science

Low-Density Supersonic Decelerator

Low-Density Supersonic Decelerator is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Low-Density Supersonic Decelerator rather than just read about it. In short: The Low-Density Supersonic Decelerator or LDSD is a reentry vehicle designed to test techniques for atmospheric entry on Mars. The disc-shaped LDSD uses an inflatable structure called the Supersonic Inflatable Aerodynamic Decelerator (SIAD), which is essentially a donut-shaped balloon, to create atmospheric drag in order to decelerate the vehicle before deploying a large supersonic parachute.

Key takeaways

Low-Density Supersonic Decelerator belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Low-Density Supersonic Decelerator to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Low-Density Supersonic Decelerator from memory before moving on to harder problems.

Reference excerpt

The Low-Density Supersonic Decelerator or LDSD is a reentry vehicle designed to test techniques for atmospheric entry on Mars. The disc-shaped LDSD uses an inflatable structure called the Supersonic Inflatable Aerodynamic Decelerator (SIAD), which is essentially a donut-shaped balloon, to create atmospheric drag in order to decelerate the vehicle before deploying a large supersonic parachute. The goal of the $230 m project is to develop a reentry system capable of landing 2- to 3-ton payloads on Mars, as opposed to the 1-ton limit of the currently used systems. The vehicle is being developed and tested by NASA's Jet Propulsion Laboratory. Mark Adler is the project manager. The vehicle was tested in 2014 and 2015.

June 2014 test flight

The test flight took place on June 28, 2014, with the test vehicle launching from the United States Navy's Pacific Missile Range Facility on Kauaʻi, Hawaiʻi, at 18:45 UTC (08:45 local). A high-altitude helium balloon, which when fully inflated has a volume of 975,000 cubic meters (34,430,000 ft3), lifted the vehicle to 36,500 meters (119,900 ft). The vehicle detached at 21:05 UTC (11:05 local), and four small, solid-fuel rocket motors spun up the vehicle to provide stability. A half second after spin-up, the vehicle's Star 48B solid-fuel motor ignited, powering the vehicle to Mach 4.32 and a peak altitude of 58,200 meters (190,900 ft). Immediately after rocket burn-out, four more rocket motors despun the vehicle. Upon slowing to Mach 4.08, the 6-meter (20 ft) tube-shaped Supersonic Inflatable Aerodynamic Decelerator (SIAD-R configuration) deployed. SIAD is intended to increase atmospheric drag on the vehicle by increasing the surface area of its leading side, thus increasing the rate of deceleration. Upon slowing to Mach 2.54 (around 86 seconds after SIAD deployment), the Supersonic Disksail (SSDS) parachute was deployed to slow the vehicle further. This parachute measures 30.5 meters (100 ft) in diameter, twice the area of the one used for the Mars Science Laboratory mission. However, it began tearing apart after deployment, and the vehicle impacted the Pacific Ocean at 21:35 UTC (11:35 local) travelling 32 to 48 kilometers per hour (20 to 30 mph). All hardware and data recorders were recovered. Despite the parachute incident, the mission was declared a success; the primary goal was proving the flight worthiness of the test vehicle, while SIAD and SSDS were secondary experiments.

2015 test flights A second test flight of LDSD took place in June 2015, at the Pacific Missile Range Facility. This test focused on the 6-meter (20 ft) SIAD-R and Supersonic Ringsail (SSRS) technologies, incorporating lessons learned during the 2014 test. Changes planned for the parachute included a rounder shape and structural reinforcement. After several weather-related scrubs, the flight occurred on June 8. As in the first test, the SIAD structure inflated successfully but the parachute was damaged during deployment, this time after 600 ms and at 80,000 pounds (36,000 kg) drag.

After 2015 A 3rd test was expected in 2016, after some smaller scale tests with sounding rockets. The parachute team wanted Mars 2020 to have a camera on the parachute deployment and opening in 2021.

Gallery

See also HIAD, NASA's Hypersonic Inflatable Aerodynamic Decelerator LOFTID, 2022 test from Earth orbit Rockoon

References

External links

LDSD project website LDSD fact sheet

Illustrations

Worked examples

Example 1 — a first encounter with Low-Density Supersonic Decelerator

Start with the simplest possible case. Write down what Low-Density Supersonic Decelerator claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Low-Density Supersonic Decelerator before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Low-Density Supersonic Decelerator ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Low-Density Supersonic Decelerator

In research: Low-Density Supersonic Decelerator appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Low-Density Supersonic Decelerator in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Low-Density Supersonic Decelerator is common in secondary-school and first-year university syllabi. It links to neighbouring topics Exploration of Mars, Inflatable aircraft, NASA programs, so understanding it makes those chapters shorter.
In everyday life: Look for Low-Density Supersonic Decelerator outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Low-Density Supersonic Decelerator in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Low-Density Supersonic Decelerator means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Low-Density Supersonic Decelerator out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Low-Density Supersonic Decelerator in simple terms?

Why does Low-Density Supersonic Decelerator matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Low-Density Supersonic Decelerator?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Low-Density Supersonic Decelerator.