astronomy

NASA Pathfinder

NASA Pathfinder is a astronomy 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 NASA Pathfinder rather than just read about it. In short: The NASA Pathfinder and NASA Pathfinder Plus were the first two aircraft developed as part of an evolutionary series of solar- and fuel-cell-system-powered unmanned aerial vehicles (UAVs). AeroVironment, Inc. developed the vehicles under NASA's Environmental Research Aircraft and Sensor Technology (ERAST) program.

Key takeaways

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

Reference excerpt

The NASA Pathfinder and NASA Pathfinder Plus were the first two aircraft developed as part of an evolutionary series of solar- and fuel-cell-system-powered unmanned aerial vehicles (UAVs). AeroVironment, Inc. developed the vehicles under NASA's Environmental Research Aircraft and Sensor Technology (ERAST) program. They were built to develop the technologies that would allow long-term, high-altitude aircraft to serve as atmospheric satellites, to perform atmospheric research tasks as well as serve as communications platforms. They were developed further into the NASA Centurion and NASA Helios aircraft.

Pathfinder AeroVironment initiated its development of full-scale solar-powered aircraft with the Gossamer Penguin and Solar Challenger vehicles in the late 1970s and early 1980s, following the pioneering work of Robert Boucher, who built the first solar-powered flying models in 1974. As part of the ERAST program, AeroVironment built four generations of long endurance unmanned aerial vehicles (UAVs) under the leadership of Ray Morgan, the first of which was the Pathfinder.

Development In 1983, AeroVironment obtained funding from an unspecified US government agency to secretly investigate a UAV concept designated "High Altitude Solar" or HALSOL. The HALSOL prototype first flew in June 1983. Nine HALSOL flights took place at Groom Lake in Nevada. The flights were conducted using radio control and battery power, as the aircraft had not been fitted with solar cells. HALSOL's aerodynamics were validated, but the investigation led to the conclusion that neither photovoltaic cell nor energy storage technology were mature enough to make the idea practical for the time being, and so HALSOL was put into storage. In 1993, after ten years in storage, the aircraft was brought back to flight status for a brief mission by the Ballistic Missile Defense Organization (BMDO). With the addition of small solar arrays, five low-altitude checkout flights were flown under the BMDO program at NASA Dryden in the fall of 1993 and early 1994 on a combination of solar and battery power. In 1994, the aircraft was transferred to the NASA ERAST Program to develop science platform aircraft technology. It was renamed "Pathfinder" because it was "literally the pathfinder for a future fleet of solar-powered aircraft that could stay airborne for weeks or months on scientific sampling and imaging missions". A series of flights were planned to demonstrate that an extremely light and fragile aircraft structure with a very high aspect ratio (the ratio between the wingspan and the wing chord) can successfully take-off and land from an airport and can be flown to extremely high altitudes (between 50,000 feet (15,000 m) and 80,000 feet (24,000 m)) propelled by the power of the sun. In addition, the ERAST Project also wanted to determine the feasibility of such a UAV for carrying instruments used in a variety of scientific studies. On October 21, 1995, the aircraft's fragility was aptly demonstrated when it was severely damaged in a hangar accident, but was subsequently rebuilt.

Aircraft description Pathfinder was powered by eight electric motors — later reduced to six — which were first powered by batteries. It had a wing span of 98.4 feet (30.0 m). Two underwing pods contain the landing gear, batteries, triple-redundant instrumentation system, and dual-redundant flight control computers. By the time the aircraft was adopted into the ERAST project in late 1993, solar cells were being added, eventually covering the entire upper surface of the wing. The solar arrays provide power for the aircraft's electric motors, avionics, communications and other electronic systems. Pathfinder also had a backup battery system that can provide power for between two and five hours to allow limited-duration flight after dark. Pathfinder flies at an airspeed of only 15 miles per hour (24 km/h) to 25 miles per hour (40 km/h). Pitch control is maintained by the use of tiny elevators on the trailing edge of the wing Turn and yaw control is accomplished by slowing down or speeding up the motors on the outboard sections of the wing.

Flight testing and records Major science activities of Pathfinder missions have included detection of forest nutrient status, forest regrowth after damage caused by Hurricane Iniki in 1992, sediment/algal concentrations in coastal waters and assessment of coral reef health. Science activities are coordinated by the NASA Ames Research Center and include researchers at the University of Hawaiʻi and the University of California. Pathfinder flight tested two ERAST-developed scientific instruments, a high spectral resolution Digital Array Scanned Interferometer (DASI) and a high spatial resolution Airborne Real-Time Imaging System (ARTIS), both developed at Ames. These flights were conducted at altitudes between 22,000 feet (6,700 m) and 49,000 feet (15,000 m) in 1997. On September 11, 1995, Pathfinder set an unofficial altitude record for solar powered aircraft of 50,000 feet (15,000 m) during a 12-hour flight from NASA Dryden. This and subsequent records claimed by NASA for Pathfinder remain unofficial, as they were not validated by the FAI, the internationally recognized aviation world record sanctioning body. The National Aeronautic Association presented the NASA-industry ERAST team with an award for one of the "10 Most Memorable Record Flights" of 1995. After further modifications, the aircraft was moved to the U.S. Navy's Pacific Missile Range Facility (PMRF) on the Hawaiian island of Kauai. On one of seven flights there in the spring and summer of 1997, Pathfinder raised the altitude record for solar-powered aircraft — as well as propeller-driven aircraft — to 71,530 feet (21,800 m) on July 7, 1997. During those flights, Pathfinder carried two lightweight imaging instruments to learn more about the island's terrestrial and coastal ecosystems, demonstrating the potential of such aircraft as platforms for scientific research.

Pathfinder-Plus

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with NASA Pathfinder

Start with the simplest possible case. Write down what NASA Pathfinder claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, 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 NASA Pathfinder 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 NASA Pathfinder 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 NASA Pathfinder

In research: NASA Pathfinder appears in astronomy 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 NASA Pathfinder 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: NASA Pathfinder is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1990s United States experimental aircraft, AeroVironment aircraft, Eight-engined tractor aircraft, so understanding it makes those chapters shorter.
In everyday life: Look for NASA Pathfinder 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 NASA Pathfinder in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NASA Pathfinder 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 NASA Pathfinder out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NASA Pathfinder in simple terms?

Why does NASA Pathfinder matter?

Because it connects several astronomy 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 NASA Pathfinder?

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 NASA Pathfinder.