Why Is Mars So Hard? A $125M Unit Error and 5 Other Reasons
By James · Published May 4, 2026 · Updated September 5, 2026
I cannot recall exactly which year of high school it was. One detail has stayed with me, though: a bitterly cold winter night, watching 1492: Conquest of Paradise with a group of friends. Outside, the cold turned our breath to mist. On screen, it was all candlelight, creaking wooden decks, and restless Atlantic swells.
The plot itself has long since faded. What remained was a single historical fact — in 1492, Columbus persuaded the Spanish Crown, Queen Isabella I and King Ferdinand II, to underwrite a westward voyage with three ships, the Niña, the Pinta, and the Santa María. That gamble set in motion Europe's sustained push to reach Asia by sea.
Recently, news of renewed lunar exploration has resurfaced across major outlets. The stated objectives are twofold: survey and eventually extract the Moon's natural resources, water ice and harvestable in-situ materials among them, and use the Moon as a staging point for humanity's longer journey toward Mars. We like to tell ourselves the age of wooden caravels is behind us. But the underlying pattern hasn't changed — risk, capital, and the promise of a world beyond the edge of the map.
We've simply traded sails for solar panels and royal crests for agency logos — the same motives of exploration and resource discovery, now layered with scientific curiosity and geopolitical competition. But does that make Mars inevitable, an obligation history has assigned to our species? Terraforming proposals and Martian settlement scenarios keep showing up in both peer-reviewed journals and mainstream media, and the question deserves more honest scrutiny. When does curiosity harden into destiny? And when does destiny quietly become ideology?
A historical illustration of three 15th-century sailing ships navigating the ocean at night. The main vessel, its sail marked with a red cross, is guided by an explorer using a navigational instrument under a vast starry sky and the Milky Way.
A $125 Million Unit-Conversion Error
Before asking whether Mars is inevitable, it's worth looking at how fast the environment of deep space undoes good engineering. A spacecraft is the product of enormous technical care, and it stays vulnerable to the most ordinary human oversight anyway. The universe doesn't care whether a failure started in a defective sensor or a mismatched unit in a contractor's data file.
In 1999, the Mars Climate Orbiter drifted off course and was lost at Mars. Its Mishap Investigation Board, reporting that November, named the root cause a unit conversion failure. Lockheed Martin, the contractor, had supplied thruster performance data in pound-force seconds. NASA's navigation software expected newton-seconds. Nobody caught it.
The spacecraft was designed to pass Mars at a periapsis of 226 kilometers. Every altitude figure here is a computed navigation solution rather than a measurement taken at Mars, which is exactly the problem: the error lived inside the arithmetic, where no instrument could contradict it. In the week before orbit insertion, that solution had the projected periapsis down between 150 and 170 kilometers — a warning sign that, in hindsight, should have stopped the maneuver. It didn't.
Post-loss analysis placed the actual trajectory at an estimated 57 kilometers, well below the roughly 80-kilometer minimum the spacecraft was built to survive. That's deep enough for atmospheric stress to tear the orbiter apart or deflect it irretrievably off course, destroying a spacecraft that had cost roughly $125 million, part of a mission budgeted at about $328 million. In deep space, the gap between almost right and exactly right isn't measured in centimeters. It's measured in kilometers of altitude, and in millions of dollars.
Seven Minutes No One on Earth Can Steer
The sheer distance between Earth and Mars imposes hard limits on how any spacecraft can be controlled. Depending on where the two planets sit in their orbits, a one-way radio signal takes anywhere from roughly 4 to more than 20 minutes to make the crossing. Even at the speed of light, Mars isn't a place you can reach with a timely response.
When Curiosity landed in August 2012, the one-way delay stood at 13 minutes and 48 seconds — nearly twice the length of the landing itself. By the time mission control saw the first signal confirming that atmospheric entry had begun, the seven-minute sequence had been over for almost seven minutes — its outcome already written in fire and dust.
NASA's own name for this is the "7 Minutes of Terror." A spacecraft arriving at Mars has to do all of it alone. Decelerate from tens of thousands of kilometers per hour. Deploy the parachute at exactly the right moment. Manage the heat, scan the ground for hazards, set itself down. No confirming command from Earth arrives in time to matter. We don't land on Mars, in other words. We build something that has to decide, entirely on its own, whether it survives.
What 520 Days of Isolation Actually Does to a Crew
While machines contend with communication delays and structural tolerances, people face a different kind of limit: isolation. The human mind evolved inside Earth's sensory environment — daylight and darkness, a familiar sky, the constant pull of gravity, the knowledge that other people are never more than a door away. Take that context away, and you introduce stresses harder to quantify than fuel margins or heat shield thickness.
To find out what actually happens, the European Space Agency and Russia's Institute of Biomedical Problems ran the Mars500 simulation. Six volunteers were sealed inside a module for 520 days, from June 2010 to November 2011. No real-time contact with the outside world. Communications delayed on purpose, the way they would be on a real crossing. Mathias Basner and colleagues published the results in PNAS and PLoS ONE, and what stands out is how differently the six men responded.
Actigraphy tracked a mission-wide drift toward hypokinesis: crew members grew steadily less active and slept more as the isolation wore on. Layered on top of that shared pattern, individual responses split sharply. Two crewmembers reported neither behavioral disturbance nor psychological distress across the full 17-month confinement. One developed a persistent sleep-onset insomnia that left him chronically short of sleep and measurably less alert. And the crewmember with the highest recorded mood-disturbance score reported depressive symptoms in 93 percent of the mission's weeks, reaching mild-to-moderate severity more than one week in ten.
Surviving the round-trip transit requires building a psychological life-support system as robust as the mechanical one. We know how to protect steel from fatigue and electronics from radiation. We're far less certain how to protect motivation, emotional stability, and cognitive clarity over years of silent travel through the void.
A digital rendering of a conceptual deep-space spacecraft firing its engine in transit, with the red planet Mars dominating the background and a distant Earth visible behind it.
Why a Single Dust Storm Can End a Mission
Assuming a crew survives the transit intact, surface conditions on Mars present a different category of threat, one that doesn't announce itself in advance. The planet generates massive dust storms, regional in scale and occasionally global. They can obscure vast areas of the surface and block incoming sunlight for weeks at a time. From orbit, Mars can transform into a single swirling ocher cloud, its geography completely erased. The dust doesn't block radio; orbiters kept relaying signals through the global storm of 2018. What it does is starve solar-powered hardware of the electricity it needs to do anything at all, transmitting included.
Opportunity worked the surface for more than fourteen years, from January 2004 to June 2018. A planet-encircling dust storm ended it. Sunlight reaching the solar panels dropped so far that the batteries stopped charging. Without power the rover could not heat itself through the Martian night, and it could not call home. No signal was ever received again.
That final transmission is worth pausing on, because most people have it wrong. The last data Opportunity sent, on June 10, 2018, was a single incomplete photograph. The rover had aimed its panoramic camera at the Sun through a solar filter, which is how these rovers measured the dust overhead. That day the reading came back at about 10.8. Almost no sunlight was reaching the ground.
What arrived on Earth is a dark frame flecked with camera noise. The signal cut out before the bottom of the image came through, so the lower portion is simply missing.
The famous line, My battery is low and it's getting dark, was never transmitted from Mars. It came from a science reporter, Jacob Margolis, who asked mission scientists what the final data meant and rendered their answer in plain English. He published a correction once the phrase escaped the context he wrote it in. By then it was on T-shirts, and at least one man had it tattooed on his shoulder.
I keep returning to that, because it is the same instinct running underneath everything else here. We take a column of voltages and a light-level reading, and we hear a voice in it. That habit isn't a defect — it's most of the reason anyone funds a rover at all. But it's worth knowing which part came from Mars and which part came from us.
For fourteen years, Opportunity had survived radiation, extreme temperature swings, and mechanical wear. In the end, it wasn't a dramatic failure that ended the mission. It was the quiet accumulation of dust between a distant star and a small, aging panel. And that same thin atmosphere, the one carrying the dust, was already posing a different problem, one built into the physics of arrival itself.
An Atmosphere Too Thin and Too Thick at Once
The Martian atmosphere creates a direct engineering contradiction. At roughly 0.6% of Earth's average sea-level pressure, it manages to be simultaneously too thin and too thick — the worst of both properties compressed into a layer of air that barely qualifies as sky. During entry, even this sparse atmosphere generates thousands of degrees of heat. Not from friction, as the popular version has it. The vehicle arrives too fast for the gas to get out of the way, so it compresses that gas into a shock layer ahead of itself, and compressed gas gets hot. Surviving it takes a heavy, carefully engineered heat shield. Yet once a spacecraft has shed most of its velocity, the atmosphere is nowhere near dense enough to decelerate a massive payload using parachutes alone.
| Martian Atmospheric Characteristic | Engineering Consequence |
|---|---|
| Surface pressure at roughly 0.6% of Earth's sea-level average | Too thin to support parachute-only deceleration for any heavy spacecraft. |
| Shock-layer compression at entry speed | Generates thousands of degrees of heat, requiring robust heat shields that add significant mass. |
| Insufficient aerodynamic braking at lower speeds | Demands supplemental touchdown systems such as retrorockets, airbags, or the sky crane mechanism. |
That contradiction is what produced the sky crane: a hovering stage driven by retrorockets that lowers surface hardware to the ground on tethers. On Mars, even falling is an active engineering problem.
The Dead Core: A Slower Problem Than It Sounds
Even if every landing problem above were solved tomorrow, a different obstacle would remain, written into the planet's core. One of the boldest colonization proposals is to generate an artificial magnetic field around Mars. Whatever its merits as a thought experiment, it points at the thing usually named as the fatal weakness in any terraforming plan. Mars has no strong global magnetic field. It is not entirely bare: patches of magnetized crust survive in the southern hemisphere, and where the solar wind meets the Martian ionosphere it induces a weak magnetosphere of its own. But neither comes close to what Earth's dipole does. The shielding they give is local and partial, and the charged particles streaming in from the Sun mostly reach the atmosphere.
Without that protection, atmospheric gas is steadily stripped away into space. NASA's MAVEN mission has been measuring the rate directly since 2014, and the number is worth stating plainly, because it cuts against the drama. The solar wind carries off roughly 100 grams of gas per second. Counting every escape route, a full Martian year of MAVEN data puts the total at one to two kilograms per second.
That is a slow leak, not a blowout. It is enough to reshape a planet over hundreds of millions of years, and close to nothing on the timescale of anything humans would build.
Which makes the missing magnetic field a stranger obstacle than it first appears. The problem isn't that a manufactured atmosphere would be torn away within a human lifetime. It's that you would be building something the planet has already demonstrated it does not keep. Whether that counts as a fatal objection or a distant accounting problem is genuinely argued over among researchers, and the disagreement doesn't turn on the measurement. Everyone is working from the same hundred grams a second.
What the absent field does do, without ambiguity, is leave the surface unshielded. That part already has partial answers: burying a habitat under a few meters of regolith, or lining it with water, blocks most of the incoming radiation for the people inside. It just doesn't touch the planet itself.
There's a more immediate obstacle that gets far less attention than the magnetic field, and the evidence for it comes from the same scientist. Bruce Jakosky led MAVEN as its principal investigator until 2021. In 2018 he published a paper in Nature Astronomy with Christopher Edwards, adding up every reservoir of carbon dioxide on Mars: the atmosphere, the polar ice, the carbon locked into surface rock.
Vent everything reachable without exotic machinery and Mars ends up with about three times its current atmospheric pressure. Against what a habitable atmosphere would require, that is roughly 2 percent of the way there. Go after the carbon in the rock as well and the ceiling rises to about 7 percent of Earth's sea-level pressure, reachable only through what the paper calls planet-scale strip mining.
So the usual sequence has it backwards. People assume the hard part is holding on to a new atmosphere and the easy part is making one. The holding is the slow problem. The making is the one nobody can currently do.
At this point it's worth setting the assumption of inevitability aside long enough to ask a harder question. Shouldn't we consider a future in which even a fraction of the resources budgeted for terraforming Mars gets redirected toward restoring Earth's environment, eradicating hunger, and advancing disease research? The question isn't whether Mars can eventually be bent toward habitability. It's whether humanity genuinely must go, or whether we've simply grown attached to the idea that salvation lies somewhere else. That's a moral and political question, not a scientific one, and it deserves to be treated as such.
As the ending of Maurice Maeterlinck's fairy tale The Blue Bird reminds us, the most precious world we so desperately seek turns out, in the end, to be right here. Home feels irreplaceable not because it's perfect, but because it holds everything we've already lived. The American continent was named after Amerigo Vespucci, not Columbus. A wry irony, and a useful one. The names we remember are rarely those who first set sail. They belong to whoever stayed long enough to redraw the map.
About the Author James is a science writer covering astrophysics, space policy, and the history of scientific discovery. He writes for thesecom.net, where the goal is to explain what scientists actually found — not just what the headlines said they found. His work draws on peer-reviewed sources and primary mission documentation throughout. Editorial profile.
Sources & References
- NASA Jet Propulsion Laboratory: Mars Climate Orbiter Mishap Investigation Board Phase I Report, release 99-134 (November 10, 1999) — nssdc.gsfc.nasa.gov
- Basner, M., et al.: "Mars-520-d mission simulation reveals protracted crew hypokinesis and alterations of sleep duration and timing." PNAS, 110(7), 2635–2640 (2013) — pnas.org
- Basner, M., et al.: "Psychological and behavioral changes during confinement in a 520-day simulated interplanetary mission to Mars." PLoS ONE, 9(3), e93298 (2014) — journals.plos.org
- NASA: "NASA's Opportunity Rover Mission on Mars Comes to End" (February 13, 2019) — science.nasa.gov
- NASA Technical Reports Server: Mars Exploration Rover Opportunity End of Mission Report — landing date, sol 5111 final transmission, recovery attempts — ntrs.nasa.gov
- NASA / JPL-Caltech: "Opportunity's Last Message" (PIA22929) — the final partial Pancam frame of June 10, 2018, and its relay through the dust storm — jpl.nasa.gov
- NPR: interview with science reporter Jacob Margolis on Opportunity's final transmission (February 12, 2019) — npr.org
- Newsweek: account of Margolis's published clarification that the "battery is low" line was a paraphrase, not a transmission — newsweek.com
- NASA: "NASA Mission Reveals Speed of Solar Wind Stripping Martian Atmosphere" — MAVEN escape-rate measurement — nasa.gov
- Jakosky, B. M., et al.: "Loss of the Martian atmosphere to space: Present-day loss rates determined from MAVEN observations and integrated loss through time." Icarus (2018) — sciencedirect.com
- Jakosky, B. M. & Edwards, C. S.: "Inventory of CO2 available for terraforming Mars." Nature Astronomy, 2, 634–639 (2018) — doi.org
- European Space Agency, Mars Express operations blog: "Time delay between Mars and Earth" (August 5, 2012) — one-way light time during Curiosity's landing — blogs.esa.int
- NASA: "Curiosity's Seven Minutes of Terror" — entry, descent, and landing (2012) — blogs.nasa.gov
- European Space Agency (ESA) & IBMP: Mars500 Study Overview and Behavioral Study Results (520-day isolation, 2010–2011)
- Encyclopaedia Britannica: "Christopher Columbus" — Columbus's three ships and Spanish Crown backing (1492)
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