Crocco's Multiplanetary Trajectory, sometimes named Crocco's Mission and Crocco's "Grand Tour", is a mathematical description of an hypothetical Earth-Mars-Venus-Earth-Research Mission, which was first proposed in 1956 by the Aeronautics and Space Pioneer G. A. Crocco during the VII. International Astronautical Congress in Rome. Crocco_Mission

History

With the beginning of spaceflight in the first half of the 20th century, theoretical mathematicians estimated the amount of energy required for interplanetary spaceflight for the first time, the energy requirement being significantly higher than that of any chemical fuel available at that time. It remained questionable if humanity would ever be capable of reaching certain locations in the

Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...

.Richard L. Dowling, Kosmann, William J.; Minovitch, Michael A.; Ridenoure, Rex W: ''The origin of gravity-propelled interplanetary space travel'' 41st Congress of the International Astronautical Federation, Dresden 1990, S. 1. Even though

Walter Hohmann Walter Hohmann (; ; 18 March 1880 – 11 March 1945) was a German engineer who made an important contribution to the understanding of orbital dynamics. In a book published in 1925, Hohmann demonstrated a fuel-efficient path to move a spacecraft ...

had already calculated the most energy-efficient trajectory between two similar circular orbits (the

Hohmann transfer orbit In astronautics, the Hohmann transfer orbit () is an orbital maneuver used to transfer a spacecraft between two orbits of different altitudes around a central body. Examples would be used for travel between low Earth orbit and the Moon, or ano ...

) at the beginning of the century,Richard L. Dowling, Kosmann, William J.; Minovitch, Michael A.; Ridenoure, Rex W: ''The origin of gravity-propelled interplanetary space travel'' 41st Congress of the International Astronautical Federation, Dresden 1990, S. 2-3. an Earth-Mars-Earth round trip utilizing this flight path would have made it a necessity to remain on the surface of Mars for a duration of 425 days, waiting for the planets to align and the next launch window to open, in addition to 259 days for both the journey to Mars and the return to Earth. For this reason,

Gaetano Crocco Gaetano Arturo Crocco (26 October 1877 – 19 January 1968) was an Italian scientist and aeronautics pioneer, the founder of the Italian Rocket Society, and went on to become Italy's leading space scientist. He was born in Naples. In 1927, Croc ...

developed the concept of a Nonstop-Round-Trip to

Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...

, which would have had a far lower energy requirement, as the rocket engines of the craft would only have to accelerate it in a single maneuver to attain the necessary velocity to reach

. During the passing of the spacecraft, onboard crew would have performed analysis of the martian surface. Even this trajectory would have amounted to a flight time of a little over one year, if the spacecraft were not accelerated in another

orbital maneuver In spaceflight, an orbital maneuver (otherwise known as a burn) is the use of propulsion systems to change the orbit of a spacecraft. For spacecraft far from Earth (for example those in orbits around the Sun) an orbital maneuver is called a ' ...

.Gaetano Arturo Crocco: ''One-Year Exploration-Trip Earth-Mars-Venus-Earth.'' Jet Propulsion Laboratory 1961, S. 228-229.

Properties

Crocco searched for an

orbit In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a p ...

with the following properties: *Crosses the orbit of the Earth *Crosses the orbit of Mars *

Orbital period The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting planets ...

of one year With proper selection of a certain

launch window In the context of spaceflight, launch period is the collection of days and launch window is the time period on a given day during which a particular rocket must be launched in order to reach its intended target. If the rocket is not launched wit ...

, this would also have allowed the spacecraft to return one year after departure. By applying slight modifications to the trajectory it would have been possible to pass by Venus in the same mission as well. Crocco realized that the flight trajectory may be disrupted by the gravitational fields of Mars and Venus, delaying or ultimately preventing return to Earth. He solved this problem by directing the flight path through the gravitational fields of Venus and Mars in such a way that their attraction would cancel each other out.Richard L. Dowling, Kosmann, William J.; Minovitch, Michael A.; Ridenoure, Rex W: ''The origin of gravity-propelled interplanetary space travel'' 41st Congress of the International Astronautical Federation, Dresden 1990, S. 12-13. The Mission Profile presented in 1956 consisted of a 154-day travel from Earth to Mars, followed by a 113-day travel to Venus including passing by the planet and using the gravitational attraction for a course correction, followed by the 98-day return to Earth.Gaetano Arturo Crocco: ''One-Year Exploration-Trip Earth-Mars-Venus-Earth.'' Jet Propulsion Laboratory 1961, S. 233. Crocco proposed the first Mission to be launched in June 1971.

Difference between Crocco's Mission and Gravity Assists

Crocco was well aware of the planet's gravitational effects, but his mission profile is neither using them to accelerate nor decelerate, instead limiting itself to utilizing them for trajectory stabilizations.Gaetano Arturo Crocco: ''One-Year Exploration-Trip Earth-Mars-Venus-Earth.'' Jet Propulsion Laboratory 1961, S. 239. Still, it is mistakenly widely assumed that G. A. Crocco would have been the inventor of the gravity assist, which was first presented in 1961 by the American mathematician Michael Minovitch as a methodMichael A. Minovitch: ''A method for determining interplanetary free-fall reconnaissance trajectories'' Jet Propulsion Laboratory, 1961. to allow for the exploration of the

outer planets The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...

which had been deemed nearly impossible beforehand.

Pioneer 10 ''Pioneer 10'' (originally designated Pioneer F) is an American space probe, launched in 1972 and weighing , that completed the first mission to the planet Jupiter. Thereafter, ''Pioneer 10'' became the first of five artificial objects to ach ...

, 11 and the Voyager probes would make use of this technique in the 1970s.Richard L. Dowling, Kosmann, William J.; Minovitch, Michael A.; Ridenoure, Rex W: ''The origin of gravity-propelled interplanetary space travel'' 41st Congress of the International Astronautical Federation, Dresden 1990.

Literature

* Michael A. Minovitch ''A method for determining interplanetary free-fall reconnaissance trajectories'' Jet Propulsion Laboratory, 23. August 1961

Archived 20 März 2019) * Gaetano A. Crocco ''One-Year Exploration-Trip Earth-Mars-Venus-Earth'' 7th Congress of the International Astronautical Federation, Rome, September 1956

Archived 15 March 2016) * Richard L. Dowling, Kosmann, William J.; Minovitch, Michael A.; Ridenoure, Rex W: ''The origin of gravity-propelled interplanetary space travel'' 41st Congress of the International Astronautical Federation, Dresden, 6-12 Oktober 1990

Archived 17 April 2021)

References

{{Reflist Astrophysics Human missions to Mars Human missions to Venus Missions to Mars Missions to Venus