A new simulation conducted by astrophysicists has mapped the lethal conditions on exoplanets discovered by NASA’s Kepler telescope, revealing environments that would 𝓀𝒾𝓁𝓁 an unprotected human within seconds or, at best, minutes. The study, led by researcher Peter at the What If Institute, modeled the atmospheric, gravitational, and thermal hazards of six representative Kepler worlds. The results are a stark reminder that while the universe may be teeming with planets, most are hostile beyond imagination.
The simulation placed a virtual astronaut, designated Chase, onto each planet’s surface to measure survivability. On Kepler-22b, the first target, the astronaut succumbed within minutes to hyperoxia—oxygen poisoning—caused by an oxygen-rich atmosphere at double Earth’s gravity. “Breathing pure oxygen under elevated pressure triggers lung inflammation, seizures, and death,” Peter explained.
The extra gravity alone was manageable for short periods, but the atmospheric composition proved fatal. Chase’s vital signs showed rapid deterioration as oxygen levels in his blood surged to toxic concentrations.
Moving deeper into the Kepler catalog, Kepler-69c presented a different kind of nightmare. Classified as a super-Earth, it functions as a “super Venus” with a runaway greenhouse effect. Surface temperatures reach 280°C (536°F), hotter than Mercury, and atmospheric pressure exceeds 92 times Earth’s, crushing anything unlucky enough to land.
“The planet is a hellscape—a pressure cooker with pools of molten sulfur,” Peter noted. In the simulation, Chase’s suit failed instantly under the external force, and his own body moisture turned into superheated steam, cooking him alive within seconds. The team rated this planet an 8 out of 10 on the deadliness scale.
Kepler-10b offers perhaps the most dramatic death. Tidally locked to its star, the planet has no atmosphere—solar radiation blasts the surface continuously, heating the day side to 1,300°C (2,400°F). “The rock itself is molten,” Peter said.
“The surface is a liquid lava soup.” Without atmospheric diffusion, the sky remains pitch black even during the day. Chase’s landing vessel could not withstand the heat; the internal cabin temperature spiked, and the astronaut was burned from his feet upward before even stepping out.
The simulation ended in less than 20 seconds. The planet earned a 9 out of 10 for sheer brutality.
Kepler-62f looked promising at first glance, with solid ground, standing water, and a mild 10°C temperature. However, its thick atmosphere is rich in carbon dioxide—five times Earth’s pressure. “If the air has too much CO2, breathing it is fatal,” Peter warned.
Worse, the planet harbors a plant-like organism with sharp blades that tore Chase’s spacesuit. Carbon dioxide poisoning, or hypercapnia, set in rapidly. “He died from CO2 toxicity, a slow, painful suffocation,” Peter added.
The simulation rated this world a 7 out of 10 for its deceptive lethality.
The gas giant Kepler-16b proved unique: a circumbinary planet orbiting two suns. No solid surface exists; the entire planet is gas. Chase free-fell into the atmosphere, reaching terminal velocity, but then the increasing pressure slowed his fall.
“You don’t need a parachute—you get crushed by the atmospheric density,” Peter explained. Intense storms and deep gas ocean pressures pulverized the astronaut’s body. The team gave it a 3 out of 10, noting the death was less spectacular but still inevitable.
Finally, Kepler-452b, a super-Earth with 60% larger diameter and double Earth’s gravity, caused long-term strain. “Walking is difficult; your heart works overtime,” Peter said. Chase suffered elevated blood pressure and a fatal fall after stumbling in the high gravity—multiple fractures and internal injuries.
Surface temperature was 48. 7°C (120°F), adding heat stress. “You’d survive a short walk, but any fall is catastrophic,” Peter concluded.
The planet scored a 6 out of 10.
The Kepler telescope has discovered over 2,784 exoplanets to date, each with unique hazards. “These six represent just a fraction,” Peter noted. “But they show that human exploration of exoplanets is not just challenging—it’s deadly.”
The simulation underscores the importance of advanced life support, radiation shielding, and terraforming concepts. For now, Earth remains the only safe harbor among billions of worlds.