In the 20th century, space exploration appeared using artificial satellites, space probes and manned spacecraft. Humans have come a long way since the first artificial satellite was launched in 1957 and sent several supermassive things into space. Here is a list of the seven largest objects in space sent from Earth.
- International Space Station (ISS)
The largest human-built space station, the ISS, is larger than a football field and measures 109 meters long, 73 meters wide and weighs over 408,233 kg. The manned space station, is an orbital laboratory where various scientific and space research, observations and experiments are carried out, is the only artificial satellite that can be seen with the naked eye from planet Earth.
2. Hubble Space Telescope
More than two buses, the Hubble Space Telescope has been the largest in its category since 1990. The space telescope is over thirteen meters long and weighs 12,247 kg.
3. Environmental satellite (Envisat)
The largest satellite to orbit the Earth, Envisat monitors primarily monitor the Earth's atmosphere. The 10-meter satellite, weighing approximately 8,210 kg, is currently out of service, but is still in Earth orbit.
4. Orbital station "MIR"
Orbital station "MIR" was the First multi-module manned orbital station sent into space, measuring 33 meters long and 31 meters wide, it weighed 140 160 kg.
5. Saturn V
Saturn V, at 104 meters high and weighing 2,721,554 kg, was the tallest, heaviest and most powerful rocket ever. Saturn V has completed 13 missions on its timeline, from its launch in 1967 to 1973.
6. Skylab
Although not as large as the ISS, Skylab was the first space station to be launched from Earth. The space laboratory weighed almost 77,111 kilograms and orbited the Earth from 1973 to 1979.
As many years as practical cosmonautics has existed, the observations of spacecraft in the sky also count. Millions of people all over the world saw the launch vehicle of the first Soviet satellite, which was in orbit for several days, hundreds of specially trained observers - the "ball" itself. Since then, there have been more than 25 thousand registered objects in near-earth space, and during one night, even without binoculars, every astronomy lover can see more than a dozen artificial earth satellites (AES).
Usually dim, they slowly creep between the stars in different directions. The brightness of some is constant, in others it changes periodically, and still others flare up. The Mir orbital complex floats majestically - the undoubted favorite in the Russian sky. The periods of its evening and morning visibility are repeated after about 60 days, although this interval floats a little with the season, and the brightness often reaches - 2 m.
It is not easy to identify the seen satellite: for this you need to make one or two precise marks of the object's position at certain points in time, and then select the most suitable candidate from the list issued by a special program, which contains the "fresh" orbital elements of more than eight thousand known objects. (I mean that you have a personal computer and Internet access at your disposal. Without both, you are severely limited in your capabilities.)
It is possible to describe all the delights and all the difficulties of observing satellites for a long time, but now I will tell only about one class of satellites, the unusually bright flares of which in the fall of 1997 made a real sensation. A word to the discoverer, Canadian Brian Hunter: “I was making observations on the evening of August 16, 1997, when a very bright object in the northeast caught my attention. It is difficult to give a reasonable estimate of brightness, but it was much brighter than Jupiter. -2m is just a guess like, "Wow, how bright!" It stayed very bright for a few seconds, then faded ... to 6th magnitude. " Hunter uniquely identified this object with one of the satellites in the Iridium series.
The next day, he sent the results of observations of the outbreak to an electronic conference connecting satellites observers with Internet access. It is clear that the short-term increase in satellite brightness by eight magnitudes has attracted a lot of attention. Within two days, reports of several more similar observations came from the USA, Sweden, France and Belgium, and soon such reports began to flood.
It's probably time to introduce the "hero" of our story. Iridium is a LEO communications system with 72 satellites (66 operational and 6 standby) located at an altitude of 780 km in 6 orbital planes with an inclination of 86 degrees. The satellites are launched on rockets from three countries: the American Delta-2 (five at a time), our Proton (seven) and the Chinese CZ-2C (two). The system has not yet been fully deployed: the first launch was carried out on May 5, 1997, and as of December 31 of the same year, nine launches were carried out (a total of 46 satellites were launched).
The body of each satellite has the shape of a triangular prism with a base edge of about 1 m and a length of about 4 m. The device flies in a "vertical" position. Two solar panels are mounted in the upper part, and three main working antennas extend upward and sideways from the lower edges of the prism. Iridium's normal magnitude does not usually exceed 7th magnitude. So why does it flare up so much?
After processing the first two dozen observations, the geometry of this phenomenon became clear: the sources of flares are working antennas - polished rectangles 0.86x1.88 m in size, inclined at an angle of 40 degrees to the vertical axis of the apparatus. The antenna just lets out a sunbeam! Moreover, if the angle between the reflected sunlight and the direction to the observer is less than 5 degrees, then he sees a flash of average brightness, and if less than one - an extremely bright flash.
The theoretical limit of the brightness of the "Iridium" flash is approximately -7.5 m. Indeed, a satellite antenna, equivalent to a circle 1.27 m in diameter and located 800 km from the observer, will shine with reflected sunlight in the same way as a mirror 237.5 km in diameter located at a distance from the Earth to the Sun. The area of such a mirror is 2.91 · 10 -8 solar, which corresponds to a brightness difference of 18.8 m (the apparent stellar magnitude of the Sun is known to be -26.2 m). The flare usually occurs at a satellite-observer-Sun phase angle in the range of 125-150 °, although sometimes at 90 °. The total duration of the flash visible to the naked eye is 30-60 seconds. The brightest part of the flash lasts a few seconds.
By the end of September last year, the Americans Rob Matson and Randy John wrote two programs IridFlar and SkySat, predicting flares based on the orbital elements of satellites inserted into them. These programs allowed early preparation for upcoming outbreaks, resulting in excellent photographs and videos of these events.
The results of visual observations turned out to be no less interesting. So, it was confirmed that due to the high brightness of the "Iridiums" at the time of the outbreak, they can be seen through rather thick clouds, and even in the daytime! But this, it turns out, is not all ... Everyone knows that satellites are visible only when it is dark below the observer, but the Sun is shining at the altitude. This truth was immutable for 40 years and ceased to be so on January 9, 1998, when the American Ron Lee observed a small flash of "Iridium" by the light reflected from ... the Moon!
The personal achievements of the author of this note in observing the Iridiums are still small. On December 2 of last year, I observed a satellite flare of about -4 m at an altitude of 28 ° against the background of sunset directly from the windows of the editorial office of the Novosti Kosmonavtiki magazine. Two more flares no brighter than -3 m were observed in the December cold. The author used the IridFlar program for forecasting, which gives a time-ordered forecast of flares for a given point, consisting of the times of the beginning, maximum and end of the phenomenon, right ascension and declination, azimuth (from the north point) and altitude, the calculated magnitude, and the coordinates of the point direct reflection (places where the satellite will have maximum brightness). It should be noted that the actual value may differ from the predicted value by about 1 m due to deviations in the orientation of the satellite and its antenna from the nominal ones and the error in knowing its own coordinates.
How often do outbreaks occur? To answer this question, I "ran" the IridFlar program for a week - from 12 to 18 January for an observer in Moscow. There were 27 simple bright flares in the range from 3 m to -3 m, as well as three superflares with magnitudes of -5.0 m, -5.9 m and -8.3 m.
Such a high frequency of flares, without a doubt, can pose another threat to astronomical observations. Englishman David Brierly was one of the first to draw the general attention to this problem: “While we all rejoice in the novelty of the brightest flares, has anyone thought of long-suffering astronomers? more and more. We are witnessing a new type of "light pollution" and it seems to me that someone should warn the Iridium developers about what they did to the night sky. "
The same topic was raised by the American Paul Malley at the congress of the International Astronautical Federation, held last fall in Turin. After contacting representatives of Motorola, the manufacturer of the Iridium spacecraft, he described the flash situation to them. To make the description clearer, Paul showed his interlocutors photographs of the brightest flashes, but, as expected, in response he heard that it was no longer possible to make any changes to the project at this stage. "The situation is such that the Iridiums are already at the top and will remain there for a very, very long time," was the reaction of the representatives of Motorola.
Fortunately, these outbreaks are quite predictable - unlike airplanes and other benefits of civilization. However, it should be remembered that Iridium can only be the first sign. After all, new low-orbit communication systems are on the way: Faisat - 26 satellites, Orbkomm - 28, Globalstar - 48, Celestri - 63, Skybridge - 64 and, finally, Teledezik, which includes 384 satellites at once! And if this entire armada, preparing to launch, behaves similarly to the flashing Iridiums, then the situation could be much more serious.
Igor Anatolyevich Lisov - editor of the Cosmonautics News magazine, employee of the Video-Cosmos company. The author thanks Brian Hunter, Paul Malie, Randy John, Bram and Chris Dorreman, Tom Smith and Ron Lee for their help with this article.
We invite you to find out some interesting and informative facts about the satellites of the planets of the solar system.
1. Ganymede is a great satellite. It is the largest satellite not only of Jupiter, but also of the solar system as a whole. He is so great. Which has its own magnetic field.
2. Miranda is an ugly companion. It is considered the ugly duckling of the solar system. It seems as if someone has blinded a satellite from pieces and sent it to revolve around Uranus. Miranda has some of the most picturesque landscapes in the entire solar system: mountain ranges and valleys form quaint crowns and canyons, some of which are 12 times deeper than the Grand Canyon. For example, if a stone is thrown into one of these, it will fall down only after 10 minutes.
3. Callisto is the moon with the largest number of craters. Unlike other celestial bodies, Callisto has no geological activity, which makes its surface unprotected. Therefore, this satellite looks like the most "battered" one.
4. Dactyl is an asteroid satellite. It is the smallest satellite in the entire solar system, being only one mile wide. In the photo you can see the moon Ida, and Dactyl is a small dot on the right. The uniqueness of this satellite lies in the fact that it does not revolve around the planet, but around an asteroid. Previously, scientists believed that asteroids were small to have satellites, but, as you can see, they were wrong.
5. Epimetheus and Janus are satellites that miraculously escaped collision. Both satellites revolve around Saturn in the same orbit. They probably used to be one companion. What is noteworthy: every 4 years, as soon as the moment of collision comes, they change places.
6. Enceladus is the bearer of the ring. It is the inner moon of Saturn and reflects nearly 100% of the light. The surface of Enceladus is filled with geysers, which eject particles of ice and dust into space, forming the "E" ring of Saturn.
7. Triton - with ice volcanoes. It is the largest moon of Neptune. It is also the only satellite of the solar system that rotates in the opposite direction from the rotation of the planet itself. Volcanoes on Triton are active, but they do not emit lava, but water and ammonia, which freeze on the surface.
8. Europe - with large oceans. This moon of Jupiter has the flattest surface in the solar system. The thing is that the satellite is a continuous ocean covered with ice. There is 2-3 times more water here than on Earth.
9. Io is a volcanic hell. This satellite is similar to Mordor from The Lord of the Rings. Almost the entire surface of the satellite, which revolves around Jupiter, is covered with volcanoes, which erupt very often. There are no craters on Io, as lava fills its surface, thereby flattening it.
11. Titan - a home away from home. This is perhaps the strangest satellite in the solar system. He is the only one with an atmosphere that is several times denser than on Earth. What was under the opaque clouds remained unknown for many years. Titan's atmosphere is based on nitrogen, just like on Earth, but it also contains other gases, such as methane. If the methane level on Titan is high, then methane rain can fall on the satellite. The presence of large bright spots on the satellite's surface suggests that there may be liquid seas on the surface, which may include methane. It should be noted that Titan is the most suitable celestial body for the search for life.
On January 19, 2006, earthlings launched a probe "" - an automatic interplanetary station, which will have to study Pluto, Charon and an object in the Kuiper belt. The full mission of the apparatus is designed for 15-17 years. The vicinity of the Earth "" left with the highest speed among the known spacecraft - 16.26 km / s relative to the Earth. The heliocentric speed is 45 km / s, which would allow the vehicle to leave the solar system without a gravitational maneuver. However, there is an apparatus in this Universe, created by human hands, which flies even faster and has no equal in speed yet.
Two Voyager space probes have broken all distance records. They sent us photos of Jupiter, Saturn and Neptune and continue to move away from the solar system. On February 22, 2014, Voyager 1 was at a distance of about 19 billion kilometers from Earth and is still sending us data - 10 hours they go from the probe to our planet. Several years ago that Voyager 1 left the solar system. How do the probes manage to transfer data so far?
The Voyager spacecraft uses a 23-watt radio transmitter. This is more than that of a regular mobile phone, but in the general order of things this transmitter is rather low-power. Large radio stations on Earth transmit tens of thousands of watts, but the signal is still weak enough.
The key to success in getting the signal to reach regardless of the power of the transmitter is a combination of three things:
- Very large antennas.
- Antennas directed at each other (terrestrial and voyager).
- Radio frequencies with little interference.
The antennas that Voyager uses are large enough. You've probably seen satellite dishes from TV fans. They are usually 2-3 meters in diameter. Voyager's antenna has a diameter of 3.7 meters, and it transmits data that is received by a 34-meter antenna on Earth. Voyager's antenna and Earth's antenna point directly at each other. Your phone's omnidirectional small antenna and the 34-meter giant are completely different things.
Voyager satellites transmit data in the 8 GHz band, with little interference at this frequency. An antenna on Earth uses a powerful amplifier and receives a signal. Then he sends the message back to the probe with the help of a powerful transmitter so that Voyager will surely receive the message.
On the front lines
Voyager 1 has been transmitting data to Earth since 1977. But the members of the team overseeing the mission at NASA's Jet Propulsion Laboratory recently gave us some interesting news. On September 12, 2013, NASA confirmed that the probe entered the heliopause, where our Sun's solar wind is no longer strong enough to collide with the solar winds of neighboring stars. At this moment, the "triaxial magnetometer" recorded a change in the magnetic field perpendicular to the direction of the probe movement. Voyager 1 was the first man-made object to leave the solar system.
Voyager Golden Record: 117 images of Earth, greetings in 54 languages, earth sounds
Cynics - like most astronomers, cosmologists, and NASA itself - say that the edge of the solar system is defined as the point where an object stops being exposed to solar gravity. But gravity, as you know, defines the universe on a huge scale. And this point is located at a distance of 50,000 times greater than the distance from the Sun to the Earth. Voyager 1 traveled 123 distances from the Earth to the Sun (approximately 18 billion kilometers). And it will take another 14,000 years to leave the gravitational grip of the Sun at its current speed.
Nothing prevents Voyager from making excellent observations. Voyager 1 and its twin, Voyager 2, which took off 15 days earlier but was late due to an excursion to Uranus and Neptune, found traces of four gas giants and many strange astronomical phenomena. And although Voyager 1 remained within the solar system for some time, it entered a zone where the charged particles of the solar wind will be replaced by dust and other materials that fill the space between the stars.
Over the years, the Voyagers have discovered a number of astronomical surprises. One of the last appeared in the summer of 2012, when Voyager 1 discovered a previously unknown phenomenon called the magnetic highway. In this region, instruments aboard the probe have shown that solar and interstellar magnetic fields collide. Edward Stone, chief of Voyager's program since 1972, explained that this happens when the low-energy particles inside the heliosphere are replaced by higher-energy particles from space.
The creators of the probes hoped that they would be strong and durable enough to withstand all the vagaries of space. Especially during the close approach to Jupiter and Saturn, as well as excursions to Uranus and Neptune performed by Voyager 2. So when, in 1973, Pioneer 10 measured the radiation around Uranus and Neptune and found it to be higher than expected, Stone's team spent 9 months replacing and reconstructing every element of the probe that might be damaged. Of course, the probes were designed with an excessive margin of safety. For example, each of the probes carries two copies of three separate computer systems. But so far, few onboard systems need to be rebooted. It's safe to say that Stone is fatherly proud of his creation and his exploits.
The care with which the probes were done here on Earth also played a role in the success of the mission. When the primary and secondary receivers on Voyager 2 failed a year after the start of the mission, the Earth team activated a backup system that is still in operation today. In 2010, after receiving a garbled message from the probe, the team ran a thorough memory dump using one of the backup computers and found that one bit in the program had changed from 0 to 1. Restarting the program fixed everything.
The team of scientists regularly updates the control system to ensure optimal use of the resources of the probes during their active operation. During the Jupiterian phase of Voyager 1 alone, this was done 18 times. Take data transfer, for example. When the Voyagers orbited Jupiter and Saturn, the probes were close enough to Earth to send uncompressed images and other data at relatively high bit rates: 115,000 and 45,000 bits per second, respectively. But since the signal strength varies inversely with the square of the distance between the transmitters, Voyager 2 transmitted data at a rate of 9000 bits / sec during its exploration of Uranus. For Neptune, the number dropped to 3,000, thus reducing the number of photos and data that can be sent home.
Most backup computers come online when the main computer crashes. However, one of the auxiliary probe systems was activated and worked in conjunction with the main one. This made it possible to send lossy 640K images of Uranus after being compressed to just 256KB.
As they say, all ingenious is simple. Stone's team equipped the probes with an advanced hardware called a Reed-Solomon decoder. The device significantly reduces the level of error that prevents the correct reading of messages in case of loss of individual bits. Voyager originally used an old and well-tried system that sent one "error-correcting" bit for every bit in a message. The Reed-Solomon decoder ruled five others with one bit. The funny thing is that in 1977 there was no way to decode corrected data using the Reed-Solomon method. Fortunately, by the time Voyager 2 reached Uranus in 1986, everything was ready.
The famous 1990 Pale Blue Dot image of Earth: Voyager 1's last mission. 6 billion kilometers
Currently, the data that comes from Voyagers to radio telescopes around the globe travels at a speed of only 160 bits per second. This decision was made deliberately to maintain a constant speed throughout the mission. The main cameras were turned off after the flyby of the last planet of the solar system, only a few instruments remained active. Every six months, for 30 minutes, data from an 8-pin digital tape is transferred to a compressed archive at a speed of 1400 bits per second.
Radioisotope thermoelectric generators based on plutonium-238 will support the operation of instruments until at least 2021. And by 2025, after nearly half a century of travel to where there is nothing human, the team will turn off the probes and communicate with them in a slightly sentimental one-way manner so that the Voyagers keep their course. And they will fly further and further into the darkness.
Voyager 1 carries enough nuclear fuel to continue serving science until 2025, and go with the flow after death. On its current trajectory, the probe should eventually be 1.5 light years away from us near the star Camelopardalis in the northern constellation, which looks like something in between a giraffe and a camel. No one knows if there are planets near this star and whether the aliens will establish a residence there by the time the probe arrives.
