In the place of the Solar system where we study the distant Universe using powerful ground and space observatories have provided us with data and knowledge that we never dreamed of. But we still have no opportunity to go somewhere beyond Mars, we were told about this mission to other planets. Despite all the resources we gave planetary science, we sent only one mission to Uranus and Neptune: “Voyager-2”, which just flew past the planets. What are the prospects for an orbital mission to the outer worlds?
There is a window in which to Uranus or Neptune, you can send the spacecraft using Jupiter for a gravitational acceleration. What you need to do to sufficiently slowed down after such a maneuver and went into orbit “ice giants”?
Uranus and Neptune: how to investigate?
Solar system is complicated, but, fortunately, familiar to us. The best way to get to the outer Solar system — that is, to any planet Jupiter is use of Jupiter. In physics, when you take a small object (e.g. a spacecraft), which passes a massive and immovable object (like a star or planet), the gravitational force can significantly change its speed.
But if there is a third object with gravitational significance in this equation, everything changes a little bit, and this is especially important to reach the outer limits of the Solar system. Spacecraft flying close to the planet bound to the Sun, may gain or lose speed due to the weaning of the pulse of the system planet-Sun. Massive planet anyway, but the spacecraft can obtain the acceleration or deceleration, depending on its trajectory.
This kind of maneuver with gravity support was required to run “Voyagers” beyond the Solar system, and most recently for the launch of “New horizons” to Pluto. Despite the fact that Uranus and Neptune have a remarkably long orbital periods of 84 and 165 years, respectively, the missions window to return to them again every 12 years or so: every time Jupiter completes an orbit.
The spacecraft, launched from Earth, typically around several of the inner planets a few times in preparation for the gravity maneuver with Jupiter. The spacecraft, flying around the planet can use the “gravitational slingshot” to the planet dispersed it. If we wanted to launch a mission to Neptune today, the alignment of the planets will allow us to do it. With Uranium, which is closer, it would be even easier to make.
Ten years ago was offered the mission of the Argo: to fly around Jupiter, Saturn, Neptune and Kuiper belt objects with a launch window from 2015 to 2019. But the mission’s flyby is just because you don’t need to slow down the machine. Throw it into orbit of another world is much more complicated, but interesting.
Instead of one aisle, the Orbiter will allow you to repeatedly explore the world for long periods of time. You will be able to observe changes in the atmosphere in the world, and constantly to explore it in a wide range of wavelengths, invisible to the human eye. You can find new moons, new rings and new phenomena, which did not expect to find. Can even send a lander or probe to a planet or one of its moons. All this and more has happened around Saturn, recently completed by the Cassini mission.
Cassini has studied not only the physical and atmospheric properties of Saturn, though this part was done brilliantly. Not only is she photographed and studied the ring, although with it. More interesting is the fact that we have seen changes and transient events, which would never have predicted. Saturn showed the change of the seasons, which corresponded to chemical and color changes in its poles. A huge storm appeared on Saturn, surrounding the planet and held out for many months. It was discovered that the rings of Saturn have pronounced vertical structure and change over time; they are dynamic, not static — a great laboratory to study the formation of planets and moons. With this information, we decided to old problems and opened up new puzzles about the satellites of the planet of yapet, Titan, Enceladus, and others.
There is no doubt that we want to do the same with Uranus and Neptune. For Uranus and Neptune were offered a lot of missions, many of which have undergone the process of the application, but neither one of them have not started planning. NASA, ESA, JPL and UK were offered the orbital of the device on Uranium, all of which are in development but nobody knows what will happen to them in the future.
So far we studied these worlds from afar. But there is great hope that the future mission many years later still held when the launch window for the achievement of both worlds will be open. 2034 conceptual ODINUS mission will send a spacecraft-Gemini to Uranus and Neptune at the same time. The mission itself will be an interesting joint venture of NASA and ESA.
One of the major flagship missions, the proposed NASA planetary scientists in 2011 was the probe and the Orbiter for Uranus. This mission was the third priority after the mission Mars 2020 and Europa Clipper. These dual machines would have to go in 2020-ies in the 21 day, which is every year: when the Earth, Jupiter and Uranus are in the optimal position. The Orbiter would take three separate tools designed for the visualization and measurement of the various properties of Uranus, its rings and satellites. Uranus and Neptune should possess a liquid ocean underneath the atmosphere, and the Orbiter would probably have to detect it. Atmospheric probe will measure a cloud of molecules, distribution of heat and change of wind speed with depth.
The proposed European space Agency program ODINUS goes further, extends this concept in two double orbital devices that will go to Neptune and Uranus. The launch window in 2034, when the Earth, Jupiter, Uranus and Neptune will be aligned appropriately, will allow you to run them at the same time.
The mission of the fly-great for first meetings, because you can learn a lot about the world, studying it from close range. Also they are really achieve a few goals, while the orbiters are stuck in any world, the orbit of which is selected. Finally, the orbiters should have on Board fuel to maneuver, slow and stable orbit, making the mission much more expensive. But the science that you get from a long-term stay on the planet, more than makes up for it.
Current limitations of such a mission are not associated with technological advances; technology to implement it today, already exist. The difficulty is this:
- Policies. Since the NASA budget is limited, resources are scarce.
- Physics. Even if we take the biggest ship of NASA, unmanned version of the SLS, we can send a limited mass in the outer Solar system.
- Practice. Given the huge distance from the Sun, solar panels will not work. Need radioactive sources to power the device so far, and this is the biggest problem.
The fact that radioactive sources for long-distance probes (like Voyager) feed on plutonium-238 — an isotope that is created during the processing of nuclear materials. A large part of the plutonium-238 was created during the active nuclear arms race. It is needed for radioisotope thermoelectric generators (RTGs) used in space probes.
However, since 1988 the production of plutonium-238 ceased, and stocks were exhausted.
The faster you move at a meeting with the planet, the more fuel you need to burn the machine to slow down and stay in orbit of the body. In the case of Pluto, there was no chance: “New horizons” was too small a device, and had too much speed, plus the mass of Pluto was too low in order for it to catch on. But in the case of Neptune and Uranus, if we choose a good path of acceleration from Jupiter and possibly Saturn, it can be feasible. If we want to go just for the Uranium, we can go in any year in 2020. If we want to visit on the planet, our year — 2034. Uranus and Neptune can be similar from afar, but up close they can be as different as Earth and Venus. There is only one way to find out.
Can we send something like a Cassini to Uranus or Neptune?
Ilya Hel