Hayadan > Technion researchers have proposed a model for finding new moons for Pluto, awaiting New Horizons photographs

Technion researchers have proposed a model for finding new moons for Pluto, awaiting New Horizons photographs

The members of the research group of Prof. Hagai Peretz from the Technion, who study Pluto and its moons, estimate that this information will greatly contribute to our knowledge of that distant region of the solar system. The spacecraft, which contains scientific equipment as well as the ashes of the man who discovered Pluto, will continue towards Pluto's main moon and from there to the outskirts of the solar system

Prof. Hagai Peretz. Photo: Nitzan Zohar, Technion

Exactly fifty years after the visit to Mars: first visit to the dwarf planet Pluto

Today at noon, the New Horizons spacecraft will pass by Pluto, and will send valuable information to Earth. The members of the research group of Prof. Hagai Peretz from the Technion, who study Pluto and its moons, estimate that this information will greatly contribute to our knowledge of that distant region of the solar system. The spacecraft, which contains scientific equipment as well as the ashes of the man who discovered Pluto, will continue towards Pluto's main moon and from there to the outskirts of the solar system

In a few hours - more precisely, one minute before 15:00 PM - the New Horizons spacecraft will pass by the closest point to the dwarf planet Pluto. Shortly after, it will pass by Charon - Pluto's main moon - and from there it will continue towards the edge of the solar system.
The historic "visit" expected today will take place exactly 50 years after the first images from the surface of Mars reached Earth. On July 14, 1965, humanity discovered for the first time what the surface of a planet other than Earth looks like. Since then, the rest of the planets, except Pluto, have been studied.

60,000 km/h. Therefore - to study Pluto - New Horizons was launched about nine years ago. The spacecraft, which weighs about 500 kg, took off into space at a record speed close to 60,000 km/h. In order to save energy, it was "put to sleep" after that for a few years, and only last December was it "turned on" so that it could transmit the information from the vicinity of Pluto. These transmissions started a few months ago, and brought to Earth a lot of information and wonderful images.

From Mars to Pluto. For decades, Pluto, discovered in 1930, was considered one of the main planets in the solar system. Since then, all the other planets have been "visited" by spacecraft that photographed them, so the closing of the circle today is a historic moment. Many around the world will hold their breath today - including those who were born long after the "visit" to Mars on July 14, 1965. Two of them are Prof. Hagai Peretz and doctoral student Erez Michaeli, from the Technion's Faculty of Physics, the researchers of "potential moons" that may be discovered around Pluto.

"Pluto was discovered in 1930," explains Michaeli, "and only in 1978 was its main moon, Charon, discovered. In the last decade, thanks to the Hubble Space Telescope, four more moons were discovered orbiting Pluto in the same plane. Since then the question has been asked: Does Pluto have other moons?"

Potential moons. In their joint research, Michaeli and Prof. Peretz predict the possible locations of additional potential moons. "We do not pretend to say if there are such moons, but only 'map' the areas where they may be found," explains Michaeli. "Our mapping is based on the given information and a system of equations, and we predict that if such moons are found, they will be in the area we 'impress'."

And if you were wrong? "As an astrophysicist, I really want new things to be discovered, so I would be very happy if moons were also found in those places. This would of course mean that there is something we haven't taken into account, but to some extent it would be even more interesting. This is one of the most beautiful things in science - surprises reveal more to us than the success of our predictions."

A planet is born. "The discovery of additional moons may help us better understand how Pluto was formed," says Michaeli. "The currently accepted explanation in the astrophysics community is that Pluto was formed as a result of an accidental celestial collision of two objects, some of the debris of which became its moons, but the simulations show that the speed of the collision was unusually slow."
"The collision of a celestial body with its moon occurs at a relatively slow speed," says Prof. Peretz, "and now we are working on a new model in which Pluto has been hit by its distant moon. Such a collision may explain what we see today. According to this model, the current moons of Pluto were formed from the collision of Pluto with one of its ancient moons."

The internal structure. Dr. Uri Melmud, a postdoctoral student of Prof. Peretz, focuses his research on the development of bodies in the solar system and their internal structure. "Since we do not have direct data from such planetary bodies, we are forced to infer the internal structure from various observations and measurement of density, gravitational field, magnetic field, surface composition and various geological formations that may testify to the processes taking place inside. In the case of Pluto and Charon, the density was already known before, which gives a good initial indication of the possible internal composition, but now we can improve existing measurements and obtain detailed information about the composition of the surface and about geological formations. In our research, we base ourselves on assumptions concerning the conditions that prevailed during the formation of these bodies, and run advanced computer simulations simulating the development of Pluto over 4.5 billion years."

A glimpse into the past. "One can of course ask why at all study a rock block that is at the edge of the solar system," says Prof. Peretz, "but from a scientific point of view there is a huge motivation here. Pluto and similar objects give us a special opportunity to study the first building blocks of the solar system, some of which have been preserved almost unchanged. Pluto gives us a look at the birth chords of the solar system and the origin of the Earth, and now we get it live.”
In an article he published together with Prof. Dina Prielnik from Tel Aviv University in the journal "Icarus", Dr. Melmud assumes that Charon and other bodies in the Kuiper belt were "born" from a homogeneous composition of rocks and ice, and developed at a later stage as a result of warming that led to the flow of Water and gas through a porous medium typical of small bodies in the solar system. "Such dwarf planets have a fairly regular structure - an ice shell covering a rocky core - but their level of porosity varies. In our article we showed that this difference stems from their different masses." In a follow-up study conducted by Dr. Melmud and Prof. Peretz, they are trying to expand the previous study, so that it will be possible to perform simulations of larger bodies such as Pluto, partly in light of the new information that will be received from New Horizons.

Pluto and the "New Horizons" mission

New Horizons was launched from Earth on January 19, 2006 - when Pluto was still considered one of the nine planets of the solar system - and since then it has traveled almost 5 billion kilometers. During its journey, the spaceship moved away from the sun so far that it is unable to generate electricity from the sun's rays. Therefore, a small plutonium-based nuclear reactor was installed there.
New Horizons was designed, built and launched with the aim "to understand the worlds at the edge of the solar system through a first tour of the Pluto system and the Kuiper belt, which is a remnant of the formation of the solar system." In addition to the scientific equipment, the spacecraft carries several objects including a coin of the state of Florida; A container with an afro of Clyde Tombaugh, who discovered Pluto in 1930; 1991 Pluto stamp; And of course the US flag.

Pluto was considered one of the nine planets in the solar system until 2006 - the year when it was removed from its status by the International Astronomical Union (IAU) and defined "only" as a dwarf planet. Several reasons were given for the decision, which was made despite the protests of many astronomers: the size of Pluto (it is smaller than many bodies in the solar system, which were discovered in recent years and are not defined as planets); The unusual fact that Pluto and its main Saturn Moon are not very different in size; Pluto, unlike "real" planets, does not clean its environment of particles and larger objects; And finally - Pluto's orbit is different from that of our familiar planets, which all move around the sun on the ecliptic plane. The plane of Pluto's movement around the Sun is at a deviation of about 17 degrees from the plane of Milka, and its rotation around itself occurs at 119 degrees from this plane, so that the direction of its self-rotation is opposite to the direction of its orbit around the Sun.

Pluto was discovered by Tombo in 1930, and its name was given to it in a public competition - the winning name was suggested by an 11-year-old girl. Due to its distance from the sun - about 6 billion kilometers on average - a very low temperature prevails on its surface: around 220 degrees Celsius below zero. Because of such a long orbit, our "Pluto year" lasts 248 years. Pluto's orbit is very elliptical, unlike most of the planets, and this fact causes strange phenomena: when it is far from the sun it is completely frozen and has no atmosphere, and when it gets closer it heats up and materials evaporate from the surface and create the atmosphere, and God forbid.

More of the topic in Hayadan: