"Compton". Because of its weight (17 tons) and the titanium parts in it, it is not expected to burn completely, and parts of it may fall to the ground. Therefore, after one of its gyroscopes broke down, NASA decided not to take a risk and dropped it in a controlled manner into the ocean
23.4.2000
By: Avishai Gal-Yam
In June 2000, the scientific activity of the satellite will end
"Compton", on board of which instruments are assembled that examine the gamma radiation
coming from outer space. The satellite, launched by NASA in 1991
Considered one of the most successful and important missions launched in recent years,
and brought about a scientific revolution in our understanding of the universe.
Gamma rays are the most energetic type of radiation that exists in nature
electromagnetic Many similar types of radiation are known today
in their visible light properties, but differ in the amount of energy stored in them.
Radio waves and microwave radiation are types of electromagnetic radiation that have
Relatively low energy. Infrared radiation, visible light and ultraviolet radiation
They are medium energy types of radiation. X-rays (also known as
X-rays) have a lot of energy, and gamma rays are even more energetic.
The amount of energy stored in gamma radiation may be ten thousand times greater
more than in visible light.
Gamma rays were discovered by the first scientists who studied the
Radioactivity (the Curies, for example). in the radioactive materials
A huge amount of nuclear energy has been stored. This energy may be released
In various forms. When it is released in the form of electromagnetic radiation,
A highly energetic radiation is received, which Magelia called "gamma radiation".
It was only after the middle of the twentieth century that it became clear that gamma radiation reaches the earth
from various sources in space (this radiation is very harmful to the human body, and to our happiness
It does not penetrate the Earth's atmosphere). later, after
The placement of detectors for this radiation on various spacecraft and satellites which
Launched out of the atmosphere, its importance to astronomy began to become clear.
"Compton", the most massive astronomical satellite ever created,
Launched in 1991 to investigate this field, which was almost unknown until now
for his launch. Several devices were installed on top of the satellite that mapped the radiation
The gamma from the universe. Although planned to operate for two to five years
Only, the satellite operated without faults for nine years, during which it yielded
Revolutionary scientific results.
As mentioned, gamma rays are the most energetic form of radiation
electromagnetic Only material subjected to extreme conditions - under the influence of
Very strong forces, at high accelerations or in conditions of heat and pressure
Enormous - will emit such radiation. Because of this, most familiar objects
For us in the universe, like stars or gas clouds, are not strong sources of radiation
Gamma. The study of gamma ray sources gives scientists the opportunity to examine parts
In a universe where the conditions are so extreme that we were also capable of it
One day we would not be able to send research spacecraft into deep space
visit them.
Such regions are found in the immediate vicinity of neutron stars and holes
blacks These objects exert tremendous gravitational forces on the material present
near them. In fact, the conditions in this environment create a kind of unique laboratory,
where researchers can examine better than any field that can be created
In a laboratory or an accelerator on Earth, how does existing matter behave
in strong gravitational fields. The study of the gamma radiation emitted from these areas makes it possible
Therefore for researchers to examine the basic laws of physics.
"Compton" brought about a real revolution in the understanding of distant cosmic objects
called "Blazars" (Blazars). The researchers assume that it is
In distant galaxies centered on massive black holes. apparently created
In this environment there is a powerful magnetic field, and large amounts of matter are accelerated
In structures called "jets" for speeds close to speed
the light. From observations conducted by "Compton" it becomes clear that the amount of energy
that is emitted in gamma radiation from such a jet is greater than the amount of energy stored
in radiation emitted from the rest of the galaxy.
The BATSE detector installed at "Compton" played a key role in the research and understanding of
Events called "Ray Bursts Gamma".
In contrast to the sources we mentioned earlier, which emit gamma radiation in a uniform manner
Permanent, gamma radiation bursts are sources of radiation that appear for a short time
in the most (seconds only) and disappear. BATSE made it possible to map the distribution of
these sources in space, and was the first to point out that these events
taking place far away from our galaxy.
The attempts to determine precisely the process of creation of gamma ray bursts
It is one of the most active research fields in astronomy today. information
Collected by "Compton" and other satellites, combined with observations
from the ground, indicates that some of these events take place at a distance
enormous and the energy released in each of them may be greater,
For a few seconds, from the radiant energy of the entire universe. their nature
The true nature of these sources is still an enigma, an "open question"
in astrophysics.
The decision to stop the activity of "Compton" was made at NASA following
A malfunction in one of the three gyroscopes installed in it. The gyroscopes are
Devices that allow the flight controllers to control the movement of the satellite in a way
accurate If another such device breaks down, the satellite will deviate from its orbit
out of control and enter the Earth's atmosphere. Because the satellite
Very heavy (weighs about 17 tons) and many parts in it are made of titanium,
A very durable metal, it is not expected to burn completely in the atmosphere,
And parts of it may fall to the ground. so as not to risk it
that the fragments of the satellite would cause casualties, the heads of NASA decided to tilt the
The satellite is orbiting in a controlled manner, so that it will crash into the Pacific Ocean
South of Hawaii.
The scientists studying gamma radiation will have to say goodbye to Compton, however
will not be left without sources of information. The HETE-2 satellite for the study of eruptions
Gamma rays will be launched at the end of this year, and in 2005 is expected
The launch of NASA's "next generation" satellite for the study of gamma radiation -
GLAST At the same time, innovative research techniques have been developed in recent years
of gamma radiation from the ground, even though this radiation does not penetrate the
Atmospheric. About this new method and its consequences - in one of the following articles.
{Appeared in Haaretz newspaper, 23/4/2000{
