If you want to go to Mars and hang out on a long weekend, how long would it take to get there? At its closest distance to the Earth, Mars is approximately 35 million miles away. At its furthest distance, Mars is about 250 million miles away. On average, Mars is about 140 miles away from the Earth.
About every two years, the distance conditions are optimal for launching spacecraft toward Mars. If a spacecraft is launched when the distance between Earth and Mars is the smallest, the one-way travel time from Earth to Mars should be around six to seven months.
If a spacecraft is launched when the distance between Mars and Earth is the greatest, the one-way travel time may be roughly four years.
The Mars launch window is approaching quickly, so let’s strap in for lift-off.
How Long Does It Take to Get to Mars?
Calculating the travel time between Earth and Mars includes constant parameters that can be used to generate the answer. Mars orbits the Sun once every 687 days at 53,979 miles per hour. Earth orbits the sun once every 365 days at about 67,000 miles per hour.
Many variables must be accounted for when calculating a flight path and time to travel between Mars and the Earth.
- How fast is the spacecraft traveling?
- When will the spacecraft be launched?
- Is the spacecraft stopping at Mars or traveling further into space?
- Will the spacecraft land on Mars or orbit Mars but not send a lander down?
- Is this a one-way ticket, or will the spacecraft return to Earth?
- Will the payload include humans?
- What’s the budget?
How Far Away is Mars from Earth?
Earth and Mars have slightly different orbits around the Sun. Mar’s orbit around the Sun (0.0934 eccentricity) is somewhat more elongated than Earth’s (0.0167) more circular orbit. The differing eccentricity values impact the distance between the two planets. Gravitational effects from the Sun and Jupiter impact Mars, and Earth only feels the gravity of the Sun, Venus, and Jupiter.
Perigee
A perigee is the distance when the planet is closest to the Sun. Mars reaches its perigee point roughly around the same time it passes Earth in its orbit of the Sun. The Sun and Earth align in a straight line with Mars when Mars is in its perigee position.
In 2003, the closest perigee on record occurred when Mars was about 34.65 million miles away from Earth. The next perigee will happen on January 12, 2025, when Mars is only 59,703,892 miles from Earth. Remember to mark your calendar!
Apogee
The slight elliptical path of Mars creates a dramatically different apogee than perigee distances. An apogee is when the planet is at its maximum distance from the Sun. The apogee of Mars is approximately 250 million miles. The distance between its perigee and apogee, about 215 million miles, is the largest in our solar system.
When Should the Launch Occur?
A spacecraft is launched to maximize the shortest travel distance between Earth and Mars. The shortest trip (perigee) requires the fewest resources. Traveling from Earth to Mars during the perigee takes about nine months. Traveling from Earth to Mars during the apogee would take roughly 64 months.
Determining a launch date is vital, but the speed at which a spacecraft travels is also essential. Let’s look at how long it took for previous spacecraft to reach Mars orbit.
| Mission Type and Country | Name and Year | Days |
|---|---|---|
| Flyby (U.S.) | Mariner 4 (1964) | 228 |
| Flyby (U.S.) | Mariner 6 (1969) | 156 |
| Orbiter (Russia) | Mars 5 (1973) | 202 |
| Lander/Rover (U.S.) | Pathfinder (1996) | 213 |
| Orbiter (India) | Mars Orbiter Mission (2013) | 312 |
| Orbiter (UAE) | Hope Orbiter (2020) | 205 |
| Orbiter/Rover (China) | Tianwen-1 (2020) | 202 |
If we exclude the high and low values (156 and 312 days), the average time to reach Mars from Earth is about 200 days. NASA is projecting that a crewed expedition to Mars would take roughly six to seven months (one way), so the past spacecraft travel times line up with the future travel projections.
The greatest distance humankind has traveled into space is to the moon. The moon is roughly 240,000 miles away, and Mars is about 140 million miles from Earth. A moon trip might take a week, but a Mars trip will take significantly longer.
Scientists are trying to find different spacecraft designs to improve the spacecraft thrust and decrease the travel time to Mars.
How Fast is the Spacecraft Traveling?
To escape the Earth’s gravity, a spacecraft must reach a speed of 25,200 mph. Once the spacecraft is in space, the speed answer is trickier.
To increase the thrust of the spacecraft, more fuel is required. To carry more fuel, the spacecraft must be bigger and heavier. A bigger and heavier spacecraft requires more fuel.
Rocket propulsion engineers must navigate the complex landscape of balancing the wish for increased speed with the practical aspect of the spacecraft’s weight. The spacecraft’s speed isn’t always the same as it travels from the Earth to Mars. As the spacecraft approaches the Sun, the rate will increase as the Sun’s gravity pulls on the spacecraft. The opposite occurs when the spacecraft flies away from the Sun.
The spacecraft must slow down to enter orbit as it approaches Mars. It can slow down by braking through firing rockets, which require additional fuel. Entering the Martian atmosphere will also slow down the spacecraft. Atmospheric breaking requires additional heat shields (friction creates heat), additional heat shields add more weight, and more weight requires more fuel.
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Speed It Up!
Time is money; additional time in space equals greater risk to the crew and spacecraft. Several key projects focus on creating a spacecraft capable of traveling to Mars faster than our present technology allows.
Conventional Rocket
In a conventional rocket’s engine, fuel and oxygen are mixed inside a combustion chamber and ignited. The gas expands through the engine nozzle and creates thrust. The spacecraft must bring oxygen along in tanks to use during combustion. The more tanks you add, the heavier the spacecraft becomes.
Nuclear Propulsion
Conventional propulsion launches the spacecraft from Earth. A nuclear-based propulsion system will engage after the spaceship is safe from Earth. Nuclear propulsion has two to three times the thrust of conventional chemical spaceship thrusters. Higher levels of rocket thrusting performance will allow the spaceship to travel faster and with less fuel than a conventional combustion-fueled spaceship.
A nuclear fission-based reactor causes a chain reaction of neutrons colliding with uranium atoms. The collision creates more neutrons and large quantities of heat. Liquid hydrogen is pumped through the core of the reactor to cool it. Thrust is created through heated hydrogen, expanding quickly and rapidly, expelling out of the thruster at high speeds.
A challenge to overcome is the storage and heating of the helium used in the fusion process. Helium is stored around -420°F and heated up to +4,400°F during the reactor cooling.
Ion Propulsion
The propulsion with the highest exhaust velocity and specific impulse is ion propulsion.
| Propulsion Type | Exhaust Velocity (km/s) | Specific Impulse (s) |
|---|---|---|
| Conventional | 3 | 250 |
| Nuclear | 8 | 887 |
| Ion | 40 | 4,077.5 |
Exhaust velocity is the rate at which exhaust gases leave the spacecraft’s engine nozzle. Specific impulse measures the efficiency of an engine’s thrust output.
An ion propulsion rocket gradually increases a spaceship’s speed but isn’t ideal for sudden events, like launching or dropping into a planet orbit. Most of the conversation around ion propulsion focuses on exploration outside our solar system, where the distances between objects become much more vast. An ion propulsion system would be capable of increasing its thrust almost indefinitely. It’s a good choice for interstellar travel but not so good (yet) for intra-solar system travel.
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Lockheed Martin
NASA is teaming up with Lockheed Martin to shorten the flight time to Mars from seven months to 45 days. NASA has tasked Lockheed Martin with designing, generating, and testing a new spacecraft propulsion system. The new spacecraft will use nuclear fusion to create power for a nuclear propulsion rocket engine.
Starship
We’d be remiss not to mention Elon Musk’s Mars ambitions. After Earth launch, Starship will perform a low Earth orbit refuel from a sister Starship. After refueling, Starship will travel to Mars and land, then launch and return to Earth. Musk has shared various Mars landing and flight predictions over the years.
Currently, Starship is awaiting FAA approval before launching again. On April 20, 2023, Starship launched successfully. The spacecraft couldn’t correctly detach from the booster rocket due to leaking fuel, causing fires that terminated the primary flight computer. The spacecraft self-destructed 24 miles above the Earth. The launch rockets were so intense that the launch pad partially melted. SpaceX reported that Starship launch engines blasted a hole measuring forty feet deep during launch.
In September 2023, the FAA released a report that the incident investigation was closed. Starship must incorporate the corrective actions and apply for a modified launch license before it launches another Starship.
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What’s the Fastest Known Time to Get to Mars?
Assuming that we’re not living in a Star Trek world, how long does it take to get to Mars? Let’s look at a few different travel plans to reach Mars orbit.
Perseverance
Unlike other hypothetical travel times, the Perseverance time is an actual flight time that reflects today’s technology. The Perseverance Mars rover took about seven months to reach Mars.
The rover has been exploring Mars and searching for signs of life since February 21, 2021. A mini-helicopter named Ingenuity is tucked into the rover’s undercarriage. Ingenuity is performing separate data collections and experiments from the Perseverance rover.
The Dragonfly is a quad-copter the size of a small car. The Dragonfly is a promising instrument to explore Saturn’s moon, Titan, slated for launch in 2027. Dragonfly movement algorithms are updated based on Ingenuity’s flight data.
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Parker Solar Probe
The Parker solar probe is the best bet option to fly in the most direct path possible. The Parker solar probe, traveling at approximately 364,660 mph (586,800 kph), will deliver you to Mars orbit in around sixteen days.
Don’t forget Mars is in motion, so you might need to build a little wiggle room to account for the planet moving after your launch.
Toyota Prius
You can’t go anywhere without seeing a Toyota Prius, so why wouldn’t we see one in space? Assuming you’ll be steady on the gas and stick with 60 mph, you’ll reach Mars in about 266 years. You better pack a snack.
Five years ago, Elon Musk sent a Tesla into an orbit around the Sun. Best-case estimates place the Tesla somewhere near Mars in 2020. Today, the Telsa is on the opposite side of the Sun from the Earth. Scientists guess that it will be close to Mars again in 2035.
It was a great publicity stunt, but no one cares about it enough to track it as it travels through space.
Light
Light travels through space at roughly 186,411 mph. If you travel at the speed of light, you can travel from Earth to Mars in about three minutes. Traveling to Mars would be quicker than brewing a cup of coffee.
The Count Down to Launch Has Begun
A current best-case scenario about how long it takes to get to Mars is based on when the Earth and Mars are roughly 60 million miles apart. An estimate of five to seven months of one-way travel time is reasonable.
Since the Earth and Mars are in constant motion, the distance between the planets changes every second. Once every twenty-six months, the planets are at their closest positions to each other. Space agencies (like NASA or the ESA) must accurately account for the changing distances to schedule spacecraft launches.
Rocket Scientists are working to breathe new life into nuclear technologies that have existed for over fifty years. Including nuclear reactors in spacecraft can potentially exponentially reduce how long it takes to get to Mars.
The image featured at the top of this post is ©Paopano/Shutterstock.com.
