[meteorite-list] Low-Density Supersonic Decelerator Test a Success Despite Parachute Snag

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Sun, 29 Jun 2014 12:08:44 -0700 (PDT)
Message-ID: <201406291908.s5TJ8i3v006952_at_zagami.jpl.nasa.gov>

http://www.spaceflightnow.com/news/n1406/28ldsd/

NASA: Mars entry test a success despite chute snag
BY WILLIAM HARWOO
Spaceflight Now
June 28, 2014
 
The inflatable aero-brake appeared to work normally in live video downlinked
from the test vehicle, but the parachute, the largest ever built for deployment
at more than twice the speed of sound, failed to fully inflate in a disappointment
for flight controllers with NASA's Jet Propulsion Laboratory.

"PI (principal investigator) has called 'no chute.' We don't have full
chute inflation," a flight controller reported.

The Low-Density Supersonic Decelerator then fell toward impact in the
Pacific Ocean northwest of Hawaii. The carrier balloon apparently came
apart after the LDSD's release and it was not immediately clear what recovery
crews standing by in the landing zone might be able to retrieve.

In any case, the test flight appeared to meet all of its major objectives
but one and engineers are hopeful recorded telemetry will shed light on
what went wrong with the parachute deploy.

"Our objectives for this first flight are to launch it from here, get
the balloon off and out over the water, to get it up to altitude where
we can drop the vehicle and conduct this powered flight and get the data
back from it to see how it works," Mark Adler, LDSD project manager at
JPL, said before launch.

He stressed the test flight was just that, a test flight, and any number
of things could go wrong. But "if we fire that motor and we get data back
from it, that is a great day. That way we can learn exactly what happened
and understand what to do for our next flights."

The idea was to put the Low-Density Supersonic Decelerator in the thin
extreme upper atmosphere, at a velocity of more than four times the speed
of sound, to mimic the conditions a Mars-bound spacecraft might experience
slamming into the atmosphere of Mars.

The goal is to develop new atmospheric braking systems that will allow
NASA to launch larger, more sophisticated landers to the red planet.

The heaviest spacecraft ever sent to the surface of Mars -- NASA's Mars
Science Laboratory, or Curiosity rover -- tipped the scales at about one
ton. To get heavier robots to the surface, and eventual crewed spacecraft
that could weigh 20 tons or more, NASA must develop better systems to
quickly slow large vehicles in the thin martian atmosphere.

Enter the Low-Density Supersonic Decelerator, or LDSD, the first of three
test vehicles to fly in a $200 million research program aimed at developing
new technologies for future Mars missions.

"Landing on Mars is an extremely challenging thing to do," Ian Clark,
principal investigator at the Jet Propulsion Laboratory in Pasadena, Calif.,
said during a preflight briefing. "The atmosphere is extremely thin, it's
about 1 percent the density of Earth's atmosphere. That means you need
very large devices to react against the atmosphere to create the drag
that we use to slow the vehicles down as they enter the atmosphere.

"If you want to land things that are even heavier than the Mars Science
Laboratory, if you want to land several tons -- and as you cast your eyes
to the horizon and you think about landing humans on the surface of Mars,
missions that will be 10 to 15 tons, 20 tons or more -- you're going to
need extremely large drag devices to slow those vehicles down. We don't
have those currently, and that's what LDSD is developing."

The test vehicle's high-altitude balloon, filled with 34 million cubic
feet of helium, lifted off from the U.S. Navy's Pacific Missile Range
Facility on Kauai, Hawaii, at 2:40 p.m. EDT (GMT-4). Initial attempts
to launch the craft earlier this month were blocked by the weather, but
conditions were acceptable Saturday and the balloon was cleared for flight.

A live television feed showed the giant balloon climbing away, pulling
the LDSD from its support cradle and up into the sky for a two-hour 25-minute
climb to an altitude of around 120,000 feet above the Pacific Ocean west
of the test range.

After a series of final readiness checks, commands were sent to release
the LDSD from the balloon. As it briefly fell back toward Earth, small
rocket motors fired to spin the vehicle up for stability before an ATK
Star 48 solid-fuel rocket motor ignited to accelerate the test article
and boost it an additional 11 miles to some 180,000 feet, or 34 miles.

The test vehicle featured two new technologies. The first was an inflatable
torus around a traditional heat shield known as the Supersonic Inflatable
Aerodynamic Decelerator, or SIAD, that gives the test vehicle the general
shape of a flying saucer. The second new technology was a huge parachute,
the largest ever designed to deploy at more than twice the speed of sound.

Flying at more than four times the speed of sound, the flight plan called
for the heavily instrumented SIAD torus to inflate, expanding the diameter
of the entry vehicle from about 15.4 feet to 19.7 feet. After slowing
to about 2.5 times the speed of sound, the parachute was expected to deploy.

All of that appeared to go like clockwork.

"All spin motors fired," someone said as the LDSD fell from the carrier
balloon. Seconds later, the Star 48 rocket motor ignited.

"Mach 1," a flight controller called, monitoring telemetry as the vehicle
accelerated through the speed of sound. Seconds later, "Mach 2."

"Acceleration is good, vehicle is stable," a controller said.

As the spacecraft passed through Mach 3, telemetry showed "acceleration
is good, vehicle is stable." Live video showed a torrent of fiery exhaust
blasting from the nozzle of the Star 48 as the limb of the Earth wheeled
about in the background.

A few seconds later, the test vehicle was moving at more than four times
the speed of sound. The rocket motor then burned out and small motors
fired to stop the vehicle's stabilizing spin.

Go-Pro video cameras capatured the inflation of the SIAD, followed by
the parachute's release. Live video showed the huge chute streaming behind
the test vehicle, but it never inflated to its full 110-foot diameter.

"Come on..." someone said anxiously.

But it was not to be. A few moments later, the a flight controller called
"PI (principle investigator) has called 'no chute.' We don't have full
chute inflation."

"I'm going to declare that a bad chute, is that your understanding?" the
flight director asked.

"That's affirm."

"Please inform the recovery director we have bad chute."

The SIAD torus initially was tested at the Naval Air Weapons Station at
China Lake, Calif., using a rocket sled to accelerate the device to several
hundred miles per hour. To test the parachute, a long cable was connected,
fed through a pulley system and attached to a rocket sled. The parachute
then was released from a helicopter, the rocket sled was fired up and
the parachute was pulled toward the ground with a force equivalent to
about 100,000 pounds of drag.

But to fully test the system engineers wanted to duplicate conditions
a spacecraft would experience at Mars.

"What we're trying to do is replicate the environment in which these technologies
would be used," Clark said before flight. "That means replicating the
atmosphere, in particular the density of the atmosphere, which at Mars
is extremely thin. To find (those conditions) we have to go halfway to
the edge of space, or about 180,000 feet here on Earth, to test these
devices. And we have to go several times the speed of sound."

Two more LDSD vehicles are being built for "flights of record" next summer.

"We've been there before, eight successful landings on the surface of
Mars, the United States leads in this area," said Mike Gazarik, director
of space technology development at NASA Headquarters. "It's one of the
more difficult challenges.

"When we look at the Curiosity rover, which landed two years ago, it's
about a metric ton on the surface of Mars. We know that for exploration,
for future robotic exploration, for future human exploration, we need
more than that. ... And so for us, it's the challenges of Mars -- how
do we get there, how do we land there, how do we live there, how do we
leave there?"

The Low-Density Supersonic Decelerator "focuses on that very difficult
challenge of landing there."

"We need to test and we need to learn," Gazarik said. "And we need to
do it quickly and efficiently. ... It's about more mass, going to more
elevations on the surface of Mars and landing more accurately."
Received on Sun 29 Jun 2014 03:08:44 PM PDT