A year ago, this might have seemed like a foolish question. An autonomous car racing in the Indianapolis 500 Mile Race? Ha! When pigs fly!
The Indy 500 Borg Warner Trophy. Source: The359 – Flickr via Wikipedia
One of the first things you may notice about the Borg Warner Trophy is that the winning driver of each Indy 500 Race is commemorated with a small portrait/sculpture of their face in bas-relief along with a small plaque with their name, winning year and winning average speed. Today, 105 faces grace the trophy.
Borg Warner Trophy close-up. Source: WISH-TV, Indianapolis, March 2016
The Indianapolis Motor Speedway (IMS) website provides the following details:
“The last driver to have his likeness placed on the original trophy was Bobby Rahal in 1986, as all the squares had been filled. A new base was added in 1987, and it was filled to capacity following Gil de Ferran’s victory in 2003. For 2004, Borg-Warner commissioned a new base that will not be filled to capacity until 2034.”
On 11 January 2021, the Indianapolis Motor Speedway along with Energy Systems network announced the Indy Autonomous Challenge (IAC), with the inaugural race taking place at the IMS on 23 October of 2021. The goal of the IAC is to create the fastest autonomous race car that can complete a head-to-head 50 mile (80.5 km) race at IMS. The challenge, which offers $1.5 million in prize money, is geared towards college and university teams. The IAC website is here: https://www.indyautonomouschallenge.com
The IAC organizers state that this challenge was “inspired and advised by innovators who competed in the Defense Advanced Research Projects Agency (DARPA) Grand Challenge, which put forth a $1 million award in 2004 that created the modern automated vehicle industry.”
All teams will be racing an open-wheel, automated Dallara IL-15 race car that appears, at first glance, quite similar to conventional (piloted) 210 mph Dallara race cars used in the Indy Lights race series. However, the IL-15 has been modified with hardware and controls to enable automation. The automation systems include an advanced set of sensors (radar, lidar, optical cameras) and computers. Each completed race car has a value of more than $1 million. The teams will focus primarily on writing the software that will process the sensor data and drive the cars. When fully configured for the race, the IAC Dallara IL-15 will be the world’s fastest autonomous automotive vehicle.
Rendering of the autonomous Dallara IL-15. Source: IACRendering of the autonomous Dallara IL-15 on the IMS race track. Source: IAC
Originally, 39 university teams from 11 counties and 14 states had applied to compete in the IAC. As of mid-January 2021, the IAC website lists 24 teams still actively seeking to qualify for the race.
The race winner will be the first team whose car crosses the finish line after a 20-lap (50 mile / 80.5 km) head-to-head race that is completed in less than 25 minutes. This requires an average lap speed of at least 120 mph (193 kph) and an average lap time of less than 75 seconds around the 2.5 mile (4 km) IMS race track.
In comparison, Indy Light races at IMS from 2003 to 2019 have had an average winning speed of 148.1 mph (238.3 kph) and an average winning lap time of 60.8 seconds. All of these races were run with cars using a Dallara chassis. The highest winning average speed for an Indy Lights race at IMS was in 2018, when Colton Herta won in a Dallara-Mazda at an average speed of 195.0 mph (313.8 kph) and an average lap time of 46.1 seconds, with no cautions during the race.
The winning team will receive a prize of $1 million, with the second and third place teams receiving $250,000 and $50,000, respectively.
The IAC race will be held more than 17 years after the first of three DARPA Grand Challenge autonomous vehicle competitions that were instrumental in building the technical foundation and developing broad-based technical competencies related to autonomous vehicles. A quick look at these DARPA Grand Challenge races may help put the upcoming IAC race in perspective.
The first DARPA Grand Challenge autonomous vehicle race was held on 13 March 2004. From an initial field of 106 applicants, DARPA selected 25 finalists. After a series of pre-race trials, 15 teams qualified their vehicles for the race. The “race course” was a 140 mile (225 km) off-road route designated by GPS waypoints through the Mojave Desert, from Barstow, CA to Primm, NV. You might remember that no vehicles completed the course and there was no winner of the $1 million prize. The vehicle that went furthest was the Carnegie Mellon Sandstorm, a modified Humvee sponsored by SAIC, Boeing and others. Sandstorm broke down after completing 7.36 miles (11.84 km), just 5% of the course.
A second Grand Challenge race was held 18 months later, on 8 October 2005. DARPA raised the prize money to $2 million for this 132 mile (212 km) off-road race. From an original field of 197 applicants, 23 teams qualified to have their vehicles on the starting line for the race. In the end, five teams finished the course, four of them in under the 10-hour limit. Stanford University’s Stanley was the overall winner. All but one of the 23 finalist teams traveled farther than the best vehicle in 2004. This was a pretty remarkable improvement in autonomous vehicle performance in just 18 months.
In 2007, DARPA sponsored a different type of autonomous vehicle competition, the Urban Challenge. DARPA describes this competition as follows:
“This event required teams to build an autonomous vehicle capable of driving in traffic, performing complex maneuvers such as merging, passing, parking, and negotiating intersections. As the day wore on, it became apparent to all that this race was going to have finishers. At 1:43 pm, “Boss”, the entry of the Carnegie Mellon Team, Tartan Racing, crossed the finish line first with a run time of just over four hours. Nineteen minutes later, Stanford University’s entry, “Junior,” crossed the finish line. It was a scene that would be repeated four more times as six robotic vehicles eventually crossed the finish line, an astounding feat for the teams and proving to the world that autonomous urban driving could become a reality. This event was groundbreaking as the first time autonomous vehicles have interacted with both manned and unmanned vehicle traffic in an urban environment.”
In January 2021, a production Tesla Model 3 with the new Full Self-Driving (FSD) Beta software package drove from San Francisco to Los Angeles with almost no human intervention. I wonder how that Tesla Model 3 would have performed on the 2007 DARPA Urban Challenge. You can read more about the SF – LA FSD trip at the following link: https://interestingengineering.com/tesla-full-self-driving-successfully-takes-model-3-from-sf-to-la
We’ve seen remarkable advances in the development of autonomous vehicles in the 17 years since the 2004 DARPA Grand Challenge race. Is it unreasonable to think that an autonomous race car will become competitive with a piloted Indy race car during the next decade and compete in the Indy 500 before they run out of space on the Borg Warner Trophy in 2034? If the autonomous racer wins the Indy 500, what will they put on the trophy to commemorate the victory? A silver bas-relief of a microchip?
The Atacama Cosmology Telescope (ACT) is a six-meter (19.7 foot) radio telescope designed to make high-resolution, microwave-wavelength surveys of the cosmic microwave background (CMB). It is located at a remote site in the Atacama Desert at an elevation of 5,190 meters (17,030 feet) in northern Chile.
The ACT site. Source: ACT Collaboration
ACT observes in three frequency bands (148, 218 and 277 GHz) and has a resolution of 1.3 arc minutes at 148 GHz, near the peak of the CMB spectrum. This is significantly higher than the 5-10 arc minute resolution of the Planck spacecraft, which observed the CMB from 2009 to 2013 in the frequency range from 30 to 857 GHz. You’ll find a detailed description of the Atacama Cosmology Telescope (ACT) at the following link: https://www.cosmos.esa.int/documents/387566/387653/Ferrara_Dec3_09h20_Devlin_ACT.pdf
New results from the ACT survey, reported in December 2020, affirm the Planck CMB survey results.
The universe is isotropic
The estimate of the age of the universe was refined to 13.77 billion years old ± 0.04 billion years, overlapping uncertainty bands with the 2015 Planck estimate of 13.813 ± 0.038 billion years
The value of the Hubble constant was refined to 67.6 kilometers / second / megaparsec, up slightly from the 2018 Planck estimate of 67.4 kilometers / second / megaparsec. The significant difference from the value derived from astrophysical measurements, 73.5 km / second / megaparsec, remains unexplained.
ACT high resolution image of the isotropic cosmic background radiation covering a section of the sky 50 times the width of a full moon. This image represents a region of space 20 billion light-years across. Source: ACT Collaboration via EarthSky
For more information:
S.K. Choi, et al., “The Atacama Cosmology Telescope: a measurement of the Cosmic Microwave Background power spectra at 98 and 150 GHz,” Journal of Cosmology and Astroparticle Physics (subscription required), Volume 2020, December 2020: https://iopscience.iop.org/article/10.1088/1475-7516/2020/12/045/pdf
On 16 December 2020, the Return Vehicle from China’s unmanned Chang’e 5 lunar spacecraft returned to Earth with the first new lunar samples since the Soviet Union’s (now Russia) Luna 24 mission returned about 6 ounces (170 grams) of lunar material on 22 August 1976. The last US lunar samples were obtained during the manned Apollo 17 mission, which returned to Earth on 14 December 1972.
The Chang’e 5 Return Vehicle touched down in Inner Mongolia carrying samples from the Moon. Source: CHINE NOUVELLE/SIPA/NEWSCOM
The Chang’e 5 Spacecraft
The basic architecture of the robotic Chang’e 5 spacecraft resembles the US Apollo manned lunar mission spacecraft in having four basic parts: a Service Module, a Return Vehicle (analog to the Apollo Command Module), and a two-stage lunar lander with a Lander stage and an Ascent stage.
The lander has two tools for acquiring samples: a drill for coring samples and a mechanical claw for grabbing surface samples.
China’s Chang’e 5 spacecraft (left) and the US Apollo spacecraft (right). Sources: spaceflight101.com (left); marked-up.blog (right)
The basic elements of the Chang’e 5 mission are shown in the following graphic.
Chang’e 5 mission elements. Source: The Planetary Society
The robotic Chang’e 5 spacecraft is named after the Chinese Moon goddess. The lunar mission began on 24 November 2020 when a Long March-5 rocket lifted off from China’s Wenchang launch site and placed the Chang’e 5 spacecraft, still mated to an upper stage rocket, into a temporary low Earth orbit. The upper stage rocket accomplished the “trans-lunar injection” and then separated from the spacecraft, which continued on toward the Moon. A rocket motor on the Service Module slowed the spacecraft for lunar orbit insertion followed by orbital adjustments in preparation for landing. From lunar orbit, the combined Lander / Ascent Unit descended and landed in the Sea of Storms region on 1 December 2020. The Service Module / Return Vehicle remained in lunar orbit.
Chang’e 5 mission profile. Source: NASA / spacecraft101.comChang’e 5 landing site. Source: Nuno Sequeira via EarthSky.org
The Lander / Ascent Unit was designed to collect about 2 kg (4.4 lb) of lunar samples. After the samples were collected, the Ascent Unit launched from the lunar surface on 3 December 2020 and rendezvoused and docked with the orbiting Service Module / Return Vehicle. After the lunar samples were transferred to the Return Vehicle, the Ascent Unit was released. The rocket motor on the Service Module accomplished the trans-Earth injection and the spacecraft departed lunar orbit for the journey back to Earth. As the spacecraft approached Earth, the Service Module separated and the Return Vehicle, which reentered the Earth’s atmosphere to complete the mission with a safe landing on 17 December 2020. The Ascent Unit was de-orbited and crashed into the lunar surface on 7 December 2020.
This lunar mission profile is quite similar to that used by the US on the manned Apollo missions in the late 1960s and early 1970s.
Meanwhile, the Chang’e 5 Service Module flew past Earth and continued toward the Sun-Earth Lagrange point known as L1, which is a gravitationally stable point in space between the Earth and the Sun, about 900,000 miles (1,500,000 km) from Earth. The spacecraft still has more than 440 pounds (200 kg) of propellant remaining and can make scientific measurements at L1 (and beyond?).
Lagrange points in the Sun-Earth system. Source: space.com
Japan’s Hayabusa2 (Japanese for Peregrine falcon 2) spacecraft returned from its six-year mission to asteroid 162173 Ryugu for a high-speed fly-by of Earth on 5 December 2020, during which it released a reentry capsule containing the material collected during two separate sampling visits to the asteroid’s surface. The capsule successfully reentered Earth’s atmosphere, landed in the planned target area in Australia’s Woomera Range and was recovered intact. The sample return capsule is known as the “tamatebako” (treasure box).
Location of Woomera Range. Source: itea.org
Hayabusa2’s sample return capsule after landing in the Woomera Range, Australia. Source: JAXACapsule containing samples from asteroid Ryugu. Source: JAXA
Background
The first asteroid sample return mission was Japan’s Hayabusa1, which was launched on 9 May 2003 and rendezvoused with S-type asteroid 25143 Itokawa in mid-September 2005. A small sample was retrieved from the surface on 25 November 2005. The sample, comprised of tiny grains of asteroidal material, was returned to Earth on 13 June 2010, with a landing in the Woomera Range.
Japan’s Hayabusa2 and the US OSIRIS-Rex asteroid sample return missions overlap, with Hayabusa2 launching about two years earlier and returning its surface samples almost three years earlier. Both spacecraft were orbiting their respective asteroids from 31 December 2018 to 12 November 2019.
You’ll find a great deal of information and current news on the Hayabusa2 and OSIRIS-REx asteroid sample return missions on their respective project website:
An extended mission to explore additional asteroids was made possible by the excellent health of the Hayabusa2 spacecraft and the economic use of fuel during the basic mission. Hayabusa2 still has 30 kg (66 lb) of xenon propellant for its ion engines, about half of its initial load of 66 kg (146 lb).
As of September 2020, JAXA’s plans are is to target the Hayabusa2 spacecraft for the following two asteroid encounters:
Conduct a high-speed fly-by of L-type asteroid (98943) 2001 CC21 in July 2026. This asteroid has a diameter between 3.47 to 15.52 kilometers (2.2 to 9.6 miles).
Continue on a rendezvous with asteroid 1998 KY26 in July 2031. This is a 30-meter (98-foot) diameter asteroid, potentially X-type (metallic), and rotating rapidly with a period of only 10.7 minutes.
Computer model view of 1998 KY26 based on radar data from Goldstone observatory. Source: NASA/JPL via Wikipedia
Fusion reactions in our Sun are predominately proton – proton reactions that lead to the production of the light elements helium, lithium, beryllium and boron. The next step up on the periodic table of elements is carbon.
Carbon is formed in our Sun by the “triple alpha” process shown in the following diagram. First, two helium-4 nuclei (4He, an alpha particles) fuse, emit a gamma ray and form an atom of unstable beryllium-8 (8Be), which can fuse with another helium nucleus, emit another gamma ray and form an atom of stable carbon-12 (12C). Timing is everything, because that fusion reaction must occur during the very short period of time before the unstable beryllium-8 atom decays (half life is about 8.2 x 10-17 seconds).
Stellar process for producing carbon-12. Source: Borb via Wikipedia
Stellar process for producing carbon-12. Source: Borb via Wikipedia
The carbon produced by the above reaction chain is the starting point for the carbon-nitrogen-oxygen (CNO) fusion cycle, which accounts for about 1% of the fusion reactions in a relatively small star the size of our Sun. In larger stars, the CNO cycle becomes the dominant fusion cycle.
The In the following diagram, the CNO cycle starts at the top-center:
First, an atom of stable carbon-12 (12C) captures a proton (1H) and emits a gamma ray (γ), producing an atom of nitrogen-13 (13N), which has a half-life of almost 10 minutes.
The cycle continues when the atom of nitrogen-13 decays into an atom of stable carbon-13 (13C) and emits a neutrino (ν) and a positron (β+).
When the carbon-13 atom captures of a proton, it emits a gamma ray and produces an atom of stable nitrogen-14 (14N).
When the nitrogen-14 atom captures a proton, it emits a gamma ray and produces an atom of oxygen-15 (15O), which has a half-life of almost 71 seconds.
The cycle continues when the atom of oxygen-15 decays into an atom of stable nitrogen-15 (15N) and emits a neutrino (ν) and a positron (β+).
After one more proton capture, the nitrogen-15 atom splits into a helium nucleus (4He) and an atom of stable carbon-12, which is indistinguishable from the carbon-12 atom that started the cycle.
The carbon-nitrogen-oxygen (CNO) cycle. Source: Borb via Wikipedia
As shown in the previous diagram, the CNO cycle generates characteristic emissions of gamma rays, positrons and neutrinos. With a neutrino detector, scientists would search for the neutrinos emissions from the nitrogen-13 and oxyger-15 decay steps in the CNO cycle.
The Borexino experimental facility is located at the INFN’s Gran Sasso National Laboratories in the Apennine Mountains, about 65 miles (105 km) northeast of Rome. The official website of the Borexino Experiment is here: http://borex.lngs.infn.it
The Borexino neutrino detector is in a underground laboratory hall deep in the mountain, which protects the detector from cosmic radiation, with the exception of neutrinos that pass through Earth undisturbed. Even with the huge Borexino detector in this very special, protected laboratory environment, the research team reported that detecting CNO neutrinos has been very difficult. Only about seven neutrinos with the characteristic energy of the CNO cycle are spotted in a day.
The Borexino neutrino detector is shown in the following diagram.
Source: INFN
INFN reported, “Previously Borexino had already studied in detail the main mechanism of energy production in the Sun, the proton-proton chain, through the individual detection of all neutrino fluxes that originate from it.”
For more information:
The Borexino Collaboration., Agostini, M., Altenmüller, K. et al. “Experimental evidence of neutrinos produced in the CNO fusion cycle in the Sun,” Nature, 587, 577–582, 25 November 2020: https://doi.org/10.1038/s41586-020-2934-0
On 15 Nov 1960, the FBM submarine USS George Washington (SSBN-598) embarked on the nation’s first Polaris nuclear deterrent patrol armed with 16 intermediate range Polaris A1 submarine launched ballistic missiles (SLBMs). This milestone occurred just 3 years 11 months after the Polaris FBM program was funded by Congress and authorized by the Secretary of Defense. The 1st deterrent patrol was completed 66 days later on 21 January 1961.
USS George Washington underway. Source: Navsource
The original US FBM submarine force consisted of 41 Polaris submarines, in five sub-classes (George Washington, Ethan Allen, Lafayette, James Madison and Benjamin Franklin), that were authorized between 1957 and l963. Through several rounds of modifications, most of these submarines were adapted to handle later versions of the Polaris SLBM (A2, A3 and A4) and some were modified to handle the Poseidon (C3) SLBM. Twelve of the James Madison- and Ben Franklin-class boats were modified the late 1970s and early 1980s to handle the long range Trident I C4 SLBMs.
A total of 1,245 Polaris deterrent patrols were made in a period of about 21 years, from the first Polaris A-1 deterrent patrol by USS George Washington in 1960, and ending with the last Polaris A-3 deterrent patrol by USS Robert E. Lee (SSBN-601), which started on 1 October 1981. By then, the remainder of the original Polaris SSBN fleet had transitioned to Poseidon (C3) and Trident I (C4) SLBMs.
The next generation of US ballistic missile submarines was the Ohio-class SSBN, 18 of which were ordered between 1974 and 1990 (one per fiscal year). The lead ship of this class, USS Ohio (SSBN 726), was commissioned in 1981 and deployed 6 September 1982 on its first strategic deterrent patrol, armed with the Trident I (C4) SLBM. Beginning with the 9th boat in class, USS Tennessee (SSBN-734), the remaining Ohio- class SSBNs were equipped originally to handle the larger Trident II (D5). Four of the early boats were upgraded to handle the Trident II (D5) missile. The earliest four, including the USS Ohio, were converted to cruise missile submarines to comply with strategic weapons treaty limits.
Evolution of the US submarine strategic nuclear deterrent fleet. Johns Hopkins APL Technical Digest, Volume 29, Number 4, 2011
The Federation of American Scientists (FAS) reported that the US Navy conducted 4,086 submarine strategic deterrent patrols between 1969 and 2017. At that time, the Navy was conducting strategic deterrent patrols at a steady rate of around 30 patrols per year. By the end of 2020, that total must be approaching 4,175 patrols.
Source: Hans Kristensen, FAS, 2018
In 2020, the US maintains a fleet of 14 Trident missile submarines armed with D5LE (life extension) SLBMs. By about 2031, the first of the new Columbia-class SSBN is expected to be ready to start its first deterrent patrol. Ohio-class SSBNs will be retired on a one-for-one bases when the new Columbia-class SSBNs are delivered to the fleet and ready to assume deterrent patrol duties.
The USS George was defueled and declared scrapped in September 1998. Owing to her place in history as the first US ballistic missile submarine and her successful completion of 55 deterrent patrols in both the Atlantic & Pacific Oceans, the George Washington’s sail was preserved and returned to New London, CT where it is now displayed outside of the gates of the US Submarine Force Library and Museum.
The USS George Washington’s sail on display outside the US Submarine Force Library and Museum in New London, CT. Source: Wikimapia
John Gibson & Stephen Yanek, “The Fleet Ballistic Missile Strategic Weapon System: APL’s Efforts for the U.S. Navy’s Strategic Deterrent System and the Relevance to Systems Engineering,” Johns Hopkins APL Technical Digest, Volume 29, Number 4, 2011: https://www.jhuapl.edu/Content/techdigest/pdf/V29-N04/29-04-Gibsonl.pdf
The Arecibo Observatory (AO) on Puerto Rico has been out of service since 10 August 2020, when a three-inch auxiliary support cable slipped out of its socket and fell onto the fragile radio telescope dish below. Three months later, on 6 November 2020, a second cable associated with the same support tower broke, damaging nearby cables, causing more damage to the reflector dish, and leaving the radio telescope’s support structure in a weakened and uncertain state.
On 19 November 2020, the National Science Foundation (NSF) announced it has begun planning for decommissioning the 57-year old Arecibo Observatory’s (AO) 1,000-foot (305-meter) radio telescope due to safety concerns after the two support wires broke and seriously damaged the antenna. You can read NSF News Release 20-010 at the following link: https://www.nsf.gov/news/news_summ.jsp?cntn_id=301674
The 1,000-foot (305-m) dish at Arecibo Observatory in better days, in Spring 2019. Source: AO/University of Central Florida (UCF)The damaged Arecibo Observatory radio telescope in November 2020. Source: NSFA view from under the damaged dish. Source: AO/University of Central Florida (UCF)
Not included in the NSF timeline is the 1974 first-ever broadcast into deep space of a powerful signal that could alert other intelligent life to our technical civilization on Earth. The 1,679 bit “Arecibo Message” was directed toward the globular star cluster M13, which is 22,180 light years away. The message will be in transit for another 22,134 years.
A key capability lost is AO’s planetary radar capability that enabled the large dish to function as a high-resolution, active imaging radar. You’ll find examples of AO’s radar images of the Moon, planets, Jupiter’s satellites, Saturn’s rings, asteroids and comets on the NSF website here: https://www.naic.edu/~pradar/radarpage.html
More impressive than the still images were animations created from a sequence of AO radar images, particularly of passing asteroids. The animations defined the motion of the object as it flew near Earth. As an example, you can watch the following short (1:07 minutes) video, “Big asteroid 1998 OR2 seen in radar imagery ahead of fly-by”:
The US still has a reduced capability for planetary radar imaging with NASA’s Deep-Space Network’s Uplink Array.
The 19 November 2020 NSF news release stated, “After the telescope decommissioning, NSF would intend to restore operations at assets such as the Arecibo Observatory LIDAR facility — a valuable geospace research tool — as well as at the visitor center and offsite Culebra facility, which analyzes cloud cover and precipitation data.”
Adieu to radio astronomy at Arecibo.
Update 1 December 2020: Arecibo radio telescope collapsed.
NPR reported, “The Arecibo Observatory in Puerto Rico has collapsed, after weeks of concern from scientists over the fate of what was once the world’s largest single-dish radio telescope. Arecibo’s 900-ton equipment platform, suspended 500 feet above the dish, fell overnight after the last of its healthy support cables failed to keep it in place. No injuries were reported, according to the National Science Foundation, which oversees the renowned research facility.”
Arecibo after the collapse. Source: Ricardo Arduengo / AFP via Getty Images
Update 8 December 2020: National Science Foundation video shows the moment of collapse.
Update 19 October 2022: No NSF funding
On 18 October 2022, Science magazine reported on NSF’s plans to convert the iconic observatory in Puerto Rico into a center for education and outreach in science, technology, engineering, and math (STEM). The limited funding available for this purpose “does not include support for remaining instruments at the site, including a 12-meter radio telescope, a radio spectrometer, and a suite of optical laser instruments for studying the upper atmosphere.”
The US Geologic Survey (USGS) provides a basic explanation of why glacial ice is blue:
“The red-to-yellow (longer wavelength) parts of the visible spectrum are absorbed by ice more effectively than the blue (shorter wavelength) end of the spectrum. The longer the path light travels in ice, the more blue it appears. This is because the other colors are being preferentially absorbed and make up an ever smaller fraction of the light being transmitted and scattered through the ice.”
Blue ice with natural lighting inside a glacial ice cave, Grindelwald, Switzerland. Source: P. Lobner photo
The key to blue ice is selective absorption, which occurs in a special kind of ice that is produced on land with the help of pressure and time. Becky Oskin provides the following general insights into how this process occurs in her 2015 article, “Why Are Some Glaciers Blue?”
When glacial ice first freezes, it is filled with air bubbles that are effective in scattering light passing through the ice. As that ice gets buried and compressed by subsequent layers of younger ice, the air bubbles become smaller and smaller. With less scattering of light by the air bubbles, light can penetrate more deeply into the ice and the older ice starts to take on a blue tinge. Blue ice is old ice.
Patches of blue-hued ice emerge on the surface of glaciers where wind and sublimation have scoured old glaciers clean of snow and young ice.
Blue ice also may emerge at the edges of a glacial icepack, where fragments of glaciers tumble into the sea and reveal a fresh edge of the old ice.
Stephen Warren’s 2019 paper, “Optical properties of ice and snow,” provides the following more technical description of the selective absorption process in ice:
“Ice is a weak filter for red light..….the absorption coefficient of ice increases with wavelength from blue to red (but the absorption spectrum is quite complex). The absorption length…… is approximately 2 meters at (a wavelength of ) λ = 700 nm (nanometers, red end of the visible spectrum) but approximately 200 meters at λ = 400 nm (blue-violet end of the visible spectrum). Photons at all wavelengths of visible light will survive without absorption, and be reflected or transmitted, unless the path length through ice is long enough to significantly absorb the red light.”…..”Ice develops a noticeable blue color in glacier crevasses and in icebergs, especially in marine ice (i.e., icebergs calved from glacial ice shelves), because of its lack of (air) bubbles (which would otherwise cause scattering and limit light transmission through the ice).”
The absorption length is the distance into a material where the beam flux has dropped to 1/e (1/2.71828 = 0.368 = 37%) of its incident flux. For light at the red end of the spectrum, that is a relatively short distance of about 2 meters. This means that, in 2 meters, absorption decreases the red light component of beam flux by a factor of 1/e to about 37% of the original incident red light. In another 2 meters, the red light beam flux is reduced to about 14% of the original incident red light. At the same distances, the blue-violet end of the spectrum has hardly been attenuated at all.
You can see that even modest size pieces of glacial ice (several meters in length / diameter) should be able to attenuate the red-to-yellow end of the spectrum and appear with varying degrees of blue tints. Looking into an ice borehole in an Antarctic ice sheet shows how intensely blue the deeper part of the glacial ice appears to the viewer on the surface. The removed ice core is a slender cylinder of ice that looks like clear ice when viewed from the side.
So… why is snow white? Light does not penetrate into snow very far before being scattered back to the viewer by the many facets of uncompressed snow on the surface. Thus, there is almost no opportunity for light absorption by the snow, and hence very little selective absorption of the red-to-yellow part of the visible spectrum.
For the same reason, sea ice, which is formed by the seasonal freezing of the sea surface, appears white because of the high concentration of entrained air bubbles (relative to glacial ice) that causes rapid scattering of incident light. Sea ice does not go through the metamorphism that produces glacial ice on land.
What is glacial ice?
The USGS describes glacial ice as follows: “Glacier ice is actually a mono-mineralic rock (a rock made of only one mineral, like limestone which is composed of the mineral calcite). The mineral ice is the crystalline form of water (H2O). It forms through the metamorphism of tens of thousands of individual snowflakes into crystals of glacier ice. Each snowflake is a single, six-sided (hexagonal) crystal with a central core and six projecting arms. The metamorphism process is driven by the weight of overlying snow. During metamorphism, hundreds, if not thousands of individual snowflakes recrystallize into much larger and denser individual ice crystals. Some of the largest ice crystals observed at Alaska’s Mendenhall Glacier are nearly one foot in length.”
A small chunk of clear glacial ice retrieved from Pléneau Bay, Antarctica. Source: P. Lobner photo
Where do glaciers exist?
The National Snow and Ice Data Center (NSIDC) reports that, “glaciers occupy about 10 percent of the world’s total land area, with most located in polar regions like Antarctica, Greenland, and the Canadian Arctic. Glaciers can be thought of as remnants from the last Ice Age, when ice covered nearly 32 percent of the land, and 30 percent of the oceans. Most glaciers lie within mountain ranges that show evidence of a much greater extent during the ice ages of the past two million years, and more recent indications of retreat in the past few centuries.”
Glaciers exist on every continent except Australia. The approximate distribution of glaciers is:
91% in Antarctica
8% in Greenland
Less than 0.5% in North America (about 0.1% in Alaska)
0.2% in Asia
Less than 0.1% is in South America, Europe, Africa, New Zealand, and New Guinea (Irian Jaya).
There are several schemes for classifying glaciers; some are described in the references at the end of this article. For simplicity, let’s consider two basic types.
A polar glacier is defined as one that is below the freezing temperature throughout its mass for the entire year. Polar glaciers exist in Antarctica and Greenland as continental scale ice sheets and smaller scale ice caps and ice fields.
A temperate glacier is a glacier that’s essentially at the melting point, so liquid water coexists with glacier ice. A small change in temperature can have a major impact on temperate glacier melting, area, and volume. Glaciers not in Antarctica or Greenland are temperate glaciers. In addition, some of the glaciers on the Antarctic Peninsula and some of Greenland’s southern outlet glaciers are temperate glaciers.
How old is glacier ice?
Some glacial ice is extremely old, while in many areas of the world, it is much younger than you might have expected.
USGS reports: “Parts of the Antarctic Continent have had continuous glacier cover for perhaps as long as 20 million years. Other areas, such as valley glaciers of the Antarctic Peninsula and glaciers of the Transantarctic Mountains may date from the early Pleistocene (starting about 2.6 million years ago and lasting until about 11,700 years ago). For Greenland, ice cores and related data suggest that all of southern Greenland and most of northern Greenland were ice-free during the last interglacial period, approximately 125,000 years ago. Then, climate (in Greenland) was as much as 3-5o F warmer than the interglacial period we currently live in.”
“Although the higher mountains of Alaska have hosted glaciers for as much as the past 4 million years, most of Alaska temperate glaciers are generally much, much younger. Many formed as recently as the start of the Little Ice Age, approximately 1,000 years ago. Others may date from other post-Pleistocene (younger than 11,700 years ago) colder climate events.”
The age of the oldest glacier ice in Antarctica may approach 20,000,000 years old.
The age of the oldest glacier ice in Greenland may be more than 100,000 years old, but less than 125,000 years old.
The age of the oldest Alaskan glacier ice ever recovered was about 30,000 years old.
Blue glacial ice along the coast of the West Antarctic Peninsula
In February 2020, my wife and I made a well-timed visit to the West Antarctic Peninsula. One particularly amazing spot was Pléneau Bay, which easily could earn the title “Antarctic Museum of Modern Art” because of the many fanciful iceberg shapes floating gently in this quiet bay. Following is a short photo essay highlighting several of the beautiful blue glacial ice features we saw on this trip.
Small blue iceberg in the Lemaire Channel. Source: P. Lobner photoZodiacs in what could be called the “Antarctic Museum of Modern Art” in Pléneau Bay. Source: J. Lobner photoCrabeater seal amid the blue icebergs in Pléneau Bay. Source: J. Lobner photoExotic blue iceberg shapes in Pléneau Bay. Source: P. Lobner photoThe tall, fluted wall of a large blue iceberg in Pléneau Bay. Source: J. Lobner photoA chunk of faceted glacial ice among the brash sea ice in Hanusse Bay / Crystal Sound. Source: P. Lobner photoBlue icebergs among the brash sea ice at Prospect Point (above & below). Source: P. Lobner photosA humpback whale resting among the blue icebergs in Cierva Cove (above) and diving (below). Source: P. Lobner photosThis iceberg (above & below) in Cierva Cove looks like a majestic blue sailing ship. Source: P. Lobner photosAnother exotic blue iceberg in Cierva Cove. Source: J. Lobner photoZodiac among blue icebergs in Cierva Cove. Source: P. Lobner photoThe large underwater part of this iceberg radiates blue in Cierva Cove. Source: P. Lobner photoA sea cave provides a view into the blue ice underlying an ice shelf. Source: P. Lobner photo
Examples of blue glacial ice in Switzerland & New Zealand
In previous years, my wife and I visited a temperate glacier and ice cave in Grindelwald, Switzerland and hiked on the temperate Franz Josef Glacier on the South Island of New Zealand. Following is a short photo essay that should give you an idea of the complex terrain of these glaciers and the smaller scale blue ice features visible on the surface. In contrast, the ice cave was a unique, immersive, very blue experience. The blue color inside the cave looked like the eerie blue light from Cherenkov radiation, like you’d see in an operating pool-type nuclear research reactor.
Inside a glacial ice cave in Grindelwald, Switzerland. Source: P. Lobner photoFranz Joseph Glacier showing a general blue tint in some surface ice (above) and more intense blue in smaller areas (below), South Island, New Zealand. Source: P. Lobner photosFranz Joseph Glacier details (above & below). Source: P. Lobner photos
Festo is a German multinational industrial control and automation company based in Esslingen am Neckar, near Stuttgart. The Festo website is here: https://www.festo.com/group/en/cms/10054.htm
Festo reports that they invest about 8% of their revenues in research and development. Festo’s draws inspiration for some of its control and automation technology products from the natural world. To help facilitate this, Festo established the Bionic Learning Network, which is a research network linking Festo to universities, institutes, development companies and private inventors. A key goal of this network is to learn from nature and develop “new insights for technology and industrial applications”…. “in various fields, from safe automation and intelligent mechatronic solutions up to new drive and handling technologies, energy efficiency and lightweight construction.”
One of the challenges taken on by the Bionic Learning Network was to decipher how birds fly and then develop robotic devices that can implement that knowledge and fly like a bird. Their first product was the 2011 SmartBird and their newest product is the 2020 BionicSwift. In this article we’ll take a look at these two bionic birds and the significant advancements that Festo has made in just nine years.
2. SmartBird
On 24 March 2011, Festo issued a press release introducing their SmartBird flying bionic robot, which was one of their 2011 Bionic Learning Network projects. Festo reported:
“The research team from the family enterprise Festo has now, in 2011, succeeded in unraveling the mystery of bird flight. The key to its understanding is a unique movement that distinguishes SmartBird from all previous mechanical flapping wing constructions and allows the ultra-lightweight, powerful flight model to take off, fly and land autonomously.”
“SmartBird flies, glides and sails through the air just like its natural model – the Herring Gull – with no additional drive mechanism. Its wings not only beat up and down, but also twist at specific angles. This is made possible by an active articulated torsional drive unit, which in combination with a complex control system makes for unprecedented efficiency in flight operation. Festo has thus succeeded for the first time in attaining an energy-efficient technical adaptation of this model from nature.”
SmartBird measures 1.07 meters (42 in) long with a wingspan of 2.0 meters (79 in) and a weigh of 450 grams (16 ounces, 1 pound). This is about a 1.6X scale-up in the length and span of an actual Herring Gull, but at about one-third the weight. It is capable of autonomous takeoff, flight, and landing using just its wings, and it controls itself the same way birds do, by twisting its body, wings, and tail. SmartBird’s propulsion system has a power requirement of 23 watts.
On 1 July 2020, Festo introduced the BionicSwift as their latest ultra light flying bionic robot that mimics how actual birds fly.
The BionicSwift, inspired by a Common Swift, measures 44.5 cm (17.5 in) long with a wingspan of 68 cm (26.7 in) and a weight of just 42 grams (1.5 ounces). It’s approximately a 2X scale-up of a Common Swift, but still a remarkably compact, yet complex flying machine with aerodynamic plumage that closely replicates the flight feathers on an actual Swift. The 2011 SmartBird was more than twice the physical size and ten times heavier.
The BionicSwift is agile, nimble and can even fly loops and tight turns. Festo reports: “Due to this close-to-nature replica of the wings, the BionicSwifts have a better flight profile than previous wing-beating drives.” Compare the complex, feathered wing structure in the following Festo photos of the BionicSwift with the previous photos showing the simpler, solid wing structure of the 2011 SmartBird.
Source: All three BionicSwift photos from Festo
A BionicSwift can fly singly or in coordinated flight with a group of other BionicSwifts. Festo describes how this works: “Radio-based indoor GPS with ultra wideband technology (UWB) enables the coordinated and safe flying of the BionicSwifts. For this purpose, several radio modules are installed in one room. These anchors then locate each other and define the controlled airspace. Each robotic bird is also equipped with a radio marker. This sends signals to the anchors, which can then locate the exact position of the bird and send the collected data to a central master computer, which acts as a navigation system.” Flying time is about seven minutes per battery charge.
4. For more information about other Festo bionic creations:
I encourage you to visit the Festo BionIc Learning Network webpage at the following link and browse the resources available for the many intriguing projects. https://www.festo.com/group/en/cms/10156.htm
On this webpage you’ll find a series of links listed under the heading “More Projects,” which will introduce you to the wide range of Bionic Learning Network projects since 2006.
You also can watch the following YouTube short videos of Festo’s many bionic creations:
BionicFinWave (2018):replicates the swimming movements of sea creatures with undulating fins to create a unique fin drive system for an autonomous underwater vehicle: https://www.youtube.com/watch?v=fRNq55EbnZc
AirRay (2010): replicates the natural underwater movements of a Manta Ray in a larger-than-life, neutrally buoyant, ray-shaped airship with a flapping wing drive: https://www.youtube.com/watch?v=c3-wIICjAhE
AquaRay (2010): replicates the natural underwater movements of a Manta Ray in a full-size autonomous underwater vehicle with a flapping wing drive: https://www.youtube.com/watch?v=F4-6oNagIvk
AirPenguin (2009): replicates the natural underwater movements of a penguin in a larger-than-life, neutrally buoyant, penguin-shaped airship: https://www.youtube.com/watch?v=jPGgl5VH5go
AquaPenguin (2009): replicates the natural underwater movements of a penguin in a small penguin-sized autonomous underwater vehicle: https://www.youtube.com/watch?v=u8tfES8gImc
AirJelly (2008): replicates the natural underwater movements of a jelly fish in a larger-than-life, neutrally buoyant, jelly fish-shaped airship: https://www.youtube.com/watch?v=divLsTtA5vk
AquaJelly (2008): replicates the natural underwater movements of a jelly fish in a small, autonomous, peristaltic drive autonomous underwater vehicle that can operate in coordination with several other AquaJellies: https://www.youtube.com/watch?v=N-O8-N71Qcw
At the start of World War II (WW II), US home ownership had dropped to a low of 43.6% in 1940, largely as a consequence of the Great Depression and the weak US economy in its aftermath. During WW II, the War Production Board issued Conservation Order L-41 on 9 April 1942, placing all construction under rigid control. The order made it necessary for builders to obtain authorization from the War Production Board to begin construction costing more than certain thresholds during any continuous 12-month period. For residential construction, that limit was $500, with higher limits for business and agricultural construction. The impact of these factors on US residential construction between 1921 and 1945 is evident in the following chart, which shows the steep decline during the Great Depression and again after Order L-41 was issued.
Source: “Construction in the War Years – 1942 -45,” US Department of Labor, Bulletin No. 915
By the end of WW II, the US had an estimated 7.6 million troops overseas. The War Production Board revoked L-41 on 15 October 1945, five months after V-E (Victory in Europe) day on 8 May 1945 and six weeks after WW II ended when Japan formally surrendered on 2 September 1945. In the five months since V-E day, about three million soldiers had already returned to the US. After the war’s end, the US was faced with the impending return of several millions more veterans. Many in this huge group of veterans would be seeking to buy homes in housing markets that were not prepared for their arrival. Within the short span of a year after Order L-41 was revoked, the monthly volume of private housing expenditures increased fivefold. This was just the start of the post-war housing boom in the US.
In a March 1946 Popular Science magazine article entitled “Stopgap Housing,” the author, Hartley Howe, noted, “ Even if 1,200,000 permanent homes are now built every year – and the United States has never built even 1,000,000 in a single year – it will be 10 years before the whole nation is properly housed. Hence, temporary housing is imperative to stop that gap.” To provide some immediate relief, the Federal government made available many thousands of war surplus steel Quonset huts for temporary civilian housing.
Facing a different challenge in the immediate post-war period, many wartime industries had their contracts cut or cancelled and factory production idled. With the decline of military production, the U.S. aircraft industry sought other opportunities for employing their aluminum, steel and plastics fabrication experience in the post-war economy.
2. Post-WW II prefab aluminum and steel houses in the US
In the 2 September 1946 issue of Aviation News magazine, there was an article entitled “Aircraft Industry Will Make Aluminum Houses for Veterans,” that reported the following:
“Two and a half dozen aircraft manufacturers are expected soon to participate in the government’s prefabricated housing program.”
“Aircraft companies will concentrate on FHA (Federal Housing Administration) approved designs in aluminum and its combination with plywood and insulation, while other companies will build prefabs in steel and other materials. Designs will be furnished to the manufacturers.”
“Nearly all war-surplus aluminum sheet has been used up for roofing and siding in urgent building projects; practically none remains for the prefab program. Civilian Production Administration has received from FHA specifications for aluminum sheet and other materials to be manufactured, presumably under priorities. Most aluminum sheet for prefabs will be 12 to 20 gauge – .019 – .051 inch.”
In October 1946, Aviation News magazine reported, “The threatened battle over aluminum for housing, for airplanes and myriad postwar products in 1947 is not taken too seriously by the National Housing Agency, which is negotiating with aircraft companies to build prefabricated aluminum panel homes at an annual rate as high as 500,000.”……”Final approval by NHA engineers of the Lincoln Homes Corp. ‘waffle’ panel (aluminum skins over a honeycomb composite core) is one more step toward the decision by aircraft companies to enter the field.…..Aircraft company output of houses in 1947, if they come near meeting NHA proposals, would be greater than their production of airplanes, now estimated to be less than $1 billion for 1946.”
In late 1946, the FHA Administrator, Wilson Wyatt, suggested that the War Assets Administration (WAA), which was created in January 1946 to dispose of surplus government-owned property and materials, temporarily withhold surplus aircraft factories from lease or sale and give aircraft manufacturers preferred access to surplus wartime factories that could be converted for mass-production of houses. The WAA agreed.
Under the government program, the prefab house manufacturers would have been protected financially with FHA guarantees to cover 90% of costs, including a promise by Reconstruction Finance Corporation (RFC) to purchase any homes not sold.
Many aircraft manufacturers held initial discussions with the FHA, including: Douglas, McDonnell, Martin, Bell, Fairchild, Curtis-Wright, Consolidated-Vultee, North American, Goodyear and Ryan. Boeing did not enter those discussions and Douglas, McDonnell and Ryan exited early. In the end, most aircraft manufacturer were unwilling to commit themselves to the postwar prefab housing program, largely because of their concerns about disrupting their existing aircraft factory infrastructure based on uncertain market estimates of size and duration of the prefab housing market and lack of specific contract proposals from the FHA and NHA.
The original business case for the post-war aluminum and steel pre-fabricated houses was that they could be manufactured rapidly in large quantities and sold profitably at a price that was less than conventional wood-constructed homes. Moreover, the aircraft manufacturing companies restored some of the work volume lost after WW II ended and they were protected against the majority of their financial risk in prefab house manufacturing ventures.
Not surprisingly, building contractors and construction industry unions were against this program to mass-produce prefabricated homes in factories, since this would take business away from the construction industry. In many cities the unions would not allow their members to install prefabricated materials. Further complicating matters, local building codes and zoning ordnances were not necessarily compatible with the planned large-scale deployment of mass-produced, prefabricated homes.
The optimistic prospects for manufacturing and erecting large numbers of prefabricated aluminum and steel homes in post-WW II USA never materialized. Rather than manufacturing hundreds of thousands of homes per year, the following five US manufacturers produced a total of less than 2,600 new aluminum and steel prefabricated houses in the decade following WW II: Beech Aircraft, Lincoln Houses Corp., Consolidated-Vultee, Lustron Corp. and Aluminum Company of America (Alcoa). In contrast, prefabricators offering more conventional houses produced a total of 37,200 units in 1946 and 37,400 in 1947. The market demand was there, but not for aluminum and steel prefabricated houses.
US post-WW II prefabricated aluminum and steel houses
These US manufacturers didn’t play a significant part in helping to solve the post-WW II housing shortage. Nonetheless, these aluminum and steel houses still stand as important examples of affordable houses that, under more favorable circumstances, could be mass-produced even today to help solve the chronic shortages of affordable housing in many urban and suburban areas in the US.
Some of the US post-WW II housing demand was met with stop gap, temporary housing using re-purposed, surplus wartime steel Quonset huts, military barracks, light-frame temporary family dwelling units, portable shelter units, trailers, and “demountable houses,” which were designed to be disassembled, moved and reassembled wherever needed. You can read more about post-WW II stop gap housing in the US in Hartley Howe’s March 1946 article in Popular Science (see link below).
The construction industry ramped up rapidly after WW II to help meet the housing demand with conventionally-constructed permanent houses, with many being built in large-scale housing tracts in rapidly expanding suburban areas. Between 1945 and 1952, the Veterans Administration reported that it had backed nearly 24 million home loans for WW II veterans. These veterans helped boost US home ownership from 43.6% in 1940 to 62% in 1960.
Two post-WW II US prefabricated aluminum and steel houses have been restored and are on public display in the following museums:
In addition, you can visit several WW II Quonset huts at the Seabees Museum and Memorial Park in North Kingstown, Rhode Island. None are outfitted like a post-WW II civilian apartment. The museum website is here: https://www.seabeesmuseum.com
You’ll find more information in my articles on specific US post-WW II prefabricated aluminum and steel houses at the following links:
3. Post-WW II prefab aluminum and steel houses in the UK
By the end of WW II in Europe (V-E Day is 8 May 1945), the UK faced a severe housing shortage as their military forces returned home to a country that had lost about 450,000 homes to wartime damage.
On 26 March 1944, Winston Churchill made an important speech promising that the UK would manufacture 500,000 prefabricated homes to address the impending housing shortage. Later in the year, the Parliament passed the Housing (Temporary Accommodation) Act, 1944, charging the Ministry of Reconstruction with developing solutions for the impending housing shortage and delivering 300,000 units within 10 years, with a budget of £150 million.
The Act provided several strategies, including the construction of temporary, prefabricated housing with a planned life of up to 10 years. The Temporary Housing Program (THP) was officially known as the Emergency Factory Made (EFM) housing program. Common standards developed by the Ministry of Works (MoW) required that all EFM prefabricated units have certain characteristics, including:
Minimum floor space of 635 square feet (59 m2)
Maximum width of prefabricated modules of 7.5 feet (2.3 m) to enable transportation by road throughout the country
Implement the MoW’s concept of a “service unit,” which placed the kitchen and bathroom back-to-back to simplify routing plumbing and electrical lines and to facilitate factory manufacture of the unit.
Factory painted, with “magnolia” (yellow-white) as the primary color and gloss green as the trim color.
In 1944, the UK Ministry of Works held a public display at the Tate Gallery in London of five types of prefabricated temporary houses.
The original Portal all-steel prototype bungalow
The AIROH (Aircraft Industries Research Organization on Housing) aluminum bungalow, made from surplus aircraft material.
The Arcon steel-framed bungalow with asbestos concrete panels. This deign was adapted from the all-steel Portal prototype.
Two timber-framed prefab designs, the Tarran and the Uni-Seco
This popular display was held again in 1945 in London.
Supply chain issues slowed the start of the EFM program. The all-steel Portal was abandoned in August 1945 due to a steel shortage. In mid-1946, a wood shortage affected other prefab manufacturers. Both the AIROH and Arcon prefab houses were faced with unexpected manufacturing and construction cost increases, making these temporary bungalows more expensive to build than conventionally constructed wood and brick houses.
Under a Lend-Lease Program announced in February 1945, the US agreed to supply the UK with US-built, wood frame prefabricated bungalows known as the UK 100. The initial offer was for 30,000 units, which subsequently was reduced to 8,000. This Lend-Lease agreement came to an end in August 1945 as the UK started to ramp up its own production of prefabricated houses. The first US-built UK 100 prefabs arrived in late May/early June 1945.
The UK’s post-war housing reconstruction program was quite successful, delivering about 1.2 million new houses between 1945 and 1951. During this reconstruction period, 156,623 temporary prefabricated homes of all types were delivered under the EFM program, which ended in 1949, providing housing for about a half million people. Over 92,800 of these were temporary aluminum and steel bungalows. The AIROH aluminum bungalow was the most popular EFM model, followed by the Arcon steel frame bungalow and then the wood frame Uni-Seco. In addition, more than 48,000 permanent aluminum and steel prefabricated houses were built by AW Hawksley and BISF during that period.
In comparison to the very small number of post-war aluminum and steel prefabricated houses built in the US, the post-war production of aluminum and steel prefabs in the UK was very successful.
UK post-WW II prefabricated aluminum and steel houses
In a 25 June 2018 article in the Manchester Evening News, author Chris Osuh reported that, “It’s thought that between 6 or 7,000 of the post-war prefabs remain in the UK…..” The Prefab Museum maintains a consolidated interactive map of known post-WW II prefab house locations in the UK at the following link: https://www.prefabmuseum.uk/content/history/map
Screenshot of the Prefab Museum’s interactive map (not including the prefabs in the Shetlands, which are off the top of this screenshot).
In the UK, Grade II status means that a structure is nationally important and of special interest. Only a few post-war temporary prefabs have been granted the status as Grade II listed properties:
In an estate of Phoenix steel frame bungalows built in 1945 on Wake Green Road, Moseley, Birmingham, 16 of 17 homes were granted Grade II status in 1998.
Six Uni-Seco wood frame bungalows built in 1945 – 46 in the Excalibur Estate, Lewisham, London were granted Grade II status in 2009. At that time, Excalibur Estates had the largest number of WW II prefabs in the UK: 187 total, of several types.
Several post-war temporary prefabs are preserved at museums in the UK and are available to visit.
St. Fagans National Museum of History in Cardiff, South Wales: An AIROH B2 originally built near Cardiff in 1947 was dismantled and moved to its current museum site in 1998 and opened to the public in 2001. You can see this AIROH B2 here: https://museum.wales/stfagans/buildings/prefab/
Chiltern Open Air Museum (COAM) in Chalfont St. Giles, Buckinghamshire: Their collection includes a wood frame Universal House Mark 3 prefab manufactured by Universal Housing Company of Rickmansworth, Hertfordshire. This prefab was built in 1947 in the Finch Lane Estate in Amersham. You can see the “Amersham Prefab” here: https://www.coam.org.uk/museum-buckinghamshire/historic-buildings/amersham-prefab/
I think the Prefab Museum is best source for information on UK post-WW II prefabs. When it was created in March 2014 by Elisabeth Blanchet (author of several books and articles on UK prefabs) and Jane Hearn, the Prefab Museum had its home in a vacant prefab on the Excalibur Estate in south London. After a fire in October 2014, the physical museum closed but has continued its mission to collect and record memories, photographs and memorabilia, which are presented online via the Prefab Museum’s website at the following link: https://www.prefabmuseum.uk
You’ll find more information in my articles on specific UK post-WW II prefabricated aluminum and steel houses at the following links:
4. Post-WW II prefab aluminum and steel houses in France
At the end of WW II, France, like the UK, had a severe housing shortage due to the great number of houses and apartments damaged or destroyed during the war years, the lack of new construction during that period, and material shortages to support new construction after the war.
To help relieve some of the housing shortage in 1945, the French Reconstruction and Urbanism Minister, Jean Monnet, purchased the 8,000 UK 100 prefabricated houses that the UK had acquired from the US under a Lend-Lease agreement. These were erected in the Hauts de France (near Belgium), Normandy and Brittany, where many are still in use today.
The Ministry of Reconstruction and Town Planning established requirements for temporary housing for people displaced by the war. Among the initial solutions sought were prefabricated dwellings measuring 6 x 6 meters (19.6 x 19.6 feet); later enlarged to 6 × 9 meters (19.6 x 29.5 feet).
About 154,000 temporary houses (the French called then “baraques”), in many different designs, were erected in France in the post-war years, primarily in the north-west of France from Dunkirk to Saint-Nazaire. Many were imported from Sweden, Finland, Switzerland, Austria and Canada.
The primary proponent of French domestic prefabricated aluminum and steel house manufacturing was Jean Prouvé, who offered a novel solution for a “demountable house,” which could be easily erected and later “demounted” and moved elsewhere if needed. A steel gantry-like “portal frame” was the load-bearing structure of the house, with the roof usually made of aluminum, and the exterior panels made of wood, aluminum or composite material. Many of these were manufactured in the size ranges requested by Ministry of Reconstruction. During a visit to Prouvé’s Maxéville workshop in 1949, Eugène Claudius-Petit, then the Minister of Reconstruction and Urbanism, expressed his determination to encourage the industrial production of “newly conceived (prefabricated) economical housing.”
French post-WW II prefabricated aluminum and steel houses
Today, many of Prouvé’s demountable aluminum and steel houses are preserved by architecture and art collectors Patrick Seguin (Galerie Patrick Seguin) and Éric Touchaleaume (Galerie 54 and la Friche l’Escalette). Ten of Prouvé’s Standard Houses and four of his Maison coques-style houses built between 1949 – 1952 are residences in the small development known as Cité “Sans souci,” in the Paris suburbs of Muedon.
Prouvé’s 1954 personal residence and his relocated 1946 workshop are open to visitors from the first weekend in June to the last weekend in September in Nancy, France. The Musée des Beaux-Arts de Nancy has one of the largest public collections of objects made by Prouvé.
Author Elisabeth Blanchet reports that the museum “Mémoire de Soye has managed to rebuild three different ‘baraques’: a UK 100, a French one and a Canadian one. They are refurbished with furniture from the war and immediate post-war era. Mémoire de Soye is the only museum in France where you can visit post-war prefabs.” The museum is located in Lorient, Brittany. Their website (in French) is here: http://www.soye.org
The three wood frame ‘baraques’ at Mémoire de Soye. Source: Elisabeth Blanchet via the Prefab Museum (UK)
In the U.S., the post-war mass production of prefabricated aluminum and steel houses never materialized. Lustron was the largest manufacturer with 2,498 houses. In the UK, over 92,800 prefabricated aluminum and steel temporary bungalows were built as part of the post-war building boom that delivered a total of 156,623 prefabricated temporary houses of all types between 1945 and 1949, when the program ended. In France, hundreds of prefabricated aluminum and steel houses were built after WW II, with many being used initially as temporary housing for people displaced by the war. Opportunities for mass production of such houses did not develop in France.
The lack of success in the U.S. arose from several factors, including:
High up-front cost to establish a mass-production line for prefabricated housing, even in a big, surplus wartime factory that was available to the house manufacturer on good financial terms.
Immature supply chain to support a house manufacturing factory (i.e., different suppliers are needed than for the former aircraft factory).
Ineffective sales, distribution and delivery infrastructure for the manufactured houses.
Diverse, unprepared local building codes and zoning ordnances stood in the way of siting and erecting standard design, non-conventional prefab homes.
Opposition from construction unions and workers that did not want to lose work to factory-produced homes.
Only one manufacturer, Lustron, produced prefab houses in significant numbers and potentially benefitted from the economics of mass production. The other manufacturers produced in such small quantities that they could not make the transition from artisanal production to mass production.
Manufacturing cost increases reduced or eliminated the initial price advantage predicted for the prefabricated aluminum and steel houses, even for Lustron. They could not compete on price with comparable conventionally constructed houses.
In Lustron’s case, charges of corporate corruption led the Reconstruction Finance Corporation to foreclose on Lustron’s loans, forcing the firm into an early bankruptcy.
From these post-WW II lessons learned, and with the renewed interest in “tiny homes”, it seems that there should be a business case for a modern, scalable, smart factory for the low-cost mass-production of durable prefabricated houses manufactured from aluminum, steel, and/or other materials. These prefabricated houses could be modestly-sized, modern, attractive, energy efficient (LEED-certified), and customizable to a degree while respecting a basic standard design. These houses should be designed for mass production and siting on small lots in urban and suburban areas. I believe that there is a large market in the U.S. for this type of low-price housing, particularly as a means to address the chronic affordable housing shortages in many urban and suburban areas. However, there still are great obstacles to be overcome, especially where construction industry labor unions are likely to stand in the way and, in California, where nobody will want a modest prefabricated house sited next to their McMansion.
You can download a pdf copy of this post, not including the individual articles, here:
Blaine Stubblefield, “Aircraft Industry Will Make Aluminum Houses for Veterans,” Aviation News, Vol. 6, No. 10, 2 September 1946 (available in the Aviation Week & Space Technology magazine online archive)
“Battle for Aluminum Discounted by NHA,” Aviation News magazine, p. 22, 14 October 1946 (available in the Aviation Week & Space Technology magazine online archive)
Nicole C. Rudolph, “At Home in Postwar France – Modern Mass Housing and the Right to Comfort,” Berghahn Monographs in French Studies (Book 14), Berghahn Books, March 2015, ISBN-13: 978-1782385875. The introduction to this book is available online at the following link: https://berghahnbooks.com/downloads/intros/RudolphAt_intro.pdf
Kenny Cupers, “The Social Project: Housing Postwar France,” University Of Minnesota Press, May 2014, ISBN-13: 978-0816689651
