Operator: “Will you accept a collect call
from Pluto?” Imagine a call home from the outer reaches of our solar
system to say you survived your journey.
That’s what NASA’s mission team cheered about just before 9 p.m. on
Tuesday, July 14, when messages from the New Horizons spacecraft finally
were received, confirming that it had accomplished the first-ever
fly-by of Pluto.
New Horizons, which launched nearly a decade ago on a 3-billion-mile
journey to Pluto, has captivated the world with stunning images showing
the dwarf planet in all of its icy wonder. A fan favorite is Pluto’s
“two-toned heart.” New Horizons took the photo about 7,750 miles from
the orb’s surface while moving at a cool 8.5 miles per second.
But there will be much more data to come on Pluto, which was once
considered the ninth planet from the sun, but was reclassified in 2006
as a “dwarf planet” — a subject of continued debate in the scientific
Pluto’s five known moons, including Charon, its largest, also have
been imaged. NASA says it will take about 16 months to transmit all of
the data from space.
John Gizis, professor, and Sarah Dodson-Robinson, assistant professor, both in the Department of Physics and Astronomy
at the University of Delaware, have been following the mission with
great interest and share their insights with UDaily readers.
Q. What are the biggest discoveries that New Horizons has revealed about Pluto so far?
Dodson-Robinson: The surface of Pluto is defined by interesting
large-scale structures. A black feature near the equator has already
been dubbed the “whale,” while there is what appears to be a white heart
next to the whale. The white probably indicates ice. It's not clear why
Pluto's surface should have such compositional variations.
Gizis: The initial images show that Pluto has a very complex surface
showing the influence of geological and atmospheric processes. The
mission has also confirmed that Pluto is the largest dwarf planet in the
Kuiper Belt in terms of its size, although Eris is actually more
Q. How will UD physicists/astronomers benefit from the mission and its findings?
Gizis: First of all, we will have to update our classes! In terms of
new research, UD astronomers are interested in how planets form and
evolve around other stars. How the Kuiper Belt in general and how Pluto
and its large moon Charon specifically formed will provide insights into
the planet formation process throughout the universe. In the far future
as it leaves the solar system, New Horizons will measure the properties
of the heliopause, where the solar wind meets interstellar space, and
this will relate directly to some of the solar wind and plasma physics research at UD.
Dodson-Robinson: One of my main research areas is the composition of
planets. The chemical makeup of planet nurseries helps determine the
size and evolutionary pathway of planets. By learning about Pluto’s
composition, we can better understand planet formation and evolution.
Q. How does New Horizons compare to Voyager, a mission that UD was involved in?
Dodson-Robinson: The Voyager spacecraft did fly-bys of the giant
planets. The fly-by nature of New Horizons is similar to Voyager.
However, New Horizons is the first spacecraft to study a Kuiper Belt
Q. Based on what you’ve seen, should Pluto once again be considered a planet?
Dodson-Robinson: It was clear before the New Horizons fly-by that
Pluto was fundamentally different from the other eight planets. It
shares an orbit with many other objects, and it’s not even the largest
dwarf planet. Calling Pluto a planet would require adding Eris, Makemake
and Haumea to the list. Pluto really belongs in a different category
than the eight planets, but that doesn't make it any less interesting.
Gizis: I think it makes the most sense to think of the solar system
as having eight planets (plus their moons), the Asteroid Belt (including
Ceres) and the Kuiper Belt (including Pluto and Eris). Pluto then gets
classified as a “dwarf planet,” but remember, amazing worlds like Titan,
Ganymede and Triton get called “moons” even though they’re larger than
Pluto. Each of the planets, dwarf planets, moons, comets and asteroids
we have studied close up with space probes has turned out to be unique.
Q. What’s on your horizon as the next big space event?
Dodson-Robinson: I’m very excited about the mission to Europa, which
is a possible habitat for life. Europa almost certainly has a subsurface
ocean, with abundant geothermal energy. I can’t wait for the Europa
data to come back.
Gizis: Like many astronomers, I am anxiously awaiting the launch of
the James Webb Space Telescope in 2018. It’s the successor to Hubble
Space Telescope. Between now and then, I expect many new discoveries of
planets and planet-forming disks around other stars from new instruments
like Gemini Planet Imager and the Atacama Large
Millimeter/submillimeter Array (ALMA).