Launched from Cape Canaveral on March 7th, 2009, NASA’s Kepler telescope has helped in the search for planets outside of the solar system (called exoplanets). In its short life, Kepler has discovered 70 percent of the 3,750 exoplanets known to date.
The $600 million Kepler mission finds alien worlds using the “transit method,” picking up on tiny brightness dips caused when orbiting planets cross a star’s face – as seen from Kepler’s perspective.
But the iconic space telescope is running low on fuel, so NASA has placed the spacecraft in a hibernation-like state in preparation to download the science data collected in its latest observation campaign.
“To bring the data home, the spacecraft must point its large antenna back to Earth and transmit the data during its allotted Deep Space Network time, which is scheduled in early August,” NASA officials wrote in a statement. (The Deep Space Network is the global array of radio telescopes that NASA uses to communicate with its far-flung spacecraft.)
So right now, the spacecraft will remain “stable and parked in a no-fuel-use safe mode,” says NASA. On August 2, the team will command the spacecraft to awaken from its no-fuel-use state and maneuver the spacecraft to the correct orientation so it can downlink the data.
Kepler’s latest mission
Since May 12, Kepler has been on its 18th observation campaign, staring at a patch of the sky towards the constellation of Cancer it previously studied in 2015. The data from this mission will help astronomers to confirm previous exoplanet candidates, as well as find any new candidates. Downloading this data is what will be attempted in August with Kepler’s remaining fuel.
NASA will provide an update after the scheduled download. The agency has been monitoring the Kepler spacecraft closely for signs of low fuel, and expects it to run out of fuel in the next few months.
If all goes well with the download of the 18th observation campaign, Kepler will begin its 19th observation campaign on August 6 with the remaining fuel.
“We expect to reach that moment within several months,” Charlie Sobeck, system engineer for the Kepler space telescope mission said in March, reports Tech Times. “Our current estimates are that Kepler’s tank will run dry within several months.”
NASA has already launched Kepler’s successor, the Transiting Exoplanet Survey Satellite, or TESS, which will also hunt for exoplanets. The spacecraft, launched in April, is designed to find Earth-sized planets that orbit within the “habitable zone” of stars.
TESS is an Explorer-class planet finder and will be used to conduct the first-ever spaceborne all-sky transit survey, mapping over 85 percent of the sky over the next two years. TESS has been selected by NASA as an Astrophysics Explorer mission. And like the older Kepler and K2 missions, TESS will also use the Transit method to find exoplanets.
Kepler has had a successful run
Besides its impressive raw planet tally, the spacecraft’s observations suggest that about 20 percent of sun-like stars host a roughly Earth-size planet in the habitable zone – a “just-right” range where liquid water exists. From 2009 through 2013, Kepler looked at about 150,000 stars, hunting for possible transits.
In 2013, the second of the spacecraft’s four orientation-maintaining reaction wheels broke, which meant that the spacecraft couldn’t hold a steady gaze at its original field of view. But using sunlight pressure, NASA engineers were able to stabilize the spacecraft.
In 2014, after getting a “‘new lease on life,” NASA gave the spacecraft a new mission, dubbed ‘K2.’This required the spacecraft to shift its orientation every three months to get a new view of the sky. Interestingly, Kepler used the pressure of the sun to maintain its gaze, ‘like a kayak steering into the current,” says Sobeck, reports the UK’s Daily Mail.
Also, in 2014, Kepler found an exoplanet 1,400 lightyears away that shares many of the same characteristics as our planet. The exoplanet was named Kepler-452b and dubbed ‘Earth 2.0’.
Kepler found a planet that orbits two stars, known as a binary star system, in 2011. Called Kepler-16b, it is about 200 lightyears away. This planet reminded experts of the ‘double-sunset’ pictured on Luke Skywalker’s home planet Tatooine in ‘Star Wars: A New Hope’.
But the Kepler’s biggest discovery was announced in February this year. In 2016, Kepler spotted what is called the “Trappist-1” star system. The system has a record seven Earth-like planets, each orbiting a dwarf star, and each likely to hold liquid water are just 39 million light-years away. Scientists say the Earth-like planets are in such good condition that life may have already evolved on them.
Refueling the Kepler spacecraft is not an option, says The Verge. Kepler orbits the sun, not Earth, and it’s currently about 94 million miles from our planet.
