Long, Strange Trips

The last quarter-century in planetary exploration has stretched the limits of human imagination: the banner image of the Venera footpad on our sister planet, Venus, illustrates the challenges and rewards of reaching out in our solar neighborhood. The crusty surface just below that circularly-spiked footprint is hot enough to melt lead.

Even fewer may recognize that international teams have flown a balloon in the clouds on Venus, or touched down on an asteroid. Missions have intentionally crashed a spacecraft into the moon, in hopes of observing from Earth an ejected spray of lunar ice. In a spectacular planetary-scale catastrophe, orbiting telescopes have witnessed comets smash into Jupiter. A steady meteor stream has been found identifiably reaching Earth from Mars, Venus and the moon– many of which land on Antarctic fields with their interior temperatures never having exceeded one hundred degrees. Mars alone contributes fifteen annually.

More than four and half million home computers have been tied together, in hopes of detecting an intelligent radio signal from another planet. Their total computer processing units have combined what would take a single computer more than one and half million years to complete. A collosal asteroid strike on Earth has been proposed as what killed the dinosaurs. The moon itself has been modelled as originating from another terrestrial impact. In excess of one hundred planets have been found outside our solar system. Water-ice has been found on martian polar caps. A remote control rover has navigated safely between sharp martian boulders, while being driven from millions of miles away. Thick sheets of ice may cover an ocean on Jupiter’s moon, Europa. The catalog of nearby habitable stars has tallied more than 17,000 candidates. Massive stars so dense that they represent a new kind of matter–so-called quark stars–populate the universe with exotic sub-atomic physics.

The quarter-century’s timeline, by mission, year, and spacecraft, are highlighted in summary below with links to more information.

As this month begins an unprecedented blitz on Mars, including the first time that multiple landers will operate at the same time since 1977, the future of planetary exploration is also worth anticipating. Even more ambitious missions will attempt to land on a comet. A probe will try to land on Saturn’s moon, Titan–the smoggy moon with a rich atmosphere almost as thick as Earth’s. Many international returns to Mars are anticipated after the January 2004 landing assault, including intelligent rovers pre-programmed for hazard avoidance. The encyclopedic cataloguing of new planets will get help from new telescopes, ones specifically trying to image distant stars that dim as their comparatively dark and tiny planets transit and eclipse the light reaching us. Both fiery Mercury and frigid Pluto will become foci of new missions. Samples of solar wind and comet dust may be returned to Earth. New techniques for projectile sampling, where bullets are fired into the moon, Europa, and comets will complement the traditional land-and-scoop methods pioneered by Viking on Mars. New landing methods will extend the controlled collisions of airbag bounces in hopes of more accurate positioning and deployments. New solar-powered, ion engines will make the most of the least–charged particles provide fuel to go further at less cost than explosive chemical drives.

Astrobiology Magazine congratulates and commemorates those who have imagined what the surface of Venus might look like up-close, and wanted to drive a car on Mars.

See also detailed spacecraft image gallery, Probes of the Planets.

– Pioneer Venus 1 – Venus Orbiter
– Pioneer Venus 2 – Venus Probes
– launch of Halley Comet Flyby (also Comet Giacobini-Zinner)
– Russian Venera 11, Venus Orbiter and Lander
– Russian Venera 12, Venus Orbiter and Lander

Ultraviolet image of Venus obtained by Pioneer-1.
Image Credit: BNSC

– patches of strong ultraviolet absorption detected circulating in Venusian clouds by Pioneer Venus Orbiter

Cosmos TV broadcast introduces a mass audience to cosmology
– Seven moons of Saturn are discovered: Atlas, Calypso, Epimetheus, Helene, Pandora, Prometheus, Telesto
– Luis and Walter Alvarez propose KT (Cretaceous-Tertiary) asteroid impact killed the dinosaurs
Voyager 1 obtains close-up images of Saturn’s rings

– First space shuttle launches
– Russian Venera 13 ,Venus Orbiter and Lander
– Russian Venera 14 ,Venus Orbiter and Lander

– Andrei Linde proposes new inflationary universe scenario
– Mars Viking Lander 1 makes its final transmission to Earth, 6 years after its rocket-powered descent

– Andrei Linde develops chaotic inflationary universe scenario
– Infrared Astronomical Satellite (IRAS) launches
– Paul Horowitz initiates Project Sentinel to search for extraterrestrial intelligence
– Russian Venera 15 , Venus Orbiter
– Russian Venera 16 , Venus Orbiter

Frost and Viking 2 Lander
White patches of frost on the ground are visible behind the Viking 2 Lander. Click to enlarge.Credit: NASA.

– SETI Institute is founded
– Russian Vega 1 , Venus Lander and Balloon/Comet Halley Flyby
– Russian Vega 2 , Venus Lander and Balloon/Comet Halley Flyby, floats balloon payload at 50 km altitude in Venusian top layer of atmosphere

– Puck, a moon of Uranus, is discovered in Voyager 2 images
– International Cometary Explorer (ICE) spacecraft flies through tail of Comet Giacobini-Zinner, becoming the first to encounter a comet
– Project META (Megachannel Extraterrestrial Assay) begins searching for signs of extraterrestrial intelligence
– Halley’s Comet makes its latest close approach to Earth
– Japanese Sakigake , Comet Halley Flyby
– European Giotto , Comet Halley Flyby
– Japanese Suisei (Planet-A) , Comet Halley Flyby

– Margaret Geller and John Huchra describe bubble structure of galaxy superclusters
SERENDIP II (Search for Extraterrestrial Radio Emissions from Nearby Developed Intelligent Populations) begins operations, surveys 30% of sky on 4 million channels
Voyager 2 flies past Uranus
– Nine moons of Uranus are discovered in Voyager 2 images: Bianca, Belinda, Cordelia, Cressida, Desdemona, Juliet, Ophelia, Portia, Rosalind
– Space Shuttle Challenger explodes

– Astronomers realize Milky Way and many local galaxies are moving toward "Great Attractor"
– Supernova 1987A is discovered

The painting titled "K/T Hit" by artist Donald E. Davis. This impact occured 65 million years ago, ending the reign of the dinosaurs.
Image Credit: Don Davis

– Numerical simulations by Martin Duncan and colleagues confirm short- period comets could come from Kuiper Belt
Phobos 1 , Attempted Mars Orbiter/Phobos Landers
Phobos 2 , Mars Orbiter/Attempted Phobos Landers

Magellan spacecraft launches as Venus Orbiter
Voyager 2 flies past Neptune
– Hipparcos astrometry mission launches
Galileo spacecraft is deployed from Space Shuttle Atlantis, as Jupiter Orbiter and Probe

– John Mather presents observations of the cosmic background radiation by the Cosmic Microwave Background Explorer (COBE) which confirm predictions of the big bang theory
– Pan, a moon of Saturn, is discovered in Voyager 2 images
– Project META II begins extraterrestrial search from southern hemisphere
– Hubble Space Telescope launches aboard Space Shuttle Discovery, as Earth Orbiting Observatory
Ulysses spacecraft is deployed by Space Shuttle Discovery, As Jupiter Flyby and Solar Probe Orbiter
– Japanese Hiten , Lunar Flyby and Orbiter

Lunar Clementine mission shows the South Pole of the Moon. The permanently shadowed region center shows evidence of meteor cratering and ice never exposed to direct sunlight.
Credit: NASA/DOD Clementine

– Burst and Transient Source Experiment (BATSE) aboard the Compton Gamma Ray Observatory finds gamma-ray burst radiation is isotropic
Alexander Wolszczan discovers two planets orbiting a millisecond pulsar

– John Mather and George Smoot find fluctuations in cosmic microwave background radiation with COBE
– First Kuiper Belt asteroid (1992 QB1) is discovered
SERENDIP III begins operations at Arecibo Observatory
MACHO project begins searching for massive compact halo objects
– NASA’s High Resolution Microwave Survey (HRMS) begins searching for extraterrestrial signals from Arecibo and Goldstone observatories

Keck Observatory begins observations
– Contact with Mars Observer is lost three days before orbit insertion
Galileo spacecraft images the first known asteroid moon, Dactyl, orbiting asteroid Ida
– Space shuttle astronauts fit Hubble Space Telescope with corrective optics

Fragments of Comet P/Shoemaker-Levy 9 colliding with Jupiter (July 16-24, 1994).
Credit: NASA

– Hubble Space Telescope finds evidence of black hole in the center of M87
– Hubble Key Project begins studying Cepheid variable stars to better define Hubble Constant, and the size of the universe
– Michael Rampino and Richard Strothers propose Earth could be periodically struck by comets dislodged from orbits when the solar system passes through galactic plane
– Comet Shoemaker-Levy 9 hits Jupiter
– US Dept. Defense/NASA Clementine mission, Lunar Orbiter/Attempted Asteroid Flyby

– Donald Lamb and Bodhan Paczynski debate the distance of gamma-ray bursts
– Andrew Gould determines distance to the Large Magellanic Cloud (LMC) using Supernova 1987A
– The SETI Institute launches Project Phoenix
– Michael Mayor and Didier Queloz announce discovery of extrasolar planet around sun-like star 51 Pegasi
– Project BETA ( Billion-Channel Extraterrestrial Assay) begins scanning the skies

Close-up of a Mars meteorite, showing what some argue appears to be fossilized evidence of ancient microbial life.
Image Credit: NASA

– Comet Hyakutake and Comet Hale-Bopp reach peak brightness
– Sidney van den Bergh and Gustav Tammann debate Hubble Constant and the scale of the universe
– Terry Oswalt and colleagues determine age of the galactic disk from old white dwarfs
– Near-Earth Asteroid Rendezvous (NEAR Shoemaker) mission launches, Asteroid Eros Orbiter
– Scientists announce they’ve found signs of primitive life in Mars meteorite ALH840001
Mars Global Surveyor launches
Carl Sagan dies

BeppoSAX determines gamma-ray bursts are extragalactic
– Two moons of Uranus are discovered: Caliban and Sycorax
– Space Very Long Baseline Interferometry (SVLBI) mission launches
– Mars Pathfinder lands on Mars
– SERENDIP IV begins operations at Arecibo Observatory
CassiniHuygens mission launches, as Saturn Orbiter and Titan probe
– First commercial lunar mission, AsiaSat 3/HGS-1 , Lunar Flyby

Spectacular gas remnants from exploding star.
Image Credit: Hubble

– Supernovae observations by the Supernova Cosmology Project and High-z Supernova Search team suggest the expansion of the universe is accelerating
Lunar Prospector launches and enters lunar orbit
– Jim Peebles and Michael Turner debate nature of universe and whether cosmology is solved
Paul Horowitz initiates an optical SETI program to search for laser pulses from other worlds
– Submillimeter Wave Astronomy Satellite (SWAS) launches
BOOMERANG (Balloon Observations of Millimetric Extragalactic Radiation and Geophysics) launches over Antarctica
Nozomi Mars Orbiter (Japanese "Hope") launched, enters detour for 2004 encounter
Galileo flyby of Jupiter’s moon, Europa, shows the infrared picture of cracks correlate to water ice and also either salts or some organics

The icy cracks of Jupiter’s moon Europa continue to intrigue astrobiologists. The white sheen is likely frost and the moon’s heat source is a combination of an underground ocean and tidal heating under the strong gravitational pull of Jupiter. Credit: Galileo Project, JPL, NASA

– John Cowan confirms age estimates of globular clusters and universe by dating metal-poor stars
Stardust mission launches
– Wendy Freedman and Allan Sandage debate Hubble Constant and the scale of universe
– SETI@Home begins distributing data to computers around the world, to accomplish millions of CPU years in search of intelligent radio signals
Chandra X-ray telescope is deployed from Space Shuttle Columbia, to probe the high-energy universe
Mars Climate Orbiter is lost during orbit insertion
Mars Polar Lander stops communicating after landing on Mars
Lunar Prospector tries to detect water on the Moon

Eleven moons of Jupiter are discovered
NEAR Shoemaker begins orbiting asteroid Eros
– Expedition One crew arrives at International Space Station
Very Large Telescope -world’s largest optical telescope array-measures the temperature of the early universe
– Mars Viking Project Scientist, Jerry Soffen, dies at 74

– Adam Reiss and colleagues announce the most distant supernova known supports "dark energy" theory
– Robert Becker and colleagues use quasar to identify cosmic "Dark Age"
Twelve moons of Saturn are discovered
– Lunar soil samples and computer models by Robin Canup and Erik Asphaug support impact origin of moon
NEAR Shoemaker lands on asteroid Eros
– Microwave Anisotropy Probe (MAP) is launched, to measure the temperature of the cosmic background radiation
Genesis mission lifts off, to capture and return 10-20 milligrams of solar wind to Earth
Deep Space 1 encounters Comet Borrelly
– 2001 Mars Odyssey arrives at Mars
Hubble Space Telescope detects an atmosphere around an extrasolar planet

Mars Odyssey detects water in martian south polar cap
Eleven moons of Jupiter are discovered
– Chandra X-ray Observatory finds evidence for new matter in "quark stars", matter so dense it exceeds terrestrial nuclear material with 1.2 million degree temperatures
– 100th extrasolar planet is discovered

Mars Spirit, to rove the Red Planet
Image Credit: JPL

– Japanese launch of Hayabusa (or falcon, formerly Muses-C), to collect a surface sample of material from an asteroid and return it to Earth
– European Mars Express, Mars Orbiter and Lander launched, encounters Mars, Christmas 2003
Spirit Mars Rover launched, MER-A encounters Mars, January 4, 2004
Microwave measurements precisely date the Big Bang at 13.7 billion years ago, with a remarkable 1% error prediction
Eight new moons of Jupiter identified
– SETI classifies 150 most promising radio signals for revisiting, Arecibo Observatory
– Jill Tarter and Margaret Turnbull publish the Catalog of Habitable Stars (17, 129 potentially habitable hosts for complex life)
Opportunity Mars Rover to launch, MER-B encounters Mars, January 25, 2004
SMART 1, to launch lunar orbiter and test solar-powered ion drive for deep space missions

Europa Orbiter.
Image Credit: JPL

What’s Next

European Rosetta mission, to land a science probe on the surface of Comet Churyumov-Gerasimenko
– Mercury orbiter, MESSENGER, to look for water-ice on the closest planet to the Sun
– Comet rendezvous, Deep Impact, to fire a bullet into comet P/Tempel 1 and study the ejecta and crater
– Japanese Lunar-A, Lunar Mapping Orbiter and Penetrator, to fire two bullets 3 meters into the lunar soil near Apollo 12 and 14 sites

– Mars Reconnaissance Orbiter (MRO) launch, Mars Orbiter to collect high-resolution, 1-meter, images in stereo-view of Mars
– European Venus Express, Venus Orbiter for two-year nominal mapping life [486 days, two Venus year]

Huygens landing probe to Saturn’s moon, Titan.
Image Credit: ESA

New Horizons, Pluto and moon Charon flyby, mapping to outer solar system cometary fields and Kuiper Belt
Dawn, Asteroid Ceres and Vesta rendezvous and orbiter, including investigations of asteroid water and influence on meteors
Kepler, Extrasolar Terrestrial Planet Detection Mission, designed to look for transiting or earth-size planets that eclipse their parent stars [survey 100,000 stars]
Europa Orbiter, planned Orbiter of Jupiters ice-covered moon, Europa, uses a radar sounder to bounce radio waves through the ice
– Japanese SELENE Lunar Orbiter and Lander, to probe the origin and evolution of the moon

– Japanese Planet-C Venus Orbiter, to study the Venusian atmosphere, lightning, and volcanoes.
– Mars Scout mission, final selections August 2003 from four Scouts: SCIM, ARES, MARVEL and Phoenix
– French Mars Remote Sensing Orbiter and four small Netlanders, linked by Italian communications orbiter

BepiColumbo, European Mercury Orbiters and Lander, including Japanese collaborators, lander to operate for one week on surface
Mars 2009, proposed long-range rover to demonstrate hazard avoidance and accurate landing dynamics

Related Web Pages

Chronology of a Scientific Safari
The Viking Files
Interview with Planet Finder