NASA’s Low-Density Supersonic Decelerator (LDSD) project conducted its second test on Monday – a major demonstration of technology that is being baselined into NASA’s ambitions for landing payloads on Mars. The test once again suffered from a parachute failure, although the other test objectives all went to plan.
LDSD Test:
NASA’s plans for landing human missions on Mars are under a major review, led by the Human Architecture Team (HAT).
Working through a number of decision points, the team has begun inserting preferred technology into Concept Of Operations (CONOPS) documentation, ahead of NASA’s goal of landing humans and support hardware on the surface of the Red Planet.
One major change relates to the refinement of the utilization of an aeroshell, parachute and propulsive techniques to allow huge landers to safely touchdown and deploy on the surface.
The new plans show the use of a Supersonic Parachute system during part of the descent phase is now being removed as an option for the larger payloads.
“The HAT held a supersonic parachute workshop in which the consensus was that supersonic parachutes are not applicable to landing human scale payloads (>10 metric tons) on Mars,” noted L2 information.
“As a result, further entry, descent, and landing studies will only consider concepts for supersonic retro propulsion in combination with deployable, inflatable, and rigid aeroshells.”
The amazing Entry, Descent and Landing (EDL) approach of Mars Curiosity involved many new technologies, including the SkyCrane decent, but that was for a one ton rover.
The huge Mars habitats will require more ambitious landing techniques.
These larger modules require “bigger brakes” to slow them down ahead of landing. LDSD will help evaluate these new options.
Testing this technology is taking place in various NASA centers. However, it’s the Low-Density Supersonic Decelerator (LDSD) project that is conducting real-life testing and gathering the required data about landing payloads on Mars and other planetary surfaces, utilizing a Supersonic Inflatable Aerodynamic Decelerator (SIAD).
The concept involves increasing the size of the aeroshell, creating a much larger surface area, generating more drag in the very thin Martian atmosphere.
The first test of the LDSD technology occurred in June 2014.
The test was a success, despite a failure of the Supersonic Disk Sail Parachute during deployment.
The latest test began around 1:45 pm Eastern with the launch of the LDSD from the launch tower, slowly pulled uphill for more than two hours below the huge helium-filled high altitude balloon. The goal to reach an altitude of 120,000 feet was achieved without any issue.
At that point, the balloon released from the vehicle and the test milestones were quickly initiated.
Four small rocket motors fired to spin up and gyroscopically stabilize the saucer.
A half second later, a Star 48B long-nozzle, solid-fueled rocket engine kicked in with 17,500 pounds of thrust, sending the test vehicle to the edge of the stratosphere at an altitude of 180,000 feet.
With a velocity of around Mach 3.8, the doughnut-shaped SIAD was tested and appeared to function as required.
The SIAD decelerated the test vehicle to approximately Mach 2.5 – with this objective successful completed.
These drag devices are attached to the outer rim of a capsule-like atmospheric entry vehicle.
SIAD will be available in two sizes, one at 20 feet in diameter, sized for future robotic missions and called SIAD-R – and inflated with pressurized hot gas.
The other will be 26 feet in diameter, sized for payloads related for human missions and called SIAD-E – and inflated with ram air pressure.
With all going to plan, the vehicle then deployed a mammoth parachute (the Supersonic Disk Sail Parachute), which was to be used to ease the test vehicle to a water impact about 40 minutes after being dropped from the balloon.
The test was initially delayed from Tuesday (and subsequent days) due the prediction of high waves in the splashdown zone.
The parachute system failed during the first test, as much as it was not part of the mission objectives.
This time, however – via improvements to the parachute – it became a major part of the test.
Sadly, just like the first test, and despite the design changes, the chute still failed to correctly deploy.
Despite the Mars planning team’s recent comments about moving away from supersonic parachutes for the larger payloads, there is still likely to be a role for supersonic parachutes for smaller payloads.
“These new drag devices can increase payload delivery to the surface of Mars from our current capability of 3,300 pounds (1.5 metric tons) to between 4,400 and 6,600 pounds (2 to 3 metric tons), depending on which inflatable decelerator is used in combination with the parachute,” NASA noted.
“They will increase available landing altitudes by 1 to 2 miles, increasing the accessible surface area we can explore. They also will improve landing accuracy from a margin of 6 miles to just 2 miles. All these factors will increase the capabilities and robustness of robotic and human explorers on Mars.”
Achieving a success with the LDSD during the test will help prove those projected improvements.
“This year’s test is centered on how our newly-designed supersonic parachute will perform. We think we have a great design ready for the challenge, but the proof is in the pudding and the pudding will be made live for everyone to see,” project manager Mark Adler added.
Despite the second successive chute failure, a third test flight is currently scheduled for the summer of 2016.
(Images via NASA).