3. astronauts
went to MARSScott Crossfield
Alvin White
Iven Kincheloe
Robert White
Robert Rushworth
Joseph Walker
Neil Armstrong
Forrest S. Petersen
Scott Carpenter
Gordon Cooper
John Glenn
Gus Grissom
Wally Schirra
Alan Shepard
Deke Slayton
Ivan Anikeyev
Pavel Belyayev
Valentin Bondarenko
Valery Bykovsky
Valentin Filatyev
Yuri Gagarin
Deniz Burnham
Vasco Ribeiro
Pete Freeland
Jamie Guined
Heidi Hammerstein
Kenneth Ham
George Zamka
4. Mission to Mars
A mission to Mars has been the subject
of science fiction, engineering, and scientific
proposals throughout the 20th century and into
the 21st century. The plans comprise proposals
to land on Mars, eventually settling
on and terraforming the planet, while exploiting
its moons, Phobos and Deimos.
Exploration of Mars has been a
goal of national space programs
for decades. Preliminary work
for missions that would involve
human explorers has been
undertaken since the 1950s,
with planned missions typically
being cited as taking place 10 to
30 years in the future when
they are drafted. The list of
manned Mars mission plans in
the 20th century shows the
various mission proposals that
have been put forth by multiple
organizations and space
agencies in this field of space
exploration.
5. THE INTERNAL STRUCTURE OF MARS
Mars has differentiated into a
dense metallic core overlaid by
less dense materials.Current
models of its interior imply a
core region about 1,794 ± 65
kilometers (1,115 ± 40 mi) in
radius, consisting primarily
of iron and nickel with about
16–17% sulfur.This iron(II)
sulfide core is thought to be
twice as rich in lighter elements
than Earth's core. The core is
surrounded by a silicate mantle
that formed many of the
tectonic and volcanic features
on the planet, but it now
appears to be dormant.
Besides silicon and oxygen, the most abundant elements
in the Martian crust are iron , magnesium , aluminum
, calcium, and potassium. The average thickness of the
planet's crust is about 50 km (31 mi), with a maximum
thickness of 125 km (78 mi). Earth's crust, averaging
40 km (25 mi), is only one third as thick as Mars's crust,
relative to the sizes of the two planets. The InSight lander
planned for 2016 will use a seismometer to better
constrain the models of the interior.
