features—such as hearths, postholes, and architectural foundations—must be thoroughly documented in place to preserve their contextual information during excavation.
Current archaeological practice incorporates advanced digital technologies, including 3D laser scanning, photogrammetry, unmanned aerial vehicles, and Geographic Information Systems (GIS), to capture complex spatial relationships.
However, these displaced materials can still provide clues about the spatial distribution and typological characteristics of unexcavated in situ deposits, guiding future excavation efforts.
[27]: 558 [31]: 13 This policy is based on the unique conditions of underwater environments, where low oxygen levels and stable temperatures help preserve artifacts over long periods.
[31]: 5 In mortuary archaeology, in situ documentation involves systematically recording and cataloging human remains in their original depositional positions.
Before identifying individuals or determining causes of death, archaeologists must carefully document spatial relationships and contextual details to preserve forensic and historical information.
[34] In contemporary aesthetic discourse, in situ has expanded into a broader theoretical construct, describing artistic practices that reinforce the fundamental unity between a work and its site.
[37] In situ refers to recovery techniques which apply heat or solvents to heavy crude oil or bitumen reservoirs beneath the Earth's crust.
The most common type of in situ petroleum production is referred to as SAGD (steam-assisted gravity drainage) this is becoming very popular in the Alberta Oil Sands.
