The effect of “Pioneer”: the first mystery of deep space

Flights to deep space will certainly bring a lot of puzzles to solve which we will be able a very long time. This is not surprising. Had only the first messengers of the Earth to escape the orbit of the giant planets, as the space immediately threw a challenge at us. And to solve it, even offered to adjust the laws of physics.


The American program of outer space exploration has always bore the sonorous names and had ambitious goals. In the framework of the program “mercury” the Americans made their first manned flight and created the first group of astronauts. During the next program “Gemini” have been worked out methods of rendezvous and docking in orbit. The third manned space program has become notorious Apollo program. It was manned flights to the moon. But to study interplanetary space and celestial bodies was launched the program “pioneer”.

In the framework of its missions of the USA in the period from 1958 to 1978 sent into space exploration probes. The spacecraft flew to the Sun, Venus and the moon, explored the us approaching the comet. “Pioneer-3” discovered a second radiation belt of the Earth, and the “pioneer 7” was involved in the study of comet Halley. For today well-known two spacecraft programs. Running is one of the last probes “pioneer 10” (the launch was made in March 1972) and “pioneer-11” (April 1973).

The probe “pioneer 10” in the build process / ©

In the future, NASA has launched other research programs. With a new, more sophisticated probes. In 1977 in the framework of the program “Voyager” to the far planets of the Solar system sent “Voyager-1 and Voyager-2”. And in 2003 launched the “New frontiers”, which was sent into space in “New horizons”, “Juno” and OSIRIS-REx. But in the 50s, when the program began, its devices in the United States were considered the pioneers of space, and therefore was named “Pioneers”. “Pioneer 10” and “pioneer-11” became the first spacecraft flew through the Main asteroid belt, and the first designed to study Jupiter from a close distance.

“Pioneers” would have been the first to go beyond the Solar system, but in 1998 more fast “Voyager 1 overtook the spacecraft “pioneer 10”, which had the yellow Jersey in this tour of the Solar system.


The first anomaly in the flight trajectory of the probes was discovered in the 1980s. at this point, the probes have already fulfilled their primary mission. “Pioneer 10” flew close to Jupiter in December 1973, specifying its mass and measuring the magnetic field. “Pioneer-11” approached the planet in a year: in December 1974. Making detailed pictures, he went to Saturn. In 1979 the unit was transferred to Earth image of the planet and its satellite Titan.

The main mission is over, but the monitoring data of the trajectory of the spacecraft “pioneer 10” decided to use for the search, as the then was supposed tenth planet of the Solar system. And now the ninth (following a decline in the status of Pluto). If there was a deviation in the trajectory, then, as scientists believed, this would be a consequence of the gravity of an undiscovered planet. The deviation found, but the cause of this anomaly was not a planet on the edge of the Solar system. But what is most interesting, subsequently, the anomaly was detected and the probe-twin.

Illustration of the output of “Pioneer” and “Voyager” beyond the Solar system / ©

Today, the devices fly off in different directions. “Pioneer 10” moves to the edge of the milky Way towards the constellation of Taurus. His twin, on the contrary, to the center of the Galaxy, towards the constellation of the Shield. You have to understand that now both tubes are in free flight. Only the previously obtained acceleration and external forces affect the flight of the spacecraft. Forces of gravitational and non-gravitational.

Among non-gravitational, for example, the pressure of solar radiation causes acceleration directed from the Sun. And the gravity of the Sun, on the contrary, stalling devices to the star, causing an acceleration directed towards the Sun, i.e. slows them down. All the forces that can influence the flight of the spacecraft, calculated and taken into account. Except one. An unknown and incomprehensible force to pull the probe back. It is the cause of a mystery “Pioneers”. Negligible power, but it is. Recent calculations obtained by 2002, say that the magnitude of the unexplained acceleration is negative (a total of 8.74±of 1.33)·10-10 m/S2.

This is negligible, but led to rejection of vehicles by approximately 400 thousand kilometers from the planned trajectory. It would seem that probes have flown millions of miles. At the time of loss of communication with “Pioneer-10” (23 January 2003) he departed from us more than 12 billion kilometers. 82 astronomical units, i.e., 82 the distance from the Earth to the Sun. Communication with “Pioneer-11” was lost on 30 September 1995, the unit already was from the Sun at a distance of 6.5 billion kilometers, or 43. E.

And that these hundreds of thousands compared to the billions of kilometers away? But for science these tiny quantities can make a huge difference. A deviation from the norm, from the usual understanding of things, that is, anomalies can indicate the presence of something meaningful, but still unopened. Especially in astrophysics.

The anomaly in the motion of Uranus led to the discovery of a new planet – Neptune. The anomaly in the motion of mercury discovered in 1859, was explained using the General theory of relativity albert Einstein developed in 1915. The solution to the anomaly of “Pioneers” could upend modern physics, or, on the contrary, will be quite trivial. That’s why she is not haunted by many scientists.

The question may arise: how do scientists estimate the speed and, consequently, the acceleration of the spacecraft? The long probes are not available for observation. Neither Hubble nor any other telescope can not see flying away from us probes. The speed control probe is done by measuring the Doppler shift frequency of the radio signal is emitted towards the probe and taken from him back. It is based on the same Doppler effect used to determine the speed of the cars. The effects in the form of so-called purple offset, the offset of the radio signal in the shortwave region of the spectrum, which means that the probes began to slow down.

But if we are talking about the effect that can influence the movement of the two probes, it can also affect other? We have already said that after the program “pioneer” was and more. Here only the “Pioneers” are in flight with no additional adjustments in course over time. But the trajectory and orientation of the other probes are still adjusted by shunting engines. Therefore, accurate measurement of the effect, if any, it is impossible to produce.

Possible causes of the anomaly

In all the years dedicated to finding solutions to this puzzle was put forward many assumptions. And the first is errors in the observations and interpretation of the data. But refused it almost immediately. The anomaly was explained by different reasons. Deceleration on the interplanetary medium (dust, gas clouds, etc.). The gravitational attraction of the Kuiper belt objects. Leakage of gas, for example helium used as the working fluid in radioisotope generators. The cause was searched for in the electromagnetic forces generated by the accumulated electric charge probes. And, of course, blamed on the influence of dark matter or dark energy. Not without proposals to adjust the existing physics. Previous assumptions were given non-gravitational explanation of the effect. In 1983, Israeli physicist Mordechai Milgroom have been proposed so-called theory of modified Newtonian dynamics (MOND). She is an example of alternative theories of gravity. According to MOND, in cases when we are dealing with bodies moving with an extremely small acceleration, Newtonian mechanics needs to be amended.

However, the cause of the abnormal acceleration “Pioneer” seems to be still found. But first say a little about the design of devices. The probes have on-Board scientific instruments and a parabolic antenna with a diameter of 2.75 meters for communication with the Ground. All this equipment needed a power supply. Look at the design of the “Pioneers”. See it as the usual satellites solar panels? No. For devices, exploring the distant planet of the Solar system, there is no sense in solar cells. The farther into space, the intensity of solar radiation decreases. Solar energy is no longer sufficient for the operation of solar cells solar cells.

The scheme of the device “pioneer-10” / ©

In contrast to probes bound for the inner planets of our system, for missions to Jupiter, Saturn and other distant planets aboard a set of radioisotope thermoelectric generators using plutonium-238. It is not nuclear reactors. They work on a different principle. Radioisotope generators use the heat energy released during the natural decay of radioactive isotopes and by using thermoelectric generators convert it into electricity. Plutonium-238 is so radioactive isotope, the decay of which feeds the equipment on Board the probes. Each probe has four generators, which are mounted on two three-meter extension rods, away from the scientific instruments unit.

To explore the anomaly “Pioneers” in the jet propulsion Laboratory of the National aerospace Agency of the USA was created by the research team. It was led by our compatriot, a graduate of the physics Department of Moscow state University Vyacheslav Turyshev. The researchers were able to construct a mathematical model that explains the anomalous acceleration of the Pioneers at least 70%. According to them, it’s all about heat flow from the probe in different directions. As the main heat source – radioisotope generators, which powered the onboard equipment. From the operation of the devices stood out warm. As shutdown devices most of the energy spent on heating of the probes. Heat was radiated into space. That is the recoil force of thermal radiation and underestimated when calculating the intended flight path. However, the pressure of the heat radiation evenly. In flight, the probes are stabilized by rotation around its longitudinal axis. Radiated perpendicular to the longitudinal axis of the heat is dissipated evenly in all directions and on the motion of the probes is not affected. But there is still radiation along the axis. And it radiates unevenly. The calculations showed that the heat flux emitted in the direction of movement of the apparatus, gives a better return than going in the opposite direction, that is, overpowers it and causes the braking effect.

The view from the back side of the transmitting antenna / ©

But what is the reason for the other 30%? Perhaps the physicists of the Portuguese Institute of plasmas and nuclear fusion was able to find an explanation. They went down the same path as the group Turysheva. But paid more attention to the transmitting antenna probes, which, recall, has a nearly three-meter diameter. Making new calculations based on the mathematical model of probes, they came to the conclusion that the reflected from the back side of the antenna’s thermal radiation and gives the same missing momentum.

Well, the mystery that haunted the scientists seem to be allowed. Humanity continues to explore the cosmos. For new mysteries and exciting finding solutions.

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