Trappist-1.

The red dwarf watched over the struggling human with complete disinterest, high in the sky of the tidally locked world.

WARNING: OXYGEN LEVELS LOW.
WARNING: ATMOSPHERIC FILTERS OFFLINE
V already had trouble breathing despite their exosuit's efforts to try and delay the inevitable. They glanced at their suit once again. Ironically what had saved their life was now going to kill them. Their light exosuit had cushioned the impact perfectly...by breaking the air recycling and filtering system beyond repair. V tried to ask the suit's systems again.
"Engage repair sequence."
The answer blinked on their helmet's head-up display.
REPAIR SYSTEMS OFFLINE.
WARNING: OXYGEN LEVELS CRITICAL.

V tried to find a more comfortable posture against the sandy rock. Several meters above them their drone watched, unable to provide anything but pep talk - it wasn't equipped to repair their model of exosuit and even if it had been, V was out of filters. They were about to die of asphyxiation at the end of this canyon, with a settlement barely a few kilometres away, on a planet full of life.
"How long until the rescue drone arrives?" they asked their suit again.
INCONCLUSIVE: UNABLE TO CONTACT RESCUE DRONE.
ADDITIONAL INFORMATION: WIRELESS SYSTEMS OFFLINE.
There. V was at the point where the lack of oxygen was starting to get really uncomfortable, way beyond what they had experienced when hiking at the top of Earth mountains without additional oxygen supply. Her breath was dying somewhere in the depths of their throat.
To hell with it... thought V as they reached for the helmet's emergency decoupling handle.
The display shot a few words back at V in angry, fiery red. 
WARNING: YOU ARE ABOUT TO OPEN YOUR EXOSUIT.
WARNING: HIGH RISK OF ENVIRONMENTAL CONTAMINATION.
WARNING: THIS ACTION IS STRICTLY PROHIBITED UNDER REG

The words vanished as V decoupled the helmet from the light exosuit. The CO2-saturated air inside the exosuit whistled as it escaped. The wind rustled against their cheeks. Alien wind. V took a very long breath. The air rushed inside their lungs, leaving a feeling of pure bliss behind. 18% oxygen, 70% nitrogen, with bits of rare gases. V inspired once more. It smelled like lilac. Yes, lilac with something more bitter hiding behind. Something they were the first human being to smell - the perfume of Trappist ground coral, the planet's dominant lifeform. V slowly extended her fingers in the wind. It carried transparent spores alongside strangely melodic sounds - this was how the coral colonies communicated with each other, a planet-wide song that would only end with the death of all life on Trappist. A small colony clung to the rock above them, bone-coloured tubes built by small creatures seemingly made of sand - in fact, self-sustaining grapes of amoeba-like creatures.

WARNING: ONGOING EXTERNAL CONTAMINATION said the display on their helmet, now abandoned in the sand.

V took a third breath. It could not last, they thought. With every single breath, they were expelling billions of microbes in the air, microbes that would form small colonies within a few hours and then...and then...and then, perhaps, those would be the start of a massive contamination cluster. For all the movies humans had made about alien encounters, very few of them had envisioned what would become the real systematic risk of exploring worlds harbouring life. External contamination by lifeforms carried by human ships and explorers. Viruses, bacteria, fungi, all forged in the evolutionary crucible of the Earth. In many cases, alien environments were not really capable of harming humans due to the advances in medicine in the Low Age, as well as the radical differences between lifeforms. The opposite was true - microscopic earthlings weren't capable of seriously harming alien life. No, the real threat was invasive species. Microbes and fungi rooting themselves deep in a planet's biosphere and ending up competing with aliens on their own turf. It had already happened in the past. It would keep happening in the future. In the sands of Trappist, V was now a potential walking bioweapon.

But at this point, it did not matter to them. They were breathing the atmosphere of another world. They were breathing oxygen produced by creatures that had never seen the light of the sun. They were living in this world, instead of just observing it from afar, from the plexiglass prison of their helmet.

V looked towards the star. It gleamed high in the sky. It seemed to approve of them.

Illustration: D. Mitryi