New Horizons begins Approach Phase 2

Artist's conception of New Horizons at Pluto. Image Credit: NASA

Laurel Kornfeld

With less than 100 days remaining before its closest rendezvous with Pluto, New Horizons began the second of its three approach phases, titled Approach Phase 2, on Sunday, April 5. During this phase, which lasts until June 23, the spacecraft’s instruments will take the first ever color and spectral photos of the Pluto system.

Observations taken during this period will provide sharper focus of Pluto and its five moons. Long exposure images will scan the region for additional moons and a possible ring system. Ultraviolet observation of both the surfaces and atmospheres of Pluto and Charon will begin during this phase.

Using the Long Range Reconnaissance Imager, or LORRI, the spacecraft will conduct the third of its four scheduled optical navigations by May 15. The Multi-Spectral Visual Imaging Camera (MVIC), part of the RALPH visible and infrared imager and spectrometer, will function as a backup camera as New Horizons studies the dust environment around Pluto.

John Spencer, a member of the mission’s science team at JHUAPL, said this phase will focus on taking detailed images of the entire region around Pluto to determine the presence of any debris that could pose a threat to the spacecraft, which is heading toward the dwarf planet at a speed of more than 31,000 miles per hour (50,000 km/h).

Should potential threats be found, “We’ll be pouncing on it; we’ll be analyzing what orbits those (additional) moons could be having, or what kind of rings we might get from those moons and make sure that the spacecraft is going to be safe as it goes through the system,” he said.

The mission team is in the process of evaluating new data to determine whether a May 15 course correction is needed for the spacecraft, which is currently 2.98 billion miles (4.79 billion km) from Earth and only 73 million miles (118 million km) from Pluto. A decision will be made around May 1.

This new phase will feature the first long-range studies of both the brightness and color variation on Pluto’s surface. While the dwarf planet takes up only 3.5 pixels in New Horizons‘ cameras as Approach Phase 2 begins, its topography will be visible by the time the phase ends.

“Currently, the best images (from New Horizons ) show Pluto as barely resolved, as only a dot in the distance,” principal investigator Alan Stern noted. “But by the time that Approach Phase 2 is over in June, you’ll be seeing images of Pluto (that will be) like nothing ever (taken) from any Earth-based system. This is the time when Pluto transforms from a planetary astronomer’s world – spied only through telescopes with just the slightest detail – to a planetary science target of the most capable flyby spacecraft ever sent on a first reconnaissance mission.”

Approach Phase 2 also involves more detailed studies of the solar wind, or high-energy particles, in the area around Pluto, which are already under way by two of New Horizons‘ instruments, the Solar Wind Around Pluto (SWAP), and the Pluto Energetic Particle Spectrometer Science Investigation (PEPPSSI).

The solar wind is approximately 1,000 times less intense near Pluto as it is near Earth. Over the last ten years, solar activity has been low overall; this means the area where the solar wind begins interacting with Pluto’s atmosphere could be larger than scientists expected.

According to New Horizons co-investigator Fran Bagenal, “This means that New Horizons may cross the interaction boundary between the solar wind and Pluto’s atmosphere up to dozens of Pluto radii (and several hours) before its closest approach on July 14, creating a scientific bonanza for studies of the composition and escape rate of Pluto’s atmosphere!”

Working in conjunction with NASA’s Deep Space Network (DSN), the mission team will conduct a test of flyby radio science observations, in part to determine whether New Horizons will face any dangers as it flies between Pluto and Charon.

In anticipation of a wide range of discoveries on the surfaces of both Pluto and Charon, Dr. Mark Showalter of the SETI Institute has organized a collaborative public outreach effort to solicit names for these features in conjunction with the New Horizons team and the IAU.

Titled “Our Pluto”, the project enlists members of the public, both children and adults, to nominate and vote for names of features that might be discovered, such as craters, mountains, valleys, chasms, volcanoes, etc.

Appropriate names are divided into 10 different themes that fit into three broad categories: the history of exploration, the literature of exploration, and mythology of the underworld. Under the theme history of exploration are several subcategories, including historic explorers, space missions and spacecraft, and scientists and engineers.

Literature of exploration includes subcategories of fictional explorers and travelers, fictional origins and destinations, fictional vessels, and authors and artists who envisioned explorations of land, sea, and space.

Because Pluto is named after the Roman god of the underworld, underworld themes such as underworlds and underworld locales, travelers to the underworld, and underworld beings comprise a third major category. Additional themes may be added in the future depending on discoveries by New Horizons.

After voting is completed, the New Horizons team and the IAU will review all submissions and rank the names submitted in each theme. Suggested names should reflect the diversity of cultures worldwide and not be limited to any one particular origin. People can vote multiple times but only once per day.

So many names were submitted from so many locations around the world that the participation deadline was extended from its original April 7 deadline to Friday, April 24. Anyone interested in taking part should visit Our Pluto.

With excitement building worldwide as the flyby date approaches, members of the New Horizons team have been conducting public outreach about the mission via Google+ hangouts.

“The History and Future of Pluto Science” hangout, led by New Horizons team member William McKinnon of Washington University, was held on Friday, April 3, and can be viewed here.

Even the White House has taken an interest. It hosted “We the Geeks: Journey to Pluto”, a Google+ hangout, on Wednesday, April 8, featuring New Horizons project scientist Hal Weaver, NASA Associate Administrator for the Science Mission Directorate and astronaut John Grunsfeld, New Horizons Guidance and Control Engineer Gabe Rogers, and three current and former members of the New Horizons Student Dust Counter instrument team: Jamey Szalay, David James, and Tiffany Finley. It is available for viewing here.

As part of “Yuri’s Night”, an annual celebration of Yuri Gagarin having become the first human in space on April 12, 1961, Alan Stern and Kelsi Singer, also of the mission team, will hold a Google+ hangout, “Exploring Our Solar System with the New Horizons Spacecraft”, on Sunday, April 12 at 2-3 PM EDT (1800-1900 UTC/GMT). You can watch online.

Exactly three months before the flyby, on Tuesday, April 14, NASA will hold two New Horizons Media Briefings at NASA Headquarters Auditorium 300 EST SW, Washington, DC 20546, US. The first will be at 1 p.m. EDT and the second at 2:30 p.m. EDT.

Both are open to the public and will be held in the Webb Auditorium at NASA Headquarters, 300 E Street SW in Washington. Discussion will focus on the mission’s goals, plus scientific observations and encounter plans.

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