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History of Mars Exploration. History of Mars Exploration. Analyze historical and modern Mars data to develop an evolving understanding of Mars. Models how scientists have historically viewed Mars. Early Exploration 1609 - 1965. Early Exploration. Nicolaus Copernicus
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History of Mars Exploration • Analyze historical and modern Mars data to develop an evolving understanding of Mars. • Models how scientists have historically viewed Mars.
Early Exploration • Nicolaus Copernicus • Published De revolutionibusorbiumcoelestium(On the Revolutions of the Celestial Spheres) in 1543
Early Exploration • Tycho Brahe • Observations of Mars in 1583 showed Mars could move closer to Earth than it did to the Sun. Possible in a heliocentric universe, but not geocentric.
Early Exploration • Ptolemaic System
Early Exploration • Tychonian System
Early Exploration • Johannes Kepler • Assistant to Brahe; derives first two laws of planetary motion in 1609. 1st law derived from Brahe’s observations of Mars.
Early Exploration • Though these early observations helped scientists accurately describe the motion of Mars in the sky, nothing about the planet itself was known. Mars retrograde motion. Image Credit: Tunç Tezel
Early Exploration • Beginning with Galileo, scientists were able to observe Mars with a new tool, the telescope. William Herschel’s 40ft telescope, 1789. Percival Lowell at Lowell Observatory.
Early Exploration Galileo Galilei observed Mars in 1610 and wrote: “…unless I am deceiving myself, I believe that I have already seen that it is not perfectly round.”
Early Exploration Christiaan Huygens made the first (known) sketch of Mars in 1659; determined a rotational period for Mars: “The Rotation of Mars, like that of the Earth, seems to have a period of 24 hours.”
Early Exploration Giovanni Cassini calculated a rotational period of 24 hrs, 40 min; may have been first to report the southern polar cap in 1666.
Early Exploration French author Bernard le Bovier de Fontenelle wrote about Mars in 1686: “Mars has nothing curious that I know of; its days are not quite an hour longer than ours and its year’s the value of two of ours. It’s smaller than the Earth, it sees the Sun a little less large and bright than we see it; in sum, Mars isn’t worth the trouble stopping there.” From Conversations on the Plurality of Worlds
Early Exploration In 1783, William Herschel determined Mars to have a diameter 0.55x Earth’s and an obliquity of ~28°; noted the south polar cap.
Early Exploration Herschel also noted: “I have often noticed occasional changes of partial bright belts…and also a darkish one, in a pretty high latitude… And these alterations we can hardly ascribe to any other cause than the variable disposition of clouds and vapors…”
Early Exploration Herschel concluded the inhabitants of Mars “probably enjoy a situation in many respects similar to ours.”
Early Exploration • Giovanni Schiaparelli popularized the straight lines he called canali (can mean “channels” or “canals”). He also used fiume or “river.” • Started a new nomenclature for Martian features.
Early Exploration Map of Mars by Schiaparelli, 1877
Early Exploration Asaph Hall of the US Naval Observatory discovered the two moons of Mars in 1877.
Moons Deimos – 15 km (9.3 miles) Phobos – 26.8 km (16.7 miles)
Early Exploration • Percival Lowell misinterpreted “canali” to mean canals (artificial); mapped 437 “canals” in 917 sketches; took the idea of artificial canals to the grave. • Calculated an atmospheric pressure of 85 millibars (8.5% of Earth’s) Lowell’s Martian canals, ca. 1900
Early Exploration How did scientists view Mars at the beginning of the 20th century?
Early Exploration How did scientists view Mars at the beginning of the 20th century? - Earthlike?
Early Exploration • How did scientists view Mars at the beginning of the 20th century? • - Earthlike? • - Like?
Early Exploration • What are limitations to this type of mission and its instruments? • What observations can you make from this data? (Please select the relevant images and prepare to post them on your poster.) • How would you interpret these observations? • How would you generalize the Mars environment from these images / data? • What new questions do you have about Mars? • What type of data do you need to answer these questions?
Early Exploration Setting aside the argument of whether or not the canals were real, astronomers knew with certainty that the surface of Mars changed - dark and light patterns did not remain the same over time. Mars Map by Eugène Michel Antoniadi, 1930
Early Exploration As telescopes improved, astronomers became confident that Mars had a polar cap. The question remained, what was it made of?
Early Exploration In 1947, Gerard Kuiper made the 1st positive ID of CO2 in the atmosphere of Mars.
Early Exploration • In 1950, the best guess* for the composition of the Martian atmosphere was: • - 98.5% N • - 1.2% Ar • - 0.25% CO2 • - <0.1% O *Estimates from Gérard de Vaucouleurs; also calculated an atmospheric pressure of 87 millibars (8.7% Earth’s).
Early Exploration • In 1963*, the “probable composition of the Martian atmosphere” was believed to be: • 72% N2 • 25% CO2 • 2% Ar • < 0.5% O2 • Trace amounts of H2O *Estimates from NASA Technical Document NASA-TM-X-56223, 1963; presented at the Symposium on Extraterrestrial Biology and Organic Chemistry, Warsaw, June 3-12, 1963.
Early Exploration “A third presence on Mars indicates a living world: vegetation. The evidence is in the blue-green areas and the changes in their appearance. Vegetation would present exactly the appearance shown…. The seasonal change that sweeps over them is metabolic; that is, it shows both growth and decay….” - Earl C. Slipher, 1962 Image Credit: Lowell Observatory
Early Exploration • Early exploration of Mars revealed it to be: • Cold; temperatures at freezing or well below freezing • Dynamic, at least regarding patterns on the surface; dust, vegetation, or both? • Low atmospheric pressure; clouds • Unsure about the atmospheric composition • Arid • Polar cap – What is it made of? • No canals/intelligent life
Early Exploration How did scientists view Mars in the early 1960s?
Early Spacecraft ExplorationMariner 3 & 4 • “…these missions are being undertaken because Mars is of physical and geological interest and offers the best opportunity in our solar system for shedding light on the possibility of extraterrestrial life. (They)…, however, are not designed to provide answers to the question of life on Mars.” Mariner 4 Press Kit, October 29, 1964
Early Spacecraft ExplorationMariner 4 • Notable observations from Mariner 4 • Images returned showed a Moon-like, cratered terrain • Surface atmospheric pressure of 4.1 to 7.0 mb and daytime temperatures of -100° C (-148° F) were estimated • No magnetic field was detected
Early Spacecraft ExplorationMariner 4 • How did Mariner 4 advance scientific understanding of Mars? • Mars looked more like the Moon • Possibility of life seemed less likely • IMPORTANT: Mariner 4 only imaged ~1% of the surface of Mars, mostly in the southern hemisphere • What technological advance(s) did Mariner 4 carry? • The Mariner 4 spacecraft
Early Exploration How did Mariner 4 change and/or reaffirm perceptions of Mars?
Early Spacecraft ExplorationMariner 6 & 7 • “Study the surface and atmosphere of Mars to establish the basis for future experiments in the search for extra-terrestrial life and to develop technology for future Mars missions. The 1969 flights will not determine the presence of life on Mars but will help establish whether or not the Martian environment is suitable for life.” Mariner (6 & 7) Press Kit, July 18, 1969
Early Spacecraft ExplorationMariner 6 & 7 • Notable observations from the Mariner 6 & 7 missions report • Temps range between -73° C (-100° F) & 15° C (60° F) • The polar cap was crusted with frozen carbon dioxide… • Features with a dimension of 900 (ft.) could be identified. • The so-called Martian canals were not in evidence. • At a location called Nix Olympica…was a huge crater 300 miles in diameter. • No indications of volcanism were found. • Mariner 6 & 7 imaged 20% of the surface of Mars, mostly in the southern hemisphere
Early Spacecraft ExplorationMariner 6 & 7 • How did Mariner 6 & 7 advance scientific understanding of Mars? • Temperature range • South polar cap composed of CO2; temp reading of -123°C (-190°F) • NO CANALS • What technological advance(s) did Mariner 6 & 7 carry? • Spacecraft with higher resolution cameras & spectrometers
Early Spacecraft ExplorationMariner 8 & 9 • “Study the surface and atmosphere of Mars in detail, and over a period of time, to provide a broad picture of the history of the planet and natural processes currently shaping the Martian environment. To accomplish this, one spacecraft will map 70% of the planet and the other will repeatedly study selected areas on Mars to observe changes on the surface and in the atmosphere.” Mariner (8 & 9) Press Kit, April 30, 1971