Neil deGrasse Tyson: A manned mission to Mars is impractical at this point

In a recent podcast, he explains why distance, launch windows, radiation, and the rocket equation make the “road to Mars” a project that requires decades of technological and political stability, and cites as an example the MARS ONE project, which was closed before it could launch even one person on a one-way flight to Mars.

Astronomer and science communicator Neil deGrasse Tyson is returning to the claim he likes to annoy optimists with: Yes, humans will one day set foot on Mars. But anyone who promises it will happen “in five years” is selling a fantasy. In a podcast segment in which he analyzes the challenge, Tyson breaks down the red dream into three cold, measurable components: launch distance and times, radiation and health risks, and the “tyranny” of the Rocket Equation—which multiplies every kilogram of equipment by yet more kilograms of fuel.

Tyson cites Mars One as an example of enormous public enthusiasm that doesn't necessarily translate into execution. Mars One, a Dutch company, has previously promoted the idea of One-way Mars missionand even reported receiving more than 200 applications/requests to join in the initial stages of the selection. (The Guardian(But over the years the initiative ran into difficulties, and its commercial arm fell into insolvency/bankruptcy proceedings.)TEAM) For Tyson (as presented in the transcript), this is not a “yellow story” about a failed startup, but a reminder: desire, inspiration, and media campaigns do not change the fact that a manned Mars mission requires working solutions for radiation, mass, landing, living infrastructure, and continuity of funding and political decision over the years.

Distance, launch windows, and separation time from Earth

Tyson's comparison to the moon is stark: The moon is about 384 miles away, and the journey to it takes days. Mars, on the other hand, is at a constantly changing distance because the two planets orbit the sun at different speeds. In a particularly close window, the distance can drop to about 55 million miles, and in a particularly far window, it can approach about 400 million miles. This means that you don't "go to Mars whenever you feel like it." You have to wait for a convenient launch window that comes around every 26 months. (ntrs.nasa.gov)

Even when the launch window arrives, the numbers don’t get nice: Tyson talks about a flight time of about seven to nine months each way using chemical engines, and a mission measured in years – because after arrival, you have to wait many months on the ground until the geometry between the planets allows for a return. The result is a long disconnect from Earth, and at certain times even a “normal” conversation with home becomes impossible: the signals are delayed by about 4 to 24 minutes each way, so real-time conversation simply doesn’t exist.

The human body versus radiation and insulation

To illustrate what such a journey does to the body, Tyson mentions Russian cosmonaut Valery Polyakov, who broke the record by staying for 437 consecutive days on the Mir space station and returning to Earth on March 22, 1995. It was a super experiment in human endurance – but still within a relatively protective envelope: close to Earth, with continuous contact, and under some influence of the magnetosphere. (NASA Jet Propulsion Laboratory (JPL))

In a manned mission to Mars, Tyson emphasizes, this envelope disappears. The most prominent risk is radiation: solar flares on the one hand and galactic cosmic rays on the other – high-energy particles that are very difficult to protect against in practice. Here too, it is important to be precise: NASA currently talks about exposure limits that are defined by an “excess risk” of cancer (3% REID), and professional documents indicate an order of magnitude of about 600 millisieverts as a cumulative limit over a career – a number that emphasizes how much one long mission can “swallow” a large part of the safe margin. (NASA)

And beyond radiation, there are other layers of wear and tear: loss of muscle mass and bone density in microgravity, vision changes observed in astronauts in space, and the psychological strain of prolonged isolation without a “safety net” of rapid rescue. Tyson doesn’t claim it’s impossible—but he does claim it’s an experiment on humans, on a scale never before done.

The rocket equation, “autonomous” landing, and life on a hostile planet

Tyson devotes much of his argument to a problem that engineering loves to hate: to accelerate, you have to throw mass back, which is fuel. But the fuel itself is mass that needs to be accelerated—so “it takes fuel to move the fuel,” and more fuel to move the fuel that moves the fuel. It’s this exponential relationship that makes it difficult to turn a manned spacecraft to Mars into a simple “a few more upgrades” project.

The complexity doesn’t end with arrival: Landing on Mars is a problematic combination of “there is an atmosphere” and “not enough atmosphere.” The atmosphere is very thin (typical pressure of only a few millibars) and composed of about 95% carbon dioxide, so parachutes alone are not enough to stop a heavy craft, but friction and heating at entry cannot be ignored either.
In addition, it is impossible to “navigate from the ground” like in the movies: due to the communication delay, the entry-descent-landing sequence must be carried out autonomously, and the team only finds out if it was successful in retrospect.

Then comes a part that Tyson describes almost as a sentence: Mars “doesn’t want you there.” There’s no air to breathe, there’s extreme cold and sharp temperature fluctuations, there’s dust everywhere, and there’s also the lesson of reality: a global dust storm in 2018 was a major factor after which contact with the Opportunity rover was lost, and NASA officially declared the mission over on February 13, 2019.

To make a mission sustainable, Tyson points to a critical reliance on in situ resource production (ISRU) – for example, producing fuel and oxygen on Mars, rather than carrying everything from Earth. In this context, he mentions (and rightly so) that this is more than a promise: the MOXIE experiment on the Perseverance rover showed that it is possible to produce oxygen from the Martian atmosphere, and JPL reports that the system reached a rate of about 12 grams of oxygen per hour, and during the experiments produced a total of about 122 grams. This is an engineering feat – but still far from what a human crew needs to breathe and fuel.

Alongside all this, Tyson also brings into the conversation the “decade-two problem”: a manned mission to Mars requires budgetary and political stability over time. He mentions that historically it is easy to announce a space program and very difficult to sustain it through changes of administrations, priorities and crises – and that this is not a physical problem, but a human one.

In the end, after the whole list, Tyson does return to the starting point: humans will fly to Mars. Not because it’s easy, not because it’s cheap, and not even just because of science. But because the urge to cross a new horizon is part of the human race. The question, for him, is not “if,” but “when” – and most importantly: will we be willing to pay the price in time, technology, and patience.

More of the topic in Hayadan:

• In the fourth episode of Cosmos, Tyson stings the creationists with a caliper
• Science deniers were angry about the second episode of the Cosmos series which dealt with evolution
• Neil deGrasse Tyson, presenter of the series Cosmos: "If Sagan were alive, he would be most surprised by the fact that we still have to argue that science is important to society."
• The mythological TV series "Cosmos" is back - it will be screened from today, on all stations, precisely on Fox
• Dark energy - a chapter from the book "Astrophysics for those who don't have time" by Neil deGrasse Tyson