9: Venus Missions

Observation of venus from Earth

• venus, mars, jupiter and saturn all ancient discoveries (naked eye)

• easily seen at sunset/sunrise

• no obvious features

• 2/3 earths distance from sun

• 2x luminosity and heat from sun on venus

What are some basic features of venus?

• same mass/radius as earth

• retrograde orbit (spins backwards on axis)

What is important about venus transit?

• when venus passes infront of the suns disk

• 2004, 2017, 2117

• establish distance and size

• establish atmosphere

What are the name of the first Venus missions?

Mariner

Mariner 2

Flyby December 1962

• mostly CO2 atmosphere, cool

• surface >400C

• no ocean or life

• no magnetic field

Mariner 5

Flyby october 1967

atmosphere measurements

What are the name of the USSR Venus missions

Vanera

Vanera 4

October 1967

• dropped into atmosphere

• pressure and temp increased till spacecraft destroyed

• 550K, 15-20x earths atmosphere

Mariner 10

• 1973

• first proper photos taken en route to planet mercury

• v-shaped structures

• active cloud and weather systems

  

How to see Venus’ surface?

1. land on it (tricky)

2. find wavelengths that penetrate through the clouds

Vanera 7

1970

• withstand 180 atmos pressure

• 23 mins weak signals from surface of venus

• first probe to return data from another planet

• discovered surface conditions : 93x earth atmosphere pressure, 700-750K

Venera 8

• 1972

• 53 minutes on surface

• confirmed venera 7 measurements

• discovered enough light for photosynthesis

Venera 9

• 1975

• first surface images

• 66kg landed at 7m/s

• landed at angle - only few m in photographs

• angular rocks - no water - low erosion

  

Venera 10

• 1975

• measured compressibility of rock surface ti discover rock density

• basalt density

Venera mission summary

• not sent anything since them

venera 13

• now using modern tech to analyse its measurements

• correct image colour

why does venus appear orangey red?

thick atmosphere absorbs blue wavelengths - mostly red light penetrates to surface of venus = orange tint

Venus topographgy according to vanera 13

• low topographic variability

• some hills seen in vanera 13

Vanera 13 & 14 chemistry

• closely resembles earth basalts

• use x-ray spectroscopy

• low in silica

• 45-49% SiO2 and rich in MgO 7.7-10%

• Venera 13 indicates high K2O content (4%) - alkali basalt composition

• partial melting of mantle

• granitic material also present

• total alkali silica diagram

• more volatile rich vesseks than we see on the moon

What are the Vega missions?

• soviet union

• vega-1: failed in atmospheric descent

• vega-2: landed in aphrodite terra, survived 1hr - discovered evolved rocks, troctolite, rich in olivine, plag

what special feature was present on the vega missions/

balloon bots to investigate atmosphere tracked by radio telescopes -3m d balloon with suspended experiment package

Pioneer Venus Mission

1978

• orbiter and 4 probes

• atmospheric composition

• data till 1992

• radar mapping 0.1-1m wavelength through clouds

• could resolve features on surface 50-140km across

• topographic map

• no plate tectonics

• first geological maps

  

What are areas on Venus named after?

Goddesses

Venera 15 and 16

1983 USSR

• primitive radar systems

• mapped regions of Venus 1.2-1.4km resolution

• revealed lava flows, volcanoes, heavily folded regions

• highly irregular surface morphology

• similar to europa (ice) but basaltic

• fault systems - not controlled by plate tectonics

  

Magellan mission

1990

• gian aperture radar system - high res

• massive - launched from space shuttle

• 250-600m res

• red: looking down through atmosphere

• coloured: topographic

What is the radar technique?

• radar pulse sent through atmosphere

• ground target interaction which is reflected back

• bright: rough surface

• dull/smooth: smooth surface

Magellan Venus Map

Venus Express mission

ESA - atmosphere

• recucled mars express

• solar panels, similar instruments

• dry atmosphere

what atmospheric composition did the venus express discover?

• CO2 and N dominated

• SO2, Ar, H20, CO, He, Ne, O2, OH, NO

• cloud structures vary with latitude

• seasonal weather

Venus climate orbiter mission

Japan

• 4 cameras at UV and IR

• Map Clouds

• detect light with high speed imager