The destination is Neptune

NASA scientists want a mission to Neptune to shed light on how the solar system formed

The next gas planet that the scientists of the American space agency have their eyes on is Neptune. Their assessment is that an in-depth study of its internal and external structure will shed light on the way the solar system formed. An initial step taken towards such an ambitious mission is a $250,000 grant provided by the Space Agency to the Boeing Company in order for it to prepare an action plan that will support the scientific goals for this mission. All this within the framework of the agency's Vision Missions. According to the general lines, this spacecraft will be equipped with a nuclear engine. From the moment the spacecraft reaches Neptune, it will be put into a polar orbit around it, and probes will be launched towards it (which will penetrate its atmosphere and perform various studies¹. The year of the launch is 2015.

It is a combination of two approaches that were each applied to a different planetary destination. The first concept is the polar orbit approach used in the Mars Global Surveyor. The advantage of this orbit is the saving of fuel. There is no need to change its orbit while circling the star, since it can observe any point on it in its entire orbit. The second approach was implemented in the Pioneer Venus Multiprobe which was launched towards Venus on August 8.8.1978, 9.12.1978 and reached it on December 4, XNUMX. It was a carrier spacecraft equipped with XNUMX small capsules. When the spacecraft arrived at Venus, the capsules were detached from it, penetrated the atmosphere at different points and during their penetration into the atmosphere, various measurements were made.

When you launch a spacecraft to Neptune, you cannot ignore its moons and the rings that surround it. Unlike the other gaseous planets that have moons whose diameter is in the range of 500 kilometers to 5100 kilometers and a very large number of very small non-spherical bodies, Neptune has another moon that is in the same range of orders of magnitude and I mean Triton whose diameter is 2800 kilometers. Similar to Titan, Saturn's moon, it also has an atmosphere, albeit a very thin one. The Galileo spacecraft that reached Jupiter and the Xsini that reached Saturn entered orbit around their target stars and each time they used their gravity to reach one moon to make measurements on it, return to the planet to circle it and throw it again towards the same moon or towards another moon. In terms of Triton's investigation a choice Optimal routes are simpler. No need to reach other moons. Neptune does have other moons, but these are small, non-spherical bodies. Most of them are tens of kilometers in size. There are 14 moons, the smallest of which has a diameter of 14 km and the largest, Proteus, has a diameter of 218 km. Excluding one moon, Narid, their distances from Neptune are small and their orbits are thousands of kilometers apart. The distance of Triton from Neptune is 354,760 km. Excluding Narid, the distance of their orbits from Neptune is smaller than that of Triton. The distance of Narid is 5,513,400 km. It is therefore an easy system to investigate from a design point of view. Considering the high resolutions of the cameras and their continuous improvement, it will be possible to photograph these bodies in the highest quality.

These data raise the question of whether it would be worthwhile to think about a different orbital configuration for the same spacecraft that will reach Neptune, an orbital geometry that will also allow an intensive investigation of Triton and its mapping. The most suitable orbit is a looping orbit where the spacecraft takes advantage of the gravity of Neptune and Triton. In orbiting Neptune, the spacecraft uses its gravity to reach Triton, makes half a circle around it, uses its gravity to reach Neptune, makes half a circle around it, uses its gravity to reach Triton again and so on. This is a trajectory whose geometrical shape is the shape of the number "8" and the launch point of the two "zeros" of the number "8" is between Neptune and Triton. Another advantage of this flight path is that the spacecraft periodically arrives close to these bodies and moves away from them. The result is close-up shots of target areas using the narrow-angle camera and panoramic shots using the wide-angle camera. While moving in its space orbit, it will be able to direct its cameras towards the small moons and towards the rings. Upon arriving at Neptune, the spacecraft will enter an equatorial orbit around it, perform a number of orbits to test systems, and then change its orbit to a looping orbit, and in every number of orbits, the inclination angle of the orbit will be changed in order to reach full coverage of Neptune and Triton.

And what about capsules? When the Pioneer Venus Multiprobe arrived at Venus it released the capsules at various points in the atmosphere, so that longitudinal and depth sections of the atmosphere could be made. The capsules stopped transmitting when the atmospheric pressure was greater than their design load capacity and they were crushed. The same will happen to the capsules that will penetrate the atmosphere of Neptune. The use of microelectronics will make it possible to minimize these capsules. To illustrate what this is about, let's imagine a capsule the size of a mobile phone. The surface area of ​​a miniaturized capsule is small and it will therefore be able to withstand high atmospheric pressures and can therefore enter greater depths in the atmosphere. Due to the small weight of such a capsule, it will be possible to place dozens of capsules on the carrier spacecraft. The capsules will be released immediately into the atmosphere after the spacecraft enters orbit around Neptune. Another more effective deployment method is to release some of the capsules upon entering orbit around Neptune and to release the rest one by one according to the observed phenomena. If, for example, you see the development of a cyclone in the atmosphere or the movement of clouds, it will be possible to send capsules towards them. It is not impossible that some of the capsules will be launched towards Triton and the rings. The closest thing to this type of carrier spacecraft with several dedicated pods on it is a nuclear missile with a fission arrowhead.

Shipping the capsules may divert the spacecraft from its course and it will be necessary to compensate for the deviation using navigation engines. It would not be desirable to operate these engines with every shipment since fuel would be wasted unnecessarily. It would therefore be necessary to plan a tolerance that deviations within this area would not cause any significant changes in the flight path. However, if the deviation exceeds this range, the navigation engines will be activated. This will be monitored by the spacecraft's computers. At first glance, it seems that the cost of developing these capsules is less than that of developing a life-sized spaceship. It is worth considering the development of these capsules in Israel and opening a new field of micro spacecraft.

Due to the great distance of Neptune from the Earth and the duration of the signal transmission to or from it, 4.5 hours, the control center will be flooded with huge amounts of information and it may collapse. It will therefore be necessary to assign unique transmission frequencies to each capsule and divide the management of the transmissions between several sub-centers with a main control center that will supervise them.

An operation of this kind will require not only appropriate technological evaluations, but also unique organizational evaluations. Most of the parts of this organizational system will be dormant and they will come into action when the spacecraft enters orbit around Neptune. The information that will reach Israel will be of unprecedented scope and will most likely contain many surprises. The investment in this kind of project is worthwhile.

Source: Boeing to study Neptune missions for NASA 2.6.2004

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