On October 30, 2018, Kepler, NASA's planet-hunting space telescope, sent its last signal. It had been on the ropes for years due to lack of reaction wheels, but engineers had managed to keep it in operation. Then last year no fuel ran out.
Its mission was originally planned for a period of 3.5 years. The telescope was in the last 9 years, 7 months and 23 days, which revolutionized our understanding of exoplanets. And it took observations right up to the end.
When a telescope takes its very first astronomical image, it's called "first light". Kepler's first slide was snapped on April 8, 2009.
Space Telescope's Last Image – Its & # 39; Last Light & # 39; – was taken on September 25, 2018.
The Kepler camera was composed of 42 charged CCD image sensors, each with a resolution of 1,024 at 2,200 pixels. You can see a picture of it below – CCD's layout is why Kepler's images are framed as they are.
As you can see in the last slide, there are a few blank squares where the CCDs have failed over the years. You can't just sip into the room to repair a telescope so this was expected with a modular array, where the fault of a sensor wouldn't knock out much of them.
That means that the last full field of view Kepler saw before it closed its eyes for the last time was still a rich one.
"For this final field of view, Kepler's last observation campaign in his extended mission, the telescope was pointed towards the constellation Aquarius," wrote NASA's Alison Hawkes.
"It got a glimpse of the famous TRAPPIST-1 system with its seven rocky planets, at least three of them thought to be temperate worlds. Another goal was the GJ 9827 system, a nearby light star hosting a planet that considered an excellent opportunity for follow-up observations with other telescopes to study an atmosphere in a distant world. "
The edge of the picture also overlaps with observations taken by TESS, Kepler's successor. TESS officially began taking science observations in August 2018, so there was a very short period when the two telescopes worked simultaneously.
This overlap means that scientists here on Earth can compare the two images to try to understand the data better.
The field-of-view was not the last thing Kepler saw. It also took video of the TRAPPIST-1 system, six planet star K2-138 and GJ 9827, showing the fluctuations in their brightness. You can watch these videos here.
Kepler was looking for planets by constantly monitoring the stars in a fixed field of vision, looking for a telltale signature – regular repetitive dimming, indicating a revolving object that goes between us and the star. A planet. This is called the shipping method, and now TESS has picked up the baton.
But TESS has large reaction wheels to fill. During his years in the Earth's orbit around the Sun, Kepler observed 530,506 stars and identified 2,662 exoplanets. And even though Kepler is gone now, it is absolutely not forgotten: astronomers use the data they delivered in the coming years.
Vale, little friend. To infinity and beyond.