Friday, May 7, 2010
Welcome to the Galaxy
Bill Welsh is part of a world-renowned team of scientists looking for Earth-like planets
It’s 2 a.m. on March 4, 2009. At a hotel near Kennedy Space Center, the night sky is full of stars, and so is Bill Welsh’s mind.
The San Diego State astronomy professor bolted awake, suddenly plagued with doubts about the computations he’d done for NASA’s Kepler space mission. The mission was to launch in less than a week and Welsh was part of its nationwide science team.
While most around him slept, Welsh stayed up until dawn reworking his calculations, which would be used for a tool to analyze data sent from Kepler.
“There’s a lot of internal pressure—you know how important this is and you feel an obligation to do the best that can be done,” he explained.
Are there other Earths?
The Kepler Mission is NASA’s 10th Discovery mission and the first of its kind to search for Earth-sized planets in the “habitable zone,” defined as a region around a star that would be suitable for life. Astronomers jokingly call it the Goldilocks zone—not too hot, not too cold, but just right.
Launched last March, Kepler will survey more than 100,000 stars over three and one-half years. The Kepler telescope uses photometry to find planets by detecting the very slight change in brightness (only 0.008%) that occurs when an Earth-sized planet passes in front of its host star.
Things malfunction; things break. And you can’t fix them when they’re up in space.”
The telescope’s power is astounding: from its view up in space, it could detect one person in a small town turning off a porch light at night. So far, five lights have gone out.
At a Jan. 4 press conference, NASA announced that Kepler’s telescope has already discovered five new extrasolar planets, also called exoplanets and defined as planets beyond our solar system. Team members expect Kepler may find as many as 50 Earth-sized planets during its mission.
“The discoveries highlight the fact that Kepler’s telescope is working well and can find planets easily,” said Welsh. “Kepler’s precision is much better than anything seen before; it can make breakthrough discoveries, given enough time.”
All five of the newly discovered exoplanets orbit stars that are hotter and larger than Earth’s sun and incapable of hosting life as we know it. Their orbits take three to five days, compared to Earth’s leisurely 365 days.
Kepler’s initial discovery is the stepping stone to the potential discovery of smaller planets with longer orbits—planets that are more similar to Earth and possibly capable of sustaining human life.
It will take years of data collection before NASA can confirm and announce the sighting of such Earth-like planets, Welsh said. If they are found, new telescopes could be built to further examine them and begin the search for life.
Managing the data
Welsh played a role in the discovery of one of the exoplanets, Kepler 8b, by measuring the planet’s characteristics. He continues to work on refining scientists’ understanding of that system with information on its size, temperature, orbit and more.
Though he is busy working on Kepler now, he was not always confident that he would have any data to work with.
“Before the launch, I was very optimistic, but very nervous. I thought, ‘Is this thing going to work?’ (This mission) is technically very difficult. Things malfunction; things break. And you can’t fix them when they’re up in space.”
Having worked with Kepler data for some months, the focus of Welsh’s worries has shifted.
“Now my concerns are, ‘Can I keep up with the data? Does my software match the quality of data Kepler is producing? Am I doing things quickly enough?’”
All are valid questions. Kepler is producing such an enormous amount of data that scientists have to be selective about which projects to pursue since their staff numbers are limited.
SDSU’s Kepler roots
NASA chose Welsh in 2007 as one of the nine astronomers nationwide to add to the Kepler science team.
While the main science working group is focused on detecting Earth-sized planets, Welsh and the other Participating Scientists carry out complementary research on the detection, characterization and understanding of exoplanets.
Welsh’s task is to complete a meticulously detailed analysis of planets similar to Jupiter using a cutting-edge analysis tool written by fellow SDSU astronomy professor Jerome Orosz.
He and Orosz have worked closely for the last few years on extrasolar planet research, and Orosz is a paid consultant for the Kepler Mission under Welsh’s grant.
In fact, SDSU’s ties to the Kepler Mission predate Orosz and Welsh. Kepler Principal Investigator Bill Borucki looked to SDSU adjunct astronomy professor Andy Young for guidance when he was getting started on this project back in the mid-1980s.
Borucki’s idea of finding other planets through photometry was pushing the limits, but fortunately, Young was an expert in the field. He helped mentor Borucki through the difficult process of perfecting the technique for locating Earth-like planets.
Now Welsh is bringing Kepler back to SDSU by using his work as an opportunity to mentor current students.
“You can believe I’ll be mentioning Kepler in my classes. My experience is that students love hearing that their professors are engaged in research. They’re not just reading a textbook; they’re being taught by someone who participates in research, and that excites them.”
Future of the mission
According to Welsh, there are two potential outcomes for the Kepler mission. One is the finding that there are many planets like Earth in the solar system, and therefore, life similar to ours may be common. The other is that Earth and life as we know it are indeed very rare.
Either outcome will have significant consequences, Welsh said. On one hand, scientists may hope to begin to detect other species and find that we are not alone in the universe; or, on the other hand, humans will realize just how important it is to preserve life and resources on our unique planet.
“This is an important project in NASA’s astrobiology path,” said Welsh. “It’s asking, are there other planets like ours out there? That’s the first question we need to answer.”
Read about the SDSU Observatory at Mt. Laguna.