The Great Planet Debate
Live from...the Hubble Space Telescope
The original HST observations are targeted for March 1996. At that time,
4 planets - Jupiter, Uranus, Neptune and Pluto - are available targets
for study. STScI suggested looking at planets because more distant, fainter
galaxies and other objects require many more orbits to secure data that's
likely to be scientifically significant. Planets are also more familiar
to students - and Jupiter and Uranus will have been introduced during
the Kuiper activities.
The introductory video will ask 4 astronomers and educators associated
with STScI to serve as PLANET ADVOCATES to
lay out the case for observing one or other of the candidate planets,
and provide documentary reports on what's already known, and what could
be discovered. (Through comments appearing on this page, HST
staff astronomer Alex Storrs provides a preview of some of the arguments
for and against the various observations.) Alex Storrs also wrote an explanation
of why the Hubble Space Telescope is specially equipped to make
certain planetary observations.
Simultaneously, NASA's K-12 Internet Initiative will
activate special on-line resources to support Live from the Hubble
Space Telescope. Organized much like LFS, students will find a great
deal of information on the planets, HST and STScI. There'll be pointers
to the extensive astronomical materials STScI and others already provide
on-line. This information is available here on these Web pages.
But most importantly, students can actively participate
in a discussion to brainstorm, research, develop and deliver suggestions
about which planet to observe with the 3 Live from the Hubble Space Telescope
orbits.
Individual students and classes will be able to collaborate from sites
all across America. We also anticipate involvement from Europe, since
the European Space Agency contributes 20% of STScI support and participates
fully in all HST activities. Students will engage in activities from the
somewhat trivial (Does one group want to be known as the "Pluto-crats",
another the "By Jovians"?) to the more significant. The discussion groups
will be (lightly) moderated by astronomer-mentors and educators with experience
with faciliating on-line collaboration. Access to expert scientific support
will be brokered by Passport to Knowledge so that students can develop
suggestions which conform to guidelines for professional research on the
HST which must focus on significant scientific questions, be achievable
within the number of orbits and time assigned, and not duplicate existing
research. STScI already posts on-line materials to assist researchers
in submitting proposals. Passport to Knowledge will work
with STScI to adapt these for student information.
By December, we need to arrive at a consensus about which planet(s)
to observe, and what research to suggest. A final determination will be
made by group consisting of educators working with Passport to Knowledge,
astronomers from STScI and student representatives communicating via the
Internet.
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Alex Storrs, STScI staff astronomer, and specialist on planets
On the pros and cons of observing the candidate planets:
"I admit that Jupiter at first seems the hands-on favorite. It's the
biggest and most dynamic planet in our solar system. Through the Hubble
telescope, Jupiter fills the screen. All other planets require a fair
amount of analysis to figure out just what you're seeing. Some of the
things that we can observe on Jupiter are very dynamic and they change
quite rapidly - such as the cloud patterns. Even though we've looked
at Jupiter quite a lot already, it's worthwhile to go back at a later
date to see how cloud patterns have changed from the last time it was
observed. These observations in the middle of March would be pretty
separated from most other observations. But for Jupiter, the big deal
is Galileo. The Galileo spacecraft is arriving at Jupiter at the end
of 1995 and is starting its long tour of the Jovian system and there
are already a lot of HST projects to back this up. Galileo will still
be on its tour in March, and perhaps we'll simultaniously be able to
image some of the satellites with the HST, along with Galileo. Jupiter's
moon, Io, also has a few active volcanoes and we could observe the effects
of those depending on how we arrange the imaging. It will be of great
interest to see what's happening through the Hubble right when Galileo
is there.
Uranus has not been quite so heavily observed. The planet itself is,
perhaps, a little bland and boring: however, there are those rings (ed.
first discovered from the Kuiper.) Uranus has rings much like Saturn
only thinner. But we don't exactly know their colors and composition.
A worthwhile project would be to use the HST spectrometer to figure
some things out, for the first time. Look at the rings, look at the
sky beyond the rings, and compare them. It would take only one orbit
to do this, and it would produce relatively quick but significant results,
and likely help us determine what the rings are made of.
Neptune's a hot topic. Neptune is ever-changing and dynamic like Jupiter.
So it would probably be beneficial to do the same sorts of observations
and procedures with Neptune that have been done with Jupiter. We can
see how the cloud patterns have changed and shifted. Unfortunately,
Neptune is not very big. It might not be that impressive but it would
still be pretty useful to get 3 orbits worth of images of Neptune.
Pluto is also interesting but not nearly as dynamic as the other outer
planets. Visible changes, if any, only emerge over a broader scale of
time. There was supposed to be a "Pluto Express" spacecraft, but funding
problems mean NASA may not be able to start any new missions, any time
soon. So all the new information that they're going to get about Pluto
in my professional lifetime will have to come from the Hubble. And this
would sure be a chance to do some of that on a little known planet.
Jupiter can be analyzed even from the raw data, pretty much as it
comes in, in real-time, which makes it unique. It also only takes one
orbit around Jupiter to gain interesting new information on it.
But I think there's a good case for looking at Uranus and those rings.
Taking low resolution spectra of the rings would be a definite "first"
and not easy to accomplish. The raw data in itself won't be very impressive
but with a little bit of time, we should be able to analyze it pretty
well. The slope and shape of that spectrum could give us an idea of
the sizes of particles in the ring. We might be able to figure out whether
the rings are rock and dust alone, or whether there's a mixture of all
sorts of different materials. The rings may not have formed from different
processes than the rings around other planets, but they probably evolved
differently. Uranus' atmosphere causes the rings to move and shape themselves
in different ways than in other planets."
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