Taking a Closer Look at Mysterious Pluto
Image: Hubble's "Mystic Mountain" -- the 20th
The Millionth Object is... an Exoplanet On Monday, July 4, the Hubble Space Telescope celebrated its latest milestone:
one million scientific observations
. Unfortunately, we can't "see" this landmark observation as a typically picturesque Hubble photograph as it was a spectroscopic analysis of a distant exoplanet's atmosphere. Analyzing the spectrum of light from worlds orbiting other stars is one component of Hubble's capabilities, but it's most famous observations recognized by fans of the space telescope are the amazingly detailed photographs of nebulae, galaxies, stellar phenomena and cosmic explosions. After 21 years, and a million observations, Hubble has transformed our perspective of the Cosmos, so in celebration of this latest milestone, Discovery News will take you on a journey of some of Hubble's recent, most striking imagery.
Image: The exoplanet Fomalhaut b as directly
Hubble's millionth observation is of the exoplanet HAT-P-7b (a.k.a. Kepler 2b), a gas giant larger than Jupiter orbiting a star 1,000 light-years from Earth. HAT-P-7b was originally discovered by ground-based observatories in 2008 and it has since been studied by NASA's Kepler space telescope. To complement these observations, Hubble has been used to analyze the exoplanet's spectrum so the chemicals present in its atmosphere can be identified. What is Hubble hoping to uncover?
Image: A nebula, located 20,000 light-years a
Atmospheric Water "We are looking for the spectral signature of water vapor," said Drake Deming of the University of Maryland and NASA's Goddard Space Flight Center in Greenbelt, MD. "This is an extremely precise observation and it will take months of analysis before we have an answer." "Hubble demonstrated it is ideally suited for characterizing the atmospheres of exoplanets, and we are excited to see what this latest targeted world will reveal."
Image: SNR 0509-67.5 is a supernova remnant r
21 Years Ago On April 24, 1990, shuttle Discovery launched with the 12 ton space telescope in its cargo bay, inserting it in a 559 kilometer (347 mile) around Earth. Last April, Hubble celebrated its 21st birthday.
Image: Spiral galaxy NGC 2841. Credit: NASA,
"For 21 years Hubble has been the premier space science observatory, astounding us with deeply beautiful imagery and enabling ground-breaking science across a wide spectrum of astronomical disciplines," said NASA Administrator Charles Bolden. "The fact that Hubble met this milestone while studying a faraway planet is a remarkable reminder of its strength and legacy." Bolden piloted the space shuttle during the 1991 Hubble mission (STS-31).
Image: Hubble can image objects in our solar
Servicing Missions Since its launch, Hubble has been visited five times by space shuttle crews. The first time, in 1993, was famous for the extensive work that had to be carried out on the telescope to correct its optics – particularly an out-of-shape mirror. After 10 days of spacewalks, the seven astronauts aboard shuttle Endeavour managed to give Hubble 20/20 vision. The following four service missions by Discovery (1997 and 1999), Columbia (2002) and Atlantis (2008) all served to upgrade the telescope, re-boost its orbit (to counter the effects of drag caused by Earth's tenuous atmosphere at that altitude) and fix failed equipment.
Image: A dramatic collision was captured in t
End of an Era? Now that the shuttle fleet is about to retire, Hubble no longer has an in-orbit support crew. It's by itself and some time within the next few years, the command will be sent to direct Hubble toward Earth to finish its dazzling career as a fireball as it reenters the Earth's atmosphere. Sadly, it appears Hubble's successor, the James Webb Space Telescope, will be canceled, so it's far from certain what shape the next "Hubble" will take. Special thanks to Ray Villard for assisting with the Hubble image selection!
In July 2015, we will see some of the most monumental photos of spaceflight history. NASA’s New Horizons probe will blast through the Kuiper belt, imaging the region beyond Neptune’s orbit and gathering an intimate view of the Pluto-Charon system. But until that fateful flyby, we will have to make do with fuzzy observations of the distant dwarf planet, although a surprising amount of detail can still be gathered by powerful telescopes and rendered by sophisticated models.
Enter the Scientific Exoplanets Renderer (SER) as used by Abel Méndez, planetary scientist and director of the Planetary Habitability Laboratory at the University of Puerto Rico, to create a very cool view of the small, yet complex world.
SER is more commonly used to generate photo-realistic images of exoplanets, renderings of which can be found in the Visible Paleo-Earth project and the Habitable Exoplanets Catalog. By gathering as much observational data about planets orbiting other stars as possible — such as data from the complex light-curves of transiting exoplanets — and feeding the SER, artistic renderings based on real observations can be generated. The more data available, the more precise the model.
So, looking a little closer to home, Méndez applied SER to Pluto. By feeding the algorithm with albedo data from the Hubble Space Telescope, he generated a “basic representation” of Pluto. For now, the model only uses albedo maps from Hubble (i.e. the brightness variations as mapped across Pluto’s surface), but Méndez plans to “produce more creative” versions, adding more detail to the apparent surface features.
“It will be fun to compare our progress, starting from our first image, until the final close-up pictures of Pluto on July 2015,” writes Méndez.
Interestingly, Méndez applied the same color palette as used to color observations of Triton, Neptune’s strange moon. Triton has a retrograde orbit around the ice giant (i.e. it orbits in the other direction to all the other 13 known Neptunian satellites) and has a very different composition leading planetary scientists to theorize that it is actually a captured Kuiper belt object and a close cousin to Pluto. Therefore there’s every reason to believe that we will spot some uncanny similarities between Pluto and Triton when seen up close.
In the run-up to the New Horizons flyby, there will be lots of opportunities to refine the model with new data.
Although he has yet to evaluate the SER Pluto model, New Horizons Principle Investigator Alan Stern, planetary scientist at the Southwest Research Institute, is keen to point out that as the spacecraft approaches the outer solar system observations of Pluto will become more and more detailed, inevitably enriching models like Méndez’s visualization.
“We will be imaging Pluto for navigational purposes beginning next summer, and then beginning in 2015 for science,” Stern said in an email to Discovery News. “We will surpass Hubble resolution in April, 2015. By June 2015 the image improvements will be dramatic, and improving noticeably each week. Approach imaging will be done both panchromatically and in color, and will be dense enough to create approach movies of Pluto and it’s satellite system.”
Before New Horizons’ robotic eyes start to resolve what promises to be an awe-inspiring moment in human ingenuity and spaceflight history, it will be fun to see computer models gain more and more detail until, eventually, we can compare them with the real thing in July 2015.
Image credit: PHL @ UPR Arecibo, NASA HST