A site from survey to decommission

01A site has a life, not a launch date

An observing site is often described by the day it went live. The more useful description is its whole life, from an early visit to a bare piece of ground to the day the last bolt is removed.

Global observing frameworks treat stations as parts of one integrated system, built through partnerships at national, regional and global levels¹. That only works if each station is documented, maintained and comparable with the others.

Each stage of a site's life answers different questions. Survey asks whether the place can see what it must see; design asks how it will be powered, connected and reached; installation and commissioning ask whether it works as designed.

Operation and maintenance ask whether it keeps working, and decommissioning asks how to leave the place, the equipment and the data in good order.

The stages are linked by a record. Notes from the survey explain choices in the design, commissioning results set the baseline for maintenance, and maintenance history tells a future user why a value changed.

A site that loses that record loses much of its value. Its data may still flow, but no one can say with confidence how it was measured or what changed along the way.

02Survey: seeing the place before building on it

A survey is where most later failures are prevented. It checks whether the place can measure what the site exists to measure, and whether people can build, reach and maintain it safely.

Measurement comes first. Guidance for observing instruments covers how each variable is measured, from temperature, wind and precipitation to snow, radar and observations from space². Where an instrument stands matters for every one of them.

A wind sensor sheltered by trees, a rain gauge beside a wall or a camera that looks into the sun will all report faithfully, and all be wrong. The survey looks for those traps before they are built in.

The surveyor also maps the ground itself: slope, drainage, soil for foundations, exposure to flood, fire and lightning, and the route a vehicle can take in the worst season of the year.

Radio and power come next. A survey notes which networks reach the site, where a satellite terminal could see the sky, and how much sun or wind the place receives across the year.

Finally the survey records people and rules: landowners, neighbours, protected areas, aviation and radio permissions, and anything the community needs to know before work begins.

03Design: power, links and access

Design turns the survey into a plan the crew can build. It sets where each instrument stands, how the site is powered and connected, and how a technician will reach every part of it.

Power is usually the hardest constraint at a remote site. The simulator lets you set the battery, the station load, the solar array and the hours of sun, and shows how long the site runs without sun and whether it gains or loses energy each day.

The worst month decides the design, not the average. A site that balances in summer may drain its battery through a dark winter, so size the array and the battery for the season with the least sun.

Links follow the same rule. Plan a primary link and a backup, decide what the site does when both are lost, and keep enough storage to hold the data until they return.

Access shapes everything else. Design for the vehicle, the tools and the weather the crew will meet, and keep heavy or frequently serviced parts at ground level where possible.

Write down the reasons for each choice. A future crew will change things, and the reasons tell them which choices were deliberate and which were simply convenient.

04Install and commission

Installation is skilled, physical and often dangerous work. Work at height must be properly planned, supervised and carried out by competent people with the right equipment, and the risks assessed first³.

A good installation leaves an as-built record: the exact position and height of every instrument, serial numbers, cable routes, firmware versions and photographs of anything that will later be hidden.

Commissioning is the step that proves the site before anyone relies on it. Each instrument is checked against a reference, each link is tested, and each alarm is triggered on purpose to see that it arrives.

Comparing instruments side by side under field conditions is an established way to find their real performance, and observing programmes run formal intercomparisons for this reason⁴.

A commissioning period also shows how the site behaves through changes of weather and load. Several days of parallel running catch problems that a single afternoon of tests would miss.

The site is accepted when the results are recorded and signed, and only then should its data be marked as operational.

05Operate and maintain

Once a site is live, the work shifts to keeping it honest. Instruments drift, enclosures leak, batteries age and vegetation grows into the view, so the site must be watched as carefully as the data it produces.

Remote monitoring catches most problems early. The site reports its own health beside its observations: battery state, enclosure temperature, link quality and each instrument's self-checks.

An operations centre turns those reports into action. It decides what can be fixed remotely, what needs a visit, and which observations must be flagged until the fault is repaired.

Planned maintenance follows the instrument guidance for each variable, with calibration intervals, cleaning and inspection matched to the conditions at the site².

Every visit is part of the record. A sensor swap, a recalibration or a moved mast can change the data, and future users need to know exactly when and why.

Training matters as much as spares. Local technicians who understand the site can solve many faults in hours, where a specialist visit may take days or weeks to arrange.

06Decommission responsibly

Every site ends. Funding changes, a better location is found, or the instruments reach the end of their useful life. A responsible end is planned from the beginning, not improvised on the last day.

Data comes first. The full record, with its calibration and maintenance history, is archived so that the site's observations stay usable after the site is gone.

Storage media must then be sanitised. Media sanitisation renders access to the data on the media infeasible for a given level of effort, chosen according to the sensitivity of the information⁵.

Electronic equipment that becomes waste can be hazardous when it contains materials such as mercury, lead or brominated flame retardants, and it can also hold metals worth recovering⁶.

The scale is large. A record 62 million tonnes of e-waste was produced in 2022, and less than one quarter of it was documented as properly collected and recycled⁷.

Batteries have their own rules in many places. European rules on batteries cover their whole life cycle, from design to collection, second-life reuse and recycling⁸.

Reuse comes before recycling. Instruments that still work can serve another site, enclosures and masts can be refurbished, and only what cannot be used again goes to an approved recycler.

Finally the ground is restored and the community is told. The decommission record lists what was removed, where it went and how the data was preserved.

07Handing over a living site

Many sites change hands during their life: from the team that builds them to the team that runs them, or from one operator to another. Each handover is a point where knowledge can be lost.

A good handover passes on the whole record, not only the keys. It includes the survey, the design reasons, the as-built drawings, commissioning results, the operations log and the maintenance history.

It also passes on skills. The new team should practise the routine tasks, the fault procedures and the safety rules on the real site before they take responsibility for it.

The disposal plan belongs in the handover too, so the people who end the site know from the start what it contains and where each part should go.

Nexus Observatory Inc. designs field services around this whole life: survey, design and integration, installation, operations, training and a planned, responsible end.