How long would a trip to Mars take?Contrary to the 'point and shoot' idea, an actual trip to mars looks very round a bout as the figure above shows for a typical 'minimum cost' trajectory. This, by the way, is called a Hoeman Transfer Orbit, and is the main stay of interplanetary space travel. t depends on the details of the orbit you take between the !arth and "ars. The typical time during "ars's closest approach to the !arth every #.$ years is about %$& days. 'gain, the details depend on the rocket velocity and the closeness of the planets, but %$& days is the numberhear most often give or take #& days. (ome high)speed transfer orbits could make the trip in as little as #*& days.+or a more detailed discussion, see the course notes for ,hysics $ by ,rof. Craig ,atten at -C. (an .iego.will capture the relevant comments below/How long does it take0 t takes the !arth one year to orbit the (un and it takes "ars about #.1 years 2 say % years for easy calculation 3 to orbit the (un. The elliptical orbit which carries you from !arth to "ars is longer than !arth's orbit, but shorter than "ars' orbit. 'ccordingly, we can estimate the time it would take to complete this orbit by averaging the lengths of !arth's orbit and "ars' orbit. Therefore, it would take about one and a half years to complete the elliptical orbit above 2 solid and dashed parts4 3. (ince it would be nice to spend some time at "ars, we are only interested in the one way trip 2 solid line 3 which is half of theorbit, and would take half the time of the full orbit, or about nine months. (o it takes nine months to get to "ars. t is possible to get to "ars in less time, but this would re5uire you to burn your rocket engines longer, using more fuel. 6ith current rocket technology, this isn't really feasible.n the nine months it takes to get to "ars, "ars moves a considerable distance around in its orbit, about *78 of the way around the (un. 9ou have to plan ahead to make sure that by the time you reach the distance of "ar's orbit, that "ars is where you need it to be4 ,ractically, this means that you can only begin your trip when !arth and "ars are properlylined up. This only happens every %$ months. That is there is only one launch window every %$ months.'fter spending 1 months on the way to "ars, you will probably want to spend some time there. n fact, you "-(T spend some time at "ars4 f you were to continue on your orbit around the (un, then when you got back to where you started, !arth would no longer be where you left it4n order to get out of your elliptical orbit around the (un, and into "ars orbit, you will again need to burn some fuel. f you want to e:plore the surface of "ars, you will also need fuel to get your lander off the surface of "ars. On the first trip to "ars, it is necessary to bring all of this fuel with you to "ars. 2 "aybe someday we could manufacture rocketfuel on "ars 3. n fact, you can only land a small part of the ship on "ars, because landing everything on the surface and lifting it off again would re5uire enormous amounts of fuel. Therefore, you will probably leave partof the ship, including all the supplies for the trip home, orbiting "ars, while part of the crew goes to e:plore the surface.;ust like you have to wait for !arth and "ars to be in the proper postion before you head to "ars, you also have to make sure that they are in the proper position before you head home. That means you will have to spend *)< months at "ars before you can begin your return trip. 'll in all, your trip to "ars would take about %# months/ 1 months to get there, * months there, and 1 months to get back. 6ith our current rocket technology, there is no way around this. The long duration of trip has several implications.+irst, you have to bring enough food, water, clothes, and medical supplies for the crew in addition to all the scientific instruments you will want to take. 9ou also have to bring all that fuel4 n addition, if you are in space for nine months, you will need a lot of shielding to protect you from the radiation of the (un. 6ater, and cement make good shielding but they are very heavy. 'll together, it is estimated that for a crew of si:, you would need to * million pounds of supplies4 The (huttle can lift about =&,&&& pounds into space, so it would take $& shuttle launches to get all your supplies into space. n the history of the (huttle, there have only been about 1& launches, and there are less than ten launches per year... (o with the shuttle, it would take si: years just to get the supplies into space. +or this reason, you would probably need to develop a launch system that could lift more than =&,&&& pounds into space. !ven with a better launch vehicle, it is unlikely that you could launch the "ars missionall at once. 9ou will have to launch it in several pieces and assemble them in orbit.(econd, you are going to be in space for an e:tended period of time, and there a physiological conse5uences of being weightless for long periods oftime. +or one, your muscles do not need to work as hard. n response to being used less, your muscles begin to shrink or atrophy. >emember, your heart is also a muscle, and pumping blood around your body is easier in theweightless environment of space, so your heart gets weaker as well. On ane:tended space voyage, your muscles might become so weak that it would be difficult for you to stand upright once you return to an environment where you are subject to gravity.;ust like your muscles have to do less work to move you around in space, your bones are not needed as much. The main function of your skeleton is to support the weight of your body. 6hen you are weightless in space, your body reali?es that the bones are not being used as much and they begin to lose calcium, and become more brittle. These are serious effectswhich may impair the ability of the astronauts to carry out e:periments and tasks when they get to "ars, where they will be subjected to gravity again.n order to study these physiological effects of long duration weightlessness, you need to do e:periments on people who have been weightless for e:tended periods of time. Currently the >ussian "ir spacestation is one place where astronauts can stay for e:tended periods of time, and research into these effect is ongoing. @ut since you will need to conduct many more e:periments, and you will also need a place to assemble the mission, it will probably be necessary to construct a larger space station to be used as a staging ground for the mission to "ars.