The muted thump of feet on dust was washed out by the louder thump of rushing blood and the ragged gasping born of exertion. None of the men and women present had the time or energy to yell "shut up" to their suits as the AI calmly encouraged them to decrease oxygen expenditure.
Mateo Espinoza's helmet flashed a distance marker. 200 metres to objective. 200 metres to their home
Hardly a problem under normal circumstances, Earth or Mars.
Although, normally Mateo and his friends were not hauling a one ton machine across the martian landscape.
The suit chimed again.
"Oxygen levels are critical. Please remain calm and reduce exertion."
The recommendation met unhearing ears as all four of them made their way up a slight incline at a fast trot, weaving past a set of rocks to catch sight of their home below.
It was a modest affair, or what passed for modest on the surface of Mars. It lay nestled between an outcrop of regolith and consisted of a series of connected structures joined together by narrow and short corridors that circled a larger, central building. Hope spurred their legs onwards, driving them down the incline towards their home.
Suddenly, Mateo's medical display flashed up a warning. Safety tolerance exceeded. Emergency protocols initiated. It was accompanied by a shock in his arms as the weight of the machine shifted, causing the group of them to cry out in shock.
Someone had stumbled and lost their grip.
Three voices groaned from the added strain.
One did not.
Someone had died.
As the group medic, Mateo's display told him it was Sofia's suit that had dipped below the safety tolerance, but he still twisted around out of habit. The suit was already forcing her into the foetal position as the helmet and suit filled with cryogel before hardening, freezing her in place. The process was fast and accompanied by a quick shot of sedatives that helped calm the colonist undergoing cryopreservation while the hardened gel would keep the visor safe from damage and the suit's contents safe.
His suit chimed as a new icon appeared on his helmet display, a red cross layered over the terrain minimap. Colonist in need of resuscitation.
The momentary shock had stilled them all, but hands gripped his suit and spun him. Catalina's steely eyes stared into his and their helmets clacked as she pushed her visor against his. Her voice was muffled but audible, the sound transferred by vibrations between their helmets.
"Pull yourself together or we're next."
He blinked at her, then nodded, but she had already stumbled off towards Alex across from him. A modicum of calm surfaced, enough to rise above the suit's relentless warnings about his O2 levels.
The three of them reached down for the machine and continued on towards their habitat, now little more than 50 metres away, though in his state, Mateo would have sworn it was 50 miles.
On they went, dragging the oft-cursed machine, their hope and burden, to the darkened base ahead.
Spots danced in front of Mateo's eyes as he stumbled forward. He felt as if he might collapse but for the weary, numb strain in his arms and his steady, defiant pacing.
Beside him, Catalina held the other side of the Energy Cell Charger.
Behind them, Alex was a dusty white egg, his face obscured by cryogel.
At last, the airlock of their home was before the two of them.
Mateo reached out, fingers slow to grip, arms sluggish. He seized the manual crank and twisted, leaning against the door. The suit continued to chime warnings, but it was meaningless noise.
The airlock swung open and in went he and Catalina. They had to wrestle the Recharger into the airlock, then seal themselves in. The interior was dimly lit, blue emergency lighting filling the space as the two of them worked on the interior crank. It swung open smoothly and they dragged the Hydrogen Energy Cell Charger inside, before pushing it upright.
Catalina was the first to speak, her voice sounded distant and raspy, "Get the O2 generator. I have this." She turned away from him, her skills and remaining oxygen entirely focused on bringing the Charger onto the emergency grid.
Mateo hauled himself within, feet like lead.
His suit chimed at him.
A new beacon appeared on his minimap, only a few paces behind him. Catalina's vitals greyed out on his display.
He had to be faster.
"Oxygen status critical. Emergency protocols initiated."
The words spoken calmly into his ears invoked pure panic. He was the only one still conscious. Mateo was no hero, but even he knew he had to make it count for something. His gloved hands reached for the partially refilled hydrogen energy cell at the Charger's base. Animal panic made clumsy work of his efforts, but it was in his hands and then he was running, stumbling, falling, crawling across the room. It felt as if he was fighting the suit itself and the cold spreading across his torso did little to soothe his fears.
The click of the standardised energy cell slotting into the receptacle of their oxygen generator was coupled with a cry of relief as it began to pressurise the room.
Then the cryogel filled his suit and Mateo was no more.
"Atmospheric pressure within tolerances. External oxygen levels within tolerance. Discharging patient."
The cryogel receded and Mateo was born again, coughing and dry heaving as he forced the worst of the fluid from his lungs. He blinked blearily before he began patting himself down. His suit's helmet had retracted automatically and it had revived him. The sound of retching down the corridor told him that Catalina had come to.
Mateo wanted nothing more than to strip out of his suit, but Alex and Sofia remained outside and would need to be rescued. The energy cell inserted in the oxygen generator would not last forever, but now they had the means to recharge it, to restore power to their home, and to survive.
If there was one lesson to draw from survival on Mars, it was that energy cells and thus power held dominion over life and death.
It was a lesson none of them would forget easily.