Tag Archives: NASA

Remarkable Multispectral View of Our Milky Way Galaxy

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Peter Lobner, updated 18 August 2023

Moody Blues cover - In search of the lost chordAlbum Album cover art credit: Deram Records

Some of you may recall the following lyrics from the 1968 Moody Blues song, “The Word,” by Graeme, Edge, from the album “In Search of the Lost Chord”:

This garden universe vibrates complete

Some, we get a sound so sweet

 Vibrations reach on up to become light

And then through gamma, out of sight

Between the eyes and ears there lie

The sounds of color and the light of a sigh

And to hear the sun, what a thing to believe

But it’s all around if we could but perceive

 To know ultraviolet, infrared and X-rays

Beauty to find in so many ways

On 24 February 2016, the European Southern Observatory (ESO) Consortium announced that it has completed the ATLASGAL Survey of the Milky Way. The survey mapped the entire galactic plane visible from the southern hemisphere at sub-millimeter wavelengths, between infrared light and radio waves, using the Atacama Pathfinder EXperiment (APEX) telescope located at 5,100 meters (16,732 ft.) above sea level in Chile’s Atacama region. The southern sky is particularly important because it includes the galactic center of our Milky Way. The Milky Way in the northern sky has already been mapped by the James Clerk Maxwell Telescope, which is a sub-millimeter wavelength telescope at the Mauna Kea Observatory in Hawaii.

The new ATLASGAL maps cover an area of sky 140 degrees long and 3 degrees wide. ESO stated that these are the sharpest maps yet made, and they complement those from other land-based and space-based observatories. The principal space-based observatories are the following:

  • European Space Agency’s (ESA) Plank satellite: Mission on-going, mapping anisotropies of the cosmic microwave background at microwave and infrared frequencies.
  • ESA’s Herschel Space Observatory: Mission on-going, conducting sky surveys in the far-infrared and sub-millimeter frequencies.
  • National Aeronautics and Space Administration (NASA) Spitzer Space Telescope: Mission on-going, conducting infrared observations and mapping as described in my 1 April 2015 post.
  • NASA’s Hubble Space Telescope: Mission on-going, observing and mapping at ultraviolet, optical, and infrared frequencies.
  • NASA’s Chandra X-Ray Observatory: Mission on-going, observing and mapping X-ray sources.
  • NASA’s Compton Gamma Ray Observatory: Mission ended in 2000. Observed and mapped gamma ray and x-ray sources.

ESO reported that the combination of Planck and APEX data allowed astronomers to detect emission spread over a larger area of sky and to estimate from it the fraction of dense gas in the inner galaxy. The ATLASGAL data were also used to create a complete census of cold and massive clouds where new generations of stars are forming.

You can read the ESO press release at the following link:

https://www.eso.org/public/news/eso1606/

Below is a composite ESO photograph that shows the same central region of the Milky Way observed at different wavelengths.

ESO Multispectral view of Milky WaySource: ESO/ATLASGAL consortium/NASA/GLIMPSE consortium/VVV Survey/ESA/Planck/D. Minniti/S. Guisard. Acknowledgement: Ignacio Toledo, Martin Kornmesser

  • The top panel shows compact sources of sub-millimeter radiation detected by APEX as part of the ATLASGAL survey, combined with complementary data from ESA’s Planck satellite, to capture more extended features.
  • The second panel shows the same region as seen in shorter, infrared wavelengths by the NASA Spitzer Space Telescope
  • The third panel shows the same part of sky again at even shorter wavelengths, the near-infrared, as seen by ESO’s VISTA infrared survey telescope at the Paranal Observatory in Chile. Regions appearing as dark dust tendrils in the third panel show up brightly in the ATLASGAL view (top panel).
  • The bottom panel shows the more familiar view in visible light, where most of the more distant structures are hidden from view

NASA’s Goddard Space Flight Center also  created a multispectral view of the Milky Way, which  is shown in the following composite photograph of the same central region of the Milky Way observed at different wavelengths.

NASA Goddard multispectralSource: NASA Goddard Space Flight Center

Starting from the top, the ten panels in the NASA image cover the following wavelengths.

  • Radio frequency (408 MHz)
  • Atomic hydrogen
  • Radio frequency (2.5 GHz)
  • Molecular hydrogen
  • Infrared
  • Mid-infrared
  • Near-infrared
  • Optical
  • X-ray
  • Gamma ray

The Moody Blues song, “The Word,” ends with the following lyrics:

 Two notes of the chord, that’s our full scope

But to reach the chord is our life’s hope

And to name the chord is important to some

So they give it a word, and the word is “Om”

While “Om” (pronounced or hummed “ahh-ummmm”) traditionally is a sacred mantra of Hindu, Jain and Buddhist religions, it also may be the mantra of astronomers as they unravel new secrets of the Milky Way and, more broadly, the Universe. I suspect that completing the ATLASGAL Survey of the Milky Way was an “Om” moment for the many participants in the ESO Consortium effort.

For more information

Relax, the Planetary Defense Officer has the Watch

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Peter Lobner

On 7 January 2016, NASA formalized its ongoing program for detecting and tracking Near-Earth Objects (NEOs) by establishing the Planetary Defense Coordination Office (PDCO). You can read the NASA announcement at the following link:

https://www.nasa.gov/feature/nasa-office-to-coordinate-asteroid-detection-hazard-mitigation

PDCO is responsible for supervision of all NASA-funded projects to find and characterize asteroids and comets that pass near Earth’s orbit around the sun. PDCO also will take a leading role in coordinating interagency and intergovernmental efforts in response to any potential impact threats. Specific assigned responsibilities are:

  • Ensuring the early detection of potentially hazardous objects (PHOs), which are defined as asteroids and comets whose orbits are predicted to bring them within 0.05 Astronomical Units (AUs) of Earth (7.48 million km, 4.65 million miles); and of a size large enough to reach Earth’s surface – that is, greater than 30 to 50 meters (98.4 to 164.0 feet);
  • Tracking and characterizing PHOs and issuing warnings about potential impacts;
  • Providing timely and accurate communications about PHOs; and
  • Performing as a lead coordination node in U.S. Government planning for response to an actual impact threat.

As you can see in the following organization chart, PDCO is part of NASA’s Planetary Science Division, in the agency’s Science Mission Directorate in Washington D.C.  PDCO is led by Lindley Johnson, longtime NEO program executive, who now has the very impressive title of “Planetary Defense Officer”.

Planetary Defense Coordination OfficeSource: NASA PDCO

You can find out more at the PDCO website at the following link:

https://www.nasa.gov/planetarydefense

The PDCO includes the Near Earth Object (NEO) Observation Program, which was established in 1998 in response to a request from the House Committee on Science that NASA find at least 90% of 1 km (0.62 mile) and larger NEOs. That goal was achieved by end of 2010.

The NASA Authorization Act of 2005 increased the scope of NEO objectives by amending the National Aeronautics and Space Act of 1958 (“NASA Charter”) by adding the following new functional requirement:

 ‘‘The Congress declares that the general welfare and security of the United States require that the unique competence of the National Aeronautics and Space Administration be directed to detecting, tracking, cataloging, and characterizing near-Earth asteroids and comets in order to provide warning and mitigation of the potential hazard of such near-Earth objects to the Earth.’’

 This was further clarified by stating that NASA will:

“…plan, develop, and implement a Near-Earth Object Survey program to detect, track, catalogue, and characterize the physical characteristics of near-Earth objects equal to or greater than 140 meters (459 feet) in diameter in order to assess the threat of such near-Earth objects to the Earth. It shall be the goal of the Survey program to achieve 90 percent completion of its near-Earth object catalog within fifteen years (by 2020)”

The contractors supporting the NASA NEO Observation Program are Jet propulsion Laboratory (JPL), Massachusetts Institute of Technology (MIT) / Lincoln laboratory, Smithsonian Astrophysical Observatory, University Space Research Association, University of Arizona, and University of Hawaii / Institute of Astronomy.

Once detected, NEO orbits are precisely predicted and monitored by the Center for NEO Studies (CNEOS) at JPL. Their website is at the following link:

http://neo.jpl.nasa.gov/neo/

The catalog of known NEOs as of 3 November 2015 included 13,206 objects. NASA reports that new NEOs are being identified at a rate of about 1,500 per year. Roughly half of the known NEOs – about 6,800 – are objects larger than 140 meters (459 feet) in diameter. The estimated population of NEOs of this size is about 25,000. Current surveys are finding NEOs of this size at a rate of about 500 per year.  Recent encounters with NEOs include:

  • Asteroid 2015 TB145, the “Halloween Pumpkin”
    • Roughly spherical, about 610 meters (2,000 feet) in diameter
    • Detected 10 October 2015, approaching from the outer solar system, 21 days before closest approach
    • Closest approach occurred on 31 October 2015 at a distance of 310,000 miles (1.3 times the distance to the Moon) at a speed of about 78,000 miles an hour.
  • Asteroid airburst near Chelyabinsk, Russia
    • Airburst occurred 15 February 2013
    • Object estimated to be about 19 meters in diameter
    • Approached from the inner solar system; not detected before airburst
    • Peter Brown at the University of Western Ontario, estimated the energy of the Chelyabinsk airbust at 400 to 600 kilotons of TNT.  You can read this analysis in at the following link:

http://www.nature.com/articles/nature12741.epdf?referrer_access_token=OvLha95ujqCh0k4maNPuFNRgN0jAjWel9jnR3ZoTv0PyqszVJsMboh07BaZDfmONEget5lbJtDTXTwE2VvrDWIEgk5iXkd1EFvngsntJFeC1wOg4ASyku1lPPrkWlAPvoRMkxnjovQe0UYqFmFkZ6v9qqq9DL9_3CwYPmTWA6e-sweRQPIyrDHMUaAQYWA9H4TNSsZGN662UcGxlW5d1GA%3D%3D&tracking_referrer=www.theguardian.com

Another result of the NEO Observation Program is the following map of data gathered from 1994-2013 on small asteroids impacting Earth’s atmosphere and disintegrating to create very bright meteors, technically called “bolides” and commonly referred to as “fireballs”.  Sizes of orange dots (daytime impacts) and blue dots (nighttime impacts) are proportional to the optical radiated energy of impacts measured in billions of Joules (GJ) of energy, and show the location of impacts from objects about 1 meter (3 feet) to almost 20 meters (60 feet) in size.  You can see a rather uniform distribution of these fireballs over the surface of the Earth.

bolide_events_1994-2013 Source: NASA NEO Observation Program

In September 2014, the NASA Inspector General published the report, “NASA’s Efforts to Identify Near-Earth Objects and Mitigate Hazards,” which you can download for free at the following link:

https://oig.nasa.gov/audits/reports/FY14/IG-14-030.pdf

Key findings were the following:

  • Even though the Program has discovered, categorized, and plotted the orbits of more than 11,000 NEOs since 1998, NASA will fall short of meeting the 2005 Authorization Act goal of finding 90 percent of NEOs larger than 140 meters (459 feet) in diameter by 2020.
  • ….we believe the Program would be more efficient, effective, and transparent were it organized and managed in accordance with standard NASA research program requirements

You will find an NEO Program update, including a reference to the new Planetary Defense Coordination Office, presented by Lindley Johnson on 8 November 2915 at the following link:

http://www.minorplanetcenter.net/IAWN/2015_national_harbor/NEO_Program_update.pdf

So, what will we see in the years ahead as technology is explored and techniques are developed to defend Earth against a significant NEO impact? There have been many movies that have tried to answer that question, but none offered a particularly good answer.

Asteroid movies 2Asteroid movies 1 Source: Google

In 1968, Star Trek explored this issue in Season 3, Episode 3, “The Paradise Syndrome”. Ancient aliens had left a planetary defense device to protect a primitive civilization against their equivalent of NEOs. Only the intervention of Capt. James T. Kirk restored the device to operation in time to deflect an incoming asteroid and save the indigenous civilization.

Star Trek - The Paradise Syndrome 1 Source: memory-alpha.wiki.comStar Trek - The Paradise Syndrome 2 Source: technovelgy.com

Our new Planetary Defense Officer has a comparable responsibility on Earth, but without the benefits of special effects.

In 2010, National Academies Press published, “Defending Planet Earth: Near-Earth Object Surveys and Hazard Mitigation Strategies.” This report explores civil defense mitigation action and three basic defense techniques:

  • Slow push-pull methods
  • Kinetic impact methods
  • Nuclear methods

If you have a MyNAP account, you can download this report for free at the following link:

http://www.nap.edu/catalog/12842/defending-planet-earth-near-earth-object-surveys-and-hazard-mitigation

NAP Defending Planet Earth Source: NAP

The Story Behind the Apollo 8 Earthrise Photo

All Posts, Spacecraft and Missions, , , ,

Peter Lobner

You’ve all seen the iconic, first-ever photo of Earthrise as seen from lunar orbit.

NASA Earthrise Source: NASA

This photo was taken during the first lunar orbital mission, Apollo 8, on 24 December 1968 by astronaut Bill Anders, with help from the other Apollo 8 crew members, Frank Borman and Jim Lovell.

NASA Goddard Spaceflight Center has reconstructed the events surrounding that historic photo using detailed lunar maps prepared from current Lunar Reconnaissance Orbiter (LRO) data, along with the photos taken by the Apollo 8 astronauts, data on the orientation and maneuvers of the Apollo 8 spacecraft, and the actual recorded conversations among the astronauts.

I think you will enjoy NASA Goddard’s 7-minute video reconstruction, which you can view at the following link:

https://www.youtube.com/embed/dE-vOscpiNc

Now, 47 years later, that photo is no less inspirational than it was the day it was first published. Thank you, Apollo 8, for a enduring Christmas present.

The Bright Spots on Ceres Come into Focus

All Posts, Planetary science, Spacecraft and Missions, , , ,

Peter Lobner

In my 20 March 2015 post, I discussed the Dawn spacecraft mission to the large asteroid Vesta and the dwarf planet Ceres, both of which are in the main asteroid belt between Mars and Jupiter. Dawn arrived in orbit around Ceres on 6 March 2015, at an initial altitude of 8,400 miles (13,518 kilometers). On approach and from this high altitude orbit, Dawn photographed two very bright spots on the surface of Ceres.

Ceres seen from Dawn  Source: NASA

After spending six months mapping the surface of Ceres and gradually descending to lower altitude orbits, Dawn currently is in a much lower “high-altitude mapping orbit” (HAMO) at 915 miles (1,470 kilometers) above the surface. Ceres’ diameter is about 587 miles (946 kilometers). Due to the low mass of this dwarf planet, Dawn’s orbital speed in the HAMO is only 400 mph (645 kph). The spacecraft completes one orbit in about 19 hours.

From its current vantage point in HAMO, Dawn has provided a much better view of the bright spots on Ceres. The following composite photo shows the bright spots at a resolution of 450 feet (140 meters) per pixel.

ceres-bright-spots-Sep2015,jpg  Source: NASA

The source of the bright spots has not yet been determined. We’ll get a more detailed view later in 2015, when the spacecraft descends to the “low altitude mapping orbit” (LAMO) at an altitude of 230 miles (370 kilometers).

You can keep up with the work of the Dawn project team at the following NASA / Jet Propulsion Lab website:

http://dawnblog.jpl.nasa.gov

 9 December 2015 Update:

NASA’s Jet Propulsion Laboratory (JPL) released closeup photos of the bright spots, which appear to be globally distributed on Ceres. JPL scientists reported that Ceres has more than 130 bright areas, and most of them appear to be associated with impact craters.   There is evidence that the bright spots may be salt deposits left behind after a subterranean briny water-ice deposit was exposed by an impact and the  ice-water sublimated into space.  Here is a closeup, false-color photo of the Occator Crater, emphasizing the deposits of bright material on the crater floor.

Occator Crater - Ceres_JPL

You can read more on this subject on the JPL website at the following link:

http://www.jpl.nasa.gov/news/news.php?feature=4785

1 November 2018 Update:

On 1 November 2018, NASA reported the end of the Dawn mission:

“Dawn missed scheduled communications sessions with NASA’s Deep Space Network on Wednesday, Oct. 31, and Thursday, Nov. 1. After the flight team eliminated other possible causes for the missed communications, mission managers concluded that the spacecraft finally ran out of hydrazine, the fuel that enables the spacecraft to control its pointing. Dawn can no longer keep its antennae trained on Earth to communicate with mission control or turn its solar panels to the Sun to recharge.”

You’ll find more information about the Dawn mission and its many accomplishments on the NASA / JPL website at the following link:

https://dawn.jpl.nasa.gov/news/news-detail.html?id=7275

New Horizons Spacecraft Rapidly Approaching Encounter with Pluto

All Posts, Planetary science, Spacecraft and Missions, ,

Peter Lobner

New Horizons is rapidly approaching Pluto for a fast fly-by encounter with closest approach at 7:49 am on Tuesday, 14 July 2015. You’ll find basic information about the New Horizons mission in my 14 March 2015 post on this subject. Detailed information is available at the NASA New Horizons mission website at the following link:

https://www.nasa.gov/mission_pages/newhorizons/main/index.html

The spacecraft will fly past Pluto at 30,800 mph (49,600 kph), and is expected to fly within 7,750 miles (11,265 km) of Pluto’s surface. The close-encounter segment of the flyby is quite brief, as shown in the following diagram of New Horizon’s trajectory through the Pluto system.

New Horizons trajectorySource: NASA/Applied Physics Laboratory/Southwest Research Institute

On 9 July, New Horizon’s Long Range Reconnaissance Imager (Lorri) took the following photo from a range of 3.3 million miles. Some basic surface features have been noted by the NASA project team, along with a diagram indicating Pluto’s north pole, equator, and central meridian.

Pluto pic 1

Source: NASA/Applied Physics Laboratory/Southwest Research Institute

On 11 July, the project team released the following slightly more detailed photo that reveals linear features that may be cliffs, as well as a circular feature that could be an impact crater.

Pluto pic 2

Source: NASA/Applied Physics Laboratory/Southwest Research Institute

Below is a photo released on 9 July showing both Pluto and it’s largest moon, Charon, which orbit each other around their common center of gravity. You’ll find more information on the unusual orbital interactions among Pluto and it’s five known moons in my 6 June 2015 post on that subject.

Pluto pic 3

Source: NASA/Applied Physics Laboratory/Southwest Research Institute

Hubble Space Telescope 25th Anniversary Didn’t Come Easily

All Posts, Astronomy, Spacecraft and Missions, , ,

Peter Lobner

The Hubble Space Telescope was launched on 24 April 1990 by the space shuttle Discovery on mission STS-31, and was deployed into orbit on 25 April. You can find details on the design of Hubble at the following link:

http://hubblesite.org/the_telescope/

During system checkout, it was determined that a design error had been made and Hubble’s primary optics suffered from spherical aberration. This optical problem was corrected in 1993 on Servicing Mission 1 (SM1), which also resolved several other issues. Over Hubble’s 25 year operating life, five servicing missions were conducted by space shuttle astronauts.

SM-1 – launched 2 Dec 1993, shuttle Endeavour
SM-2 – launched 11 Feb 1997, shuttle Discovery
SM-3A – launched 19 Dec 1999, shuttle Discovery
SM-3B – launched 1 Mar 2002, shuttle Columbia
SM-4 – launched 11 May 2009, shuttle Atlantis

The Hubble today is quite a different machine than the one launched in 1990. You can see details of each servicing mission at the following NASA website:

http://asd.gsfc.nasa.gov/archive/hubble/overview/timeline.html

NASA’s Hubble mission website is at the following link:

http://www.nasa.gov/mission_pages/hubble/main/index.html

Here you have access to details about Hubble’s 25-year mission, including an extensive photo gallery. NASA’s official photo to commemorate the 25th anniversary is the following photo of the Westerlund 2 star cluster taken by Hubble’s near-infrared Wide-Field Camera 3, which was installed during SM-4.

image Source:  NASA

Messenger Spacecraft Mission at Mercury About to End

All Posts, Planetary science, Spacecraft and Missions, , ,

Peter Lobner

Updated 12 January 2016

The 1,069 pound Messenger (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft is only the second spacecraft sent to Mercury. Mariner 10 flew past Mercury three times in 1974 and 1975. Messenger was launched on 3 August 2004 and flew for 6-1/2 years on a circuitous trajectory that included 15 orbits of the sun, one flyby of Earth, two flybys of Venus, and three flybys of Mercury before entering orbit around Mercury in 18 March 2011. The series of planetary flybys allowed Messenger to decelerate relative to Mercury and achieve orbit with minimal use of fuel.

The NASA Messenger mission website is at the following link:

http://www.nasa.gov/mission_pages/messenger/main/index.html

Messenger is solar-powered, with its science payload and propulsion system located behind a sunshade to protect against the intense solar radiation encountered at Mercury’s close orbit of the Sun.

image  Source: Johns Hopkins University/APL

Messenger has instrumentation for mapping and characterizing Mercury using imaging cameras, laser altimeter, various spectrometers, magnetometer, and a radio science package to measure slight velocity changes in orbit. You can read details on the spacecraft instrumentation systems at the following link:

http://messenger.jhuapl.edu/the_mission/spacecraft_design.html

After four years in orbit, fuel needed to maintain orbit is expected to be depleted in April. Messenger’s orbit will decay and the spacecraft eventually will crash at perigee into Mercury’s surface at its orbital speed of 8,750 mph.

12 January 2016 update:

On 30 April 2015, Messenger crashed into the surface of Mercury on the side facing away from Earth.  Before crashing, Messenger orbited Mercury 4,105 times and collected more than 277,000 images.  A composite photograph of Mercury created from thousands of Messenger images is shown below:

Mercury composite imaages from MessengerSource: NASA /  Johns Hopkins University/APL

Radioisotope Thermoelectric Generators (RTG) for Spacecraft: History and Current U.S. Pu-238 Production Status

All Posts, Chemical engineering, Power Generating Technology - Nuclear, Spacecraft and Missions, , , , , , , , , , , , , , , , , , , , , , , ,

Updated 5 March 2021

Peter Lobner

Radioisotope Thermoelectric Generators (RTG), also called Radioisotope Power Systems (RTS), commonly use non-weapons grade Plutonium 238 (Pu-238) to generate electric power and heat for National Aeronautics and Space Administration (NASA) spacecraft when solar energy and batteries are not adequate for the intended mission. In comparison to other RTG heat sources (Strontium-90, Cesium-137), Pu-238 has a relatively long half-life of 87.75 years, which is a desirable property for a long-life RTG.

Approximately 300 kg (661 lb) of Pu-238 was produced by the Department of Energy (DOE) at the Savannah River Site between 1959 – 1988. After U.S production stopped, the U.S. purchased Pu-238 from Russia until that source of supply ended in 2010.

Limited production of new Pu-238 in the U.S re-started in 2013 using the process shown below. This effort is partially funded by NASA.  Eventually, production capacity will be about 1.5 kg (3.3 lb) Pu-238 per year. The roles of the DOE national laboratories involved in this production process are as follows:

  • Idaho National Engineering Lab (INEL):
    • Store the Neptunium dioxide (NpO2) feed stock
    • Deliver feed stock as needed to ORNL
    • Irradiate targets provided by ORNL in the Advanced Test Reactor (ATR)
    • Return irradiated targets to ORNL for processing
  • Oak Ridge National Lab (ORNL):
    • Manufacture targets
    • Ship some targets to INEL for irradiation
    • Irradiate the remaining targets in the High Flux Isotope Reactor (HFIR)
    • Process all irradiated targets to recover and purify Pu-238
    • Convert Pu-238 to oxide and deliver as needed to LANL
  • Los Alamos National Lab (LANL):
    • Manufacture the Pu-238 fuel pellets for use in RTGs

Pu-238 production process

Source: Ralph L McNutt, Jr, Johns Hopkins University APL, 2014

In 2015, the U.S. had an existing inventory of about 35 kg (77 lb) of Pu-238 of various ages.  About half was young enough to meet the power specifications of planned NASA spacecraft. The remaining stock was more than 20 years old, has decayed significantly since it was produced, and did not meet specifications.  The existing inventory will be blended with newly produced Pu-238 to extend the usable inventory. To get the energy density needed for space missions while extending the supply of Pu-238, DOE and NASA plan to blend “old” Pu-238 with newly produced Pu-238 in 2:1 proportions.

Since 2010, NASA’s RTG for spacecraft missions has been the Multi-Mission Radioisotope Thermoelectric Generator (MMRTG), which It is based on the SNAP-19 RTG flown on the two Viking Mars landers (circa 1975) and the Pioneer 10 and 11 deep space probes (circa 1972). At beginning of life, the current MMRTG can provide about 2,000 watts of thermal power and 110 watts of electrical power from eight General Purpose Heat Source (GPHS) modules that contain a total of 10.6 pounds (4.8 kilograms) of plutonium dioxide fuel. Electric conversion efficiency is about 6%.

Assembled MMRTG on a transport dolly.  Source: NASA

MMRTG cut-away diagram.  Source: NASA

You’ll find a NASA MMRTG Fact Sheet here:  https://rps.nasa.gov/resources/86/multi-mission-radioisotope-thermoelectric-generator-mmrtg/?category=fact_sheets

NASA had a program to develop an Advanced Stirling Radioisotope Generator (ASRG), which was designed to produce about four times the power of the MMRTG per unit of Pu-238. Electric conversion efficiency was about 26%. The ASRG required a total of 2.7 pounds (1.2 kilograms) of plutonium dioxide in two GPHS modules. However, the ASRG would produce less waste heat, which can be used productively to warm electronics in the interior of a spacecraft, such as the Mars rover Curiosity.  In November 2013, NASA announced that ASRG development had been discontinued because of budget cuts. You’ll find a NASA ASRG Fact Sheet at the following link:  https://rps.nasa.gov/resources/65/advanced-stirling-radioisotope-generator-asrg/

You can read a history of RTGs and more information on current U.S. Pu-238 production status in a 2014 presentation by Ralph L McNutt, Jr, at the following link: https://www.lpi.usra.edu/sbag/meetings/jan2014/presentations/08_1545_McNutt_Pu238_SBAG.pdf

9 February 2016 Update:

On 22 December 2015, DOE reported the first U.S. production in nearly 30 years of Pu-238.   This production demonstration, which was partially funded by the NASA, was performed at ORNL and yielded 50 grams of Pu-238.  The last U.S. production of Pu-238 occurred in the late 1980s at the Savannah River Plant in South Carolina.

DOE reported that it plans to set an initial production target of 300 – 400 grams (about 12 ounces) of Pu-238 per year. After implementing greater automation and scaling up the process, ORNL expects to reach the the production target of 1.5 kg (3.3 lb) Pu-238 per year.

The next NASA mission that will use an RTG is the Mars 2020 rover, which will use an MMRTG,  as used on NASA’s Mars rover Curiosity. 

You can read the ORNL announcement of initial Pu-238 production at the following link: https://www.ornl.gov/news/ornl-achieves-milestone-plutonium-238-sample

3 January 2019 Update:

In the past three years, ORNL has made scant progress in producing Pu-238.  In a 13 December 2018 article, “NASA Doesn’t Have Enough Nuclear Fuel For Its Deep Space Missions,”author Ethan Siegel reports:  “Although current production (at ORNL) yields only a few hundred grams per year (less than a pound), the laboratory has the eventual goal of ramping up to 1.5 kilograms (3.3 pounds) per year by 2023, at the earliest.  Ontario Power Generation in Canada has also begun producing Pu-238, with the goal of using it as a supplemental source for NASA.”  You can read the complete article on the Forbes website at the following link: https://www.forbes.com/sites/startswithabang/2018/12/13/nasa-doesnt-have-enough-nuclear-fuel-for-its-deep-space-missions/#1a73d47e1c18

The Canadian plans for becoming a source of Pu-238 was announced on 1 March 2017:  “Ontario Power Generation (OPG) and its venture arm, Canadian Nuclear Partners, are participating in a project to produce isotopes in support of deep space exploration. Under the agreement, OPG would help create isotopes at the Darlington nuclear station east of Toronto that will help power space probes.” You can read the complete OPG press release here: https://www.opg.com/news-and-media/news-releases/Documents/20170301_DeepSpace.pdf

Also see the OPG public relations piece, “OPG looks to the stars,”  here: https://www.opg.com/news-and-media/our-stories/Documents/20170802_OPG_Deep_Space.pdf

4 August 2020 Update:

The NASA Mars rover, Perseverance, was launched from Cape Canaveral on 30 July 2020, with an expected landing date of 18 February 2021 in the Jezero crater on Mars. Once on the surface, Perseverance will be powered by an MMRTG.

The Pu-238 and some other special materials for the Perseverence MMRTG were produced in the U.S. at ORNL, as described in the following short (2:03 minutes) video, “ORNL-produced tech fuels NASA’s Perseverance mission to Mars”:

In a 20 July 2020 news release, ORNL provided more information on the U.S. production process for Pu-238 and reported that, “the lab has been consistently increasing its Pu-238 production capabilities, aiming to produce 1.5 kilograms per year by 2026.”  You can read this ORNL press release here: https://www.ornl.gov/news/ornl-produced-plutonium-238-help-power-perseverance-mars

At the planned U.S. production rate for Pu-238, NASA should be able to conduct an MMRTG mission at about four-year intervals. If NASA MMRTG missions will be more frequent than this, the U.S. will need to purchase additional Pu-238 from another source, perhaps Canada.

5 March 2021 Update:

The Perseverance rover landed on Mars on 18 February 2021, in the planned target area in Jezero Crater.  Power from the MMRTG was nominal after landing.  Perseverance will spend at least one Mars year (two Earth years) exploring the landing site region.

The next NASA mission with an MMRTG-powered spacecraft is the Dragonfly mission to Saturn’s moon Titan, which will launch in 2026 and arrive on Titan in 2034.

The Voyager 1 and 2 spacecraft were launched in 1977, each with three RTGs delivering a maximum of 470 watts of electrical power at the beginning of the mission.  Both spacecraft have left the solar system (Voyager 1 in 2013 and Voyager 2 in 2018) and continue to transmit from interstellar space in 2021 with their RTGs operating at a reduced power level of about 331 watts after 44 years of Pu-238 decay during the mission.  NASA plans to continue the Voyager missions until at least 2025.

For more information:

Where on Earth Does Lightning Flash Most?

All Posts, Global Climate, Remote Sensing, , , , ,

Peter Lobner

According to satellite observations summarized in the following map, lightning occurs more often over land than over the oceans and more often closer to the equator.

image   Source: NASA

The map above shows the average yearly counts of lightning flashes per square kilometer from 1995 to 2013. The map was created using data collected from 1998–2013 by the Lightning Imaging Sensor (LIS) on NASA’s Tropical Rainfall Measuring Mission satellite, and from 1995–2000 by the Optical Transient Detector (OTD) on the OrbView 1/Microlab satellite. Flashes above 38 degrees North were observed by OTD only, as the satellite flew to higher latitudes.

Areas with the fewest number of flashes each year are gray or purple; areas with the largest number of lightning flashes—as many as 150 per year per square kilometer—are bright pink.  Be careful where you pitch your tent if you go on safari in central Africa.

Check out the story at the following link:

http://earthobservatory.nasa.gov/IOTD/view.php?id=85600

Spitzer Space Telescope “Warm Mission” Continued into 2020

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

Peter Lobner

Updated 19 February 2020

The Spitzer Space Telescope, an infrared space observatory, was launched on 8 August 2003 into an “earth-trailing” orbit around the Sun. It is one of four “Great Observatories” launched by NASA; the others being the Hubble Space Telescope, the Compton Gamma-ray Observatory; and the Chandra X-ray Observatory.

Spitzer_Telescope_Handbook013   Diagram source: NASA

The primary mirror is 85 cm in diameter, made of beryllium, and until May 2009, was cooled by liquid helium to 5.5 degrees K. With the on-board liquid helium supply exhausted, most of the instruments were no longer usable. However, the two shortest wavelength modules of the Infrared Science Archive (IRAC) camera remained operable at their original sensitivities. This allowed the mission team to continue with the “Spitzer Warm Mission”.

You can read about the design of the Spitzer Space Telescope at the following link:

http://irsa.ipac.caltech.edu/data/SPITZER/docs/spitzermission/missionoverview/spitzertelescopehandbook/9/

An example of an image from the Spitzer Space Telescope is this view of Eta Carinae:

The tortured clouds of Eta Carinae  Photo source: NASA

You can see this and many other images from the Spitzer telescope, and related image data, at the following NASA / JPL / Caltech website:

http://www.spitzer.caltech.edu

Update 19 February 2020

On 30 January 2020, NASA reported,

“After more than 16 years studying the universe in infrared light, revealing new wonders in our solar system, our galaxy and beyond, NASA’s Spitzer Space Telescope’s mission has come to an end…..the spacecraft was placed in a safe mode, ceasing all scientific operations.”

You can read the NASA announcement and a summary of the accomplishments of the Spitzer mission here:

http://www.spitzer.caltech.edu/news/2252-ssc2020-08-NASA-s-Spitzer-Space-Telescope-Ends-Mission-of-Astronomical-Discovery