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

Early Exploration  Nicolaus Copernicus  Published De revolutionibus orbium coelestium (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 st 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. Percival Lowell at Lowell Observatory.William Herschel’s 40ft telescope, 1789.

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 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.

Deimos – 15 km (9.3 miles) Phobos – 26.8 km (16.7 miles) Moons

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) Early Exploration Lowell’s Martian canals, ca. 1900

Early Exploration How did scientists view Mars at the beginning of the 20 th century?

Early Exploration How did scientists view Mars at the beginning of the 20 th century? - Earthlike?

Early Exploration How did scientists view Mars at the beginning of the 20 th 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?

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. Early Exploration 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?

In 1947, Gerard Kuiper made the 1 st positive ID of CO 2 in the atmosphere of Mars. Early Exploration

In 1950, the best guess* for the composition of the Martian atmosphere was: % N - 1.2% Ar % CO 2 - <0.1% O Early Exploration *Estimates from Gérard de Vaucouleurs; also calculated an atmospheric pressure of 87 millibars (8.7% Earth’s).

In 1963*, the “probable composition of the Martian atmosphere” was believed to be: 72% N 2 25% CO 2 2% Ar < 0.5% O 2 Trace amounts of H 2 O Early Exploration *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 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 Exploration

Early Spacecraft Exploration Mariner 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 Exploration Mariner 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 Exploration Mariner 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 Exploration

Early Spacecraft Exploration Mariner 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 Exploration Mariner 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 Exploration Mariner 6 & 7  How did Mariner 6 & 7 advance scientific understanding of Mars?  Temperature range  South polar cap composed of CO 2 ; 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 Exploration Mariner 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

Early Exploration How did Mariner 6 & 7 change and/or reaffirm perceptions of Mars?

Early Spacecraft Exploration Mariner 9

 Arrived at Mars only to find a global dust storm blanketing the planet  Circular features peaking through the dust

Early Spacecraft Exploration Mariner 9  Notable results from Mariner 9  Global mapping (imaging) of the surface of Mars  The first detailed views of the Martian volcanoes, Valles Marineris, the polar caps, and the satellites Phobos and Deimos  Provided information on global dust storms, the planet’s rugged gravity field, and evidence for surface aeolian (wind) activity.

Early Exploration Mariner 9  How did Mariner 9 advance scientific understanding of Mars?  Mars is more geologically diverse than had ever been presumed  Evidence water once flowed on the surface, not in artificial canals, but natural river channels  What technological advance(s) did Mariner 9 carry?  Spacecraft orbited Mars, first unmanned planetary orbiter in history

Early Exploration How did Mariner 9 change and/or reaffirm perceptions of Mars?