Tuesday, June 9, 2015

JHU Applied Physics Lab: World-Class Innovation in Howard County

The largest employer in Howard County, with roughly 5000 employees, is Johns Hopkins University's Applied Physics Lab (APL), just 3 miles down Gorman Road from Emerson.

Today APL is a center for scientific and space research, while also hosting graduate classes in engineering and other scientific disciplines.

But APL has a long history of innovation, to include literally creating from scratch one of the modern technologies that virtually all of us have come to depend on -- the first satellite navigation system, which would eventually become the Global Positioning System, better known as GPS.

History of APL: World War II
The Applied Physics Lab was born in Silver Spring, MD in 1942 during World War II, searching for a way to defend US Navy ships against air attacks.

The solution was the proximity fuze, which implemented a British idea for using Doppler radar to determine the proximity to a plane or missile and detonate an explosive at a pre-determined distance.

The APL scientists successfully miniaturized the radar while making it capable of withstanding the stress of being fired from a cannon, giving the Allies a crucial (and secret) advantage during the war.

This achievement was followed by the first successful supersonic, ramjet surface-to-air guided missile (the Bumblebee) and then post-war testing of captured German V2 rockets.

Over the next decade APL would continue to lead development of guided missiles and rockets, and took the first photograph of Earth from space from a V2 rocket.

In 1954, APL would move from its Georgia Avenue location to a "bucolic" campus in then-rural Howard County.

Sputnik Inspires GPS
When Sputnik was launched by the Soviet Union in 1957, APL had already developed expertise in telemetry and signals processing, and the Lab was able to create precise orbital tracks of the satellite by analyzing its signals.

But amid the wonderment (and fear) of the time, a small group of APL scientists and engineers would get the idea that became the modern GPS system.

Two APL scientists realized during a lunchtime conversation in the APL cafeteria that no one had been trying to track Sputnik, and they devised a system to analyze the Doppler shift of the regular signals emitted by the satellite and thus determine its position.

Frank McClure, APL's director, then had the inspiration for the converse problem: if a satellite's orbit was known, the location of the listening station on earth could also be determined, and this could be used by the US Navy to track its ships and Polaris missile submarines.

Using a grant from the Advanced Research Projects Agency (ARPA), APL scientists then proceeded to build some of the very first satellites, and after some launchpad mishaps the first GPS constellation of satellites, dubbed Transit, was operational by late 1961.

Though Transit would eventually be superseded by other systems, it remained operational until 1996 and made possible other scientific discoveries along the way, such as the discovery that the Earth is not round but a "lopsided ball", as well as the theory of continental drift.

The Rest of the Story
APL has continued to evolve through the years, but just a partial listing of its many achievements as chronicled on the Lab's 70th Anniversary page from 2012 include:

  • Proximity Fuze (1943)
  • First supersonic guided missile (Bumblebee, 1945)
  • Supersonic stabilization (1947)
  • Cosmic ray tests (1948)
  • Pioneering telemetry for missile testing (1950)
  • Terrier supersonic missile (1950)
  • First successful ramjet engine guided missile (1951)
  • Molecular beam mass spectrometer (1953)
  • Homing guidance system developed for Terrier missile (1954)
  • APL tracks Soviet Sputnik (1957)
  • APL invents Transit, first GPS system (1958)
  • APL launches satellites carrying first solid-state particle detectors, and with first electronic memory and radioisotope (nuclear) power source (1961)
  • Transit GPS system operational (1961)
  • APL launches first geodetic satellites (for studying the Earth) (1962)
  • Biomedical collaboration with JHU Medical Institutions begins (1965)
  • APL Terrier and Tartar missiles evolve into Standard missiles in Aegis weapons system (1966)
  • APL expands civilian research program: automated mass transit, fire research, energy, prosthetics (1968)
  • APL's rechargeable pacemaker is the first implanted in a human subject (1973)
  • APL demonstrates methane recovery from landfills as energy source (1977)

The innovations would continue through the next four decades, to include multiple satellites and their payloads; biomedical inventions including prosthetic limbs; and many other contributions to such disciplines as computer simulation, radar, lidar, guidance systems, chemical and biological warfare sensors, and many other advanced technologies.

Here's a recent article about how engineers at JHU-APL have developed a next-generation prosthetic controlled with a person's mind just like their original arm:

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