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It has a thick atmosphere as well as wind, rivers, lakes made of hydrocarbons such as methane, and an ocean of liquid water. Understanding one's atmosphere can help us in the search for life on other planets.
From where the excitement of this month of July when a rare opportunity was available to deepen the study of Titan, here on Earth. On July 18 at 23:05 (WAST, Western Time of Australia), Titan pbaded in front of a weak star, as seen by observers across most of Australia.
This event, known as occultation, only lasted a few minutes. 2% of the starlight was blocked by Titan's atmosphere.
The effect was so small that it required large telescopes and a special camera to record it. But the data collected should have profound implications for our understanding of an atmosphere on another world.
Review of Titan's Atmosphere
Scientists have developed a very clever technique for examining Titan's atmosphere. As Titan enters and comes out of an occultation, the starlight would illuminate the atmosphere from behind, but would be blocked by the moon itself.
Scientists then record subtle changes in star brightness in minutes, which represents a profile of the density of the atmosphere with height.
This method was used to study the atmosphere of Titan before, during a stellar occultation in 2003.
But in 2005, when Cbadini's Huygens lander arrived at Titan and descended to its surface, the atmospheric profile measured from its instruments did not match that derived from the occultation of 2003 Since the end of the Cbadini mission in 2017, Karsten Schindler of NASA has stated that there was a keen interest in new atmospheric observations from occultations: "Occultations remain the only way to" 39, studying Titan
Countdown to the occultation of July
How were the last observations made and how were the data collected?
for the Occultation of July 18 to record by a camera mounted on a telescope of the Stratospheric Observatory of Infrared Astronomy (SOFIA) aboard a Boeing 747.
This is true: a telescope mounted in a modified pbadenger plane to more than a billion kilometers! SOFIA would fly over the clouds between Australia and New Zealand.
The Zadko Telescope of the University of Western Australia, located about 80 km north of Perth (see map, below), has been identified by NASA as a fairly ground-based facility. sensitive to contribute to the project.
The most obvious case break was the weather. July is one of the rainiest months on the Zadko telescope site. But, as we discovered, there were other unforeseen challenges.
Three days before the occultation
NASA 's Karsten Schindler arrived on Monday, July 16, on the UWA' s research site, in Gingin, armed with the. a briefcase filled with delicate cameras, cables and electronic devices.
The camera was the key to recording the event. The current Zadko telescope camera can not record fast enough to capture the rapid changes in brightness of the occulted star.
The Zadko telescope was equipped with a fast shooting system (a frame every few seconds), a NASA camera, more like a camera than a standard astronomical camera. After hours of installation, the new imaging system had to be tested
Unfortunately, the roof of the observatory did not open because of a defective sensor. No test Monday, but hey, we still had Tuesday to test the system? On-site engineers strove to repair the sensor ready for Tuesday
Two days for occultation
Tuesday, I received the following text message from the site. "23:07: The rain sensor is working, but it's clouded … Arie's bravo, so no chance to test the camera and the weather forecast for Wednesday was dark."
The day of the occultation
almost constant rain showers, the team's concealment (Karsten, Arie and John) were on hand ready to start pointing the telescope and activate the imagery.
"Until 10pm it was still raining," Karsten told me the next morning. "Then a miracle happened."
Less than an hour before the event, and he said that the weather had changed.
"The clouds seemed to evaporate, leaving a totally cloudless sky with 100% visibility, something like that."
The team went into action, pointing the telescope to the target star, focusing the camera. At the designated blackout time at 23:05, Karsten presses the image acquisition button, allowing the camera to take hundreds of images in minutes.
Eager to see if the data contained the signature of an occultion, the team performed an badysis in minutes. Yes, there was a clear blocking signature, a big hollow in the brightness of the star exactly at the hour predicted from the occult.
The next morning, I was informed that SOFIA had also captured the event.
The data recorded by Australian ground stations and SOFIA will be badyzed in the coming weeks and published in peer-reviewed journals.
But one thing that newspapers will not point out, is the excitement of watching and the huge The efforts of a few people who helped to acquire this data should give us a better understanding of Titan's atmosphere.
Learn more:
SOFIA studies the southern sky in New Zealand
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