My Science School

How deep are lunar craters?

Lunar craters can be several kilometers deep. The crater Newton near the South Pole is so deep that it could almost accommodate Mount Everest, the highest mountain on Earth.

What are lunar craters actually?

Lunar craters are circular in shape with raised walls and sunken floors. They are not the conventional type of craters and are more in the nature of walled depressions.

How large are lunar craters?

Lunar craters vary vastly in size from tiny craters to huge walled plains hundreds of kilometers wide.

How were the lunar craters formed?

It is believed the lunar craters were formed partly by volcanic action (when part of the inside of the Moon was still liquid many millions of years ago), and partly due to meteor impacts later.

 

 

 

 

What is the Linne Crater mystery?

There is recorded evidence of a crater named Linne estimated to be about 10 km across and about 300 m deep. The last record of Linne was in 1843. However, an observation in 1866 revealed that there was virtually no evidence of Linne. Between 1843 and 1866, Linne had apparently just vanished. No satisfactory explanation is available.

 

Mare Crisium                        Sea of Crises.

Mare Fecunditatis                 Sea of Fecundity.

Mare Nectairs                        Sea of Nectar.

Mare Tranquillitatis               Sea of Tranquility

Mare Serentitatis                    Sea of Serenity

Mare Frigoris                          Sea of Cold.

Mare Imbrium                         Sea of Showers.

Mare Vaporum                         Sea of Vapors.

Mare Nubium                            Sea of Clouds.

Mare Humorum                         Sea of Humors.

 

 

How high are the mountains on the Moon?

Lunar mountains are mainly found in the southern part of the Moon. The highest lunar mountains are higher than the mountains on Earth.

How is the height of lunar mountain measured?

The height of the lunar mountains can be estimated by studying the type of lighting and the shadows cast by the almost mountains at the terminator and mathematically analyzing them.

 

What are the lunar seas?

The lunar seas refer to the vast dark plains on the Moon. There is no water on the Moon and the name “Seas” is therefore a misnomer.

How are the lunar seas named?

Seas in Latin are “Mare” (pronounced “Mahri”) and its plural is Maria (pronounced “Mah-ri-ah”). Lunar seas are denoted by the word Mare followed by the Latin name for each sea.

Is there any significant difference between the near side of the Moon and the far side?

Yes. The far side of the Moon does not have any “Seas” like in the near side.

 

 

 

 

 

 

Why is the last quarter of the Moon less brilliant than the first quarter?

In the last quarter the eastern portion of the Moon is shining. Since no bright seas cover most of this portion, the last quarter is less bright than the first quarter.

 

What is the lunar limb?

The lunar limb is the Moon’s apparent edge as seen from the Earth.

Does the limb remain in the same position on the Moon’s disc?

Yes. The limb remains in more or less the same position on the Moon’s disc except for very minor shifts due to perturbations.

What is the terminator?

The terminator is the boundary between the day and night sides of the Moon.

Does the terminator remain stationary?

No. The terminator sweeps right across the Moon’s disc, once when the Moon is waxing (called morning terminator) and again when the Moon is waning (called evening terminator).

Why is the terminator important for studying features on the Moon’s surface?

The terminator does not appear as a smooth line, due to the unevenness of the Moon’s surface. At the morning terminator line when the Sun has just started rising, the peaks of the mountains which catch the first rays of the sun are brightly lit while the valleys are still in shadow. A study of the lights and shadows at the terminator therefore can provide a valuable insight into the topography of the lunar terrain.

What are the main parts of a lunar map?

Basically two maps of the Moon are used, one representing the near side and another representing the far side of the Moon.

How many features on the surface on the Moon have been recorded?

Over 100,000 features on the surface of the Moon have been recorded but many are not of importance and only the large ones are visible to the naked eye.

 

 

 

 

 

 

 

What are the different types of features visible on the Moon’s surface?

Some of the important features on the Moon’s surface are seas, mountains, valleys, peaks, domes, faults, ridges, craters, walled plains, small craters, ruined craters, twin craters, crater lets, plateaus, clefts, crater chains, rays, etc.

 

What is a solar-sail spacecraft?

A solar-sail spacecraft employs a large sail just like a sailing ship. However, the wind that strikes the sail and provides thrust to the spacecraft is not the normal wind but the solar wind. Hence, the spacecraft exploits the tiny force generated by the solar radiation, when it is reflected off a surface.

That solar radiation reflected by a surface exerts pressure is well known, but the pressure is too weak to be of any practical use on Earth. In space, where Earth’s gravity is negligible, solar sails can be used to propel a spacecraft.

A spacecraft designed by a group of universities and companies in Europe has a solar sail 100 meters long 100 meters wide made of aluminum coated mylar as thick as a human hair.

When solar radiation is reflected from the sail, it will generate a thrust of 0.08 Newton (one Newton is the force that will accelerate one kg of mass by one metre).

Computer simulation studies have shown that this craft would complete the lunar fly-by mission in about 700 days by always keeping the reflecting surface of the sail pointed towards the Sun.

This European spacecraft will also have a payload of 80-kg of scientific instrumentation.

 

Arthur C. Clarke, who predicted the use of synchronous satellites, also predicted the use of solar-sail spacecraft. Name his science fiction story.

“The Wind from the Sun”.

 

What is the ESA space sail contest?

The European Space Agency (ESA) has announced the first race in spaced open only to solar- sail spacecraft.

The winner of the “Space Sail Cup” will be the first craft that makes a loop around the Moon, flies into deep space and gets as close as 10,000 km to the planet Mars.

Launching of the spacecraft will be done free of cost by Ariane rocket. After reaching the high Earth orbit, the spacecraft must exclusively exploit the weak thrust of the solar radiation to escape the Earth’s gravity and, after a lunar fly-by, reach an interplanetary orbit around the Sun heading towards Mars.

The solar-sail spacecraft is nominally expected to make the lunar fly-by in two years and arrive near Mars in less than three and half years.

How many persons have walked on the Moon as part of the Apollo missions?

Twelve persons (all American astronauts) have walked on the Moon as part of the Apollo missions. They are:

 

Apollo 11 – Neil Armstrong, Edwin Aldrin.

 

Apollo 12 – Charles Conrad, Alan Bean.

 

Apollo 14 – Alan Shepard, Thomas Mitchell.

 

Apollo 15 – David Scott, James Irwin.

 

Apollo 16 – Charles Duke, John Young.

 

Apollo 17 – Eugene Cernan, Harrison Schmitt.

 

Continue reading "ARTIFICIAL SATELLITES AND SPACE TRAVEL"

 

 

 

When did man first land on the Moon?

On 20 July 1969, the lunar module “Eagle” (launched from the spacecraft Apollo 11) landed on the Moon, carrying two astronauts.

 

 

 

 

 

 

 

 

 

 

What was the first message from the Moon?

Immediately after Eagle landed, the astronauts sent the message “The Eagle has landed”.

 

 

 

 

 

 

 

 

 

What was the rocket used for the Apollo lunar missions?

The Apollo lunar missions used the Saturn V rocket. The Saturn V was the largest rocket ever successfully flown. With the Apollo spacecraft attached, it stood 111 meters high and lifted off the launch pad with a thrust of more than 3 million kilograms. It was a three-stage rocket and the third stage provided the power to speed the spacecraft on its three-day journey to the Moon.

What are the main sections of Saturn V rocket?

In the three-stage rocket, the upper part contains the third stage with the Apollo command, service and lunar modules, the launch escape system and steering jet.

The second stage lies just below the much smaller third stage and has five steering jets.

The first stage is the largest and has five jets through which its fuel of kerosene and liquid oxygen can fire.

What was the type of spacecraft lifted into space by the Saturn V rocket for the Apollo lunar missions?

The Apollo missions to the Moon were achieved with a cleverly   designed spacecraft made up of three main modules. One housed the crew, the next one contained equipment and the third was the Moon landing craft. The Moon-landing craft itself was designed in two parts. The astronauts left the Moon in the upper part of this module.

 

What kind of food do astronauts eat in space?

The food is frozen and dried to retain its freshness and to conserve space. Some types of food are stored in concentrated form. Liquid and even solids are consumed from squeeze bottles to avoid any spilling of crumbs or droplets. Since there is no gravity, any food crumbs or liquid bubbles will float around inside the spacecraft, causing inconvenience.

Continue reading "ARTIFICIAL SATELLITES AND SPACE TRAVEL"

Why does an astronaut seem weightless, while orbiting the Earth in space?

Actually, an astronaut orbiting the Earth in space is still firmly in the Earth’s gravitational field and seems weightless only because, he is moving in free fall i.e. in the same direction and at the same speed as the spacecraft.

1. Stationary Elevator.


2. Falling Elevator.


3. Spacecraft with engine on.


4. Spacecraft with engineer off.

  g :     Force of gravity.

  a :     Force of engine.

 

What are the main physical problems the astronauts face while remaining in space?

The lack of gravity in space tends to make the muscles weaker and the bones more porous, as comparatively less strength has to be used in space. This creates some problems on long space journeys and also when the astronauts return to Earth. Providing artificial gravity on spacecraft can solve this problem to a certain extent.

 

Continue reading "ARTIFICIAL SATELLITES AND SPACE TRAVEL"

 

 

What is a spacewalk?

When astronauts go outside their spacecraft briefly in protective suits they are said to be taking a spacewalk. Actually they do not walk but drift beside the spacecraft.

 

 

 

 

 

 

 

 

What is an umbilical cord?

It is a safety cord which keeps the astronaut tethered to the spacecraft during a spacewalk. Without the umbilical cord, the spacewalking astronaut would drift away into space. It is called the umbilical cord as it is analogous to the umbilical cord that connects the unborn baby to its mother.

 

 

 

 

 

 

 

Who was the first man to walk in space?

In March 1965, the Russian cosmonaut Alexei Leonov left his spacecraft and performed the first spacewalk.

 

 

Can artificial gravity be provided in spacecraft or a space station?

Artificial gravity is created by the centrifugal force produced by rotating the spacecraft. Hence, there is really no ‘up’ and ‘down’, but only ‘inwards’ and ‘outwards’ from the axis of rotation. Also the gravity is not uniform and increases as one moves away from the axis of rotation.

 

 

 

 

What is the difference between an astronaut and a cosmonaut?

Both words are from Greek, astronauts “Sailors among the stars” and cosmonauts meaning “Sailors of the universe”. Americans call their space explorers astronauts, and the Russians call their’s cosmonauts.

 

 

 

What is a space station?

A space station is a special kind of large satellite much bigger than a space capsule that is placed in orbit around the Earth. A space station is usually designed to accommodate a number of astronauts for a comparatively longer period.

 

 

 

 

 

 

What is a space colony?

A space colony is a very large space station similar to an island in space, where a very larger number of persons can live and work. So far, no space colonies have been placed in orbit.

 

 

Name the first man-made object to reach another world.

Luna -2 became the first man-made object which reached another world, when it crashed on the Moon on 14 September 1959.

 

 

 

 

 

 

 

 

 

 

Has any spacecraft left the Solar System?

On 2 March 1972, the spacecraft Pioneer-10 was launched with a mission to leave the Solar System and travel for at least two million years. It will never come back.

 

 

 

 

 

 

 

 

 

 

 

 

 

What is meant by docking of spacecraft?

Docking means linking of spacecraft in space. The spacecraft have to be specially designed for docking, with access doors, tiny rockets for steering and alignment, and clamps to keep the spacecraft locked together after the docking.