[meteorite-list] Scientists Plan For New Horizons Probe's Second Act

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu, 13 Aug 2015 17:41:52 -0700 (PDT)
Message-ID: <201508140041.t7E0fqA0027931_at_zagami.jpl.nasa.gov>


Scientists plan for New Horizons probe's second act
by Stephen Clark
Spaceflight Now
August 11, 2015

Scientists are about to decide where to send NASA's New Horizons spacecraft
next, and it is down to two candidates at the frozen frontier of the solar
system to become the most distant object ever visited by a human-built
space probe.

New Horizons' flyby of Pluto was the mission's main act, but the plutonium-powered
explorer is on an irreversible high-speed course barreling outward from
the planets. Scientists will decide later this month to steer the spacecraft
on a trajectory toward one of two newly-discovered mini-worlds in the
Kuiper Belt, a ring of icy objects thought to be leftovers from the solar
system's creation.

Scientists and NASA managers will pick between the two objects lurking
in the Kuiper Belt, then prepare commands to guide New Horizons toward
it for a one-shot flyby much like its encounter with Pluto last month.

Alan Stern, New Horizons' principal investigator, told Spaceflight Now
on Tuesday the decision would be announced by NASA in late August.

"The team will have to turn its attention to going back and thinking about
the next possible thing that New Horizons will do in an extended mission,
and there are quite a few things it can do," Jim Green, director of NASA's
planetary science division, told reporters just before the July 14 encounter
with Pluto.

Scientists have two candidates to choose from - 2014 MU69 and 2014 PN70
- discovered by the Hubble Space Telescope in 2014. Little is known about
the two targets other than their locations 4 billion miles from Earth,
according to Simon Porter, a scientist on the New Horizons mission from
the Southwest Research Institute.

A ten-year survey for Kuiper Belt Objects past Pluto by ground-based observatories
turned up 55 candidate targets, but they were all out of reach of New
Horizons, which carries a finite fuel supply and is limited to steering
in a narrow cone.

Pluto is currently in the constellation Sagittarius, with the brightest
part of the Milky Way in the background, complicating searches for Kuiper
Belt Objects, Porter said.

"It's the stupidest possible place in the entire sky to look for a Kuiper
Belt Object, but that's where we had to go," Porter said.

Scientists say the candidates for New Horizons' next target appear 100,000
times dimmer than Pluto to Hubble's imaging instruments.

These two Kuiper Belt Objects, seen in these annotated images, were discovered
by the Hubble Space Telescope in a survey to find a second target for
New Horizons. The objects were too faint to detect with ground-based telescopes.
Credit: NASA, ESA, SwRI, JHU/APL, and the New Horizons KBO Search Team

New Horizons was expected to have about 35 kilograms, or about 77 pounds,
of propellant left in its tank after the Pluto flyby, said Chris Hersman,
a mission systems engineer at the Johns Hopkins University Applied Physics

That is enough for New Horizons to adjust its speed by up to 130 meters
per second, or about 290 mph, according to mission managers.

Green said scientists will propose to NASA which of the two secondary
targets to aim for some time in August, and Hersman said a series of rocket
burns in late October or early November will steer New Horizons toward
the object.

"We will set up the mission to be able to do that, but they still have
to justify why it would be important to go by another Kuiper Belt Object,"
Green says.

New Horizons scientists will submit a thorough proposal outlining the
goals and costs of an extended mission. NASA has only committed to pay
for the mission through late 2016, when the spacecraft will finish sending
down the reams of data it collected during the July 14 flyby of Pluto.

NASA will put the proposal through peer review, where a board of independent
scientists will determine how the New Horizons extended mission measures
up against submissions from other NASA projects, such as the Curiosity
Mars rover. If the proposal wins favorable marks from the review panel,
NASA will likely decide to fund it.

The senior review board convenes every two years to prioritize NASA spending
on long-lived robotic missions exploring other planets and observing the

Scientists could also use New Horizons' plasma instruments to monitor
the solar wind at the edge of the solar system, extending measurements
currently being made by NASA's Voyager probes exploring the border between
the heliosphere and interstellar space.

The high-resolution telescopic camera aboard New Horizons could also help
astronomers track the motions of nearby stars by comparing their positions
in the sky with views from Earth.

But most attention is on 2014 MU69 and 2014 PN70, which New Horizons would
fly past in early 2019, if the mission's second act is approved by NASA.
Each object is approximately the size of Pluto's mini-moons, roughly between
15 miles and 34 miles (25-55 kilometers) in diameter.

The object 2014 MU69 is easier to reach, requiring half the propellant
needed to steer toward the other candidate target. But 2014 PN70 appears
brighter and possibly larger, easing navigation on the way toward the

"This will be the most distant object ever visited by a spacecraft, and
we're not going to have a chance to do this again probably in my lifetime,"
Porter said.
Received on Thu 13 Aug 2015 08:41:52 PM PDT

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