The bottom line is a sea level rise of 216 feet (65.8 m).
The article includes a link to a short, dramatic 2015 animated video by the same title, posted by Insider Science, which shows the global effects a 216 ft sea level rise. You can watch this video on YouTube here: How Earth Would Look If All The Ice Melted
So, what about your neighborhood? You can explore a topographical map of the San Diego area here: https://en-us.topographic-map.com/map-n9tp/San-Diego/. Zoom in to determine the land elevations in specific neighborhoods and find the locations of the 216 ft elevation contour lines.
In the above map, everything in blue would be underwater after a 216 ft sea level rise, including all of Coronado, the Silver Strand, the downtown areas of San Diego, National City and Chula Vista, Lindberg Airport, Pacific Beach, Mission Valley and parts of Point Loma. Ironically, the submarine base near the tip of Point Loma would be underwater.
After you’ve found your house and the houses of families and friends in San Diego, you can expand your topographical search of the whole world. All it takes is a bit of scrolling & zooming. Some countries would be completely underwater.
On 9 May 2023, Lockheed Martin announced that its hybrid airship business, including intellectual property and related assets, had been transitioned to a newly formed, commercial company called AT2 Aerospace. The Lockheed Martin press release reported, “AT2 Aerospace, based in Santa Clarita, California, is extending our work to bring hybrid airships to fruition. The AT2 team is developing airship solutions to support commercial and humanitarian applications around the world. Dr. Robert Boyd, retired Lockheed Martin Hybrid Airship program manager, is president and chief operating officer of AT2 Aerospace.”
2. Background on Lockheed Martin’s hybrid airship program
Since the 1980s, Lockheed Martin has been developing several different design approaches for semi-buoyant, hybrid airships with lifting body hulls. That work became focused in Lockheed Martin’s Advanced Development Programs (the Skunk Works) in Palmdale, CA, and produced an extensive series of patents related to large, hybrid airship design.
The only Lockheed Martin hybrid airship to fly was the P-791, which was a 120 foot (36.6 meter) long, tri-lobe, semi-buoyant hybrid airship that flew under a Defense Advanced Research Projects Agency (DARPA) sponsored Project WALRUS Phase 1 contract, and also served as a sub-scale technology demonstrator for future Lockheed Martin heavy-lift hybrid airships. The first flight of the P-791 took place on 31 January 2006 at Lockheed Martin’s facility in Palmdale. Airship magazine reported that the P-791 flew six times. Lockheed Martin claimed that all flight test objectives were successfully met and there were no subsequent flight tests.
Lockheed Martin P-791. Source: Lockheed Martin (2006)
In March 2011, Lockheed Martin announced that it planned to develop a larger commercial version of the P-791, to be called SkyTug, which would be a scaled up hybrid airship designed to carry at least 20 tons of cargo. A trademark application for the term “SkyTug” was filed on 25 August 2011.
By 2013, reference to SkyTug had disappeared and Lockheed Martin was promoting the LMH-1 as their next large commercial hybrid airship based on the P-791 design.
General arrangement of the LMH-1 hybrid airship. Source: Lockheed Martin
Rendering, LMH-1 bow quarter view.Source: Lockheed Martin via BBC (November 2019)
On March 12, 2012 the U.S. Federal Aviation Administration (FAA) announced that Lockheed Martin Aeronautics submitted an application for type certification for the model LMZ1M (LMH-1), which is “a manned cargo lifting hybrid airship incorporating a number of advanced features.” The FAA assigned docket number FAA-2013-0550 to that application.
To address the gap in airship regulations head-on, Lockheed Martin submitted to the FAA their recommended criteria document, “Hybrid Certification Criteria (HCC) for Transport Category Hybrid Airships,” which is a 206 page document developed specifically for the LMZ1M (LMH-1). The HCC is also known as Lockheed Martin Aeronautics Company Document Number 1008D0122, Rev. C, dated 31 January 2013. You can download the HCC document and related public docketed items from the FAA website here:
In November 2015, the FAA’s Seattle Aircraft Certification Office approved Lockheed’s project-specific certification plan for the LMZ1M (LMH-1). In a 17 November 2015 press release, Lockheed Martin announced:
“Given that Hybrid Airships did not fit within existing FAA regulations, the team worked to create a new set of criteria allowing non rigid hybrid airships to safely operate in a commercial capacity. Transport Canada was also involved in the development of this criteria to ensure it included safety concerns unique to Canada.”
“Lockheed Martin and the FAA have been working together for more than a decade to define the criteria to certify Hybrid Airships for the Transport Category. This criteria was approved by the FAA in April 2013. Following that approval, the team has been developing the project specific certification plan over the past two years, which details how it will accomplish everything outlined in the Hybrid Certification Criteria.”
“Earlier this year Lockheed Martin along with Hybrid Enterprises LLC kicked off sales for the 20 ton variety of the Hybrid Airship. They are on track to deliver operational airships as early as 2018.”
No new documentation was subsequently added to the public webpage for docket FAA-2013-0550, so there was no public visibility of the type certification effort.
In September 2017, Lockheed Martin reported it had Letters of Intent (LOIs) for 24 LMH-1 hybrid airships, with their largest customer being Straightline Aviation (https://www.straightlineaviation.com), which had signed an LOI for 12 LMH-1s. At that time, the first “float out” of the LMZ1M (LMH-1) had slipped to 2019. As of May 2023, the airship has not yet been “floated out”.
On 9 May 2023, Lockheed Martin reported, “For some time, we have been in search of a transition partner to continue development of this important commercial work.” That “transition partner” is the newly formed, commercial company AT2 Aerospace.
3. The AT2 Aerospace Z1 Hybrid Airship
As portrayed on the AT2 Aerospace website, their Z1 hybrid airship appears to be the current incarnation of the former Lockheed Martin LMH-1. AT2 Aerospace summarizes the main attributes of their Z1 hybrid airship as follows:
“AT2 Aerospace’s revolutionary hybrid airship is the future of aviation technology. Capable of operating in the most remote and inaccessible locations, this innovative aircraft offers a cost-effective solution for heavy cargo transpiration while minimizing environmental and social impact.”
“The Z1’s unique Air Cushion Landing System (ACLS) allows the Z1 to land and takeoff from almost any location on the planet.
The Z1 utilizes buoyant lift technology delivering exceptional fuel efficiency, minimizing carbon emissions, and ultimately reducing transportation costs.
The Z1 will connect emerging economies to global trade networks.
The Z1 moves cargo faster than sea and land transportation at a fraction of the cost of existing cargo aircraft, filling a major gap in the global transportation market from a speed vs. cost perspective.”
AT2 Aerospace also identified the following attributes:
Simple controls minimize human error
Large volume cargo bays, larger payloads
Safer in icing effects
Quiet: Ideal for noise sensitive locations
AT2 Aerospace expects that their Z1 hybrid airship will “open the entire world to commerce, humanitarian aid and exploration with affordable and reliable operations.”
General arrangement of the Z1 hybrid airship. Source: AT2 Aerospace
The near-term challenge for AT2 Aerospace will be to get clarity from the FAA on the actions remaining, and the approximate time scale, to conclude the first-ever type certification process for a hybrid airship in the U.S. With a type certificate in hand, the Z1 can be put to the test by a few early-adopters in what hopefully will become an emerging worldwide commercial airship market.
Craig Breedlove is best known as the first person to set land speed records above 400 mph (643.7 kph), 500 mph (804.7 kph) and 600 mph (965.6 kph) in the mid-1960s with his turbojet-powered Spirit of America and its successor, the Spirit of America Sonic 1. He later achieved a peak speed of 675 mph (1,086.3 mph) on a one-way run in his last land speed record car, the Spirit of America Sonic Arrow, in the 1990s.
The first two LSR cars were part of an intense duel from May 1963 to November 1965, primarily between Breedlove and Art Arfons, that resulted in a rapid and exciting increase of the land speed record, from John Cobb’s long-standing 16 September 1947 record of 394.196 mph (634.4 kph) in the piston-engine Railton Mobile Special, to Craig Breedlove’s 15 November 1965 record of 600.601 mph (966.6 kph) in the Spirit of America Sonic 1. In this two-and-a-half year period, there were 10 incrementally faster unofficial (not FIA certified) and official FIA land speed records. You’ll find a complete list of land speed record holders here: https://landspeedrecord.org/speed-records/
Needless to say, this was an exciting time that commanded attention to the latest news from the Bonneville salt flats.
Breedlove’s last LSR car, the Spirit of America Sonic Arrow, made its first test run on the Black Rock Desert in Gerlach, NV, on 28 October 1996. During the run, Breedlove reached a peak speed of about 675 mph (1,086 kph), but encountered higher-than-expected crosswinds that caused a dramatic high-speed U-turn that severely damaged the vehicle, which survived but was in need of significant repairs.
In 1997, the repaired Sonic Arrow experienced a series of mechanical problems during speed runs at Black Rock and program funding issues prevented Breedlove from completing another land speed record attempt.
Later in 1997, the British LSR team, which also was at Black Rock with driver Andy Green and their Thrust SSC LSR car, had a series of successful speed runs and they beat Breedlove to the milestones of setting land speed records greater than 700 mph (1,126.5 kph) and at supersonic speed (greater than 761.2 mph / 1,225 kph / Mach 1.0 at sea level at 15ºC/59ºF).
On 25 September 1997, Andy Green set a new land speed record of 714.144 mph (1149 kph / Mach 0.94), and less than a month later, set the first ever two-way supersonic land speed record at 763.035 mph (1,228 kph / Mach 1.02) on 15 October 1997. This record still stands in 2023.
After almost a decade without making another LSR run, Breedlove sold his Sonic Arrow in 2006 to adventurer Steve Fossett in 2006. Unfortunately, Fossett was killed in a September 2007 aircraft crash before being able to mount his own LSR challenge in his improved Sonic Arrow, which was rolled out in October 2007.
Craig Breedlove passed away on 4 April 2023, at the age of 86. He was an inspiration to me, and perhaps to many in my generation who shared an interest in the enormous challenges of raising the land speed record, and surviving to tell about it.
Where are these LSR cars now?
Breedlove loaned the original Spirit of America to the Museum of Science and Industry in Chicago where it was on display from 1965 to 2015, when the museum returned the LSR car to Breedlove, but not before inflicting significant damage to the car. Breedlove said he intended to repair the LSR car. Howerver, its current whereabouts is not known.
The Spirit of America Sonic I vehicle currently is on display at Indianapolis Motor Speedway Hall of Fame Museum.
The Steve Fossett’s updated Spirit of America Sonic Arrow LSR car currently is on display in the Wings Over the Rockies Air & Space Museum in Denver.
In March 2023, the United States Government Accountability Office issued their report GAO-23-105813, “Technology Assessment – Fusion Energy – Potentially Transformative Technology Still Faces Fundamental Challenge.” This GAO report provides a comprehensive overview of the current status of several different fusion energy concepts being developed worldwide. You can download a copy of this GAO report here: https://www.gao.gov/assets/gao-23-105813.pdf
ANS summarized GAO’s finding: “Despite decades of research and recent promising developments, the report notes, fusion science has still not achieved net energy gain.”
To illustrate this point, GAO commented on the recent high-profile announcement that a net fusion energy gain had been achieved during a test at the National Ignition Facility (NIF). GAO graphically showed how this claim is only true from the perspective of the small fusion reaction chamber (the Hohlraum) at the heart of NIF. As shown in the following GAO diagram, which appropriately treats the whole NIF as a “black box,” a total of 300 Megajoules (MJ) were input to the facility and only 3.15 MJ were generated by fusion reactions in the Hohlraum. That fusion power was absorbed by the Hohlraum and adjacent NIF structures and systems. No “net power” left the NIF “black box,” but then, NIF wasn’t designed to be a power plant.
As future claims of net energy gain are made by the various fusion power reactor development teams, think of each of their fusion facilities as a black box. The future of fusion-generated electricity depends first and foremost on being able to get much more energy out of the black box than went into it.
National Submarine Day, which occurs each year on 11 April, honors the anniversary of the day in 1900 when the U.S. Navy acquired the Holland VI submarine, which has been generally recognized as the world’s first modern submarine.
Similar, though slightly larger variants of the original Holland VI design also were acquired by the UK (1901 – 1904) and Japan (1904).
2. The Holland VI and the original U.S. Holland-class submarines
Designed in 1896 by Irish-American inventor John Phillip Holland and his Holland Torpedo Boat Company, the Holland VI was built at the Crescent Shipyard in Elizabeth, New Jersey, where Arthur Leopold Busch was the chief constructor / naval architect. The Holland VI was launched on 17 May 1897. This diminutive submarine (by today’s standards) had an overall length of 53 ft 10 in (16.41 m), displacements of 65 tons surfaced / 75 tons submerged, and was operated by a crew of six.
The Holland VI brought together a host of impressive features for the first time in one vessel, including:
Efficient hydrodynamic hull shape [teardrop-shape with bulbous bow and tapered stern] with good seakeeping ability on the open ocean.
Separate main and auxiliary ballast systems enable rapid diving and surfacing with minimial changes to the longitudinal center of gravity while underway.
Accomplished by operating with full or nearly full ballast tanks when submerged.
Allowed precise control of trim angle while submerged.
Able to dive to and accurately maintain a significant depth [up of 75 feet (23 m)].
Diving planes provide the means to precisely control depth [stern planes only, located behind the propeller].
Dual propulsion systems driving a single propeller at the stern.
Internal combustion engine provides reliable power on the surface, enabling long transits while charging the batteries [up to 200 nautical miles (370 km) at 6 knots]
Lead-acid storage batteries provide power to run submerged for a considerable distance [about 30 nautical miles (56 km) at 5.5 knots].
Conning tower for directing ship and weapons activities on the surface or semi-submerged.
No periscope. View ports around the top of the conning tower provided the commander with intermittent views while “porpoising” semi-submerged near the surface.
Offensive weapons systems.
One reloadable torpedo tube at the bow, with three self-propelled torpedoes carried internally.
One pneumatic dynamite gun at the bow that, on the surface, fired large projectiles, sometimes called “aerial torpedoes.” [This was subsequently removed].
John P. Holland first demonstrated the Holland VI to the U.S. Navy on 17 March 1898. It appears that Submarine Day originally was celebrated to mark anniversaries of this date.
The U.S. Navy purchased the Holland VI for $150,000 on 11 April 1900. The Navy renamed and commissioned the submarine as the USS Holland on 12 October 1900. While the Navy previously owned and operated two submarines, Alligator (1862 – 63) and Intelligent Whale (1869 – 73), the USS Holland was the first commissioned submarine in the fleet. Lieutenant H.H. Caldwell became the first commanding officer of a modern commissioned submarine.
On 25 August 1905, the USS Holland made history by being the first American submarine to carry a U.S. President, Theodore Roosevelt, while she ran submerged for 55 minutes.The Navy ordered six more Holland-class submarines from the Electric Boat Company, which was founded in 1899 and had acquired the Holland Torpedo Boat Company and the continuing services of John P. Holland as Manager. Patent US702729 was granted on 17 June 1902 for Holland’s submarine design and assigned to Electric Boat Company.
The U.S. Navy’s Holland-class subs rapidly became obsolete as submarine technology advanced. USS Holland finished out her naval career in Norfolk, VA, was stricken from the Navy Register of Ships on 21 November 1910, and was sold for scrap in 1913. The USS Holland did not receive its “SS-1” designation until the Navy’s modern hull classification system was instituted on 17 July 1920.
3. The UK Holland-class submarines
In their online history, BAE Systems reports, “Following meetings with the Admiralty, an agreement was made on 27th October 1900 between the Electric Boat Company and Vickers Sons & Maxim Ltd of Barrow-in-Furness, giving Vickers 25-year license to manufacture the Holland-class of submarines, using Electric Boats patents.”
Vickers built five Holland-class subs for the Royal Navy. These were somewhat larger than their U.S. counterparts, with a length of 63 ft 4 in (19.3 m), a submerged displacement of 107 tons and a crew of eight.
The first sub, designated Holland 1, was launched in 1901. After 12 years of service, it was decommissioned in 1913 and sank at sea while under tow near Plymouth, on its way to be scrapped. The location of the sunken sub was discovered in 1981 and the largely intact vessel was raised in 1983. Today, the Holland 1 is on display at the Royal Navy’s Submarine Museum in Gosport, UK, in a climate-controlled environment designed to arrest further corrosion.
The last of the UK’s Holland-class submarines, Holland 5, was launched in 1904. After eight years in service, Holland 5 sank off the coast of Sussex in 1912 while being towed for decommissioning. In 1985, the intact, but encrusted, submarine was located on the seabed at a depth of 35 meters (115 ft), where it remains today, subject to the Protection of Wrecks Act 1973.
4. The Japanese Holland-class submarines
Japanese representatives had sailed aboard Holland IV during early testing in 1898 and during trials on the Potomac River in 1900. During the Russo-Japanese War, the Japanese government purchased five “improved” Holland-class submarines from the Electric Boat Company in great secrecy, since the U.S. was a “neutral” nation. These submarines had a length of 67 ft (20.4 m) and a submerged displacement of 126 tons. They were delivered to Japan partially assembled in December 1904. Assembly was completed at the Yokosuka Naval Arsenal, the crews were trained, and the submarines were ready for combat operations in August 1905. None saw action before the war ended in September 1905. They served as training boats until being retired from service 1920.
5. Comparison with today’s nuclear-powered submarines
Since the first production run of Holland-class submarines built for the U.S. Navy, Electric Boat Company (now General Dynamics Electric Boat) has been delivering submarines to the Navy for more than 120 years.
The Navy’s Virginia-class SSNs, which started entering the fleet in 2004 with USS Virginia(SSN-774), are 7,800 ton behemoths in comparison to the USS Holland.
Almost 20 years later, the latest Virginia-class Block V SSNs are even bigger, with an overall length of 460 ft (140 m) and a submerged displacement of over 10,000 tons. The largest submarines currently in the Navy’s fleet are the aging Ohio-class SSBNs (strategic missile submarines) and SSGNs (cruise missile submarines). With an overall length of 560 ft (170 m) and a submerged displacement of about 18,750 tons, the Ohio-class subs dwarf all the other U.S. subs.
Since 2018, the U.S. Navy has been testing a large, autonomous, unmanned underwater vehicle (UUV), Echo Voyager, which is 51 feet (15.5 meters) long and has a displacement of about 50 tons. This is approximately the same size as the USS Holland (SS-1).
John P. Holland would be amazed at the progress made in submarine design and operation over the 123 years since the USS Holland was acquired by the U.S. Navy in 1990 and commissioned that same year.
Enjoy National Submarine Day on 11 April, and remember that, in the U.S., it’s pronounced “sub-marine-er,” not “sub-mariner,” as they say in the UK and in Marvel Comics. If you’re going to dress up for the occasion, may I suggest this stylish T-shirt.
On 30 September 1968, the first Boeing 747 was rolled out at the company’s plant in Everett, WA. The first flight took place on 9 February 1969, and the FAA certified the 747 in December of that year. Pan Am was the first airline to offer Boeing 747 service on 22 January 1970, flying from New York to London.
After a 54-year production run, the last 747, a 747-8 freighter, was rolled out of the factory on Tuesday, 6 December 2022. Boeing built a total of 1,574 747s in a range of models for commercial and military customers.
This is good news for all Californians and California businesses that depend on the State’s rather fragile electrical grid as their primary source of electric power!
On 2 March 2023, the U.S. Nuclear Regulatory Commission (NRC) granted an exemption to Pacific Gas & Electric Co. (PG&E) that would allow the Diablo Canyon 1 & 2 nuclear power plants to continue operating while the NRC considers its license renewal application. The NRC press release stated:
“The exemption granted today will allow those licenses to remain in effect provided PG&E submits a sufficient license renewal application for the reactors by Dec. 31, 2023. The NRC will continue its normal inspection and oversight of the facility throughout the review to ensure continued safe operation. If granted, the license renewal would authorize continued operation for up to 20 years.”
You may recall that, in 2016, many environmental groups and state legislators claimed victory in getting the commitment from PG&E to close the Diablo Canyon nuclear power plant early. Here’s just one example of that sentiment at the time:
“In a major victory for environmentalists, California is going nuclear-free, ending atomic energy’s more than half-century history in the state. On Tuesday, one of the state’s largest utilities agreed to a proposal endorsed by environmental groups and labor unions to shutter California’s last operating nuclear power plant, Diablo Canyon, by 2025.” (Source: Democracy Now, 22 June 2016).
“On 21 June 2016, PGE issued a press release announcing that they will withdraw their application to the NRC for a 20-year license extension for the Diablo Canyon 1 & 2 nuclear power plants and will close these plants by 2025 when their current operating licenses expire. PGE will walk away from about 41 GW-years of carbon-free electric power generation.”
Almost seven years ago, it was quite apparent to many that the early closure of Diablo Canyon would not be good for California or the environment. It took that long for the state government to understand the situation and support the current effort to get the Diablo Canyon operating licenses extended. Better late than never. However, in their shortsighted view, the state government seems to be supporting a license extension only through 2030. If the legislators have their way, California will reclaim only a small portion of the carbon-free electric power generation that would be available from the 20 year operating license extensions that the NRC may grant.
I’d like see the California legislature and the associated complex web of state agencies that have a stake in this matter unanimously acknowledge that nuclear power is an important contributor toward energy de-carbonization. In addition, I’d like to see that same group acknowledge that nuclear power plants are important for delivering reliable 24/7 generating capacity to the CALISO grid, and thereby helping maintain stability on a grid with a large fraction of variable-output, renewable generators. If those factors are important to California’s government, then perhaps there is a future for nuclear power in the state, including the new generation of small, modular reactors (SMRs). California state support for nuclear power generation would open many exciting options for modernizing and decarbonizing electric power generation, transmission and distribution throughout the state, while ensuring that reliable electric power is available to all residents and business, many of which are seeking to decarbonize their activities by replacing their fossil fuel use with electricity that is available as needed, 24/7.
Well, NASA actually has done this thru their Sonification Project, which they explain as follows:
“Much of our Universe is too distant for anyone to visit in person, but we can still explore it. Telescopes give us a chance to understand what objects in our Universe are like in different types of light. By translating the inherently digital data (in the form of ones and zeroes) captured by telescopes in space into images, astronomers can create visual representations of what would otherwise be invisible to us. But what about experiencing these data with other senses, like hearing? Sonification is the process that translates data into sound. Our new project brings parts of our Milky Way galaxy, and of the greater Universe beyond it, to listeners for the first time. We take actual observational data from telescopes like NASA’s Chandra X-ray Observatory, Hubble Space Telescope or James Webb Space Telescope and translate it into corresponding frequencies that can be heard by the human ear.”
I hope you’ll enjoy NASA’s ” Universe of Sound” website, which includes sonifications of more than 20 astronomical targets, each with descriptions of the target and details on how the sonification was made. Start your audio exploration of the Milky Way galaxy and the Universe beyond here: https://chandra.si.edu/sound/
Good luck trying to pick a favorite.
Many of NASA’s sonifications also are available individually on YouTube. Here are two very different samples:
See my April 2016 post, “Large Autonomous Vessels will Revolutionize the U.S. Navy,” for background information on the Navy’s autonomous vessel program and the Sea Hunter prototype developed by Leidos and tested in San Diego: https://lynceans.org/tag/continuous-trail/
The Navy’s San Diego-based Unmanned Surface Vessel Division One is playing an important role in developing and testing several autonomous vessels.
For more information on the Navy’s autonomous vessel program, check out these US Naval Institute articles:
NASA’s Double Asteroid Redirection Test (DART), which was launched on 24 November 2021, was the first test of a technology for defending Earth against potential asteroid or comet hazards. DART’s target was the small “moonlet” named Dimorphos orbiting the larger near-Earth asteroid Didymos, which itself is only a half mile in diameter. You can explore at the Didymos – Dimorphos binary system on NASA’s Solar System Exploration webpage here: https://solarsystem.nasa.gov/asteroids-comets-and-meteors/asteroids/didymos/in-depth/
The goal is for the DART spacecraft was to strike the moonlet Dimorphos at high speed while being trailed by another small spacecraft, the Italian Space Agency’s (ASI) cubesat, dubbed LICIACube, that would directly observe the encounter and report back to NASA and ASI.
By comparing pre- and post-impact measurements made with powerful Earth-based and orbiting telescopes, the NASA / Johns Hopkins Applied Physics Lab (JHAPL) team could determine what changes occurred to Dimorphos’ orbit around Didymos. These results will help assess the feasibility of using a high-energy impactor as a tool for deflecting the trajectory of an asteroid, particularly one that represents a significant risk to Earth. Learn more about the DART spacecraft and its mission objectives on NASA’s Planetary Defense Coordination Office website here: https://www.nasa.gov/planetarydefense/dart/dart-news
The Hubble Space Telescope was used to capture images of the impact. The NASA/ESA Hubble Space Telescope team reported:
“The Hubble movie starts at 1.3 hours before impact. The first post-impact snapshot is 20 minutes after the event. Debris flies away from the asteroid in straight lines, moving faster than four miles per hour (fast enough to escape the asteroid’s gravitational pull, so it does not fall back onto the asteroid). The ejecta forms a largely hollow cone with long, stringy filaments.
At about 17 hours after the impact the debris pattern entered a second stage. The dynamic interaction within the binary system started to distort the cone shape of the ejecta pattern. The most prominent structures are rotating, pinwheel-shaped features. The pinwheel is tied to the gravitational pull of the companion asteroid, Didymos.
Hubble next captures the debris being swept back into a comet-like tail by the pressure of sunlight on the tiny dust particles. This stretches out into a debris train where the lightest particles travel the fastest and farthest from the asteroid. The mystery is compounded later when Hubble records the tail splitting in two for a few days.”
The results are in, and on 1 March 2023, the NASA / JHAPL team reported a much greater change to Dimorphos’ orbit than originally expected.
“…the investigation team, led by Cristina Thomas of Northern Arizona University, arrived at two consistent measurements of the period change from the kinetic impact: 33 minutes, plus or minus one minute. This large change indicates the recoil from material excavated from the asteroid and ejected into space by the impact (known as ejecta) contributed significant momentum change to the asteroid, beyond that of the DART spacecraft itself.”
After the success of the DART mission, maybe the U.S. Planetary Defense Officer will have fewer sleepless nights, but this is only the first small, but successful step toward an operational planetary defense system.
28 June 2023 update: Hubble sees bolder swarm surrounding Dimorphos
In June 2023, NASA reported that the Hubble Space Telescope had observed a swarm of 37 boulders that appears to have been knocked loose from Dimorphos upon impact.
An image of the impacted asteroid, Dimorphos, with drawn-in circles around the areas where boulders have been detected. Note that the relationship between north and east on the sky (as seen from below) is flipped relative to direction arrows on a map of the ground (as seen from above). Source: NASA, ESA, David Jewitt (UCLA); Alyssa Pagan (STScI)
“The 37 free-flung boulders range in size from three feet to 22 feet across, based on Hubble photometry. They are drifting away from the asteroid at little more than a half-mile per hour – roughly the walking speed of a giant tortoise. The total mass in these detected boulders is about 0.1% the mass of Dimorphos…… The boulders are most likely not shattered pieces of the diminutive asteroid caused by the impact. They were already scattered across the asteroid’s surface, as evident in the last close-up picture taken by the DART spacecraft just two seconds before collision, when it was only seven miles above the surface.”
The loose composition of the surface of Dimorphos can be seen in this last complete image just prior to DART impact. Source: NASA, APL