Mars, the fourth planet from the Sun, is nicknamed "the Red Planet" due to its iron(III) oxide dust-covered surface. Its brightness and distinct features make it easily observable from Earth. As a terrestrial planet, it is the second smallest in our Solar System with a diameter of 6,779 km. A Martian day (sol) lasts 24.5 hours, while a Martian year is 1.88 Earth years. Its two natural satellites, Phobos and Deimos, are small and irregularly shaped.
1909: Campbell and Slipher Repeat Spectroscopic Observations
Campbell and Slipher conducted a repeat study in 1909, utilizing improved instruments, but their spectroscopic observations of Mars yielded the same results as Campbell's 1894 study. These observations failed to detect significant amounts of water vapor or oxygen, further challenging the idea of a habitable Mars.
1909: Antoniadi's Observations Challenge "Canali" on Mars
In 1909, using an 84-centimeter telescope, Antoniadi observed irregular patterns on Mars but couldn't confirm the existence of long, straight "canali." This cast doubt on the prevailing belief in Martian canals, a concept that fueled speculation about life on Mars.
1925: Adams Confirms Lack of Oxygen and Water Vapor on Mars
In 1925, W. S. Adams confirmed the findings of Campbell and Slipher, solidifying the scientific consensus against the idea of Mars having an Earth-like, habitable environment. This marked a significant turning point in understanding the nature of Mars.
1938: C.S. Lewis Publishes "Out of the Silent Planet"
In 1938, C.S. Lewis published his science fiction novel "Out of the Silent Planet", which featured Mars as a setting and contributed to the ongoing fascination with the possibility of life on Mars.
1948: Marvin the Martian Debuts in "Haredevil Hare"
The iconic cartoon character, Marvin the Martian, made his debut in the Warner Brothers Looney Tunes animated short "Haredevil Hare" in 1948. This humorous depiction of an intelligent Martian added to the popular culture surrounding Mars.
November 1964: Mariner 4 Launch
NASA launched Mariner 4 in November 1964, marking the beginning of the first mission to visit Mars. This mission aimed to capture images and gather data about the red planet.
July 1965: Mariner 4 Mars Flyby
In July 1965, Mariner 4 made its closest approach to Mars, becoming the first spacecraft to successfully visit another planet from deep space. The mission provided the first close-up images of Mars and revealed its weak radiation belt.
1965: First Flyby of Mars
In 1965, NASA's Mariner 4 probe conducted the first successful flyby of Mars, marking the beginning of Mars exploration.
1971: First Orbit of Mars
The Soviet Union's Mars 2 probe achieved the first orbit of Mars in 1971, marking a significant step in Mars exploration.
1972: Defining Mars' Prime Meridian
Following detailed imagery of Mars provided by Mariner 9 in 1972, Merton Davies, Harold Masursky, and Gérard de Vaucouleurs selected the small crater Airy-0 in the Sinus Meridiani to define 0.0° longitude, aligning with the prior selection by Mädler and Beer in 1830.
1976: First Landing on Mars
NASA's Viking 1 probe achieved the first successful landing on Mars in 1976, marking a major milestone in the exploration of the planet.
1996: Mars Global Surveyor Mission Launch
NASA launched the Mars Global Surveyor mission in 1996, initiating a comprehensive mapping project of the Martian topography, magnetic field, and surface minerals. This mission provided a detailed understanding of Mars's surface features.
1999: Hypothesis on Plate Tectonics on Mars
A hypothesis published in 1999 suggested that the alternating magnetic bands observed on Mars' crust could indicate plate tectonic activity occurring four billion years ago before the cessation of the planet's dynamo and the disappearance of its global magnetic field.
2001: 2001 Mars Odyssey Mission Launch
The 2001 Mars Odyssey orbiter was launched in 2001, becoming one of the longest-operating spacecraft at Mars. The mission has contributed significantly to mapping and studying the Martian surface and environment.
2003: Mars Close Approach to Earth
Mars had a close approach to Earth (opposition) in 2003, near its perihelion, resulting in a shorter distance between the two planets.
2004: Water-Ice Clouds Photographed
In 2004, the Opportunity rover captured images of water-ice clouds on Mars, providing visual evidence of the presence of water in the planet's atmosphere.
2004: Detection of Jarosite
In 2004, the Opportunity rover detected the mineral jarosite on Mars, providing further evidence of water's past presence on the planet, as jarosite forms only in the presence of acidic water.
October 2005: Re-examination of Paleomagnetism Data
In October 2005, scientists re-examined paleomagnetism data from Mars Global Surveyor, supporting the 1999 hypothesis that alternating magnetic bands on Mars' crust suggest plate tectonic activity approximately four billion years ago, before the planet's magnetic field disappeared.
2006: End of Mars Global Surveyor Mission
The Mars Global Surveyor mission concluded in 2006 after a decade of operation. The mission generated highly detailed maps of Mars, which are publicly accessible online, significantly advancing our knowledge of the planet's surface.
2007: Evidence of Wet Conditions in Mars' Past
In 2007, the Spirit rover found concentrated silica deposits on Mars, suggesting past wet conditions on the planet.
July 2008: Direct Sampling of Water Ice
On July 31, 2008, NASA's Phoenix lander directly sampled water ice in the shallow Martian soil, confirming the presence of water ice on the planet.
December 2011: Discovery of Gypsum on Mars
In December 2011, NASA's Opportunity rover found gypsum on the Martian surface, indicating the presence of water in the planet's past as gypsum forms in the presence of water.
2012: Valles Marineris: A Possible Plate Boundary
In 2012, a study proposed that Valles Marineris, a large canyon on Mars, may be a plate boundary where 150 kilometers of transverse motion has occurred, suggesting the possibility of a two-tectonic plate arrangement on Mars.
March 2013: Evidence of Mineral Hydration
In March 2013, NASA reported findings from the Curiosity rover's instruments, indicating mineral hydration, possibly hydrated calcium sulfate, in several rock samples, suggesting the presence of subsurface water.
2014: Analysis of Martian Meteorite EETA79001
Analysis of the Martian meteorite EETA79001 in 2014 revealed high concentrations of chlorate, perchlorate, and nitrate ions, suggesting their widespread presence on Mars. These compounds, under UV and X-ray radiation, could form reactive oxychlorines, posing challenges for the survival of organic molecules on the surface.
March 2015: Scientists Propose an Ancient Ocean on Mars
In March 2015, scientists suggested that a vast ocean, potentially the size of Earth's Arctic Ocean, might have once covered Mars's low northern plains. This theory stems from the high ratio of deuterium to protium in the Martian atmosphere, suggesting larger historical water presence, but it remains controversial as climate models haven't confirmed a warm enough past to support liquid water.
September 2015: Evidence of Hydrated Brine Flows
In September 2015, NASA announced that they had found strong evidence of hydrated brine flows in recurring slope lineae on Mars, based on spectrometer readings. However, later studies suggested that these lineae may be dry granular flows, casting doubt on the definitive presence of liquid water.
November 2016: Discovery of Large Underground Ice Deposits
In November 2016, NASA announced the detection of significant underground ice in Mars's Utopia Planitia region. The estimated volume of water is comparable to that of Lake Superior, marking a major discovery in understanding Mars's water resources.
September 2017: Intense Aurora Observed on Mars
In September 2017, NASA reported a significant increase in radiation levels on the surface of Mars, linked to an aurora 25 times brighter than any previously observed. This event was attributed to a massive and unexpected solar storm.
2017: NASA Authorization Act Directs Mars Mission Feasibility Study
In 2017, the NASA Authorization Act directed NASA to conduct a feasibility study for a crewed mission to Mars in the early 2030s. The resulting report concluded that such a mission would be unfeasible within the given timeframe.
2018: Indications of Water in Valles Marineris
Between 2018 and 2021, the ExoMars Trace Gas Orbiter observed signs of water, likely subsurface ice, within the Valles Marineris canyon system, adding to the growing evidence of water ice on Mars.
2018: Mars Close Approach to Earth
Mars had another close approach to Earth in 2018, coinciding with its perihelion, leading to a reduced distance between the two planets.
2019: Seismic Activity Confirmed on Mars
In 2019, NASA's InSight lander confirmed that Mars is seismically active, detecting and recording over 450 marsquakes and related events.
2020: Particularly Close Mars Opposition
In 2020, a particularly close opposition of Mars occurred, with the planet being near its perihelion, resulting in a significantly reduced distance between Mars and Earth.
2021: Continued Water Ice Detection in Valles Marineris
Observations through 2021 by the ExoMars Trace Gas Orbiter continued to indicate the presence of water, potentially in the form of subsurface ice, in the Valles Marineris, reinforcing findings from 2018.
2021: China Plans Crewed Mars Mission
In 2021, China announced plans to send a crewed mission to Mars in 2033.
April 2023: New Global Maps of Mars
In April 2023, The New York Times reported on an updated global map of Mars based on images from the Hope spacecraft. A more detailed global Mars map was also released by NASA on April 16, 2023.
2023: Evidence of a Former Ring System Around Mars
A 2023 study presented evidence suggesting that Mars may have possessed a ring system between 3.5 and 4 billion years ago, based on the orbital inclination of its moon Deimos. The study proposed that the ring system originated from a moon significantly larger than Phobos, and that Phobos could be a remnant of this ancient ring.
2023: Ten Functioning Spacecraft on Mars
As of 2023, Mars is host to ten functioning spacecraft, including eight orbiters and two rovers, signifying the extensive ongoing exploration of the red planet.
2023: Active Probes Exploring Mars
As of 2023, there are at least 11 active probes orbiting Mars or on its surface, continuing the exploration and study of the planet.
February 2024: Accumulation of Space Debris on Mars
By February 2024, over seven tons of debris from space missions, including crashed spacecraft, inactive probes, and discarded components, had accumulated on the surface of Mars, raising concerns about the long-term impact of exploration on the Martian environment.
April 2024: NASA Initiates Commercial Mars Exploration Services
In April 2024, NASA selected several companies to begin research on providing commercial services for robotic science on Mars. This initiative aims to enhance capabilities in telecommunications, payload delivery, and surface imaging, marking a shift towards commercial involvement in Martian exploration.
April 2024: SpaceX Plans for Mars Colonization
In April 2024, SpaceX, led by Elon Musk, shared their ambitious plans for establishing a human colony on Mars within the next two decades. These plans involve the mass production of Starship spacecraft, initially sustained by resupply from Earth and gradually transitioning to self-sustainability through in-situ resource utilization on Mars.
2033: Particularly Close Mars Opposition
Another particularly close opposition of Mars is predicted for 2033, with the planet near its perihelion, resulting in a notably shorter distance between Mars and Earth.
2033: China's Planned Crewed Mars Mission
This year marks the target date for China's planned crewed mission to Mars, as announced in 2021.
2035: Mars Close Approach to Earth
Mars is predicted to have a close approach to Earth in 2035, around its perihelion, leading to a closer proximity between the planets.