Planet Pailly

This month, as part of the 2015 Mission to the Solar System, we’ve been visiting the planet Mars. How could we not spend at least one post talking about Mars’s two moons, Phobos and Deimos?

Someday, humanity will colonize Mars. When we do, these two moons should provide some interesting stargazing opportunities.

Phobos, as observed from the surface of Mars, may not be quite as large as Earth’s Moon as observed from the surface of Earth, but it’s still a large, easy to spot object. Now imagine watching this large object racing through the sky, rising and setting two or sometimes three times per day (I mean per sol). That’s what Martian colonists will get to see.

Meanwhile, Deimos only rises and sets once per day. That seems a bit more normal, expect for Martian stargazers, Phobos and Deimos will seem to be moving in opposite directions. This is because Deimos lags slightly behind Mars’s rotation, making it appear to be moving backwards compared to Phobos.

Deimos is also slowly drifting away from Mars.

Eventually, Deimos will break free of Mars’s gravity and escape into a new orbit around the Sun.

Phobos, on the other hand, is getting gradually closer to Mars. At some point, tens of millions of years from now, it’s expected to crash into the planet’s surface.

Lastly, both Phobos and Deimos look suspiciously like asteroids. On that note, our month-long tour of Mars comes to an end. The 2015 Mission to the Solar System will continue in July as we enter the asteroid belt (a region that went into an uproar after two of its asteroids mysteriously went missing).

P.S.: There’s another possible fate for Phobos: rather than crashing to the surface of Mars, it might be shredded by tidal forces. If so, the fragments could end up forming a faint planetary ring around Mars, which would be pretty cool.

Before you plan your next trip to Mars, be sure to check the weather forecast. Martian sandstorms can be rather extreme, in some cases spreading over the whole planet, reducing visibility to almost zero.

Totally legit Hubble images of Mars before and during a global sandstorm.

However, the dangers associated with these sandstorms are sometimes exaggerated.

Attempting to land during a Martian dust storm can be hazardous. In 1971, a global storm happened to occur just as a pair of Soviet landers arrived. Let’s just say things didn’t go well.

But if you’re already on the surface of Mars when a dust storm begins, as quite a number of NASA landers and rovers have been, you really don’t have much to worry about. Yes, there are 60 mile per hour winds, but atmospheric pressure on Mars is less than 1% that on Earth. So while these storms have wind speeds comparable to Earth hurricanes, they are nowhere near hurricane force.

Dust storm season takes place during summer in the planet’s southern hemisphere. Martian southern summer happens to coincide with Mars’s closest approach to the Sun, making it warmer than northern summer. This extra heat releases extra volatiles (mostly CO₂ gas) from the south polar ice cap. This agitates the atmosphere, which in turn whips up some spectacular sandstorms.

So if you’re planning a vacation on Mars, try to avoid landing during southern summer. Since you can only schedule your trip for times when Earth and Mars line up properly, this greatly reduces the number of possible launch windows. But trust me: crash landing on Mars during a sandstorm could really spoil your trip.

Links

What are the Risks of Dust and Sand on Mars? from Mars One.

Spacecraft Monitoring Martian Dust Storm from NASA.

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Today’s post is part of Mars month for the 2015 Mission to the Solar System. Click here to learn more about this series.

So you’re planning a vacation on Mars and want to know when is the best time to go. This may seem counterintuitive, but you might want to schedule your launch for when Earth and Mars are on opposite sides of the Sun. This is known as a conjunction-class mission.

Keep in mind that any journey to Mars will take months. During that time, the planets will move around in their orbits, with Earth moving slightly faster than Mars (66,000 m.p.h. versus 54,000 m.p.h.). Earth’s orbit is also smaller than Mars’s, so if the two planets were racing, Earth would be lapping Mars on the racetrack quite frequently.

In conjunction-class missions, Mars may be on the far side of the Sun at launch, but your spacecraft takes full advantage of Earth’s greater momentum and soon catches up. This gives conjunction-class missions certain benefits over the alternative opposition-class missions (which we covered on Monday):

• You need a lot less fuel.
• You get to spend a lot more time on Mars—almost two years! For this reason, conjunction-class missions are also known as long-stay missions.
• Unlike in opposition-class missions, you don’t have to cut through the Inner Solar System on your way home to Earth. This makes conjunction-class missions far less complicated and, at least on the return leg of your voyage, safer.

The only real downside is that your journey to and from Mars will take longer. Although spending more time in space does raise a few health and safety concerns, almost every serious plan for the long-term exploration and colonization of Mars seems to favor conjunction-class missions.

Personally, if I were going on a Martian vacation, I’d choose a conjunction-class flight. The lower fuel requirements mean lower ticket prices. Having more time to go sightseeing on Mars is an added bonus. I just have to convince my day job to let me take a two-year vacation.

So how would travel to Mars? Would you prefer the faster, marginally safer opposition-class flight or the longer, less expensive conjunction-class?

P.S.: If you want to learn more about opposition- and conjunction-class missions to Mars or about humanity’s future on Mars in general, I highly recommend The Case for Mars by Robert Zubrin. The book lays out the most believable and compelling plan for the exploration and eventual colonization of Mars I’ve ever seen.

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Today’s post is part of Mars month for the 2015 Mission to the Solar System.

Planning a vacation to Mars? Wondering when is the best time to go? Here’s one option:

Once every 26 months, while Earth and Mars are on the same side of the Sun, the two planets line up just right for a launch. Although Mars is not necessarily in opposition at this time, it’s close to it, so your flight is known as an opposition-class mission.

Your journey will take several months (exact time estimates vary depending on spaceship design and other mission parameters). Keep in mind that during your voyage, both Earth and Mars continue moving through their orbits. In fact, Earth will rapidly move ahead of you, so you’ll only be able to stay on the surface of Mars for a short time before you have to come home. For this reason, opposition-class missions are also known as short-stay missions.

On your return flight, Earth is still moving away from you, so to catch up, your spacecraft will have to cut through the inner Solar System, swinging in a wide arc around the Sun, possibly utilizing a difficult and dangerous gravity assist maneuver at Venus.

Opposition-class missions aren’t the only way to get to Mars, but they do offer some advantages:

• You get to Mars faster.
• You get home faster.
• Some argue the trip is safer. Since you spend less time in space, you should suffer less radiation exposure and less bone-loss due to zero-gravity.

However, there are some noteworthy disadvantages too:

• Opposition-class missions require a whole lot of fuel, significantly more than alternative conjunction-class missions.
• You only get to spend a few weeks on Mars. Depending again on mission parameters, you might get a little over a month.
• About that safety thing… some argue opposition-class missions aren’t so safe after all because more things can go wrong, especially during your return flight.

I’d guess that the first manned mission to Mars may well be opposition-class. I think humanity might prefer to dip its toe in the water, so to speak, with a short-stay mission.

Subsequent missions (and vacations) will probably be conjunction-class, long-stay missions, for reasons that we’ll examine on Wednesday.

P.S.: It’s difficult to find reliable information about opposition- and conjunction-class missions online, so for further research, I recommend The Case for Mars by Robert Zubrin. Zubrin, a former aerospace engineer for Lockheed Martin and founder of the Mars Society, lays out one of the most believable and compelling plans for Mars exploration and eventual colonization that I’ve ever seen. If you have any interest in going to Mars (or writing science fiction about Martian colonists), you should read Zubrin’s book.

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Today’s post is part of Mars month for the 2015 Mission to the Solar System.