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Hi! I'm Lisa and this week
on NASA Now we'll meet the team chief of the NASA spacecraft
that recently flew by comet Hartley 2.
But before we get to that,
let's find out what else is happening at NASA NOW!
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After undergoing major upgrades,
the X-48 Blended Wing Body research aircraft has resumed
flight testing at NASA's Dryden Flight Research Center.
Join us next time to learn more
about this extraordinary aircraft.
Scientists involved with the first space mission attempting
to sample asteroid surface material, and return it
to Earth, have confirmed the presence
of comet particles collected
from a small container aboard Japan's Hayabusa spacecraft.
The samples were collected 5 years ago from the surface
of asteroid Itokawa and were only recently brought back
to Earth...
concluding a remarkable mission of exploration
in which NASA scientists
and engineers played a contributing role.
NOW, let's take a look back at the past!
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September 11, 1985 - ICE,
the International Cometary Explorer passes
within 5,000 miles of the nucleus
of Comet 12-P becoming the first spacecraft to encounter a comet.
Encountering a comet.
It may sound like science fiction,
but today it is science fact.
Recently scientist and engineers
at NASA repurposed the Deep Impact spacecraft,
which was previously used
to explore the comet Tempel 1 in 2005.
Then five years later, the spacecraft while in orbit
around Earth, was reprogrammed and sent
on a two million mile journey
to intercept its second target, comet Hartley 2.
The second mission of the Deep Impact spacecraft was
named EPOXI.
This time the spacecraft traveled
at 26,000 miles per hour as if flew by the comet
at an altitude of 400 miles.
The EPOXI spacecraft encounter
with comet Hartley 2 provided scientists with amazing images
and new information about comets.
Here to give us technical insight
on this extraordinary mission is Steven Wissler,
Spacecraft Team Chief for the EPOXI Mission.
My name is Steve Wissler I am the spacecraft team chief
for the EPOXI Mission at the Jet Propulsion Laboratory,
we just flew by comet Hartley 2 on November 4th.
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About two months before we got
to the comet we started observing it with the cameras
on board the spacecraft and then those images are sent
to the ground and the navigation team uses those
to help refine the orbit of the comet.
We were getting constantly surprised
at how much it was moving and the inability to really nail
down exactly where the comet was.
Once we get within an about an hour
of the comet then the spacecraft takes over
and analyses those pictures itself.
It analyzes where is the comet in the picture
and then it recalculates the ephemeris of the spacecraft
as it's flying by the comet
and that again further refines the orbit and allows us
to point the instruments.
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There certainly is a lot of math and physics involved.
You have calculus, geometry, trig.
These are all very important in order to figure
out where the comet is, where the spacecraft is and how
to get their trajectories to line up.
Think of it like firing a gun in NY and firing a gun
in Los Angeles and having the bullets hit each other,
that's about how difficult it is to do that particular job.
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Comets all originate in the cloud outside
of Pluto's orbit called the Oort cloud
and occasionally they get kicked out of their orbits
and they will come in closer to the sun.
Typically, when you see a comet you see a coma around it
where there is a lot of dust and gases in the area.
So as we fly by, there's some risk
that we might hit something.
The tiny dust particles generally don't do too much
damage, but as we flew by this comet we were really surprised
by what looked like a reverse snow storm coming off
of the comet with particles maybe as big
as a softball or a basketball.
So if you can image getting hit
by a snowball 26,000 miles per hour,
it would not have been a good day.
To operate a spacecraft you have to be a jack of all trades.
You really have to understand every subsystem
on the spacecraft: attitude control, power, thermal,
telecom, metadata handling.
And you have to understand the science to some extent also,
you have to understand what it is scientists really
want accomplish.
The scientists have a good idea of what they want to do
with the instruments, they'll tell us I want
to take these series of pictures and we have to figure out how
to have the spacecraft actually do it.
It was very exciting when the images first started
coming down.
This comet is very spectacular looking.
Completely different than most other comets.
The characteristics of it were pretty wild.
So, everybody was pretty surprised.
The scientists were just beaming as soon
as they saw those first pictures
because this is what it's all about, it's about getting
that science down
and understanding what these comets are all about.
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Did you know that the small, but active,
Comet Hartley 2 became the fifth comet
to be imaged close-up by a spacecraft?
Now it's time to check out what's up!
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If the sky is clear, and you're an early riser,
look for Mercury climbing over the Eastern horizon
about an hour before sunrise.
The planet Venus will also be visible...
glowing majestically in the pre-dawn South Eastern sky.
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Today we learned about the EPOXI mission, now, it's your turn!
Check out these activities and resources
on the NASA Explorer Schools' Virtual Campus!
This week there are two great activities
for you and your teammates!
First, you'll construct a scale model
of your own flyby spacecraft.
Then, test your comet I.Q. in the "Tails of Wonder" quiz.
If you get 8 out of 10 correct, Stardust will capture samples
of the comet and bring them home to Earth.
Visit the NASA Explorer Schools' Virtual Campus
for activity instructions and mission resources!
Well that's it for NASA NOW, Join us next time
when we'll take a look at NASA's "X-48," a blended wing aircraft
that features "green technology!"
We'll see you next time on NASA NOW!
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NASA NOW comes to you from the Virtual Campus
at NASA Explorer schools.