2. What is a Space Probe?
A space probe is an un-piloted spacecraft that
is used to make observations and send
information back to Earth regarding the
observed objects by going into the deep
space (moon, interplanetry space) by
escaping Earth's gravity.
3. Unlike an artificial satellite, which is placed in
more or less permanent orbit around the earth, a
space probe is launched with enough energy to
escape the gravitational field of the earth and
navigate among the planets.
Radio-transmitted commands and on-board
computers provide the means for midcourse
corrections in the space probe's trajectory.
4. After a spacecraft has been launched from the
Earth's surface on a trajectory beyond the influence
of Earth's gravitational field, the spacecraft's
navigation(a system that provides information useful in determining the
position and course of a ship or aircraft ) system keeps it on
course.
This job is performed by tracking sensors and an on-
board computer.
One sensor fixes on the Sun and one sensor fixes on
a star such as Arcturus to determine the spacecraft's
position in space.
6. On-board thrusters make the necessary
corrections in both position and attitude.
It basically consist of three segments:
i. Command Module
ii. Service Module
iii. Landing Module
7. Command Module
The command module which housed the
crew( ) and the equipment needed for re-
entry and splashdown.
It is a conical shaped and about 12.7 ft wide
at the base and 12.3 ft high.
There is a docking tunnel at its nose through
which astronauts could crawl into other
spacecraft.
8.
9. Service Module
It is cylindrical shaped about 24.4 ft long.
It contains air, water, fuel and power
supplies and a large engine called Service
Propulsion System (SPS) .
This SPS is responsible for :
i. Making course corrections
ii. Entering and leaving the orbit.
10. It also has thrusters.
The service module
would be cast off and
allowed to burn up in
the atmosphere before
the command module
re-entered and brought
the crew home.
11.
12.
13.
14. Landing Module
The module that ultimately lands on the
surface of the celestial body (planet, moon).
After the job the top half of the landing
module lifts off and gets attached to the
remaining body (SM & CM)
15.
16. Communication
Radio contact between the control station on
earth and the space probe also provides a
channel for transmitting data recorded by on-
board instruments back to earth.
A probe may be directed to orbit a planet, to
soft-land on a planetary surface, or to fly by
as close as a few thousand miles from one or
more planets.
17. A very critical part of the spacecraft is the
communications system, which receives and
transmits signals across the vast reaches of
space.
Much has been learned from probes about
the origins, composition, and structure of
various bodies in the solar system.
18. All of the space probes have low and
medium-gain antennas for communication.
Probes to the outer planets such as the
Voyager and the Pioneer carry large parabola
antennas to amplify the signals sent back to
Earth.
19. Components
i. Entry Subsystem
ii. Inner Structure Subsystem
iii. Thermal Control Subsystem
iv. Electrical Power Subsystem
v. Command and Data Management
Subsystem.
vi. Probe Data Relay Subsystem
20. Entry Subsystem
This subsystem functioned only during
the release of the probe from the orbiter
and its subsequent entry into the planet’s
atmosphere.
It consisted of three main elements:
i. The spin-eject device that propelled the
probe away from the orbiter
21.
22. ii. A front shield, covered with special thermal
protection material, that protected the probe
from the heat generated during atmospheric
entry.
iii. An aft cover (The back cover, which
experienced far less heating during
atmospheric entry) also covered with thermal
protection material, that reflected heat away
from the probe during entry.
23. Three parachutes were used during the
probe's descent.
When the onboard accelerometers detected a
speed of Mach 1.5 near the end of the
deceleration phase, the 2-meter (6.6-foot)-
diameter pilot parachute deployed, pulling
off the aft cover.
24.
25.
26. Inner Structure Subsystem
The inner structure of the probe consisted of
two aluminum honeycomb platforms and an
aluminum shell.
The upper platform carried the parachute
(when stowed) and the antennas needed for
communication with the orbiter.
27. Thermal Control Subsystem
At different times during the mission the
probe was subjected to extreme thermal
environments requiring a variety of passive
controls to maintain the required
temperature conditions.
28. Electrical Power Subsystem
During probe checkout activities, the probe
obtained power from the orbiter via the
umbilical cable.
After separation the probe power was
provided by five lithium sulphur-dioxide
(LiSO2) batteries.
The probe carried two redundant S-band
transmitters, each with its own antenna.
29. On-Board Sensors
Infrared sensors:
To measure the temperature of an object.
Radars:
To see planetary surfaces through clouds.
Ultraviolet sensors:
To analyze atmospheric conditions.
Magnetometers:
To measure magnetic fields.
30. Spectrometers and sensors:
To study wind velocities or chemical compositions,
Special detectors for micrometeors, cosmic rays,
Gamma rays, and solar wind.
Synthetic Aperture Radar (SAR):
An instrument that uses radar to see through
dark, clouds and fog.
This type of equipment is on board only three
satellites in the world, including Radarsat &Lacrosse.
31. Power supply:
There are several ways to provide electrical power
and depends on how long it has to operate, what
conditions it will operate in, where it will operate,
and how much power it needs.
Thermoregulation
All spacecraft need to maintain a temperature
between certain specified limits.
32. Command & Control
The command & control subsystem is the brain
of
the spacecraft.
It will be one computer (with possibly one or two
redundant computers) able to control the
operations of the spacecraft.
33. Attitude control
Nearly all spacecraft need a way to keep themselves
pointing the same way.
Propulsion:
Occasionally, a satellite might not have a propulsion
system. But some have propulsion system that is
used to maneuver a spacecraft out of the way of
space debris, to refine or maintain an orbit, or to
make a trajectory correction
34. Some Facts:
How big the rocket needs to be depends on how big
the space probe is and how fast it has to go in order
to reach the desired trajectory.
Most of the time, it's a multiple-stage rocket, and
sometimes there's an extra rocket attached to the
spacecraft called a kick motor.
The kick motor boosts the spacecraft into its final
orbit and makes the orbit more circular if needed.
35. A deep space probe is usually placed onto a rocket
with a restartable upper stage so that after it reaches
Earth orbit, the upper stage restarts to put it onto
the desired Earth escape trajectory.
Once the spacecraft is away from Earth, it cruises
without any propulsion at all (apart from occasional
trajectory correction maneuvers) until it reaches its
target.
36. They are various cameras, navigation, and
communications systems.
There also has to be a power supply and
protection against heat, cold, and cosmic
radiation.
Exactly what equipment is on any deep space
probe, of course, depends upon it's mission.
