On 13 November 2015, British polar explorer Henry Worsley undertook a feat of endurance no person has yet achieved: a solo, unassisted crossing of Antarctica. His sledge contained 80 days’ worth of food, fuel and survival gear, and weighed more than 150kg – nearly double the weight of his slim but muscled frame. His body had been hardened by months of focused training, and his mind was sharpened by years of experience.

As he heaved the sledge over tiny bumps dotting an endless expanse of ice, the 55-year-old former army officer reveled in Antarctica’s “unbelievable science”.

He was exuberant as he made the first call-in of the expedition, after setting up camp under “glorious sunshine”. His tone portrayed a joy that transcended even his lofty ambitions: to travel 1,000 miles across the uninhabited continent and raise more than £100,000 for wounded veterans in Great Britain. Those were his goals, but this was his reward.

“It’s the best place on Earth right now,” Worsley reported.

Seventy days later, Worsley was pinned down in a storm more than 900 miles from his starting point. He had shed at least 50 pounds, lost a tooth after biting on a frozen energy bar, and been alone without basic comforts for more than two months. He hadn’t moved in two days.

The blue ice of the Transantarctic mountains was just 30 miles away, almost in sight. But dehydration and exhaustion had drained him to the core. He scarcely had the energy to collect snow for his kettle, and a whiteout continued to rage outside his tent. His voice was strained, and he had to take a breath after every few words.

“There is nothing to see but white darkness.”

Channeling the courage of famed polar explorer Sir Ernest Shackleton, who was forced to turn around during the 1915 expedition that Worsley set out to finish a century later, Worsley called Antarctic Logistics and Explorations to request a rescue.

“My journey is at an end,” he announced in an emotional final call. “I have run out of time and physical endurance – the simple, sheer inability to slide one ski in front of the other to cover the distance required to reach my goal.”

The following day, Worsley was flown to Punta Arenas, Chile, where was found to have bacterial peritonitis – an infection in the abdomen that often presents in patients with liver damage. He soon lapsed into complete organ failure and died on 24 January.

For everything Worsley accomplished during his life, his death will inevitably raise questions about risk and safety in modern exploration. Just how far should a person push the limits of human endurance? In an endeavor that relies on mental fortitude to boost physical performance, how can one objectively determine their own breaking point?

It’s a conundrum that all adventurers face, whether they’re polar explorers or hikers on a well-trodden trail. Turning one’s back on a goal or summit is often a heart-wrenching decision, and regret can reverberate long after physical discomforts have been alleviated and injuries have healed. But no one will disagree that safety – and coming home alive – is the ultimate goal of any adventure.

In commentary intended to celebrate Worsley’s brave decision to pull the plug, recorded one day before he died, fellow polar explorer Robert Swan paraphrased Shackleton: “It’s best to be a live donkey than a dead lion.”

Throughout the 71-day journey, Swan frequently commended Worsley for knowing when to push forward, and when to hold back and rest. Worsley had the experience, preparation and levelheadedness to balance all the variables in an equation that had never been solved. If successful, he would complete what no one had in 100 years of trying, and expand knowledge about human endurance. That, Swan acknowledged, was in itself a noble cause.

“All of us kind of played on the edges of what those real explorers went through, and Henry has become in my view a truly real explorer,” Swan said. “He has touched, as Shackleton said, ‘the naked soul of man’.”

In exploring the outer limits of endurance, did Worsley not realize he’d surpassed his own? Gauging his slow deterioration over two months of hard physical labor on limited calories would be difficult to do on his own, and perspectives often shift as the body adapts to increasing demands. Could Worsley have deduced that the fatigue, chills, nausea and malaise he was possibly experiencing – symptoms of bacterial peritonitis that resemble those commonly experienced by healthy endurance athletes during hard efforts – were the beginnings of organ failure?

Would he have made the call sooner if he hadn’t been so close to this as-yet-unreached destination?

There’s also the question of whether Worsley sensed that it might already be too late. Having come within 30 miles of his goal before stopping, he likely felt he had no choice but to request what he previously referred to as “the world’s most expensive taxi ride”. Still, he probably held on to uncertainties. He was physically weak, but his determination had taken him so far. Perhaps, like many who have struggled with the decision to stop short of a lifelong goal, he wondered if after just a few more cups of tea, and one more night of sleep, the blizzard would subside and his strength would return. Either way, he decided it wasn’t a risk he was willing to take.

“I’ll lick my wounds, they will heal over time, and I’ll come to terms with the disappointment,” he said, his voice cracking into the satellite phone.

Worsley’s last journey stands as a remarkable achievement of endurance and the human spirit, but it’s also a reminder of the more sobering realities that anyone who seeks the joy of adventure must face: not all wounds heal.