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The Question
(Submitted October 06, 1997)
I have heard that NASA will be Launching a Nuclear Rocket which
contains a fuel in it that could possibly lead to death of
Thousands of Innocent Floridians. No one has the Right to Murder Innocent
people for science. That is wrong. I'm sorry if I have the story wrong, but
this is what I have heard. I deeply believe that this is a Huge mistake
and should not happen. Please tell me what is going on.
The Answer
The upcoming Cassini mission to Saturn contains plutonium to power some of the
scientific instruments on board Cassini. Plutonium is very toxic, but every
precaution has been taken to ensure that the chance of any significant threat
to humans will be very small even in the worst case scenario. The plutonium is
in devices called radioisotope thermoelectric generators (RTGs) and in fact 23
NASA missions have been flown with RTGs on board. The current design of the RTG
has been on two space missions which have had mishaps (from other causes)
causing the the RTGs to return to Earth. One spacecraft fell into the ocean
during a launch accident. The RTG was recovered from the ocean floor with no
escape of radiation, and it was later re-used. Apollo 13's lunar module was
carrying an RTG. After the accident the lunar module had to re-enter Earth's
atmosphere at high velocity and fall into the ocean, but no radiation release
was observed.
You may want to check out JPL's web pages on Cassini,
http://saturn.jpl.nasa.gov/.
Also attached below is a press release explaining that other government agencies
have given their approval for the mission. For more information, there are
links concerning this (and all other) NASA missions on the NASA WWW page at
http://www.nasa.gov
Andy Ptak, David Palmer, Gail Rohrbach and Allie Cliffe
for the Ask an Astrophysicist Service
Douglas Isbell/Don Savage
Headquarters, Washington, DC
(Phone: 202/358-1547)
Matthew Donoghue
Department of Energy, Washington, DC
(Phone: 202/586-0619)
October 3, 1997
RELEASE: 97-225
NASA RECEIVES APPROVAL TO LAUNCH CASSINI MISSION
NASA today received formal approval from the White House
Office of Science and Technology Policy (OSTP) to proceed toward
the launch of the robotic Cassini mission to explore Saturn and its
moon Titan.
"NASA and its interagency partners have done an extremely
thorough job of evaluating and documenting the safety of the
Cassini mission. I have carefully reviewed these assessments and
have concluded that the important benefits of this scientific
mission outweigh the potential risks," said OSTP Director Dr. John
H. Gibbons, who signed the launch approval.
NASA Administrator Daniel S. Goldin said, "I am confident in
the safety of the Cassini mission, and I fully expect that it will
return spectacular images and scientific data about Saturn, in the
same safe and successful manner as the Voyager, Galileo and Ulysses
missions."
White House launch approval is required by presidential
directive due to the type of power source used to provide
electrical power for the Cassini spacecraft and its scientific
instruments, and the heater units that it carries to keep the
spacecraft's instruments and electronics warm in deep space.
The Radioisotope Thermoelectric Generators (RTGs) and
Radioisotope Heater Units used to power Cassini and keep its
internal systems warm have been used in previous NASA missions
ranging from Apollo to Galileo, and have been approved by five
previous administrations ranging from Nixon to Bush. RTGs produce
power by the heat generated through the natural radioactive decay
of non-weapons grade plutonium dioxide, which is transformed into
electricity by solid-state thermoelectric converters.
Before Administrator Goldin sent the request for launch
approval to OSTP, two separate processes were completed to address
the environmental and safety aspects of the mission. NASA
completed an Environmental Impact Statement in June 1995 and a
supplement in June 1997, as required by the National Environmental
Policy Act and NASA policy.
Consistent with long-standing Presidential policy, the
Department of Energy (DOE) prepared over the past seven years a
comprehensive Safety Analysis Report. In addition, an Interagency
Nuclear Safety Review Panel, including safety experts from DOE,
NASA, the Department of Defense (DOD), the Environmental Protection
Agency (EPA), and a technical advisor from the Nuclear Regulatory
Commission conducted a comprehensive evaluation of the safety
analysis. This panel was supported by over 50 scientific experts
from academia and industry.
DOD, EPA and DOE have written to the NASA Administrator
confirming that, in their view, the safety analysis conducted for
the mission is comprehensive and thorough.
Cassini is a cooperative endeavor of NASA, the European Space
Agency (ESA) and the Italian Space Agency, or Agenzia Spaziale
Italiana. The mission will send a sophisticated robotic spacecraft,
equipped with 12 scientific experiments, to orbit Saturn for a
four-year period and study the Saturnian system in detail. The ESA-
built Huygens probe that will parachute into Titan's thick
atmosphere carries another six scientific instrument packages.
Saturn is the second-largest planet in the solar system and is
made up mostly of hydrogen and helium. Its placid-looking,
butterscotch-colored face masks a windswept atmosphere where jet
streams blow at 1,100 miles per hour and swirling storms roil just
beneath the cloud tops. Previous spacecraft passing by Saturn
found a huge and complex magnetic environment, called a
magnetosphere, where trapped protons and electrons interact with
each other, the planet, rings and surfaces of many of the moons.
Although it is believed to be too cold to support life, haze-
covered Titan is thought to hold clues to how a primitive Earth
evolved into a life-bearing planet. It has an Earth-like, nitrogen-
based atmosphere and a surface that many scientists believe
probably features chilled lakes of ethane and methane. Scientists
believe that Titan's surface is probably coated with the residue of
a sticky brown organic rain.
The launch of Cassini aboard a Titan IV-B/Centaur launch
vehicle is scheduled for 4:55 a.m. EDT on October 13 from Cape
Canaveral Air Station, FL. An on-time launch will deliver the
Cassini mission to Saturn almost seven years later on July 1, 2004.
Cassini's primary mission concludes in July 2008.
Questions on this topic are no longer responded to by the "Ask an Astrophysicist" service. See http://imagine.gsfc.nasa.gov/docs/ask_astro/ask_an_astronomer.html
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