On New Year's Day the New Horizons
spacecraft will make the most distant
planetary encounter ever attempted, and
for the first time, it has its target in
its sights. Welcome back to Launch Pad
Astronomy, I'm Christian Ready your,
friendly neighborhood astronomer. New
Horizons took this image of the tiny
Kuiper belt object 2014 MU69 when it
was at a distance of over 6 billion
kilometers from Earth. The Kuiper belt is
a doughnut shaped region of small icy
bodies out beyond the orbit of Neptune.
Some of these objects, such as Pluto and
Eris can be relatively large, while most
of these objects are small primordial
icy bodies - essentially comet nuclei.
MU69 was discovered by the Hubble Space
Telescope which searched for potential
objects New Horizons could fly past
after its encounter with Pluto in 2015.
Hubble was able to determine MU69's
orbit and verified that it did in fact
lay within New Horizons flight path. That
allowed the New Horizons team to adjust
the spacecraft's trajectory to intercept
the object on New Year's Day 2019. The
team gave MU19 the unofficial nickname
of Ultima Thule, latin for 'beyond the
borders of the known world'. However, New
Horizons itself hadn't actually seen its
target yet. So in August 16th of this
year, the New Horizons team pointed its
Long Range Reconnaissance Imager or
LORRI telescope at the position where
they expected Ultima Thule to be. The
object was located amidst a crowded
field of bright stars. But after doing
some extensive image processing, Ultima
emerged as a faint glow exactly where
the team predicted it would be. And this
is important because it meant that New
Horizons would not have to make any
additional course adjustments, and that
saved precious onboard fuel for science.
But in order to do that science, the team
needs to know as much about Ultima as
possible. An opportunity to learn more
about Ultima came in 2017 when it passed
in front of a star causing the star to
temporarily wink out. This event is known
as an occultation,
and by observing the occultation from
slightly different locations along a
north-south line in Argentina, the team
was able to put together a picture of
the possible shape of Ultima Thule. But
what they found was a surprise; Ultima
Thule may not be one object but could be
two! It has a double lobe structure and
we've seen the structure like this
before when the Rosetta spacecraft
encountered Comet 67P/Churyumov-Gerasimenko.
Its two lobes may
in fact be two smaller comets that came
together and are bound by gravity. Or it
could be a single large object that lost
most of its central region either
through outgassing or a possible
collision. However, Comet 67P is only four
kilometers wide - Ultima Thule has two
lobes of 20 and 18 kilometers,
respectively. Now obviously we're going
to learn a lot more about Ultima when
New Horizons passes by on New Year's Day.
It will pass just 3,500 kilometers away
from the object - that's three times
closer than New Horizons got to Pluto!
But the encounter will only last a
couple of hours because New Horizons is
traveling more than 14 kilometers per
second. That's fast enough to go from New
York to LA in under five minutes. But
here on Earth, were going to have to be
patient because it takes light over six
hours to travel from the spacecraft
across the solar system to Earth. Not
only that but the download rate is
pretty low - about one kilobit per second.
That means it'll take several days and
weeks just to get the low-res preview
images, and another couple of years to
download all of the data from the
spacecraft. But it'll be worth the wait
because this is an opportunity to
glimpse the earliest formation of our
solar system from 4.6 billion years ago when
the solar system was just beginning to
form. Now if you'd like to learn more
about the formation of the solar system
and a few of the cool things that have
been happening in it, I'll have some
links here and in the description below.
So let me know what are your plans for
New Year's Day? You gonna to catch the
game, watch the Mummers parade, or download
telemetry from an outbound
spacecraft? Let me know in the comments
below and I'll be sure to check them out.
And if you'd like to join me on this
journey through this amazing universe of
ours, well please make sure to subscribe
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you don't miss out on any new videos.
Until next time, I'm Christian Ready, and
keep watching the skies. [BEEP] Horizons is the
same spacecraft that flew past Pluto in
2015. This mission was designed as a
flyby mission because to slow down... this
mission was designed to be a flyby of....[BEEP]
New Horizons made history when a
flew past Pluto and .... how many times
have I said this line man? [laughs] It's nice and
quiet though cicadas finally stopped...
...well sort of...
[cicadas singing] no they didn't. [BEEP]