"New Horizons", the spacecraft that is supposed to rewrite the textbooks
For more than forty years humans have been sending spacecraft to explore the known planets in the solar system. It's time to visit the last planet. Today, the "New Horizons" spacecraft is supposed to be launched on a journey to the outer limits of the solar system, with the aim of taking a close look at Pluto for the first time. If the mission is successful, it will mark the completion of the study of the nine planets in the solar system.
The spacecraft will launch from Earth at a record speed of 58 km/h, which is enough to pass the surface of the moon in nine hours - this is compared to the two and a half days it took the Apollo spacecraft to reach the moon - so that New Horizons will be able to reach Jupiter in only 13 months. Then, with the help of the giant planet's gravity, it will accelerate on its way to Pluto.
When New Horizons is close to its goal, in 2015, it will begin a study that will last about five months and will include a foray that will bring it closer to a distance of about 10,000 km from the surface of Pluto and about 27,000 km from Charon, the planet's largest moon. In addition, the spacecraft will explore two smaller moons of Pluto, discovered last year by the Hubble Space Telescope.
Although the mission begins at high speed, the journey to Pluto, which is about five billion km from Earth, will take at least nine and a half years, during which the spacecraft will have to conserve energy. Therefore, for most of the flight it will be in a state of "hibernation", and will send a single weekly signal back to Earth to report its status. The control center will "wake up" the spacecraft only once a year, to perform an instrument check.
The benefit inherent in the mission is worth the long wait, says Dr. Alan Stern, head of the research team: "This is the last stop in the array of missions to explore the planets. Pluto, its moons and this part of the solar system are so shrouded in mystery that 'New Horizons' will rewrite the textbooks."
Discovered in 1930, Pluto is the first known example of a new class of planetary bodies called ice dwarfs, Stern explained. According to scientists, these cold objects, which are found in their hundreds in the region beyond Neptune called the Kuiper belt, are remnants of the original building materials of the solar system.
Stern rejects the recent debate over whether Pluto is really a planet, since it is so different from the two main types of planets in the solar system: the four rocky inner planets - like Earth and Mercury, and the four outer gas giants - like Jupiter and Jupiter. "Just as a Chihuahua is still a dog," says Stern, "so these ice dwarfs are still planetary bodies. Bodies similar to Pluto are much more typical of our solar system than the nearby planets we initially knew."
The spacecraft weighs about 480 kg, and is the size of a grand piano. Since the mission will be carried out at a great distance from the sun, the spacecraft will not be able to use solar energy and will receive its power from a thermoelectric generator that is fueled by plutonium and produces about 200 watts of electricity. The use of plutonium, a substance with a high level of radioactive radiation, is controversial, and recently activists opposed to the use of nuclear energy demonstrated against the launch of the spacecraft. According to them, an explosion during launch could spread dangerous amounts of radiation.
However, NASA claims that the chance of an accident during launch is slim, and that the fuel system and generator were designed to limit the spread of radiation. But in any case, as a precaution, emergency management teams will be stationed around the Air Force Base in Cape Canaveral, Florida, at the time of launch.
The spacecraft instruments include three cameras that will take pictures in visible light, infrared light and ultraviolet light. In addition, the spacecraft is equipped with three spectrometers that will study the composition and temperature of Pluto's thin atmosphere, and the characteristics of the ground surface. The instruments are the most compact and cost-effective ever flown on a planetary research mission.
The spacecraft will also carry a dust measuring instrument, which is part of an experiment by students from the University of Colorado. This is the first time that in a space mission to explore planets, students plan and conduct an experiment completely by themselves. This is also the only experiment that will be activated even when the spaceship sleeps its "winter sleep". "New Horizons" will also carry several symbolic items from Earth, including a US flag, a small piece of SpaceshipOne, the first private manned spacecraft - and a CD containing the names of the 435,000 people registered on the mission's website (http://pluto.jhuapl.edu).
Astronomers have for the first time been able to measure the size of Charon (right), the largest of Pluto's three known moons (left). The researchers, who observed the moon from telescopes located in South America, recently took advantage of a time window of less than a minute, in which Charon blocked the light coming from a bright star, and thus could gather a lot of information about its properties. According to observations, the diameter of Charon, discovered in 1978, is between 750 and 753 km - about half the diameter of Pluto. The researchers also determined that the moon probably does not have a significant atmosphere
