| Question: |
Is there a precise calculation
of the Mir station de-orbiting trajectory to provide
safe impact of its fragments in the prescribed area
of the Earth? |
| Answer: |
First, RSC
Energia has a great experience in providing controlled
de-orbiting of Progress-type transport cargo vehicles.
All these vehicles are brought strictly to a definite
area of the Pacific Ocean.
Second, the Corporation possesses necessary programs
and means to support precise calculations of orbital
flight trajectories in the upper rarified atmosphere
and de-orbiting of complex space objects - controlled
and uncontrolled space objects of different configurations,
space vehicle stages and Mir-type multi-module stations.
Now, such calculations for the station are performed
regularly: its orbit and descent trajectory are calculated,
water landing area dimensions are defined for those
station fragments that will not burn in the atmosphere
and will reach the water surface. The calculations are
performed by specialists of RSC Energia and other specialized
organizations, the Mission Control Center (MCC) included. |
| Question: |
What area
of the Earth is the station descent planned to? |
| Answer: |
The station
descent is planned so as to bring it on de-orbiting
to the assigned target point. This point is located
on the water surface of the Pacific Ocean in the area
far from existing aircraft and shipping routes, populated
islands. This area was already used before to submerge
expended rocket stages, satellites and space vehicles,
including Progress cargo vehicles, during controlled
descent from near-earth orbits. |
| Question: |
When is
the station descent from the near-earth orbit planned? |
| Answer: |
The date of descent depends
on many factors. Among them is: the Earth atmosphere
condition, a station's changing attitude, implementation
of the assigned program of controlled lowering of its
orbit under which the Progress M1-5 transport cargo
vehicle-tanker shall be launched. After the docking
with the station the vehicle will be in the dormant
phase till the moment when the station orbit altitude
will reach 230-240 km. Then the vehicle will begin active
generation of a controlled descent trajectory of the
station. At present, the date of de-orbiting can be
defined with an accuracy of several days. This date
will be clarified with time. A more accurate forecast
presents problems for objective available errors in
calculations of the Earth upper atmosphere density with
regard to its fluctuations because of solar activity
changes. Permanent tracking of these processes will
be provided and a decision will accordingly be made
on the station de-orbit. |
| Question: |
Will the station be
divided into separate modules before de-orbiting? Is
there a danger that before de-orbiting it will divide
spontaneously into modules and fragments that will fall
in another Earth's area? |
| Answer: |
The Mir
station will de-orbit as an integral body without separation
into modules and separation of the Progress M1-5 vehicle
from it. The cargo vehicle propulsion system will impart
several braking impulses in series to the station to
provide accurate generation of the trajectory of bringing
to the target point. No hazard exists that the station
will spontaneously divide into modules and fragments
before de-orbiting. Beginning from the altitude of about
110-120 km, when the station with the cargo vehicle
passes the upper atmosphere, as a result of increasing
aerodynamic drag followed by heating of structural elements,
fragments will begin to separate as from an ordinary
meteor body entering the Earth atmosphere at a tremendous
velocity. These fragments will, in its turn, fall to
smaller pieces. |
| Question: |
It is known that the Salyut-7
station de-orbit was uncontrolled. Is there a danger
of such de-orbit for the Mir station? |
| Answer: |
The Salyut-7
station is a passed stage in cosmonautics. Its control
on de-orbiting was not envisaged. This station was flying
in a near-earth orbit loosing height in the upper atmosphere
under the action of natural aerodynamic drag and was
uncontrolled over a long period of time. The forecast
of the de-orbit date was made at regular intervals based
on a more strong "capture" by the Earth atmosphere.
The station de-orbited on February 7, 1991 as it was
calculated during operational short-term forecast. Its
elements reached the Earth surface mainly in the Atlantic
Ocean water. A minor amount of them burnt over Argentina
and a still more minor amount fell on its territory.
They did not cause damages or fractures. According to
official information from Argentina, no damage was caused. |
| Question: |
How many people are engaged
in solving this problem? What will be the costs to implement
the Mir station controlled de-orbit procedure? |
| Answer: |
Many groups
of experienced highly skilled designers, testers, managers,
developers of onboard and ground systems are engaged
in solving the problem. The work is underway in different
lines: ballistics, strength, thermal and other design,
analysis of telemetry data, provision of monitoring
and control of the station and vehicles, preparation
of launch vehicles and spacecraft for launch at the
Baikonur cosmodrome and many other operations. The best
specialists at RSC Energia and tens of enterprises included
in the cooperation of developers under the Mir station
program are involved in the resolution of this problem.
The Corporation being the prime company of this program
is in full control of the situation.
As regards the costs, it depends on many factors as
you have evidently understood. The Progress M-43 cargo
vehicle that docked to the station in October 2000 and
provided implementation of operations scheduled under
the program of safe completion of the station flight
through maintaining the automatic controlled flight
and performing the Mir station orbit correction, will
be undocked from the station before docking of a new
cargo vehicle-tanker and brought, as it was made before,
to the above-assigned area of the Pacific Ocean. The
costs only for launch of these two cargo vehicles (Progress
M-44 and Progress M1-5) make up about 600 million roubles
without regard for the costs of other works, including
the services of ground facilities and personnel of space
infrastructure.
|
| Question: |
What and how many station's
pieces will reach the Earth surface? |
| Answer: |
The mass
of the station with the Progress M1-5 cargo vehicle
before de-orbiting will make up about 130 t. On passage
through the upper atmosphere this manmade celestial
body will break into many thousands of pieces the major
portion of which will burn over the Earth leawing flame-coloured,
quickly vanishing traces in the sky at altitudes of
more than 10-20 km. No more than 1500 pieces will reach
the Earth surface. The mass of these small pieces will
not exceed several kilograms. There will not be very
large pieces. As estimated, the largest fragment that
can reach the ocean surface can be no more than 300-400
kg in mass. |
| Question: |
What will the Mir station velocity be
on entering the upper atmosphere? What velocities will
its fragments have when they reach the Pacific Ocean
surface? |
| Answer: |
The station
will begin to break into pieces beginning from the altitude
of about 110-120 km. At this altitude the, as well as
the station, will move at a velocity close to the first
space velocity - about 8 km/s. Due to aerobraking this
velocity will be decreased and depending on the relationship
between the mass and effective cross-section area will
be decreased by a factor of tens, hundreds and thousands
- and will not exceed several meters per second for
the majority of pieces. Heavy and compact pieces will
have the greatest velocity - up to 300-400 m/s. They
can reach the Pacific Ocean surface. Light pieces of
structure burn in the atmosphere as a rule. |
| Question: |
Should appropriate ground
services, states, air and sea companies be notified
to prevent aircraft and ships coming to the mentioned
area of the Pacific Ocean at a period of the station
de-orbiting? |
| Answer: |
The scheme
of the station de-orbiting will of necessity be proclaimed
and the area of its debris full will be marked. All
states, air and sea companies, world public will be
notified.
By decision of the Government of Russia of December
30, 2000, a special interdepartmental commission, was
formed of authoritative managers and specialists that
was assigned to control constantly the station condition,
its operability, to inform regularly the public of this
problem, including notification of the date of station
planned de-orbiting. It assumed that the more detailed
information will be presented the 7-10 days before the
day when the active manipulation will begin for the
descend trajectory, with the subsequent regular updating
of this information. |
| Question: |
Are there radioactive sources
aboard the Mir station? Is there a danger of environment
contamination? |
| Answer: |
There are
no radioactive sources, toxic substances aboard the
station. It is a manned station and shall provide safe
conditions of crew life throughout long-duration multi-month
expeditions aboard the station without ill effects on
cosmonauts health and after return to the Earth.
Therefore, taking into account these factors, we can
state: no hazard for the Earth ecology exists. Burning
of station's pieces in the Earth atmosphere and fall
of its structure fragments in the ocean water do not
present a hazard for the ecology; in any case, it can
be compared with a catastrophy of one large air-liner,
not to mention sinking of a sea ship. |
| Question: |
Do You feel sorry for the
station? |
| Answer: |
Undoubtedly,
we feel sorry. A lot of creative forces and energy of
hundred thousands of engineers, scientists, workers,
employees of not only Russian enterprises but also foreign
companies and organizations was contributed to this
unique project of the end of the XX century. It was
a part of our life. Unfortunately, everything comes
to an end in life. And we have also got to this moment.
The station has been functioning in orbit for 15 years.
It was our concern to implement its flight programs
we set and solve new tasks, thought of future projects
of stations of a new generation. The Mir station could
continue a controlled manned flight, unfortunately it
was not supported with necessary financial resources
in due time. Many of us have got used to the station.
Nevertheless, without regard to our personal attitude
to the station the Government of Russia has made a decision
to terminate the station flight, and its implementation
shall be provided. |
| Question: |
What will you feel when the
station is falling? |
| Answer: |
There will
be no time for sentimentality at that moment. The phase
of de-orbiting and atmospheric descent is a complex
stage of operation of the Mir station project technical
management, interdepartmental commission, all services
of control, personnel of RSC Energia and other enterprises
participating in the project. We shall be at the Mission
Control Center, shall supervise the implementation of
the station de-orbiting procedure. It is a very intense
operation. Its final stage takes one-three days and
is preceded by a mouth and a half of important work. |
| Question: |
Will You be at the Mission
Control Center during this time? |
| Answer: |
Yes, all
this time period we shall have to be at MCC. And upon
completion of the station descent the results can be
summed up in the circle of work participants. But it
will not be funeral repast. Actually, the decisions
tested on the Mir station were used as the basis for
the ISS project - International Space Station. The stage
of manned cosmonautics associated with the Mir station
comes to an end. A new stage - ISS - has already begun.
We always said: when the ISS will begin functioning
in a manned mode the problem on the Mir station fate
may be considered. Now it has happened - the Zvezda
service module has been launched and docked to the ISS,
the crew of the first prime expedition has proceeded
to work. |
| Question: |
Will the fall of station's
pieces to the Earth look like a meter flow? |
| Answer: |
There will
be a firework, of flame - coloured stripes in the sky.
When Salyut-7 de-orbited, a colourful sight was observed
in Argentina. Magazines wrote that it was very spectacular.
The area of falling of the Mir station pieces is for
from islands and routes, difficult of access. Therefore,
it is unlikely that some-body can observe the sight.
It will not be observed at MCC as well, as to support
it, a specially equipped ship should be sent to that
area and operational transmission of video surveys through
telecommunication satellites should be provided; and
it will result in significant financial expenditures
and risks. |
| Question: |
Can we say to our readers
that they should not worry abort falling of Mir station
pieces on the Germany territory? |
| Answer: |
We can say
with confidence: the probability that the station's
pieces will fall on the Germany territory is essentially
zero. The station flight routes are within the latitude
range from 51.6o S.L. to 51.6o N.L., i.e. pass only
over the southern part of the country, and the passage
over this region lasts no more than 2 minutes. Every
day no more than two-three station's passages over the
region can occur, and sometimes the station route can
be back from it. Thus, it is beyond reasons to worry. |
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