The press release announcing the loss of the unmanned submersible Nereus reads like the obituary of an old, deeply beloved and respected friend. As well it should, since that’s what Nereus was to her dedicated team of human handlers, who spent six years using it to explore the ocean’s depths.

Built to withstand 1,000 atmospheres of pressure, Nereus had seen the bottom of the Mariana Trench (the ocean’s deepest point) and discovered new hydrothermal vents, collected samples and laid down instruments for a host of scientific projects. The deep-sea robot could operate either autonomously or on a tether to a surface ship; at the time of her demise, she was 6.2 miles (10 kilometers) deep in the Kermadec Trench, a plummeting pit in the Pacific Ocean northeast of New Zealand.

Almost 24 hours after the operating surface ship lost contact with Nereus last Saturday, fragments of the submersible bobbed to the surface. It seems that the vessel was lost to an implosion: At 16,000 pounds per square inch of pressure, the slightest imperfection can result in a catastrophic failure.

Members of the team accompanying Nereus compared her loss to the loss of a child. The analogy highlights the intimacy of this particular scientist-instrument relationship: a sometimes-finicky robot that nonetheless united dozens of scientists shipboard (and hundreds of land-based onlookers, on the occasions when Nereus’s explorations were broadcast live over the internet) on a common scientific mission of exploration.

Though nothing can soften the blow of Nereus’s fate, at least in this case, no human lives were lost.

Yes, people like filmmaker James Cameron – who wrote a letter to Woods Hole Oceanographic Institution expressing his condolences on the loss of Nereus – may still mount manned expeditions to the sea floor. But Nereus, a pioneer among robotic deep-sea explorers, was a member of the true workhorses of today’s oceanic exploration – the robots that boldly go where no man has gone before and likely no man will follow.

We have a deep and abiding faith in human perception – in the ability of the human senses to collect data and the human brain to assimilate these data into insights that only an on-the-ground (or in-the-water) observer could obtain. Yet as our technology advances, it becomes increasingly capable of doing a human’s job as well as – and in some cases, better than – humans themselves, and moreover, the use of robots avoids risking human life.

Our fleet of sea explorers includes far-ranging gliders, passively drifting buoys and Nereus’s successors, the Nereids. Robots are taking over our more hazardous (and tedious) jobs on land as well: defusing bombs, doing surveillance and tending crops. And we’ve turned over our space exploration to probes and rovers that leave the surface of our planet, never to return.

In fact, in 2010, President Barack Obama announced the shutdown of the government’s manned space shuttle program. The task of putting humans in space has been turned over to the private sector; the truly far-ranging exploration is best left to robots.

This makes economic sense – as well as sense safety-wise. Supporting human life in space – particularly for the vast amounts of time required to traverse even our own planetary system – is infinitely more complicated than simply transporting machinery. At a minimum, humans require food, water and oxygen for the journey – all of which take up space, require money and induce logistical nightmares. And while there would surely be no shortage of volunteers for a one-way trip to Mars, such a venture would be more stunt than actual scientific progression.

Since the practicalities of unmanned exploration seem so obvious, I was surprised when a survey of scientists conducted by the esteemed journal Nature revealed how heavily they supported manned space flight. Many of the 800 scientists surveyed cited the Apollo missions to the moon as inspiration for their careers in science and manned missions as important to the pursuit of science. Yet even they would prioritize funding for unmanned missions.

This shift will be cemented by future generations of scientists. Neil Armstrong’s first steps on the moon may have inspired my parents’ generation, but they long pre-dated mine. Instead, I remember the sleek yellow cylinder of the Rutgers University glider, hanging in the atrium of the Institute of Marine and Coastal Sciences. I walked beneath it almost every day for two years, a constant reminder of the vast new frontier opened to us by automated exploration.

Holly welcomes reader feedback, especially arguments in favor of manned exploratory missions, at hollyvm “at” stanford.edu.