Let’s talk about what it would be like to spend a day on Phobos (one of Mars’ moons).

Unfortunately, you will need to save a bit of vacation time before you can spend a day on Phobos. With current technology, it will take about 8 months to get there, and that’s not including the return trip. But maybe you have a super awesome boss who won’t mind if you take a year and a half off of work.

Let’s hope so.

Because Phobos is a loyal little moon and it definitely deserves a visit. Of all the moons in the solar system, none orbits closer to its planet. Just 3,700 miles (6,000km) from the Martian surface, Phobos is only a little bit farther from Mars than New York is from Ireland. And the escape velocity for Phobos is only 25mph (41 km/h). So you could spend part of your day making a ramp, and then use it to drive your car off the moon and take a short trip to Mars. Honestly, you could.

But you probably shouldn’t, because you would die. Cars don’t have proper landing gear.

And then there’s the motion sickness. Since it is so close to Mars, Phobos has to travel extremely fast to maintain its low orbit. By the time the Earth has completed one rotation, Phobos has whipped around Mars three times. So if you spend a day on Phobos, you could see Mars rise and set three times....that is, you could if the moon wasn't tidally locked to its host planet. But the moon is rather smallish, so you could just keep walking around it to make Mars rise and set.

And it really is rather smallish

Phobos is only 16 by 13 by 11 miles in diameter (27/22/18km). To help you understand just how small that is I have compiled a list of things that are larger than Phobos: Rhode Island, Rwanda, The Grand Canyon, The Marianas Trench, Santa’s tummy (okay, the last one I made up). Since it’s so small, there really isn’t all that much to see on Phobos.


Its mass is just 1.0659 x 1016 kg. Don’t know what that means? If you can do a two foot high jump on Earth (.5m), then you can jump over a half mile (1.4 km) straight up on Phobos, and your trip will take about 26 minutes (13 up and 13 down). So you might not be faster than a speeding bullet, or more powerful than a locomotive, but on Phobos you will be able to leap tall buildings in a single bound. And that’s something.

The problem? Poor little Phobos isn’t going to be around much longer.

You know how our moon is getting further and further from Earth (if you didn’t, now you do), Phobos is gradually spiraling in towards Mars. The two are on a collision course. Every century brings Phobos 6 feet (1.8m) closer to Mars. In 50 million years the moon will either crash into the planet or be pulverized into a pretty, pretty ring. 50 million years sounds like a long time, so you may be thinking about putting off this trip. But in cosmic terms it’s barely even a blip. So err on the side of caution and make your travel plans now.

Best of all?

Unlike most of the planets and moons in our solar system, visiting Phobos doesn’t necessarily mean you’ll be visiting the Grim Reaper. Although there is no water to drink or atmosphere to protect you from solar radiation, Mars conveniently blocks Phobos from the Sun’s rays for two thirds of every orbit. So you won’t be turned into human bacon, yay! And you can just bring some bottled water.

And those of you who enjoy a cool mountain breeze will find Phobos simply delightful. High temperatures for Phobos reach 25 degrees Fahrenheit (-4 degrees Celsius) and lows reach a chilly -170F (-112C). Maybe a bit too cool; you should probably bring a coat.

And you’ll feel lively on Phobos!!

Some objects in our solar system are so massive that it would be nearly impossible to get out of bed in the morning. And that hardly makes for an enjoyable vacation. Take the Sun. If a 150 pound person (68kg) were to stand on the Sun—you can't stand on the Sun as it has no surface (obviously) and you would be incinerated long before you got close enough to stand on the Sun, but run with me here people—this person would tip the scales at a little over 4000 pounds (1814.3kg). However, tiny Phobos only has 1/1000th the gravitational pull of Earth, which means that a person who weighs 150 pounds on Earth would weigh a mere two ounces (68g) there.

But I should tell you, the last mission to Phobos didn’t go so swell.

The Russian’s Phobos-Grunt didn’t even make it out of Earth’s orbit. In fact, 20 to 30 fragments of Phobos-Grunt are currently resting somewhere at the bottom of the Pacific Ocean…we think. We’re not really sure. But you probably don’t have to worry about any travel mishaps because the NASA mission to Mars is going swimmingly, which brings us to…

The plus!!! The big, exciting plus!!!

The Mars Science Laboratory (MSL) has recently announced an “Earth-Shaking” discovery on Mars. Haven’t heard the news? Check here: http://news.discovery.com/space/mars-mystery-what-has-curiosity-discovered-121120.html

Maybe it’s life! Maybe Mars has life!! Maybe Phobos has life!!! Maybe it has flying unicorns!!!!

(probably not.)




Sources and Further Readings:


Carl Sagan's Cosmic Connection: An Extraterrestrial Perspective. Cambridge : Cambridge University Press, 2000.








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