Planetary Exploration

Mariner 10 Mercury. Three flybys in 1974-1975

- Planet heavily cratered
- Large impact basin (Caloris) ~ 1300 km diameter
- Unique planetary feature - long curved cliffs produced by crystal compression
- Internal magnetic field
- Very little atmosphere

Viking . Mars Landers and orbiters beginning 1976.

- No definite evidence for biological activity in soil despite some unusual chemical reactions
- Surface rocks resemble basaltic lava
- N-polar cap is H2O - ice and CO2 - ice
- Loss of Nitrogen to space (15N retained)
- Erosional channels suggest atmosphere was denser in past - WATER
red color due to oxidized Fe (iron), water, and Sulphur compounds in soil
- Water and sulphur compounds in soil
- Temperature on surface -120øF (night) to -20øF (day)
- Surface features suggest large quantities of water were once present

Apollo

- Lunar landings (6 manned landings from 1969-1972)
- A complex, evolved planet
- Rocks are 3.0 - 4.6 billion years old most older than any preserved on 3 types of rock:
1. Volcanic lavas (Maria)
2. Al-rich (Highlands)
3. Unusual lavas with abundant radioactive elements
- Lunar regolith (soil) is powdery, 10-100m thick, formed by bombardment
- Differentiated interior - crust, mantle, core
- No atmosphere
- No plate tectonics
- Not seismically active - (weak moonquakes)
- Remnant magnetism in rocks
- No evidence of life, past or present
- No internal water, no granitic continent

Pioneer

- Venus probes and orbiters. 4 probes entered atmospere in 1978.
- Pioneer Venus orbiter completed 3000th orbit in Feb. 1987.
- Atmosphere ~ 96% CO2, 4% N and minor H2O, O2, S compounds
- Greenhouse effect - high surface temperature, at least 4 distinct
cloud and haze layers above surface
- SO2 at cloud tops; decreasing since 1978 - weak magnetic field
- Pioneer 7 made observations of comet Halley, 1986
- Pioneer 6,7,8 operable into 1990's
- Pioneer 9 was last tracked in 1983 - "dead"
- Investigations near Earth's orbit
- Pioneer 10 and 11 returning data in 1989
- Pioneer Venus orbiter is still operating

Magellan

- Mission: Radar mapping of surface of Venus using synthetic aperture radar (SAR) 50m resolution.
Gravity data will be obtained by radio tracking (subsurface mass distribution)
- Launched: April, 1989
- Arrived: August 1990, mapping to be completed in April, 1991
(mission duration 2 years)

Galileo

- Mission: To send an instrumented probe into the atmosphere of Jupiter and to conduct an orbital tour of the Jovian system to study the planet, its satellites, ring, and magnetosphere.
- Launched: October 18, 1989 from space shuttle atlantis
- Cost: $1.4 Billion
- To reach Jupiter in December 1995 thru a circuitous route using "gravity assists" from inner planets it will pass Earth in 1990 and 1992 - will search for the broad, tenuous ring of debris which some scientists think the Earth "shepherds" around the sun
- A 700lb. instrument package will enter Jupiter's atmosphere

CRAF - Comet Rendezvous/Asteroid Flyby

- Mission: To conduct a close flyby of an asteroid, to fly in close formation with a short-period comet, to study the comet during quiescent and active phases, and to send a penetrator/lander into the core of the comet to determine subsurface properties and composition.
- Launch: August 1995 with Titan IV/Centaur G'
_ Arrival: 1. January 1998 - will fly past the asteroid Hamburger
2. August 2000 - will arrive at comet Kopff and fly with it for 959 days

Voyager 1 and 2

- Launched: 1977


1. Jupiter in 1979

- Thin planetary ring
- Discovered varied geology on Galilean moons
1. Io 10 active volcanoes - heat from tidal energy
2. Europa - covered by frozen ocean, may be liquid at depth
H2O
3. Ganymede - evidence of plate tectonics
4. Callisto - craters
- Atmosphere = Methane, Ammonia, H2O vapor, similar to sun -
He(11% by vol.), H
- Internal energy source (heat)
- Planetary aurora, lightning
- Strong magnetic field


2. Saturn in 1980, 81



- Atmosphere = He(6% by vol.), H, Ammonia, Methane, Phosphine,
Ethane, Acetylene, Methylacetylene, Propane
- Large internal heat source
- Winds up to 1000 mph (1500 km/hr)
- Auroras near poles
- UV emissions at lower latitudes
- Many ringlets, some with spokes
- Inner moons formed of ice
- cratered strong magnetic field
-Titan - Life?


3. Uranus in 1986



- He in atmosphere is 15% (close to sun's)
- Discrete methane cloud deck
- Prograde winds near poles (700 km/hr)
- Retrograde winds near equator (300 km/hr)
- Intense UV light emission
- 10 new moons discovered
- The 5 largest moons have very different tectonic histories
Miranda is most complex
- Photos of narrow rings
- Strong magnetic field, tilted at 60ø to axis of rotation and off center
- Radio emissions from dark side


4. Neptune in 1989



- Large dark blue spot
- Ring arcs - clumps
- Triton has geyser-like plumes of gas and debris
- Temperature 38øK (coldest object in solar system)
- Clouds of Nitrogen ice
- Both voyagers will continue to operate and take measurements well into the next century.
Increase knowledge of outer regions of Sun's heliosphere and interstellar environment.


Cassini (Saturn orbiter/Titan Probe)

- Mission: To orbit Saturn and study its rings in detail; to study its moons; to send a probe into the atmosphere of Titan.
- Unlike any other moon, Titan has a thick atmosphere composed
chiefly of Nitrogen and Methane. Within this atmosphere, a
complex process of chemical evolution has occured, and continues
to produce organic compounds. It may be repeating some of the
earliest steps in the processes that led to the appearance of
Life on Earth.
- Launch: April 1996 (Titan IV/ Centaur G')
Asteroid Maja flyby in March 1997, arrive at Saturn
October 2002.
- Joint mission with ESA


Mars Rover/Sample Return

- Mission: To land a robotic rover on Mars to perform in situ analyses and collect samples for return to Earth.
It will determine chemistry and mineralogy of surface materials, will help us understand the complex evolutionary history of the planet, and understand the
structure and dynamics of its interior, and nature of past and present magnetic fields.
- Will search for evidence of pre-biotic evolution and origin of
life.
- Launch: Between 1998 and 2001
- Time span from launch to sample return will be 3-5 years.
- Part of NASA's long-range planning for eventual human
exploration of Mars.


Mars Observer

- Mission: To conduct an orbital mapping mission to determine the global chemistry, elemental and mineralogical character< of the Martian surface and to investigate Martian climate.
- will provide systematic data over a Martian year. Will also establish the nature of the magnetic field.
- Launch: Scheduled for 1992 using Titan III.
- Arrival: August 1993
- Blew up in Martian orbit. Back to the drawing board.


Ulysses

- Mission: To investigate the properties of the heliosphere as a function of solar latitude. (SUN)
- Launch: October 6, 1990 from space shuttle Discovery
- Duration: 5 years
- Will follow a trajectory to intercept Jupiter and use its gravity to leave the ecliptic plane and acheive high latitude orbit relative to the sun - Joint mission with European Space Agency (ESA). Was built by ESA.