(FTS) is to make the path of an errant
rocket more predictable by ending
thrust from the engines immediately.
This is the first line of defense against
a failing vehicle and is one of the
most highly reliable systems involved
in the launch.
This is done by strategically
placed linear-shaped charges which
release a tremendous amount of
very focused force. These charges
can rip open an engine or fuel tank
like a zipper. Remaining fuel either
dissipates into the atmosphere or
explodes destroying the rest of the
vehicle. It’s a sad way to see a highly
anticipated launch end, but at least
the team knows the debris can land
safely inside a predefined zone.
The first few seconds of the flight
are critical and where most problems
occur. This is also the most difficult
to track electronically. Since the
earliest days of rocketry, liftoff has
been observed through a vertical
wire sky screen developed by James
Van Allen in his work ensuring tests of
the V2 and Aerobee rockets could
be done safely. A long rectangular
frame with 2 or more wires provides a
visual reference for the rocket’s path
off the pad. Should the Range Safety
Office see the rocket touch either
wire during liftoff, the command to
terminate flight is given.
As a rocket flies, its instantaneous impact point (IPP), or point where debris would land should the flight be
terminated, is constantly updated. If the IPP strays beyond predetermined destruct lines, the flight is terminated
ensuring debris does not land on populated areas. Credit: USAF/Rice
each launch based on the type of
rocket, its engines, fuel and payload.
This information helps determine
where destruction lines radiating out
from the launch site are drawn.
Before launch day this information
is used to create Notices to Airman
(NOTAMs) and Notices to Mariners
(NOTMARs) about areas
to avoid around launch
time. On launch day the
United States Coast Guard
supports NASA in launches
from Wallops Island
Virginia, Cape Canaveral
Florida and Vandenberg
Air Force Base, California
in enforcing these avoidance areas. Launches
have been postponed
or even scrubbed when
a small boat ventures
into these areas covering
many square miles. These
Before making the go-nogo decision wind conditions are evaluated not represent not just the area
just for how they will affect the vehicle’s flight but how debris might
where a rocket stage
spread should that flight be terminated. Credit: NASA/CCT Corp
is planed to fall back
to Earth but also where
Once the vehicle is safely off the
debris could fall.
pad and enters the downrange portion of its flight, all flight termination
The data gathering isn’t through
decisions are based on maps prethough. Monitoring weather condipared far in advance of the launch
tions, especially wind continues
day. A new map is drawn up for
up until the launch. While weather
conditions near the pad may be
perfect, high winds elsewhere in
the area or downrange may cause
Range Safety to deny permission to
launch. This ensures the maps remain
reliable.
Throughout the launch, Range
Safety officers track the vehicle’s
position and instantaneous impact
point (IPP); an unpowered, ballistic
path where debris is predicted to
land if the rocket is destroyed at
that moment. If the rocket goes off
course and its IPP reaches a destruction line, the flight is terminated. This
ensures debris lands within a safe
zone while giving the rocket every
chance to straighten up and flight
right either through-automated systems or commands from the ground.
Six months later a Progress resupply spacecraft launched from the
Baikonur Cosmodrome in Kazakhstan
failed when controllers in Russia lost
communication and the capsule
tumbled out of control before reentering Earth’s atmosphere 11 days
later. In June 2015, SpaceX experienced their first launch failure after 18
successful ones. This was particularly
difficult for a group of high school
students from Palmetto Scholars
Academy in North Charleston, South
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