NASA spent billions on the James Webb Space Telescope and now they’re going to launch
it really far away. I'm talking about over 1.5 million kilometers to be exact. But why
do we need to send it so far and what kind of technology did we put on board to support
mission success? Affectionately known as Webb, or JWST, this next-generation observatory
has been in development for over 25 years. And fun fact, as a Mechanical Engineer, I actually
got the chance to work with NASA on this incredible telescope, specifically with the instrument
module, which holds cutting-edge infrared technology. Webb is set to tackle some of
humanity’s biggest goals like searching for the first galaxies in our universe and
observing various signs for potential life in planetary systems. Mostly known as the
successor of the incredibly popular Hubble Space Telescope, Webb will observe the universe
with detectors that target near and mid-infrared wavelengths. This means that the instruments
on board Webb are specially designed to combat some of the historic challenges astronomers
have faced when trying to observe the early universe, like huge dust clouds that block
the view of celestial objects, cosmological redshifting, and even interference from other
bodies. In fact, there are three things necessary to create the perfect environment for an infrared
telescope: a large mirror to collect as much light as possible, extremely cold temperatures,
and a clear line of sight to your target. Each detail has been thought out meticulously
over the past two decades leading to this point, like where it will orbit. 1.5 million
kilometers is a bit of a trip to say the least. So why are we putting Webb in such a distant
orbit? Well, it’s heading to L2, the second Lagrange point around the Sun and Earth. These
five points are stable configurations that allow bodies to orbit each other, but still
remain in the same position relative to one another. The key to L2 is centripetal force,
which you can imagine as the tension in a rope o a tether ball that keeps it connected
to the pole. At L2, the centripetal force required for a small satellite-sized object
to move with respect to the Earth is equal to the gravitational pull of the two larger
masses. Meaning that this particularly cozy orbit has several benefits to support Webb’s
mission. The first is that because of the gravitational pull from the larger bodies,
Webb will move in sync with the Earth as it orbits the Sun. Which is great for commanding
and telemetry data drops back to our ground stations.
This allows us to use the Deep Space Network to stay in constant communication with the
satellite and cuts down on any potential delay time you might see on some other missions.
The second is thanks to centripetal force, it takes very short bursts of rocket thrust
to keep the observatory in the original L2 orbit, which can ultimately increase mission
life. The third benefit of the L2 position is that Webb’s tennis court-sized sun shield
can effectively block out any excess light from the Sun, Earth, and even the Moon. Thus
voila! Creating a beautiful and open line of sight between Webb and our target. So remember
the reason why we use the shield is because infrared light can also be interpreted as
heat. Since one of Webb’s main goals is to study extremely distant and usually faint
wavelengths, engineers had to ensure the observatory is protected from all heat sources, including
itself. For this reason, the telescope is uniquely
divided into two separate sections: the Cold and the Hot Side with the sunshield layers
acting as the dividing line between the two. The cold side handles the observation functions,
meaning it's where we get our data.
This side includes the primary and secondary mirrors, infrared instruments, and the detectors
with an operating temperature of -233 degrees Celsius.
The hot side includes mainly spacecraft operation elements. This includes the sunshield, solar
panel, communication antenna, spacecraft bus, and star tracker with an operational temperature
of 85 degrees Celsius.And it’s insane to think that this telescope has to operate at
these two extreme temperatures simultaneously. Having the opportunity to work on this satellite
was an absolutely amazing experience, and I have to say although I'm Team Cold Side, I can’t think
of a better group to have fully integrated this amazing telescope with. And just think
following launch, it will take Webb approximately 30 days to fully deploy and reach its desired
L2 orbit. From there, a series of calibrations will occur and we can expect to see data within
six months. I'm not sure about you, but I'm beyond excited to get one step closer to answering
the question, “Where did it all begin?”
So what are some of your biggest questions
about the Webb telescope? Let us know in the comments below and make sure to subscribe. Thanks so much for
watching Seeker and I’ll see you next time.