Write An Essay Of Space Science And Research

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Sample Essay - Week 5: The Pluto Controversy: What's A Planet, Anyway?
This essay was developed for the AMNH online course The Solar System . The Solar System is a part of Seminars on Science, a program of online graduate-level professional development courses for K-12 educators.

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Okay, everyone, it's official. Pluto is not a planet. As decreed in August 2006 by a vote of the General Assembly of the International Astronomical Union (IAU), Pluto is now a "dwarf planet." On the other hand, who does the IAU think it is—indeed, who do we astronomers think we are—to be able to demote Pluto? Isn't that sort of like California declaring that Liechtenstein isn't a country?

The word planet seems to hold an irrational sway over our hearts and minds. That made sense in the days when, along with stars, they were the only familiar objects in space—before telescopes could observe the birth of distant galaxies, before space probes had bulldozed into a comet, and before we understood the history of cosmic collisions that links celestial bodies large and small.

In these past four weeks, we've looked at the Solar System as scientists do: at its structure and composition, its origin, and its contents, rocky and gassy. Let's look at Pluto once again—not in terms of rigid classification or nursery-school mnemonics but in the context of its scientific importance—and at how learning more about Pluto contributes to the human endeavor of understanding the cosmos.

What's a planet, anyway?

All the Sturm und Drang about Pluto stems from a simple problem. The label planet originated in ancient Greece. The word simply meant "wanderer" and referred to the seven prominent celestial objects—Mercury, Venus, Mars, Jupiter, Saturn, the Sun, and the Moon—that moved against the background of stars.

Life got more complicated in 1543, when Nicolaus Copernicus described a newfangled Solar System. In his heliocentric universe, instead of remaining stationary in the center, Earth moved around the Sun, just like the other bodies. At that moment, planet lost its astronomical meaning. Astronomers tacitly agreed that whatever orbits the Sun is a planet and whatever orbits a planet is a moon.

Evolving Our Understanding
Petrus Apianus's Earth-centric engraving of the Solar System (left) from 1540 shows the planets and the Sun orbiting Earth, with a band of constellations around the perimeter. In 1543, Copernicus's revolutionary heliocentric system (center) paved the way for modern astronomy, including way-finding diagrams like the plaque (which includes Pluto) on the Pioneer 10 spacecraft (right), now heading into interstellar space. ©Library of Congress/NASA

This wouldn't be a problem if cosmic discoveries had ended with Copernicus. But shortly thereafter, we learned that comets, too, orbit the Sun and are not local atmospheric phenomena, as was long believed. Comets are icy objects on elongated orbits that throw off a long tail of gases as they near the Sun. Are they planets too? How about the chunks of rock and metal that orbit the Sun between Mars and Jupiter in the asteroid belt? When Ceres, the first such object, was detected by Giuseppe Piazzi in 1801, everyone called it a planet. With the discovery of dozens more, however, it became clear that this new community of objects deserved its own classification. Astronomers called these small bodies made of rock and minerals asteroids, and have now cataloged tens of thousands of them.

Even the traditional planets don't fit into one neat category. The rocky planets (Mercury, Venus, Earth, and Mars) form a family because they are relatively small and rocky, while the gassy planets (Jupiter, Saturn, Uranus, and Neptune) are large, gaseous, have many moons, and bear rings.

And who's counting?

The number of planets dropped to six when the Sun and the Moon were deleted and Earth was added. When Uranus was found in 1781, the figure rose to seven again. It was bumped up to 11 with the discovery of the four largest bodies in the zone between Mars and Jupiter. Then it dropped back to seven again after these four bodies—along with others in the zone yet to be discovered—were demoted to asteroids. Once Neptune was spied in 1846, the total became eight.

When astronomer Clyde Tombaugh found Pluto in 1930, after a dogged search for a long-suspected Planet X beyond Neptune, the tally rose to the now-familiar nine. But refined measurements showed the object to be much, much smaller than originally thought: smaller, in fact, than six of the satellites in the Solar System, including Earth's Moon.

The Kuiper Belt thickens the plot

The story took another twist in 1992, when David C. Jewitt of the University of Hawaii and Jane Luu of the Massachusetts Institute of Technology began to detect a swath of frozen objects on the Solar System's fringes, out beyond Neptune. This region of icy bodies was named the Kuiper Belt in honor of the Dutch-born American astronomer Gerard Kuiper, who predicted its existence. Pluto is one of its largest members. Akin to the asteroids in the belt between Mars and Jupiter, these bodies nevertheless made up another category of objects in the Solar System. Over 800 other Kuiper Belt objects have since been cataloged. Should they all be called planets?

The Kuiper Belt
A disk-shaped region of icy debris beyond the orbit of Neptune, the Kuiper Belt likely contains remnants of the early Solar System, as does the asteroid belt. Because many asteroids and comets never formed planetary bodies that melted, they record early Solar System processes—a record that has been erased elsewhere. ©NASA/JHU
So we find ourselves at the International Astronomical Union General Assembly, meeting in Prague in August 2006. At first the IAU seemed ready to defend Pluto's planetary standing. On August 16, after many meetings over the course of a year, its seven-member Planet Definition Committee stated that round objects in orbit around the Sun are planets. Roundness (though not necessarily a perfectly spherical shape), reasoned the committee, indicated a balance between the gravitational forces pulling matter inward and the internal pressure pushing outward within a celestial body: a scientifically significant state called hydrostatic equilibrium.

Since Pluto qualifies, this would have given everyone the right to place Pluto and Jupiter in the same category, even though Jupiter is 250,000 times larger. The draft resolution would also have rendered at least three additional objects eligible for planet status, objects that had achieved hydrostatic equilibrium but had previously been deemed "too small."

So for that one week in 2006, there were 12 planets. The IAU's roundness criterion added Ceres, the largest asteroid; Pluto's moon Charon, which is unusually large relative to Pluto; and another Kuiper Belt object, 2003 UB313, affectionately dubbed Xena after the leather-clad warrior princess from cable television, but now officially named Eris, after the Greek goddess of discord.

Plutophiles had about a week to rejoice before the astronomers refined their definition: a planet must also be the most massive object in its orbital zone. Poor Pluto is crowded by thousands of other icy bodies in the outer Solar System, some bigger than Pluto itself, so it fails the test. This criterion also eliminated Ceres, Charon, and Eris. To soothe the Pluto boosters, the IAU elected to call it a dwarf planet, without clearly qualifying what that is.

And Then There Were Eight
In 2006, the International Astronomical Union published a draft illustration of the Solar System containing 12 planets (bottom). One week later, a final illustration was published (top), with four of those objects reclassified as "dwarf planets." ©IAU
How much should counting count?

So today we're officially back to eight planets—the nine we memorized in grade school, minus Pluto.

Counting planets does encourage clever mnemonics, such as "My Very Educated Mother Just Served Us Nine Pizzas"—or its likely successor: "My Very Educated Mother Just Served Us Noodles." Or Nectarines. Or Nopalitos! It could be argued that such counting exercises have stunted the curiosity of an entire generation of children. Counting and memorizing just stands in the way of appreciating the full richness of our cosmic environment, right? On the other hand, it's well known that the concreteness of lists and lyrics helps students tie abstract concepts to tangible learning tools.

The best solution probably rests in the middle ground. For now, a dwarf planet is defined as a Solar System body that orbits the Sun, is near-spherical in shape, isn't a satellite, and shares the region around its orbit with other celestial bodies. And who knows how long that classification will stick?

The best question of all: What questions intrigue you?

Imagine a Solar System curriculum that begins with the concept of density—a big concept for third graders, but not inaccessible. Rocks and metals have high density. Balloons and beach balls have low density. Divide the inner and outer planets in this way, as cosmic examples of high and low density. Have fun with Saturn, whose density, like that of a cork, is less than that of water. (Unlike any other object in the Solar System, Saturn would float.)

You might wonder about the joint criteria of roundness and isolation. They're general enough to be shared by both tiny, rocky, iron-rich Mercury and massive, gaseous Jupiter. But what if other characteristics or phenomena pique your interest? Suppose, for example, that you're interested in cyclones. The thick, dynamic atmospheres of Earth and Jupiter are fertile breeding grounds for these storms, so they could be lumped together under that criterion. Fascinated by the chemistry of life? Icy moons like Jupiter's Europa and Saturn's Enceladus may be the best extraterrestrial destinations in the search for liquid water, a crucial ingredient for life as we know it. Perhaps you think ring systems are cool, or magnetic fields, or size, or mass, or composition, or proximity to the Sun, or formation history. Each attribute could serve as a vector for exploring the bodies that populate the Solar System.

These classifications say much more about an object than whether it is round, or unique in its neighborhood, or what category we assign it to. Why not rethink the Solar System as multiple, overlapping families of objects? Then the way you organize them is up to you. The fuss over Pluto doesn't have to play out as a death in the neighborhood. Instead, it could mark the birth of a whole new way of thinking about our cosmic backyard.

No matter how the scientific debate about Pluto rages in the years to come, it will remain a beloved little icy dirtball to millions—and a catalyst to scientific curiosity and excitement. And if you're a Pluto lover, you can rest assured that the dwarf planet won't be forgotten. Guess what the American Dialect Society declared as the 2006 Word of the Year? "Plutoed."


Space research is scientific studies carried out using scientific equipment in outer space. It includes the use of space technology for a broad spectrum of research disciplines, including Earth science, materials science, biology, medicine, and physics. The term includes scientific payloads everywhere from deep space to low Earth orbit, and is frequently defined to include research in the upper atmosphere using sounding rockets and high-altitude balloons. Space science and space exploration involve the study of outer space itself, which is only part of the broader field of space research. Major Space Research Agencies in the World.


For centuries, the Chinese had been using rockets for ceremonial and military purposes. But it wasn’t until the latter half of the 20th century that rockets were developed to overcome Earth's gravity. Such advances were made simultaneously in three countries by three scientists. In Russia, Konstantin Tsiolkovski, in the United States was Robert Goddard, and in Germany was Hermann Oberth.

After the end of World War II, the United States and the Soviet Union created their own missile programs and space research emerged as a field of scientific investigation based on the advancing rocket technology. In 1948–1949 detectors on V-2 rocket flights detected x-rays from the Sun.[1]Sounding rockets proved useful for studies of the structure of the upper atmosphere. As higher altitudes were reached, the field of space physics emerged with studies of aurorae, the ionosphere and the magnetosphere. Notable as the start of satellite-based space research is the detection of the Van Allen radiation belt by Explorer 1 in 1958, four months after the launch of the first satellite, Sputnik 1 on October 4, 1957. In the following year space planetology emerged with a series of lunar probes, e.g. the first photographs of the far side of the Moon Luna 3 in 1959.

The early space researchers obtained an important international forum with the establishment of the Committee on Space Research (COSPAR) in 1958, which achieved an exchange of scientific information between east and west during the cold war, despite the military origin of the rocket technology underlying the research field.[2]

On April 12, 1961, Russian Lieutenant Yuri Gagarin was the first human to orbit Earth in Vostok 1. In 1961, US astronaut Alan Shepard was the first American in space. And on July 20, 1969, astronaut Neil Armstrong was the first human on the Moon. On April 19, 1971, the Soviet Union launched the Salyut 1, which was the first space station of any kind. On May 14, 1973, Skylab, the first American space station was launched using a modified Saturn V rocket.[3]

Research fields[edit]

Space research includes the following fields of science:[4][5]

  • Earth observations, using remote sensing techniques to interpret optical and radar data from Earth observation satellites
  • Geodesy, using gravitational perturbations of satellite orbits
  • Atmospheric sciences, aeronomy using satellites, sounding rockets and high-altitude balloons
  • Space physics, the in situ study of space plasmas, e.g. aurorae, the ionosphere, the magnetosphere and space weather
  • Planetology, using space probes to study objects in the planetary system
  • Astronomy, using space telescopes and detectors that are not limited by looking through the atmosphere
  • Materials sciences, taking advantage of the micro-g environment on orbital platforms
  • Life sciences, including human physiology, using the space radiation environment and weightlessness
  • Physics, using space as a laboratory for studies in fundamental physics.

Space research by satellites[edit]

Upper Atmosphere Research Satellite[edit]

The Upper Atmosphere Research Satellite was a NASA-led mission launched on September 12, 1991. The 5,900 kg (13,000 lb) satellite was deployed from the Space Shuttle Discovery during the STS-48 mission on 15 September 1991. It was the first multi-instrumented satellite to study various aspects of the Earth's atmosphere and have a better understanding of photochemistry. After 14 years of service, the UARS finished its scientific career in 2005.[6]

International Gamma-Ray Astrophysics Laboratory[edit]

The INTEGRAL is an operational space satellite launched by the European Space Agency in 2002. INTEGRAL provides insight into the most energetic forms of in space, such as black holes, neutron stars, and supernovas.[7] INTEGRAL also plays an important role in researching one of the most exotic and energetic phenomena that occurs in space, gamma-rays.

Hubble Space Telescope[edit]

The Hubble Space Telescope was launched in 1990 and it sped humanity to one of its greatest advances to understand the universe. The discoveries made by the HTS have changed the way scientists look at the universe. It winded the amount of space theories as it sparked new ones. Among its many discoveries, the HTS played a key role in conjunction with other space agencies in the discovery of dark energy, a mysterious force that causes the expansion of the universe to accelerate. More than 10,000 articles have been published by Hubble data, and it has surpassed its expected lifetime.

Gravity and Extreme Magnetism Small Explorer[edit]

The launch of the NASA-led GEMS mission is scheduled for November 2014.[8] The spacecraft will use an X-Ray telescope to measure the polarization of x-rays coming from black holes and neutron stars. It will also conduct research on remnants of supernovae stars that have exploded. Few experiments have been conducted in X-Ray polarization since the 1970s, and scientists expect GEMS will break new ground. Through GEMS, scientists will be able to improve their knowledge in black holes, in particular whether matter around a black hole is confined to a flat-disk, a puffed disk, or a squirting jet.

Space research on space stations[edit]

Salyut 1[edit]

Salyut 1 was the first space station ever built. It was launched in April 19, 1971 by the Soviet Union. The first crew failed entry into the space station. The second crew was able to spend twenty-three days in the space station, but this achievement was quickly overshadowed since the crew died on reentry to Earth. Salyut 1 was intentionally deorbited six months into orbit since it prematurely ran out of fuel.[9]


Skylab was the first American space station. It was 4 times larger than Salut 1. Skylab was launched in May 19, 1973. It rotated through three crews of three during its operational time. Skylab’s experiments confirmed coronal holes and were able to photograph eight solar flares.[10]


From 1986 to 2001, Russian space station Mir served as a permanent microgravity research laboratory in which crews conducted experiments in biology, human biology, physics, astronomy, meteorology and spacecraft systems with a goal of developing technologies required for permanent occupation of outer space.

International Space Station[edit]

The International Space Station has played a key role in advances in space research. Since the arrival of Expedition 1 in November 2000, the station has been continuously occupied for 17 years and 132 days, having exceeded the previous record of almost ten years set by the Russian station Mir.[11] The ISS serves as a microgravity and space environment research laboratory in which crew members conduct tests in biology, physics, astronomy and many other fields.

See also[edit]


  1. ^A Brief History of High-Energy Astronomy: 1900-1958, NASA web page
  2. ^Willmore, Peter: COSPAR’s first 50 years, Public Lecture
  3. ^A Brief History of Space Exploration | The Aerospace Corporation. (n.d.). The Aerospace Corporation | Assuring Space Mission Success. Retrieved May 7, 2013
  4. ^COSPAR Scientific Structure, COSPAR web page
  5. ^Advances in Space Research, Elsevier web page
  6. ^UARS Science main page. (n.d.). UARS Science main page. Retrieved May 7
  7. ^ESA Science & Technology: Fact Sheet. (n.d.). ESA Science and Technology. Retrieved May 6, 2013
  8. ^GEMS
  9. ^Salyut 1Archived 2008-05-09 at the Wayback Machine.. (n.d.). Encyclopedia Astronautica. Retrieved May 7, 2013
  10. ^The SkyLab Project. (n.d.). Solar Physics Branch Home Page, Naval Research Laboratory. Retrieved May 7, 2013
  11. ^NASA - Facts and Figures. (n.d.). NASA - Home. Retrieved May 7, 2013

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