Recently Ceres came out of contrast, where it is on the other side of the Sun, which limited the spacecraft's contact with Earth for a while. Upon exiting contrast, the flight engineers can plan the essential maneuvers for the encounter with the asteroid. Today the spaceship's distance from Keres is 640,000 km and its flight speed is 725 km/h
Translation - Haim Mazar
Asteroids and this year also comets have become the hot targets of all space agencies. Now NASA reports that the Dawn spacecraft is about to study the asteroid Keres and enters an orbit from which it will gradually approach it until it moves to the coffee orbit.
The spacecraft was launched in 2007 and will enter orbit around the asteroid in March 2015. Dawn mission principal investigator Christopher Russell says Crass is a complete mystery to researchers. There are no craters on it, which may make it difficult to discover its north. The only thing that can be said about it is that we will be surprised. In the last months with the approach of the spacecraft, the quality of the photographs of Keres that will come from it will gradually improve. Starting at the end of January, Dawn will surpass the imaging capability of the Hubble Space Telescope and giant ground-based telescopes on the largest asteroid in the Solar System.
Recently Ceres came out of contrast, where it is on the other side of the Sun, which limited the spacecraft's contact with Earth for a while. Upon exiting contrast, the flight engineers can plan the essential maneuvers for the encounter with the asteroid. Today the spaceship's distance from Keres is 640,000 km and its flight speed is 725 km/h.
This is the first case in history where one spacecraft orbited two bodies in the solar system. The first mission took place between 2012-2011 and studied the asteroid Vesta for 14 months. This study included various photographs and measurements of it. Between these two asteroids there are several differences. Ceres is believed to have formed later than Vesta and its interior is colder. The measurements show that Vesta retained a small amount of water. The reason, its early formation occurred when the radioactive materials were more common, which allowed for a greater generation of heat. Keres in contrast has a thick ice shell and may also have an underground ocean. Cers because of its size, 950 km in diameter is the largest of the asteroids. Vesta is second to him with a diameter of 525 km.
Unlike other spacecraft that use chemical engines to propel them, here an ion engine is used, since this engine is found to be more effective in putting spacecraft into orbit around asteroids. In this case, xenon gas is used. The gas is introduced into the engine body and with the help of electrical charging of the internal walls of the engine, the gas is pushed from one wall to the other until it is ejected through the exhaust nozzle. The spacecraft's acceleration is cumulative, so it took five years to reach the necessary flight speed.
A film describing the Dawn spaceship and in particular its ion engine
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The second option is a sail with a diameter of about 4 km, which collects mass particles from space like a funnel and routes them according to the funnel. An MDB option of the type that Carl Sagan would have presented in Cosmos. I don't think we know how to make a 4 km sail and protect it from asteroids.
Since we're all going to be engineers for a moment on the way to billing, here's a proposal for your consideration.
I meant: an electric source will emit ions - this is the principle of the new ion engine of the spacecraft that already exists. The ions come from plasma. know how to produce plasma. Even an electric laser is possible. Ions are particles with mass. The reactor will operate to turn a turbo-fan engine on the heat of steam, recycling the steam, instead of on oxygen that it carries with it in rocket propulsion, on the ions.
The ions will be accelerated to speeds. The reactor will provide energy to spin a jet engine instead of solid fuel. That is, in short, the ion engine carries the mass with it through the fact that by creating a plasma it is the source of the particles. Now the question is whether plasma is enough.
The crashed spaceship flew in my memory with an ion engine.
http://en.wikipedia.org/wiki/Ion_thruster
a thousand
There are no controlled atomic explosions. There is a quiet nuclear reactor of the i-cat type (which is currently disputed if it even works) but it does not emit anything significant, except heat. Will probably be used to generate electricity in space flights, if it works, but not to drive the spacecraft.
As we mentioned, in order to propel the spacecraft, it needs to emit a mass of material, since the mass in space is limited by carrying its own mass, this is not really a solution. Ejecting a small mass at a huge mass speed to create a large momentum is not feasible because as mentioned today there are no controlled sealed explosions nor are there any serious proposals for this.
Propulsion with nuclear power can be carried out with controlled explosions that create thrust or an electrical source, instead of solar panels.
The problem with a nuclear engine is not the lack of ability to generate momentum. In a nuclear reactor in a power plant steam is produced from the heat and this steam is propulsion. The problem is the lack of the raw material from which momentum is produced. The production of a fan with a diameter of several kilometers to collect particles from space seems too advanced for the technology of our time. But nuclear material emitting particles actually sounds good. Ion engine if you search on Wikipedia it produces ions by plasma. It is not a nuclear engine but only electric. The combination between the two sounds desirable for nuclear propulsion for many years in space without refueling. This is exactly what we need.
An ion source on the one hand, and a nuclear engine that spins a turbine on the other, and there is no need for solid fuel and oxygen.
http://en.wikipedia.org/wiki/Ion_thruster
Dan
It actually makes sense - note, 725 km/h is the relative speed between the spacecraft and the asteroid. Do the math - that's a total of 36 more flight days.
725 km/h??? Impossible... much faster, probably 20 or thirty times...
Ionic propulsion gains acceleration gradually, in the end the progress is fast. The use of such propulsion is used to test/improve and gain experience in this propulsion.
Joseph
In space, there is only one way to move forward, and that is to throw mass back. A nuclear reactor creates heat, which is converted into electricity. Electricity, in submarines and ships, is used to turn a propeller that provides "lift" in the direction of movement, by pushing water backwards.
In space... it won't work.
Another option is an ion engine, which produces thrust with the help of ion emissions. That's exactly what Dawn has.
Joseph
The reason may be financial. Several spacecraft were equipped with a nuclear power source. It is possible that the development of a nuclear propulsion system will significantly increase the cost of development. Even so, NASA is not flush with budgets. It may be that some breakthrough will come that will enable the development of new propulsion methods. If you have an engineering education try to develop a new drive method. You never know.
Why not use nuclear engines, not engines with nuclear fuel.
After all, propulsion is produced in submarines and aircraft carriers by turning a rotor. But what is able to drive a rotor is able to release gas under pressure. True, this is not done in airplanes, so maybe there is a factor that prevents spaceships as well. Assume the amount of thrust it generates. A nuclear engine allows propulsion without refueling for about 13 years and the core volume is the size of an orange.
True, it complicates life a lot: a) A reactor requires cooling and monitoring systems and backup systems for cooling and a chain reaction stopping system and more. But this is done in submarines and aircraft carriers.