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

[Ron Baalke]

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."