All posts by Peter Lobner

NASA’s DART spacecraft impact measurably redirected the asteroid Dimorphos

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Peter Lobner, updated 28 July 2023

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/

Simulation of the Didymos – Dimorphos binary system. 
Source: NASA’s Solar System Exploration
Actual view of the Didymos – Dimorphos binary system as 
DART approached impact with Dimorphos (background). 
Source: NASA / JHAPL

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

NASA successfully guided DART to a collision with Dimorphos on 26 September 2022.   You can watch the final five minutes of DART’s approach to the Didymos – Dimorphos binary system up to the final image before impact here: https://www.nasa.gov/feature/dart-s-final-images-prior-to-impact

DART closeup image of Dimorphos moments before impact.
Source: NASA / JHAPL
ASI’s LICIACube image just before its closest approach to Dimorphos (background). The debris plume cast off from Dimorphos after DART’s impact is clearly visible. Didymos is in the foreground. Source: ASI / NASA

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.”

8 October 2022 photo by the Hubble Space Telescope shows Dimorphos with its debris tail. Source: NASA/ESA/STScI/Hubble

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.”

Source: NASA/JHAPL

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)

NASA reported: 

“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

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A UAE Rover Carried by a Japanese Lander Attempted a Moon Landing in April 2023

All Posts, Artificial Intelligence, Materials, Remote Sensing, Spacecraft and Missions, , , , ,

Peter Lobner, updated 13 September 2023

1. Introduction

To date, only Russia, the U.S. and China have accomplished soft landings on the Moon, with each nation using a launch vehicle and spacecraft developed within their own national space programs. 

On 8 October 2020, Sheikh Mohammed bin Rashid announced the formation of the UAE’s lunar rover program, which intends to accomplish the first moon landing for the Arab world using the commercial services of a U.S. SpaceX Falcon 9 launch vehicle and a Japanese ispace lunar landing vehicle named HAKUTO-R. Once on the lunar surface, the UAE’s Rashid rover will be deployed to perform a variety of science and exploration tasks. This mission was launched from Cape Canaveral on 11 December 2022.

Emirates Lunar Mission (ELM) patch. 
Source: MBRSpaceCenter tweet

2. Japan’s ispace HAKUTO-R lunar lander

The Japanese firm ispace, inc. was founded in September 2010, with headquarters in Tokyo, a U.S. office in Denver, CO, and a European office in Luxembourg.  Their website is here: https://ispace-inc.com

ispace’s HAKUTO team was one of six finalist teams competing for the Google Lunar XPRIZE. On 15 December 2017, XPRIZE reported,” Congratulations to Google Lunar XPRIZE Team HAKUTO for raising $90.2 million in Series A funding toward the development of a lunar lander and future lunar missions! This is the biggest investment to date for an XPRIZE team, and sends a strong signal that commercial lunar exploration is on the trajectory to success. One of the main goals of the Google Lunar XPRIZE is to revolutionize lunar exploration by spurring innovation in the private space sector, and this announcement demonstrates that there is strong market interest in innovative robotic solutions for sustainable exploration and development of the Moon. The XPRIZE Foundation looks forward to following Team HAKUTO as they progress toward their lunar mission!”

The Google Lunar XPRIZE was cancelled when it became clear that none of the finalist teams could meet the schedule for a lunar landing in 2018 and other constraints set for the competition.  Consequently, Team HAKUTO’s lander was not  flown on a mission to the Moon.

In April 2021, the Mohammed Bin Rashid Space Center (MBRSC) of the United Arab Emirates (UAE) signed a contract with ispace, under which ispace agreed to provide commercial payload delivery services for the Emirates Lunar Mission. After final testing in Germany, the ispace SERIES-1 (S1) lunar lander was ready in 2022 for the company’s ‘Mission 1,’ as part of its commercial lunar landing services program known as ‘HAKUTO-R’.

HAKUTO-R, aka SERIES-1 (S1), lunar lander general arrangement. 
It is more than 7 feet (2.3 meters) tall. Source: ispace

After its launch on 11 December 2022, the lunar spacecraft has been flying a “low energy” trajectory to the Moon in order to minimize fuel use during the transit and, hence, maximizes the available mission payload. It will take nearly five months for the combined lander / rover spacecraft to reach the Moon in April 2023.

The low-energy trajectory being flown for the Emirates Lunar Mission shows spacecraft position (end of blue line, at top) as of 4 March 2023. The spacecraft will enter lunar orbit (yellow circle) in April 2023, before landing on the Moon.
Source: ispace

The primary landing site is the  Atlas crater in Lacus Somniorum (Lake of Dreams), which is a basaltic plain formed by flows of basaltic lava, located in the northeastern quadrant of the moon’s near side.

Lake of Dreams is highlighted in the yellow square.
Source: The Lunar Registry
Hakuto-R Mission 1 Moon landing milestones. Source: ispace

If successful, HAKUTO-R will also become the first commercial spacecraft ever to make a controlled landing on the moon.

After landing, the UAE’s Rashid rover will be deployed from the HAKUTO-R lander. In addition, the lander will deploy an orange-sized sphere from the Japanese Space Agency that will transform into a small wheeled robot that will move about on the lunar surface. 

3. UAE’s Rashid lunar rover

The Emirates Lunar Mission (ELM) team at the Mohammed bin Rashid Space Centre (MBRSC) is responsible for designing, manufacturing and developing the rover, which is named Rashid after Dubai’s royal family.  The ELM website is here: https://www.mbrsc.ae/service/emirates-lunar-mission/

The Rashid rover weighs just 22 pounds (10 kilograms) and, with four-wheel drive, can traverse a smooth surface at a maximum speed of 10 cm/sec (0.36 kph) and climb over an obstacle up to 10 cm (3.9 inches) tall and descend a 20-degree slope. 

Rashid rover general arrangement. Source: MBRSC

The Rashid rover is designed to operate on the Moon’s surface for one full lunar day (29.5 Earth days), during which time it will conduct studies of the lunar soil in a previously unexplored area. In addition, the rover will conduct engineering studies of mobility on the lunar surface and susceptibility of different materials to adhesion of lunar particles. The outer rims of this rover’s four wheels incorporate small sample panels to test how different materials cope with the abrasive lunar surface, including four samples contributed by the European Space Agency (ESA).

The diminutive rover carries the following scientific instruments:

  • Two high-resolution optical cameras (Cam-1 & Cam-2) are expected to take more than 1,000 still images of the Moon’s surface to assess the how lunar dust and rocks are distributed on the surface.
  • A “microscope” camera
  • A thermal imaging camera (Cam-T) will provide data for determining the thermal properties of lunar surface material.
  • Langmuir probes will analyze electric charge and electric fields at the lunar surface.
  • An inertial measurement unit to track the motion of the rover.

Mobility and communications tests of the completed rover were conducted in March 2022 in the Dubai desert.

Rashid rover during desert tests. Source: Gulf News (March 2022)

The Ottawa, Ontario company Mission Control Space Services has provided a deep-learning artificial intelligence (AI) system named MoonNet that will be used for identifying geologic features seen by the rover’s cameras. Mission Control Services reports, “Rashid will capture images of geological features on the lunar terrain and transmit them to the lander and into MoonNet. The output of MoonNet will be transmitted back to Earth and then distributed to science team members….Learning how effectively MoonNet can identify geological features, inform operators of potential hazards and support path planning activities will be key to validating the benefits of AI to support future robotic missions.”

This color-coded image is an example of the type of output the MoonNet AI system is expected to produce.
 Source: Mission Control Space Services

4. Landing attempt failed

The Hakuto-R lander crashed into the Moon on 25 April 2023 during its landing attempt.

In May 2023, the results of an ispace analysis of the landing failure were reported by Space.com:

“The private Japanese moon lander Hakuto-R crashed in late April during its milestone landing attempt because its onboard altitude sensor got confused by the rim of a lunar crater. the unexpected terrain feature led the lander’s onboard computer to decide that its altitude measurement was wrong and rely instead on a calculation based on its expected altitude at that point in the mission. As a result, the computer was convinced the probe was lower than it actually was, which led to the crash on April 25.”

“While the lander estimated its own altitude to be zero, or on the lunar surface, it was later determined to be at an altitude of approximately 5 kms [3.1 miles] above the lunar surface,” ispace said in a statement released on Friday (May 26). “After reaching the scheduled landing time, the lander continued to descend at a low speed until the propulsion system ran out of fuel. At that time, the controlled descent of the lander ceased, and it is believed to have free-fallen to the moon’s surface.”

On 23 May 2023, NASA reported that the its Lunar Reconnaissance Orbiter spacecraft had located the crash site of the UAE’s lunar spacecraft. The before and after views are shown in the following images.

Hakuto-R crash site, before (left) and after (right) the crash. Source: NASA/GSFC/Arizona State University

5. The future

ispace future lunar plans

ispace reported, “ispace’s SERIES-2 (S2) lander is designed, manufactured, and will be launched from the United States. While the S2 lander leverages lessons learned from the company’s SERIES-1 (S1) lander, it is an evolved platform representing our next generation lander series with increased payload capacity, enhanced capabilities and featuring a modular design to accommodate orbital, stationary or rover payloads.”

Ispace was selected through the Commercial Lunar Payload Services (CLPS) initiative to deliver NASA payloads to the far side of the Moon using the SERIES-2 (S2) lander, starting in 2025.

UAE future lunar plans

In October 2022, the UAE announced that it was collaborating with China on a second lunar rover mission, which would be part of China’s planned 2026 Chang’e 7 lunar mission that will be targeted to land near the Moon’s south pole. These plans may be cancelled after the U.S. applied export restrictions in March 2023 on the Rashid 2 rover, which contains some US-built components. The U.S. cited its 1976 International Traffic in Arms Regulations (ITAR), which prohibit even the most common US-built items from being launched aboard Chinese rockets.

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DoD’s Project Pele microreactor is being developed by BWXT with a target for initial operation at a DoD facility in 2027

All Posts, Military technology, Power Generating Technology - Nuclear, Transportation, , , , , , , ,

Peter Lobner

In 2016 the Defense Science Board (DSB) identified energy as a critical enabler of future military operations. The DoD’s Strategic Capabilities Office (SCO) launched Project Pele with the objective to design, build, and demonstrate a prototype mobile nuclear reactor to provide reliable and resilient electric power, while minimizing risk of nuclear proliferation, environmental damage, or harm to nearby personnel or populations. 

The Pele reactor will be the first electricity-generating Generation IV nuclear reactor built in the United States. Check out the DoD Office of the Under Secretary of Defense, Research and Engineering (OUSD(R&E)) website for the Project Pele Environmental Impact Statement (EIS) here: https://www.cto.mil/pele_eis/

In June 2022, Department of Defense (DoD) selected BWXT to produce a single prototype Pele mobile microreactor, which will be a Brayton-cycle high-temperature gas-cooled reactor (HTGR) capable of generating an electrical output of 1 MWe to 5 MWe. See the story in Power magazine here: https://www.powermag.com/dod-picks-bwxt-to-manufacture-project-pele-prototype-nuclear-microreactor/

The Pele reactor will use High-Assay, Low-Enriched Uranium (HALEU, <20% enriched) fuel in the form of TRstructural ISOtropic (TRISO) coated fuel pellets (each about the size of a poppy seed). 

Cross-section of a TRISO particle, greatly magnified.
Source: DOE

The reactor will be assembled and initially operated at the Idaho National Laboratory (INL), under the safety oversight of the Department of Energy (DOE).  The Pele reactor is expected to be transportable by rail, truck or cargo aircraft.

Pele reactor modes of transportation. Source: GAO

There’s a good status update on Project Pele in a February 2023 article on the Energy Intelligence website, “Interview: Pentagon’s Jeff Waksman on Project Pele Microreactor,” at the following link: https://www.energyintel.com/00000186-7b02-d1cb-a3ee-ffbf32940000

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Kelvin-Helmholtz Clouds Look Like Ocean Waves in the Sky

All Posts, Extreme weather, Weather, , ,

Peter Lobner

I recently saw the following spectacular photos of Kelvin-Helmholtz clouds that had occurred a few days earlier in Wyoming. The website EarthSky, which posted the first photo, reported, “Kelvin-Helmholtz clouds are named for Lord Kelvin and Hermann von Helmholtz, who studied the physics of the instability that leads to this type of cloud formation.” 

 Kelvin-Helmholtz clouds in Sheridan, Wyoming, 6 December 2022.
Source: Abbie Long, via EarthSky Community Photos: https://earthsky.org/earthsky-community-photos/entry/54020/
Kelvin-Helmholtz clouds in Wyoming, 9 December 2022
Source: Rachel Gordon / Facebook via BBC: https://www.bbc.com/news/world-us-canada-63912257

The Hydrometeorology Group website (https://hydrometeology-group1.weebly.com/kelvinndashhelmholtz-instability.html) reports, “Kelvin-Helmholtz clouds are the product of a strong wind shear. Wind shear refers to the rate of change of wind speed, or wind direction, over a set distance. The formation of Kelvin-Helmholtz clouds requires the presence of two vertical air layers of different densities that travel at different speeds. The upper layer must be the warmer and less dense of the two. Given a great enough wind shear, eddies will develop where the two air layers meet.”This type of process is illustrated in the following diagram.

Formation of Kelvin-Helmholtz clouds. 
Source: SKYbrary (https://www.skybrary.aero/articles/kelvin-helmholtz-waves)

You’ll find more photos and details on Kelvin-Helmholtz clouds in the following March 2022 EarthSky article, which notes that Kelvin-Helmholtz formations also can be observed at the interfaces of some cloud bands encircling Jupiter and Saturn: https://earthsky.org/earth/kelvin-helmholtz-clouds/

Kelvin-Helmholtz clouds pattern formed between two of Saturn’s cloud bands.
Source: Astronomy.com (https://astronomy.com/news/2004/10/turbulent-clouds-and-a-rock-steadied-ring

Could Kelvin-Helm clouds have been the inspiration for Vincent Van Gogh’s post-impressionistic masterpiece, The Starry Night, which he painted while recovering in an asylum in Saint Rémy (Provence) France in June 1889?

Source: MoMA, https://www.moma.org/collection/works/79802

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Webb Space Telescope Provides an Extraordinary View of the Planet Neptune

All Posts, Astronomy, Spacecraft and Missions, , , , , , , , , , ,

Peter Lobner

In April 2021, I posted a short article entitled, “Multi-messenger Astronomy Provides Extraordinary Views of Uranus,” which included two composite views of Uranus, created by combining near-infrared images taken by the Keck-1 telescope at an elevation of 4,145 meters (13,599 ft) on Maunakea, Hawaii, with X-ray images taken with the Advanced CCD Imaging Spectrometer (ACIS) aboard the orbiting Chandra X-Ray Observatory.

Now, the Webb Space Telescope has taken stunning near-infrared images of the next, and outermost, planet in our solar system, Neptune (sorry, Pluto). You can read NASA’s 21 September 2022 news release on these images here: https://www.nasa.gov/feature/goddard/2022/new-webb-image-captures-clearest-view-of-neptune-s-rings-in-decades

The Webb images of Neptune, taken on July 12, 2022, are reproduced below.

NASA: “Webb captured seven of Neptune’s 14 known moons: Galatea, Naiad, Thalassa, Despina, Proteus, Larissa, and Triton. Neptune’s large and unusual moon, Triton, dominates this Webb portrait of Neptune as a very bright point of light sporting the signature diffraction spikes seen in many of Webb’s images.”
Source: NASA, ESA, CSA, STScI
NASA: “…image of Neptune……brings the planet’s rings into full focus for the first time in more than three decades. The most prominent features of Neptune’s atmosphere in this image are a series of bright patches in the planet’s southern hemisphere that represent high-altitude methane-ice clouds. More subtly, a thin line of brightness circling the planet’s equator could be a visual signature of global atmospheric circulation that powers Neptune’s winds and storms. Additionally, for the first time, Webb has teased out a continuous band of high-latitude clouds surrounding a previously-known vortex at Neptune’s southern pole.” Source: NASA, ESA, CSA, STScI

The Space Telescope Science Institute (STScI) has created a Resource Gallery of Webb Space Telescope images, which you can browse here: https://webbtelescope.org/resource-gallery/images. Currently there are 280 images in the Webb Resource Gallery.  I think this is a website worth revisiting from time to time.

NASA’s Solar System Exploration website provides views of Neptune from several earlier sources, including the 1989 Voyager 2 deep space probe, the Hubble Space Telescope and the European Southern Observatory’s (ESO) Very Large Telescope (VLT). Check it out here: https://solarsystem.nasa.gov/planets/neptune/galleries/

2018: The following image was taken in July 2018 during the testing of the narrow-field, adaptive optics mode of the optical/infrared MUSE/GALACSI instrument on ESO’s VLT, which is located at an elevation of 2,635 m (8,645 ft) at Cerro Paranal, in the Atacama Desert of northern Chile.

2018 VLT image of Neptune. The corrected image is sharper than a comparable image from the NASA/ESA Hubble Space Telescope. Source: ESO/P. Weilbacher (AIP)

1994: The more recent Webb Space Telescope and VLT images are much better than the Hubble Space Telescope optical-range images of Neptune taken more than two decades earlier, in 1994.

NASA: “The images were taken in 1994 on October 10 (upper left), October 18 (upper right), and November 2 (lower center). Hubble is allowing astronomers to study Neptune’s dynamic atmosphere with a level of detail not possible since the 1989 flyby of the Voyager 2 space probe. Building on Voyager’s initial discoveries, Hubble is revealing that Neptune has a remarkably dynamic atmosphere that changes over just a few days. The temperature difference between Neptune’s strong internal heat source and its frigid cloud tops (-260 degrees Fahrenheit) might trigger instabilities in the atmosphere that drive these large-scale weather changes. In addition to hydrogen and helium, the main constituents, Neptune’s atmosphere is composed of methane and hydrocarbons, like ethane and acetylene.” Source: NASA, JPL, STScI

1989: In October 1989, the following whole planet view of Neptune was produced using images taken through the green and orange filters on the narrow angle camera during the Voyager 2 spacecraft flyby of the planet.

NASA: “This picture of Neptune was taken by Voyager 2 less than five days before the probe’s closest approach of the planet on Aug. 25, 1989. The picture shows the “Great Dark Spot” — a storm in Neptune’s atmosphere — and the bright, light-blue smudge of clouds that accompanies the storm”. 
Source: NASA/JPL-Caltech (1989)
 

In the future, we can hopefully look forward to more detailed multi-messenger images of Neptune, combining the near-infrared images from Webb with images from other observatories that can view the planet in different spectral bands.

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