The following is a piece I wrote the spring of my super senior year in college as a means of demonstrating my skills a a writer and science analyst while applying to graduate school. Although I did not conduct any interviews to complete this story, the content is completely based on material gathered from press releases and science articles detailing the Kepler mission. The prompt for this assignment was to write an article which could speculatively be published, something which I do believe I achieved. I enjoyed writing this piece immensely, and I hope you enjoy reading it, too.
Although it may be ages before
Earth-born explorers safely travel to other solar systems, their first
destination may well be the planet Kepler-22b, which is located 600 light-years
away. Discovered in 2009 as an anomaly
in the light from the star Kepler-22, the existence of this planet was
validated on December 5, 2011 by NASA’s ongoing Kepler Mission.
Named for sixteenth century astronomer Johannes
Kepler, the purpose of NASA’s mission is to locate and study planets which
orbit nearby stars in our galaxy. Launched
in March of 2009, the ultimate goal of the Kepler Mission is to find examples
of extra-solar planets, or “exoplanets,” which orbit their suns within a
specific region known as the Habitable Zone.
At this distance, NASA scientists theorize that planets would receive
sufficient heat to contain liquid water, the most essential element for life on
Earth, thereby increasing the possibility that they may also support thriving,
living ecosystems. While many planets
have met this criteria, Kepler-22b is one of the first proven to be roughly
Earth-sized, meaning it could also sustain an atmosphere and environment much
like that of our home planet.
The Kepler Mission’s primary means
of detecting planets orbiting other stars is the transit method which measures
their luminosity, or the rate that stars puts out light. Kepler looks for a slight dimming in a star’s
luminosity which captures the moment that a planetoid passes across the face of
a star, called a transit. Each transit
momentarily blocks some of the star’s output of light, thereby altering the
overall brightness seen from Earth.
NASA’s primary tool for recognizing these events is the Kepler spacecraft,
a photometric telescope freely orbiting the sun capable of capturing and
measuring very slight changes in starlight caused by each transit. The Kepler probe is permanently fixed on a
small patch of the northern sky between the constellations Cygnus, Lyra, and
Draco and is capable of simultaneously monitoring nearly 150,000 stars.
A planet’s presence is confirmed
when a catalogued star’s luminosity decreases periodically and by the same
amount, indicating a sizeable body in a stable orbit. Because NASA’s criteria requires three
consistent transits before it will confirm the presence of a planet, the first
planets Kepler found circled their stars quickly and at extremely close range,
heating them unimaginably. Many of these
earliest finds are gas giants much larger than Jupiter, which were calculable
based on their immense size blocking large amounts of starlight. As the Kepler Mission gathered more data it
was able to locate a range of planetoids, from small rocky worlds to gaseous
monoliths. Kepler-22b is one of the
smallest planets found to date, but it is also one of the most intriguing as
the search continues for planets which support life.
The star Kepler-22 is a G5-type,
meaning it is slightly smaller and less bright than our sun. Additionally, while most stellar objects are
partnered in groups of two or more, the Kepler-22 system has no companion star. The first signal from the planet Kepler-22b
was captured only three days after NASA’s mission commenced in 2009, but due to
its 290 day orbit it took nearly three years to authenticate it as a
planet. At present, Kepler-22b is the
only known planet in its system, and is situated 15% closer to its parent star
than the Earth is to ours. This places
Kepler‑22b in the habitable zone, which differs for each star based on its
gravity and heat output. Researchers
believe this location may allow Kepler-22b to maintain a relatively temperate
climate with an average temperature near 72°F (22°C) if its atmosphere is also
similar to Earth’s.
Although it may initially appear
this exoplanet is Earth’s twin, or almost so, the two worlds are still vastly
different. Kepler-22b has a radius 2.4
times larger than the earth’s, and although its mass has not been determined,
it could be many times heavier than our own planet. The more massive an object, the more gravity
it has, which could be the difference between Kepler-22b retaining an
atmosphere suitable for life or it crushing everything on its surface under
tons of air pressure.
The actual composition of Kepler-22b is still under
debate, and will take many more observations using both ground and space
telescopes to deduce whether it is primarily solid, liquid, gas, or a
combination of all three. Unfortunately
the technology of spectroscopy, which can be used to determine the chemical
makeup of stars, is not sophisticated enough to measure Kepler-22b’s
atmosphere. Spectroscopy looks at the
range of colors reflected from far away objects and specifically studies gaps
in this spectrum. The atoms which make
up different elements absorb the energy in light rays, and missing colors
indicate the presence of particular elements by the signature pattern they
leave. Gathering this spectral
fingerprint, as it were, would reveal the components of the planet’s atmosphere,
and most importantly whether it has liquid water. However, taking a spectral image of a planet
600 light-years away is a major task and easily overwhelmed by the light from
its host star. Hopefully, advancements
in telescopic imagery will eventually make this possible.
NASA recently announced the existence of Kepler-22b
alongside over 1,000 new planetary candidates from data it collected over the
past year, bringing the total number of discoveries by the Kepler Mission to
2,326. Of these, 207 are Earth-sized
planets, 680 are so-called super-Earths at least twice as large as our planet,
over 1,000 are similar in size to Neptune, and the remainder are the size of
Jupiter or larger. However, it will take
years of research to verify true planets from random anomalies in starlight,
companion stars in close proximity transiting each other, or even simple
glitches in the data collection. Kepler-22b
is the first officially confirmed planet among the 48 habitable zone candidates
currently studied by NASA. Its size and
distance to its star, in relation to the star’s size and brightness, make
Kepler-22b the most Earth-like of all planetary bodies discovered by the
mission.
One possibility researchers face is that Kepler-22b
is not Earth-like at all, but rather a different classification of planet. The fact that Neptune’s radius is 3.8 times
the size of Earth, and it is 17 times as massive, has lead some astronomers to
wonder if Kepler-22b is not a solid planetoid at all but instead a miniature
gas planet. However, this concern is
based solely on speculation and has yet to be proven or disproven.
Kepler is not the only mission locating exoplanets,
especially those which may harbor life.
One of the most notable findings is the star system Gliese 581 which
contains several super-Earths, at least two of which rotate in the habitable
zone. Meanwhile, the planet Gliese 370b,
rests just within the habitable zone of its own star, and could potentially
sustain life if its atmosphere is similar to Earth’s.
Kepler-22b is the latest in an impressive list of
destinations astrobiologists are eager to study with the hopes of proving the existence
of life elsewhere in our galaxy. Still,
there are many other factors than a planet’s distance from its sun which
determine whether it is viable for life, and until these can be demonstrated the
question whether there is life on other worlds cannot be answered. According to the Rare Earth Hypothesis, there
are many determining criteria which must be present on a planet or within a
solar system for organisms to survive.
For instance, the planet’s sun must provide enough energy while existing
long enough for life to evolve; there must be a moon to stabilize the planet’s
rotation; a gas giant must be present in the solar system to attract asteroids
which could otherwise strike the planet; and the planet must be able to
regularly renew its land, water, and atmosphere. The likelihood all these factors, and more,
can be accounted for on any one planet such as Kepler-22b is extremely small,
but luckily not impossible given the billions of different stars and planets in
our galaxy alone.
Though the Kepler Mission is scheduled to last
throughout 2012, team leaders and supporters throughout the scientific
community are pushing to extend the operation, claiming that the program has
only just begun to accumulate usable data on the sheer expanse of star systems
within our galaxy. Kepler is in constant
coordination with numerous scientific teams throughout the world, uniting with
ground-based observatories, NASA engineers, university professors and
specialists, and even the SETI program, the Search for Extra Terrestrial
Intelligence. Increasing technologies,
like the launch of the James Webb Space Telescope in the next 5-10 years, will
refine and increase the ability to observe nearby stars and planets, and may
boost the Kepler Mission’s ability to find and classify new planets. At present, though, our knowledge of
Keplter-22b and many other planets is limited, but their existence has already
sparked the imagination of scientists, students, artists, and everyday people
whose desire to push the limits of space exploration is the fuel needed for
future success.
No comments:
Post a Comment