Human space travel to planet Mars will require huge payloads of material, merchandise, supplies, etc., that are larger than the unmanned spacecraft itself. The fact remains that nobody knows how to prepare for such an adventure because nobody has ever done it before on such a large scale, making it extremely dangerous for everyone concerned at this time. This danger will involve everyone concerned-human travelers, astronauts, engineers, or any space professional en route. Preparing for a robotic spacecraft to the planet Mars or even to the Moon involves unforeseen risks.
Many things are still unknown about the planet Mars, making what is required for human survival a big question. And fuel to get so far with such a payload may not make it back unless resources are supplied on the planet for a return trip back. The Apollo lunar lander was about 10 metric tons while the human mission to Mars that is planning on staying for a year will weigh up to six times that. The fuel involved for that one trip up would be astronomical.
Traveling to Mars cannot occur at the spur of the moment. The term "launch window" is a period that all astronomers look for when launching a spacecraft from Earth to another planet, a period when the time is favorable to saving energy, allowing for the reduction of a spacecraft's total payload. To obtain this, the space engineers have taken advantage of the Earth's solar orbit and daily rotation by using the rocket trajectory, bringing the spacecraft to the planet goal by the time the mission is completed. To achieve this, they need to know where the targeted planet will be with the spacecraft-such as the Martian and Earth orbit. Space professional will look seriously at the 60% of failed missions to Mars, and how they would affect a future human mission to the red planet.
Landing payloads on Mars, especially one that is exceptionally heavy, is impossible with our current capabilities. The Martian atmosphere is too much to land the same heavy vehicles that we land on the moon, while using propulsive technology. At that same time, to land on Mars using the same technology as we do on Earth is also impossible, as the atmosphere is too little. Somewhere in the middle is what we need to develop before we can arrive on Mars. Not only are human missions presently impossible, but to use a large robot missions that would require the landing of payloads of one metric ton or more cannot be accomplished either. Until the drawing tables bring up something else, we seem to be a dead end for safe human space travel to Mars.
"It turns out that most people aren't aware of this problem and very few have worried about the details of how you get something very heavy safely to the surface of Mars," says Rob Manning the Chief Engineer for the Mars Exploration Directorate and presently the only person who has led teams to land three robotic spacecraft successfully on the surface of Mars.