Amit Oren
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"Blow things up? Yes, I have no problem with that," says Richard Grammier, project manager at the Jet Propulsion Laboratory.
The spacecraft is called "Deep Impact", just like the name of the movie from 1998 that told about a comet that turned exactly in the direction of the Earth. NASA's goal is to cause a part of the spacecraft called the "Impactor" to collide with the comet Tempel 1 [Tempel 1]. Scientists hope that the collision will create a crater into the body of the comet, and thus the ice, dust and other primordial materials that came out of the crater can be studied in more depth.
Mission planners say the energy produced is equivalent to exploding 4.5 tons of TNT, providing a sort of firework display for stargazers around the world to watch.
Scientists know little about comets, and even less about their nuclei. They believe that penetrating the inner region of the comet for observations with the help of space and ground telescopes is the best thing after landing on it, collecting samples and sending them to the Earth.
"Returning samples from the comet will be the highlight, but this mission is also exciting because for the first time we are breaking boundaries and creating our own crater," says Donald Yeomans, a senior research scientist at JPL in California, and a consultant to the film.
"We will understand how the comet is composed, its density, its porosity, whether it has a crust on its surface and sub-layer ice, whether it is built of layers of ice, whether it is a 'soft' comet or a rock-hard sphere that is all ice. All these elements will become visible immediately after he is hit."
Astronomers are counting on "Deep Impact" to survive until it lives up to its Hollywood name on July 4, six months after its launch in mid-January. This is one spacecraft that NASA wants to smash and destroy.
"It will be like she's standing in the middle of the road and a huge truck comes at her at a speed of 37,000 km per hour, you know, just boom!" says Germier.
If all goes well, "Deep Impact" will be the first spacecraft to touch the surface of a comet. NASA's previous spacecraft, "Stardust", on its way back to Earth, collected dust samples from the head of the comet "Wild 2".
"Deep Impact" will travel a distance of approximately 431 million km from the moment it is launched on an unmanned rocket from ESA, until it meets Comet Temple-1 just beyond the orbit of Mars, at a point that is more than 130 million km from ESA.
Due to software and rocket problems, the takeoff was delayed for two weeks and is currently scheduled for January twelfth. NASA has all the time in the world to launch "Deep Impact", until the twenty-eighth of January - after that, "Temple-1" will be far from the reach of missiles, and NASA scientists will be forced to choose another comet and endure a continuous delay.
This is what happened to the European Space Agency's "Rosetta" spacecraft, which will try to make a controlled landing on a comet, but not until 2014.
"Deep Impact", in contrast, will provide "immediate satisfaction", says Gramier. The entire $330 million mission will end a month after the collision.
Comet Temple-1 is ideal from a scientific and destruction perspective. This is a typical comet, and is better for scientific testing, but still has a large nucleus and a small [Coma] head, thus making it easier for the "impactor" to survive the dust barrier and penetrate the nucleus.
Germier says that the latest calculations indicate that the chances of the "impactor" missing its target are less than one percent. The automatic navigation software has already been tested in space; It will be a fancier version of what was successfully flown on NASA's experimental spacecraft, Deep Space 1, launched in 1998, and on "Stardust" - the early comet chaser.
"We all feel quite comfortable with the chances, but as we said already, we are doing something we have not done before," says Germia.
Be that as it may, fans of the 1998 disaster film can breathe a sigh of relief. Coincidentally, the movie and the spaceship people came up with the same name without coordination between them, around the same time.
NASA promises that no matter how strong the smashing will be, or how big the crater, "Deep Impact" will barely change the comet's orbit around the sun and no - they repeat, it will not put the comet or any part of it on a collision course with the Earth.
Yeomans calculated that in order to move Temple-1 or part of it into an orbit that intersects with the orbit of DHA, the "impactor" must be 6,000 times more massive than what was fired from the mothership on the third of July. The next day, the "impactor", weighing 370 kg, will hit the heart of the comet, creating a massive show for the Fourth of July [Independence Day in the US].
In heavenly terms, the resulting crater, whether the size of a house to the Colosseum of Rome, or two or fourteen stories deep, is considered a mere hole. Apart from that, comets are showered with interstellar material all the time, and are therefore scarred with craters and cliffs.
"You have an object the size of a 'bushel' basket ("a basket big enough to hold 8 pounds [3.5 kg]" basically it's a sort of carrying basket, made of wicker) flying into an object that's 14 km long, so we're not really going to cause The comet has considerable damage," Yeomans says.
Some scientists, however, claim that the comet will break into several pieces. Others assume that "Deep Impact" will create a crater but push everything into it, so that hardly or no material will be ejected.
"It's the uncertainty in the predictions, or the wide variety in them, that makes it especially important to do this simple experiment," says Michael A'Hearn of the University of Maryland, the lead scientist on the mission.
Whatever the results, scientists hope to learn something about the shift in the trajectory of a threatening comet, or asteroid, if one happens to cross the path of the Earth's orbit. Comets, after all, have hit the Earth in the past, and may have brought water with them.
Another practical benefit from the mission is that by knowing the contents of comets, NASA will be able to use them in the future as "watering holes" and gas stations. Robots or astronauts, for example, will be able to break down the comet's water into its basic elements - hydrogen and oxygen, which are needed to fuel rockets.
Then there is all the scientific knowledge that will be gained from the study of comets, which are basically huge and dirty snowballs that surround the sun.
Formed at the same time as the planets, 4.5 billion years ago, comets are considered the remains of the building blocks of the solar system. When comets periodically pass near the Sun, their surface heats up and changes, and only their inner region is protected from the cosmic environment.
The "impactor", consisting mainly of a copper disk weighing 140 kg, will maneuver itself into the orbit of the approaching comet, and basically - will be run over by the comet. The relative speed at the moment of collision will be 37,000 km per hour, enough to vaporize the "impactor".
Copper was chosen because, like silver and gold, it does not react with water and will not tarnish the observations. Also, it is extremely cheap.
A camera on the "impactor" will photograph the comet and transmit the images back, almost until the moment of destruction. A pair of cameras on the mother ship, which will be at a safe distance from the hazard of 480 km, will record the impact itself, the resulting eruption and the crater, and then - will send all the images.
"We're looking forward to putting on a great fireworks show for everyone," says Garmier, "and it's even more exciting to do it on the Fourth of July." For news on CNN
They knew the asteroids and comets
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