InSight
Landing on Mars
Rob Manning: Although
we've done it before,
landing on Mars
is hard.
And this mission
is no different.
The process to get from the
top of the atmosphere of Mars
to the surface we call "entry,
descent, and landing" or EDL.
It takes thousands of steps
to go from the top of the
atmosphere to the surface.
And each one of them
has to work perfectly
to be a successful mission.
The process starts well above
the atmosphere of Mars.
The cruise stage faces the Sun.
It also has its radio antenna
which faces Earth.
But now we don't need
the cruise stage.
Its job is done.
The next step, just
7 minutes before
arriving to the top of
the Mars atmosphere,
is to separate the
cruise stage.
Before you hit the top of
the atmosphere though,
the space capsule has
to orient itself
so that the heat shield
is precisely facing
the atmosphere.
Now the fun begins.
The vehicle is moving at nearly
13,000 miles an hour.
But it's hitting the
top of the atmosphere
at a very shallow angle.
12 degrees.
Any steeper, the vehicle
will hit the thicker part
of the atmosphere and
will melt and burn up.
Any shallower, the vehicle
will bounce off
the atmosphere of Mars.
At the very top
of the atmosphere
it's about 70 miles above
the surface of Mars.
And the air is starting to get
thicker and thicker and thicker.
As it does that, the temperature
in the heat shield
gets well over a thousand
degrees centigrade--
enough to melt steel.
Over the next 2 minutes,
the vehicle decelerates
at a back-breaking 12 Earth G's.
From 13,000 miles an hour to
about 1,000 miles an hour.
At about 10 miles above
the surface of Mars
a supersonic parachute
is launched
out of the back of the vehicle.
Fifteen seconds after the
parachute inflates
it's time to get rid
of the heat shield.
Six pyrotechnic devices
fire simultaneously
allowing the heat shield to fall
and tumble away
from the vehicle,
exposing the lander to
the surface of Mars.
Ten seconds after the heat
shield is dropped,
three pyrotechnically
deployed legs
are released and
locked for landing.
About a minute later the
landing radar is turned on,
sending pulses toward
the surface of Mars
as the vehicle starts
to try to measure
how high it is
above the surface
and how fast it's going.
At about a mile above
the surface of Mars
the lander falls away
from the backshell
and lights its engines.
And very quickly the vehicle
must rotate out of the way
so that the parachute
and the backshell
doesn't come down to hit it.
The last thing
that has to happen
is that on the moment of contact
the engines have to
shut down immediately.
If they don't, the
vehicle will tip over.
So if all the steps
of entry, descent, and landing
happen perfectly
and we are safely on
the surface of Mars,
we'll be ready to do some
exciting new science.
InSight mission landing
November 26, 2018
NASA Jet Propulsion Laboratory
California Institute
of Technology
