Viking

Launched in 1975, the twin spacecraft Viking 1 and Viking 2 reached Mars in 1976. Each spacecraft consisted of an orbiter and an attached lander. After spending a month in orbit gathering images of potential landing sites, the landers separated from the orbiters and descended to their respective sites. Viking 1 landed on the western slopes of Chryse Planitia. Viking 2 landed at Utopia Planitia.

Viking 1 08.20.75:  Launch (21:22 UT) 06.19.76:  Arrival at Mars 07.20.76:  Mars Landing (11:53:56) 08.07.80:  End of Mission (Orbiter) 02.01.83:  End of Mission (Lander)

Viking 2 09.09.75:  Launch (18:39 UT) 08.07.76:  Arrival at Mars 09.03.76:  Mars Landing (22:37:50 UT) 07.24.78:  End of Mission (Orbiter) 04.12.80:  End of Mission (Lander)

These spacecraft produced our most complete global maps of Mars as seen from orbit. You can find a nice Viking orbiter atlas at the Roving Mouse Mars Atlas: http://www.roving-mouse.com/planetary/Mars/Atlas/ The Viking Orbiters were able to make a more complete and detailed survey of the planet than was possible from Mariner 9. You can find out more about the Viking missions (and all the other NASA Mars missions, past, present, and future by going to the NASA Missions Profile web site http://solarsystem.nasa.gov/missions/profile.cfm and hit the Past tab. An 8-page description of the spacecraft and their mission can be obtained by clicking on the link labeled Viking Fact Sheet (Links section).

The Quest for Water

Canyons, Outflow Channels, Runoff Channels

	Vallis Marineris. This entire canyon complex is most likely due originally to crustal fracture during the creation of the Tharsis Rise.
	Noctis Labyrinthus, extending westward from Vallis Marineris

Graben structure

Ouflow channels	Outflow channel originating in jumbled terrain

Outflow channels emptying into Chryse Planitia

These are found in both hemispheres, but most of the major ones are those “flowing” from the south to the north in places like Chryse Planitia.

Sinuous runoff channels most resemble dried-up riverbeds on Earth.

Almost all known runoff channels are found exclusively in the southern hemisphere.

Lobate Craters

These “soft” craters are not found within 30° of the equator. The equatorial craters are sharp and distinct.

Subsurface Ice

Polar Caps

North Polar Cap	South Polar Cap

CO₂ caps – seasonal advance & retreat

H₂O caps – little/no change. Proof of existence at SPC only recently.

The Viking Landers were the first spacecraft to successfully land on Mars and send back data.

Viking 1 landing site

The Viking 2 landing site. It was less “sandy” than the Viking 1 site.

Landers – Life Experiments

By far the most important experiments were the 3 biological experiments: Gas-Exchange (GEX), Labeled Release (LR), and Pyrolytic Release (PR) experiments, along with a biology-related one, the Gas Chromatograph Mass Spectrometer (GCMS). Reactions were observed, but seemed to be due to nonbiological processes. The combined results of these instruments suggested that Mars was lifeless, although some have argued that the LR results were most consistent with biological activity.

You can find a nice description at the Viking and the Biology Experiments site: http://www.resa.net/nasa/mars_life_viking.htm

Please read this carefully.

You can find out more about the Viking missions (and all the other NASA Mars missions, past, present, and future by going back to the NASA Mission Profile site: http://solarsystem.nasa.gov/missions/profile.cfm

There are some nice Viking images and movies here: http://www.etsimo.uniovi.es/solar/cap/mars/