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Why We Explore
T. Keith Glennan, Administrator

The Birth of NASA

29th in the series:
It may well be argued that NASA has become the world's premier agent for exploration, carrying on in "the new ocean" of outer space a long tradition of expanding the physical and mental boundaries of humanity.

  • The three men responsible for Explorer 1, America's first Earth satellite, from left to right are William H. Pickering, James A. van Allen and Wernher von Braun.

    A Moment in Time: Explorer 1

    28th in the series:
    The year 2008 will be a year of 50th anniversaries for space exploration. Following in the wake of Sputnik I and Sputnik II, on January 31, 1958 the United States launched Explorer 1.

  • Phobos

    Under the Moons of Mars

    27th in the series:
    A recent conference on the moons of Mars reminded me of the wonders that await us even in our own solar system.

  • A composite of the Jovian system, includes the edge of Jupiter with its Great Red Spot, and two of Jupiter's four largest moons, known as the Galilean satellites.

    Mission to Jupiter

    26th in the series:
    Galileo represented a new phase in the study of the outer planets. Pioneer and Voyagers 1 and 2 together completed the preliminary reconnaissance of those gas giants, but Galileo undertook a much more systematic, in-depth and holistic analysis of the entire Jupiter system.

  • Voyager 1 and 2 spacecraft

    Voyages Beyond the Solar System: The Voyager Interstellar Mission

    25th in the series:
    Originally planned to explore the gas giant planets and their satellites, the Voyager spacecraft have continued their journeys and are now the most distant human objects in the cosmos.

  • John Mather, 2006 Nobel Prize Winner for Physics

    Voyages to the Beginning of Time

    24th in the series:
    The recent award of the Nobel Prize in Physics to NASA astrophysicist John Mather and University of California Berkeley astrophysicist George Smoot reminds us that NASA not only undertakes voyages in space, but also in time.

  • Pluto, center and it's previously known moon Charon

    Pluto, Classification and Exploration

    23th in the series:
    The universe is what it is, not what we want it to be, and science must always be open to correcting its mistakes.

  • This global view of the surface of Venus is centered at 0 degrees east longitude.

    Voyages to the Planets: Venus

    22th in the series:
    Less than a century ago, the planet Venus was most often referred to as "Earth's sister planet."

  • Project Mercury Astronauts

    The Voyagers

    21th in the series:
    Exploration doesn't happen by sitting still, physically or intellectually.

  • Astronaut Edwin E.

    The Voyages of Apollo

    20th in the series:
    No single essay can do justice to the events that took place between 1968 and 1972, four years that, as time passes, seem all the more remarkable for human history.

  • Voyage to the Moon

    Voyages to the Moon: Robotic Reconnaissance

    19th in the series:
    It is hardly cause for surprise that with the beginning of the Space Age humans set their sights on the nearest celestial body, the Moon.

  • These color images of Eros was acquired by NEAR on February 12, 2000, at a range of 1800 kilometers (1100 miles) during the final approach imaging sequence prior to orbit insertion.

    Voyages to the Asteroids

    18th in the series:
    Daring though voyages to comets have been, with comet material often pelting and even damaging passing spacecraft, voyages to asteroids have gone one step further, achieving an actual landing, or maybe two landings.

  • Deep Impact

    Voyages to Comets

    17th in the series:
    Among the more adventurous voyages of exploration are those whose destinations are comets.

  • The Sun is indeed our nearest star, a mere 8 light minutes away, compared to 4.5 light years for the next star, the Alpha Centauri system. A nuclear furnace generating prodigious amounts of energy, the Sun provides the conditions necessary for life on Earth. It is a matter of practical importance that we know how the Sun works, as well as a matter of theoretical importance, since its proximity gives us the best information on how other Sun-like stars work.

    Voyages to the Sun

    16th in the series:
    Humanity's epic voyages to the Moon are well known, the stuff of history. But what about voyages to the Sun?

  • Great Images at NASA: Orion

    Discovering New Worlds

    15th in the series:
    In October 1995 - ten years ago this month - two Swiss astronomers announced the discovery of the first planet around a Sun-like star outside of our solar system.

  • Risk and Exploration Revisited

    Risk and Exploration Revisited

    14th in the series:
    Exploration is necessary for a creative society and risk is the inevitable companion of exploration.

  • Cosmic evolution is depicted in this image from the exobiology program at NASA Ames Research Center, 1986. Cosmic evolution begins (upper left) with the formation of stars and planetary systems, proceeds (bottom) to primitive and complex life, and culminates with intelligence, technology and astronomers (upper right) contemplating the universe.

    Our Place in the Universe

    13th in the series:
    The study of cosmic evolution allows us to see the universe as it really is, to reflect on our place in it, and to "know the place for the first time."

  • First picture clearly showing craters on Mars

    The Search for Life

    12th in the series:
    Why do we explore? Since the beginning of the Space Age one of the chief drivers has been the search for life beyond Earth.

  • Image of Mars from Spirit rover

    Exploration and Science

    11th in the series:
    Human exploration is more than the sum of all science.

  • Jesco von Puttkamer, Boris Chertok, and Steven J. Dick

    International Cooperation

    10th in the series:
    One of the benefits of space exploration is international cooperation.

  • Capture of Intelsat VI

    Societal Impact of the Space Age

    9th in the series:
    As controversies swirl about funding, resources, motives and methods for spaceflight, it is well to consider the consequences of exploring space - and of choosing not to do so.

  • Barred Spiral Galaxy NGC 1300 - image by the Hubble Space Telescope

    Voyages of Discovery

    8th in the series:
    At the core of the Age of Space are the voyages themselves, and not by accident have spacecraft been named Mariner or Voyager.

  • Sailing ship replicas sail by the Shuttle Endeavour

    Conditions for Exploration

    7th in the series:
    Both the Age of Discovery and the Age of Space had ships, heroic explorers and navigators, but very different motivations.

  • President Kennedy at Rice University in 1962

    The Age of Space

    6th in the series:
    A continuous story of voyages further and further from the home planet.

  • Viking on Mars in 1976

    Reflections from the Past

    5th in the series:
    Recalling the ideas of previous thinkers.

  • Neil Armstrong

    Knowns and Unknowns

    4th in the series:
    Then and Now

  • Earthrise

    Consequences of Exploration

    3rd in the series:
    Learning From History

  • Astronaut John Grunsfeld on Hubble servicing mission

    Risk and Exploration

    2nd in the series:
    How do we balance risk and rewards?

  • Footprint on the Moon

    Historical Perspectives

    First in the series:
    The Importance of Exploration

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