You have probably heard of the Kepler space observatory, a spacecraft that hunted for
exoplanets in our galaxy.
It carefully examined a patch of space which contained roughly 150,000 visible stars, and
with its combined camera resolution of 94 megapixels, it searched for stars that dip
in brightness periodically.
The theory is that if a star dims regularly in constant intervals, it’s because one
of its planets has passed in front it from Kepler’s perspective, which causes that
star to dim.
The Kepler mission has been wildly successful, beyond the expectations of most, discovering
a total of 2,662 planets since 2009.
But sadly, Kepler hasn’t been in full operation since 2013 as two out of four of its reaction
wheels have failed.
These reaction wheels keep the viewing angle of the spacecraft stable, otherwise it loses
sight of its fixed field of view.
The reaction wheels that were still working couldn’t keep Kepler steady enough to continue
its mission.
So instead of abandoning the spacecraft altogether, NASA came up with a new mission.
Instead of fighting against its rotation as it orbits, it would see what it can find in
different fields of view.
The way they did this was quite ingenious, using solar wind pressure, they could keep
the spacecraft aligned for about 3 months looking at one patch of sky, all the while
preventing rotation of the spacecraft, so very much a balancing act.
During the second mission, or K2 as they called it, it found even more exoplanets which brought
it to the 2,662 total, with about twice that still considered exoplanet candidates.
On the 30th October, just 2 weeks ago from writing this script, Kepler finally ran out
of fuel, and the mission has been retired.
Kepler will be left roughly 100 million kms away from us, forever orbiting the Sun now
that it can finally rest after its almost 10 year mission.
Because of this mission, 2,946 scientific papers have published, it found worlds similar
in size to our own, and has confirmed that there are more planets than stars in our galaxy.
But what now?
Is this the end for exoplanet hunting?
Fortunately, it’s not!
Earlier this year, NASA launched the TESS spacecraft, an ambitious upgrade to Kepler.
But what sets TESS, or the Transiting Exoplanet Survey Satellite, apart from Kepler?
Unlike Kepler, TESS will be in orbit of the Earth and not the Sun.
Its orbit is quite interesting, in that it approaches the orbital distance of the moon,
except its orbital plane is about 40 degrees compared to the moon.
This highly elliptical orbit maximises the time it can spend observing the stars.
During its orbit, it approaches close to the Earth, during which time it will transmit
the data it has collected, before setting its cameras back to the sky.
It orbits the Earth roughly twice a month, meaning it avoid the gravitational tugs of
the moon that would otherwise affect its orbit.
TESS began testing its cameras as it approached its orbital plane in July 2018.
It fixed its view on a region of space, and this is what is saw over the course of 17
hours.
The first thing that comes into view is this big white blob that moves across the image.
This is actually a comet, and you can even see the direction of its tail shift as it
moves around the Sun.
These two stars here are variable stars, stars that change in brightness very quickly for
astronomical standards.
Most of the other dots in the image are fixed stars, although, if we speed up the footage,
you can even see a few asteroids moving across the image.
Here are a few of them moving here!
In August of 2018, TESS reached its intended orbit, and began its own mission in earnest.
Although still using the transit photometry method to find exoplanets like Kepler did,
it is different in that it has four 16-megapixel cameras which each covers a square 24 degrees
across.
That’s wide enough to easily fit in an entire constellation.
These four cameras are arranged so TESS can view a whole strip of the sky at once.
It will lock onto this section of the sky for 27 days before moving on to the next,
eventually covering the whole southern sky over the course of its first year.
After that, it will move on to the northern sky, eventually observing 85% of the total
sky, an area 350 times bigger than the Kepler telescope.
Here you can see the Kepler and K2 fields of view for comparison.
Through this method of observation, the poles will be under constant surveillance, meaning
it will be able to detect exoplanets even if their orbital periods are greater than
27 days in these sectors.
TESS won’t be the only exoplanet hunting mission either.
The ESA will be launching their own version of this mission in 2026 called Plato.
And once the James Webb space telescope is in finally in operation, it will look at trying
to image these exoplanets to see what kind of atmosphere they have.
One last exciting proposal which hasn’t been approved yet is the New Worlds mission.
It would be a large occulter that would block the intense light of a distant star in order
to see the planets around it.
It could work with missions like the James Webb telescope, or have its own dedicated
telescope.
Have you been inspired to learn about more about exoplanets?
How about with a more hands on approach?
Passively learning about exoplanet discovery is great, but actively grappling with the
process of how scientists do it means you can truly understand and retain this knowledge!
An excellent place to start exploring astronomy is through Brilliant.
They have a bunch of courses teaching you how to think like a scientist.
Each course is interactive and breaks up complicated concepts into bite-sized chunks!
As Brilliant have supported this video, you can try Brilliant out for free today by using
the link brilliant.org/astrum.
Then, if you like what you see, the first 200 people that used that link will get 20%
off the annual Brilliant premium subscription!
Also, want to know more about the exoplanets we have already discovered?
Check out my previous video by clicking the card here.
And a big thanks for watching!
If you enjoyed what you saw, consider supporting the channel on Patreon.
It really helps me to make more videos like these in the future!
All the best, and see you next time.