A Manned mission to Mars is a first step in the colonization process. There are two types of mission, a one way mission, with planned death or the start of a colony, and a Manned two-way mission. A one way mission is cheaper, but a two way mission will likely be a first step to developing a colony on Mars. As of 2019, exploration of Mars has been limited to unmanned robotic missions. Despite this, there is strong interest in the human exploration and settlement of Mars by a variety of government agencies, private companies, and countries. A few of the better known plans are listed below:
The Mars Project
In the late 1940s, Dr. Wernher von Braun was the first person to seriously study the possibility of sending humanity to Mars. The results were published in a book titled The Mars Project (German language version titled Das Marsprojekt). Dr. von Braun’s plan involved constructing several large spacecraft in earth orbit that would ferry 70 astronauts to the Martian surface. Components of the Mars bound ships would be sent to earth orbit using multiple launches of a fully reusable three stage rocket launched from Johnston Island in the Pacific. The Mars spacecraft would use energy efficient Hohmann transfers for the transit between Earth and Mars. While The Mars Project was ahead of its time, it was never pursued, and advances in space exploration eventually proved von Braun’s plan to be unworkable. Examples of this include lack of knowledge about cosmic radiation and the density of the Martian atmosphere.
Post-Apollo Mars Plans
Following the 1969 moon landing of Apollo 11, many suggested manned trips to Mars in the 1980s as the next logical step in space exploration. Eventually, however, these plans were scrapped, and NASA was only provided funding for the Space Shuttle.
Space Exploration Initiative
On July 20, 1989 (the 20th anniversary of Apollo 11), the elder President Bush proposed a program known as the Space Exploration Initiative. SEI proposed the assembly of Space Station Freedom (later redesigned as the International Space Station), a return to the Moon, and journeys to Mars. SEI was quickly met with hostility and was defeated in Congress due to the estimated $500 million price tag. Manned Mars missions once again were abandoned by NASA, and the International Space Station was built instead.
During the time of SEI, engineers Robert Zubrin and David Baker of Martin Marietta (later Lockheed Martin) designed a mission architecture known as Mars Direct. This plan was developed as an alternate to the troubled SEI program. Both engineers felt Mars missions under SEI suffered from many serious problems. SEI called for a complicated mission plan involving an assortment of technologies that didn’t exist at the time. This was a contributing factor in the huge expense. Furthermore, missions were reduced to little more than “flag and footprints” exercises as astronauts would spend a short amount of time actually exploring the Martian surface. Zubrin and Baker’s Mars Direct was designed as a relatively cheap and simple way to explore Mars using current rocket technology of the time.
Mars Direct called for designing a new heavy lift rocket called the Ares that was derived from the Space Shuttle. The Ares booster had approximately the same payload capability to low earth orbit as the Apollo era Saturn V and could accomplish a four person Mars flight in just two launches. The first Ares booster would send an unmanned vehicle to Mars known as an Earth Return Vehicle or ERV. Upon arrival on Mars, the ERV would use a process known as a Sabatier reaction to produce fuel for the trip back to Earth. This would be done by combining liquid hydrogen in the ERV’s tanks with carbon dioxide in the Martian atmosphere to produce liquid methane and oxygen.
Only after fuel production is complete would astronauts be launched on a second Ares booster. The crew is launch in a module called the hab, which serves as their living quarters. After a six month trip, the four astronauts land their hab near the earlier launched ERV. Following a year and a half exploration of Mars, the crew board their ERV and head home.
Mars Direct was initially liked by many within NASA. However, the space agency had some concerns and wanted a six person crew. This resulted in a revised version of Zubrin and Baker’s plan that was christened Mars Semi Direct. Under the new plan, a third Ares booster would be used to send an unmanned Mars Ascent Vehicle or MAV to the surface. The crew would blast off from Mars in this vehicle and rendezvous with the ERV, which now would be left in Mars orbit.
The same group that gave SEI a $500 million price tag estimated the cost of Mars Direct at $55 billion over a period of ten years. This could have been done using NASA current budget at the time. However, Zubrin and Baker’s Mars mission was never flown. Nonetheless, Zubrin continued to advocate for humans to Mars. In 1998, he founded the Mars Society.
Journey to Mars
In 2010, Mars once again was suggested as a target for NASA astronauts. Since 2004, NASA had been working on a return to the Moon program known as Constellation, but this program was never fully funded and was canceled. The new Mars effort was dubbed the Journey to Mars. This program called for a new rocket called the Space Launch System (SLS) and retained the Orion spacecraft from the defunct Constellation program. By 2017, however, focus shifted back to manned lunar exploration in the form of the Artemis program.
Mars One, a Dutch proposal for a manned Mars mission, existed from 2011-2019. The plan was notable as it proposed one-way trips to Mars. Proponents of one-way missions argue that the long term focus of Martian exploration should be permanent human colonization, and human settlers therefore should spent the rest of their lives on the Red Planet. One-way journeys to Mars would also be cheaper than a round trip due to the fact that no return propellant was needed for an Earth return. Mars One pegged the cost to send four astronauts to Mars at $6 billion. Options to finance Mars exploration included a reality TV show and a crowdfunding campaign. By early 2019,however, Mars One declared bankruptcy.
Since being founded in 2002, the private spaceflight company SpaceX has shown a very strong interest in going to Mars. In 2016, SpaceX revealed it was working on a massive rocket called the Interplanetary Transport System (ITS) capable of sending a 550 metric ton payload to low Earth Orbit. By the next year, SpaceX released a scaled down design called the Big Falcon Rocket (BFR) with a 150 metric ton payload capability.
More design changes followed. By 2019, the vehicle’s name was changed again. It had a first stage named Super Heavy and a second stage called Starship. Both stages are completely reusable and fabricated out of stainless steel. The Super Heavy will be 223 feet in height and have a diameter of 30 feet. Propulsion will be provided by up to 37 Raptor rocket engines, which burn a mixture of liquid methane and oxygen. This will provide approximately twice the takeoff thrust of the Saturn V’s first stage booster. Super Heavy will also conduct landings using the supersonic retropropulsion techniques pioneered by SpaceX’s Falcon 9 rocket. For this purpose, Super Heavy will be outfitted with six landing legs.
The Starship will be 160 feet tall and 30 feet in diameter. Propulsion for the system consists of three Raptor engines for atmospheric flight; three other vacuum optimized Raptors will be used for propulsion in space. After being sent into low earth orbit, a Starship will be refueled by a tanker version of the same spacecraft. The Starship then will be capable of sending up to 100 future Martians to the Red Planet. Long term, it is planned to use this vehicle to construct a large human colony on Mars. The first manned mission to Mars using Starship is targeted for 2024.
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