NASA has chosen a research team that includes an MIT scientist to pursue a possible 2006 mission to Pluto and the Kuiper Belt, a distant source of comets believed to be responsible for much of Earth's water and the chemical precursors of life.
Richard P. Binzel, professor of earth, atmospheric and planetary sciences, is a member of the Pluto-Kuiper Belt mission science team. Binzel's Pluto research over the past two decades includes the first confirming observations of the planet's moon, the discovery of polar caps and the first maps of its surface. He is on sabbatical from MIT until next September.
The PKB misson team wants to reach Pluto and its moon Charon as soon as possible before 2020. Since 1989, Pluto has been moving farther from the sun. As Pluto gets colder, its atmosphere may freeze out, diminishing the chance to "see" its atmosphere.
The double planet system (the last in our solar system to be visited by spacecraft) also is becoming increasingly shadowed, impeding a spacecraft's ability to take pictures in reflected sunlight.
"One of the most exciting aspects of this mission is that it will complete the first reconnaissance of our solar system by closely examining Pluto and one or more Kuiper Belt objects," Binzel said.
A spacecraft passing by Pluto and Charon would use a remote sensing package as well as spectroscopic and other experiments to characterize the global geology and morphology of the bodies, map their surface composition, and characterize Pluto's neutral atmosphere and its escape rate.
The fastest route to Pluto would require a trip past Jupiter, whose intense gravitational field would help slingshot the spacecraft into the outer solar system at 50,000 mph. An opportunity to launch to Pluto by way of Jupiter occurs in January 2006. After a year en route to Jupiter, the spacecraft would fly by Pluto and Charon between 2016 and 2018.
The spacecraft would then pass the Kuiper Belt Objects (KBOs)--small, icy bodies that orbit past Neptune--by 2026.
PLANNING THE MISSION
To ensure this launch date, NASA has established two conditions. First, the mission must pass a confirmation review of scheduling, technical milestones and regulatory approval for launch of the mission's nuclear power source. Second, funds must be available. Congress provided $30 million in fiscal 2002 to initiate Pluto-Kuiper Belt spacecraft, science instrument development and launch vehicle procurement; however, there is no funding for subsequent years in the administration's budget plan.
The mission, called "New Horizons: Shedding Light on Frontier Worlds," is led by principal investigator S. Alan Stern of the Southwest Research Institute in Boulder, Colo. He will lead a team including the Johns Hopkins University Applied Physics Laboratory; Ball Aerospace Corp.; Stanford University; and NASA's Goddard Space Flight Center and Jet Propulsion Laboratory. Binzel is part of the team Stern is bringing together from academia, industry and NASA centers to lead the PKB mission.
Sending a spacecraft on this long journey will help answer basic questions about these bodies' surface properties, geology, interior makeup and atmospheres. KBOs are small, with diameters typically around 100 kilometers (62 miles), very faint and extremely hard to study from Earth. The first KBOs were discovered only in 1992, but already the Kuiper Belt is changing the way scientists think about the outer solar system and the formation of the outer planets and comets.
Pluto, the smallest planet, is actually a KBO composed of material left over after the formation of the other planets. It has large quantities of ices of nitrogen and simple molecules containing carbon, hydrogen and oxygen that are the necessary precursors of life. Given Pluto's weak gravity, these ices would be largely lost to space if Pluto had come close to the sun. Instead, they remain there as a representative sample of the primordial material that set the stage for the evolution of the solar system as it exists today, including life.
"Visiting Pluto and other Kuiper Belt objects would be like visiting a deep freeze containing samples of the most ancient material in our solar system, the stuff that all the other planets including Earth were made of," said Colleen Hartman, solar system exploration director in NASA's Office of Space Science. "But the most exciting thing about going to an unexplored planet is what we may find there that we're not expecting."
A version of this article appeared in MIT Tech Talk on December 5, 2001.