Finally an Answer to why Gamma Rays are Coming From Seemingly Empty Space

Gamma rays strike Earth from all directions of the sky. Our planet is bathed in a diffuse glow of high-energy photons. It doesn’t affect us much, and we don’t really notice it, because our atmosphere is very good at absorbing gamma rays. It’s so good that we didn’t notice cosmic gamma rays until the 1960s when gamma-ray detectors were launched into space to look for signs of atomic weapons tests. Even then, what we noticed were intense flashes of gamma rays known as gamma ray bursts.

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Cosmic Rays Erode Away All But the Largest Interstellar Objects

So far we know of only two interstellar objects (ISO) to visit our Solar System. They are ‘Oumuamua and 2I/Borisov. There’s a third possible ISO named CNEOS 2014-01-08, and research suggests there should be many more.

But a new research letter shows that cosmic ray erosion limits the lifespan of icy ISOs, and though there may be many more of them, they simply don’t last as long as thought. If it’s true, then ‘Oumuamua was probably substantially larger when it started its journey, wherever that was.

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Astronomers Locate the Source of High-Energy Cosmic Rays

Roughly a century ago, scientists began to realize that some of the radiation we detect in Earth’s atmosphere is not local in origin. This eventually gave rise to the discovery of cosmic rays, high-energy protons and atomic nuclei that have been stripped of their electrons and accelerated to relativistic speeds (close to the speed of light). However, there are still several mysteries surrounding this strange (and potentially lethal) phenomenon.

This includes questions about their origins and how the main component of cosmic rays (protons) are accelerated to such high velocity. Thanks to new research led by the University of Nagoya, scientists have quantified the amount of cosmic rays produced in a supernova remnant for the first time. This research has helped resolve a 100-year mystery and is a major step towards determining precisely where cosmic rays come from.

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Astronomers Have Tracked Down the Source of High Energy Cosmic Rays to Regions Within the Milky Way Itself

This image of the supernova remnant SN 1987A was taken by the NASA/ESA Hubble Space Telescope in January 2017 using its Wide Field Camera 3 (WFC3). Since its launch in 1990 Hubble has observed the expanding dust cloud of SN 1987A several times has helped astronomers get a better understanding of these cosmic explosions. Supernova 1987A is located in the centre of the image amidst a backdrop of stars. The bright ring around the central region of the exploded star is material ejected by the star about 20 000 years before the actual explosion took place. The supernova is surrounded by gaseous clouds. The clouds’ red colour represents the glow of hydrogen gas. Image Credit: NASA, ESA, and R. Kirshner (Harvard-Smithsonian Center for Astrophysics and Gordon and Betty Moore Foundation) and P. Challis (Harvard-Smithsonian Center for Astrophysics)

Using a new observatory, a team of Chinese astronomers have found over a dozen sources of ultra-high energy cosmic rays. And those sources aren’t from some distant, exotic corner of the cosmos. They come from our own backyard.

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The Universe is Constantly Bathing you in Radiation. Incredibly, This Could be Used for Medical Diagnosis

Walk into any modern hospital, and you’ll find a medical imaging department. Medical imaging uses x-rays, magnetic resonance imaging (MRI), and other arcane-sounding methods like positron emission tomography (PET) to image the body’s interior for analysis and diagnosis. To a non-specialist, these techniques can sound almost otherwordly. But in one way or another, these technologies rely on natural phenomena, including radiation, to do their thing.

Now a new study suggests that the Universe’s naturally occurring radiation could be used in medical imaging and could be particularly useful when it comes to COVID-19. The type of radiation in question is cosmic rays.

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Balloon-Based Cosmic Ray Observatory is Now on its Second Trip Around Antarctica

In 2012, the balloon-borne observatory known as the Super Trans-Iron Galactic Element Recorder (SuperTIGER) took to the skies to conduct high-altitude observations of Galactic Cosmic Rays (GCRs). Carrying on in the tradition of its predecessor (TIGER), SuperTiger set a new record after completing a 55-day flight over Antarctica – which happened between December of 2012 and January of 2013.

On December 16th, 2019, after multiple launch attempts, the observatory took to the air again and passed over Antarctica twice in the space of just three and a half weeks. Like its predecessor, SuperTIGER is a collaborative effort designed to study cosmic rays – high-energy protons and atomic nuclei – that originate outside of our Solar System and travel through space at close to the speed of light.

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When it Comes to Gamma Radiation, the Moon is Actually Brighter Than the Sun

The eerie, hellish glow coming from the Moon may seem unreal in this image, since it’s invisible to our eyes. But instruments that detect gamma rays tell us it’s real. More than just a grainy, red picture, it’s a vivid reminder that there’s more going on than meets human eyes.

It’s also a reminder that any humans that visit the Moon need to be protected from this high-energy radiation.

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Science Laden SpaceX Dragon Set for Aug. 14 ISS Launch, Testfire Inaugurates Triad of August Florida Liftoffs: Watch Live

SpaceX Falcon 9 rocket rests horizontally at Launch Complex 39A at the Kennedy Space Center on 13 Aug. 2017 while being processed for liftoff of the Dragon CRS-12 resupply mission to the International Space Station (ISS) slated for 14 Aug. 2017. Credit: Ken Kremer/

KENNEDY SPACE CENTER, FL – A triad of August liftoffs from the Florida Space Coast inaugurates Monday, Aug. 14 with a science laden commercial SpaceX Dragon bound for the International Space Station (ISS) – loaded with over 3 tons of NASA science, hardware and supplies including a cosmic ray detector, medical research experiments dealing with Parkinson’s disease and lung tissue, vegetable seeds, mice and much more, following a successful engine test firing of the Falcon 9 booster on Thursday.

“Static fire test of Falcon 9 complete,” SpaceX confirmed via Twitter soon after completion of the test at 9:10 a.m. EDT, Aug 10. (1310 GMT) “—targeting August 14 launch from Pad 39A for Dragon’s next resupply mission to the @Space_Station.”

Check out our photos & videos herein of the Aug. 10 static first test of the Falcon 9 first stage that paves the path to blastoff – as witnessed live by Ken Kremer and Jeff Seibert.

The triple headed sunshine state space spectacular kicks off with Monday’s lunchtime launch of the next unmanned SpaceX Dragon cargo freighter to the ISS from seaside pad 39A at NASA’s Kennedy Space Center in Florida, now targeted for Aug. 14 at 12:31 p.m. EDT (1631 GMT).

The closely spaced trio of space launches marches forward barely 4 days later with liftoff of NASA’s amazingly insectoid-looking TDRS-M science relay comsat slated for Friday morning Aug. 18 atop a United Launch Alliance (ULA) Atlas V rocket.

Lastly, a week after TDRS-M and just 11 days after the SpaceX Dragon an Orbital ATK Minotaur 4 rocket is due to blastoff just before midnight Aug. 25 and carry the ORS 5 mission to orbit for the U.S. military’s Operationally Responsive Space program. The Minotaur IV utilizes three stages from decommissioned Peacekeeper ICBMs formerly aimed at the Russians.

Of course getting 3 rockets off the ground from 3 different companies is all highly dependent on Florida’s hugely fickle hurricane season weather and the ever present reality of potential technical glitches, errant boaters and more – possibly resulting in a domino effect of cascading launch scrubs.

And sandwiched in between the Florida Space Coast blastoffs is the Total Solar ‘Eclipse Across America’ on Monday, Aug. 21 – for the first time in 99 years!

Although KSC and central Florida are not within the path of totality, the sun will still be about 85% obscured by the Moon.

So if you’re looking for bang for the space buck, the next two weeks have a lot to offer space and astronomy enthusiasts.

1st Reused SpaceX Dragon cargo craft lifts off from Launch Complex 39A at NASA’s Kennedy Space Center in Florida at 5:07 p.m. June 3, 2017 on CRS-11 mission carrying 3 tons of research equipment, cargo and supplies to the International Space Station. Credit: Ken Kremer/

The Dragon resupply ship dubbed Dragon CRS-12 counts as SpaceX’s twelfth contracted commercial resupply services (CRS) mission to the International Space Station for NASA since 2012.

SpaceX conducts successful static fire test of the Falcon 9 rocket on Aug. 10, 2017 at Launch Complex 39A on NASA’s Kennedy Space Center, Fl as seen from Playalinda causeway. Liftoff of the uncrewed Dragon CRS-12 resupply mission for NASA to the International Space Station (ISS) is scheduled for Aug. 14, 2017. Credit: Ken Kremer/

Watch this video of the Aug. 10 static hotfire test:

Video Caption: Hot fire test of the SpaceX Falcon 9 rocket in preparation for it launching the NASA CRS-12 Dragon resupply mission to the International Space Station from Pad 39A at Kennedy Space Center in Florida. Credit: Jeff Seibert/AmericaSpace

The 20-foot high, 12-foot-diameter Dragon CRS-12 vessel is carrying more than 6,400 pounds ( 2,900 kg) of science experiments and research instruments, crew supplies, food water, clothing, hardware, gear and spare parts to the million pound orbiting laboratory complex. 20 mice are also onboard. This will support dozens of the 250 research investigations and experiments being conducted by Expedition 52 and 53 crew members.

SpaceX conducts successful static fire test of the Falcon 9 rocket on Aug. 10, 2017 at Launch Complex 39A on NASA’s Kennedy Space Center, Fl as seen from Playalinda causeway. Liftoff of the uncrewed Dragon CRS-12 resupply mission for NASA to the International Space Station (ISS) is scheduled for Aug. 14, 2017. Credit: Ken Kremer/

If you can’t personally be here to witness the launch in Florida, you can always watch NASA’s live coverage on NASA Television and the agency’s website.

The SpaceX/Dragon CRS-12 launch coverage will be broadcast on NASA TV beginning noon on Aug. 14 with additional commentary on the NASA launch blog.

SpaceX will also offer their own live webcast beginning approximately 15 minutes before launch at about 12:16 p.m. EDT.

You can watch the launch live at NASA TV at –

You can also watch the launch live at SpaceX hosted Webcast at –

In the event of delay for any reason, the next launch opportunity is Tuesday, Aug. 15 with NASA TV coverage starting about 11:30 a.m. EDT.

The weather looks decent at this time with a 70% chance of favorable conditions at launch time according to U.S. Air Force meteorologists with the 45th Space Wing Weather Squadron at Patrick Air Force Base. The primary concerns on Aug. 14 are cumulus clouds and the potential for precipitation in the flight path.

The odds remain at 70% favorable for the 24 hour scrub turnaround day on Aug. 15.

Everything is currently on track for Monday’s noontime launch of the 230 foot tall SpaceX Falcon 9 on the NASA contracted SpaceX CRS-12 resupply mission to the million pound orbiting lab complex.

However since the launch window is instantaneous there is no margin for error. In case any delays arise during the countdown due to technical or weather issues a 24 hour scrub to Tuesday will result.

The lunchtime launch coincidently offers a convenient and spectacular opportunity for fun for the whole family as space enthusiasts flock in from around the globe.

Plus SpaceX will attempt a land landing of the 156 foot tall first stage back at the Cape at Landing Zone 1 some 8 minutes after liftoff – thus a double whammy of space action !!– punctuated by multiple loud sonic booms at booster landing time that will figuratively knock your socks off.

SpaceX Falcon 9 booster deploys quartet of landing legs moments before precision propulsive ground touchdown at Landing Zone 1 on Canaveral Air Force Station barely nine minutes after liftoff from Launch Complex 39A on 3 June 2017 from the Kennedy Space Center in Florida on the Dragon CRS-11 resupply mission to the International Space Station for NASA. Credit: Ken Kremer/

To date SpaceX has successfully recovered 13 boosters; 5 by land and 8 by sea, over the past 18 months. It’s a feat straight out of science fiction but aimed at drastically slashing the high cost of access to space.

The recent BulgariaSat-1 and Iridium-2 missions counted as the eighth and ninth SpaceX launches of 2017.

CRS-12 marks the eleventh SpaceX launch of 2017 and will establish a new single year record.

In contrast to the prior CRS-11 mission which flew a recycled Dragon, the CRS-12 Dragon is newly built.

The CRS-12 Dragon will be the last newly built one, says NASA. The remaining SpaceX CRS mission will utilize reused spaceships.

The Falcon 9 is also new and will attempt a land landing back at the Cape at Landing Zone-1 (LZ-1).

If the Aug. 14 launch occurs as scheduled, the Dragon will reach its preliminary orbit about 10 minutes later and deploy its life giving solar arrays. Dragon then begins a 2 day orbital chase of the station via a carefully choreographed series of thruster firings that bring the commercial spacecraft to rendezvous with the space station on Aug. 16.

Dragon will be grappled with the station’s Canadian built robotic arm at approximately 7 a.m. EDT on Aug. 16 by astronauts Jack Fischer of NASA and Paolo Nespoli of ESA (European Space Agency). It then will be installed on the Harmony module.

The Dragon spacecraft will spend approximately one month attached to the space station, returning to Earth in mid-September with results of earlier experiments.

Dragon CRS-12 is SpaceX’s third contracted resupply mission to launch this year for NASA.

The prior SpaceX cargo ships launched on Feb 19 and June 3, 2017 on the CRS-10 and CRS-11 missions to the space station. CRS-10 is further noteworthy as being the first SpaceX launch of a Falcon 9 from NASA’s historic pad 39A.

SpaceX leased pad 39A from NASA in 2014 and after refurbishments placed the pad back in service this year for the first time since the retirement of the space shuttles in 2011.

Previous launches include 11 Apollo flights, the launch of the unmanned Skylab in 1973, 82 shuttle flights and five SpaceX launches.

Cargo Manifest for CRS-12:

TOTAL CARGO: 6415.4 lbs. / 2910 kg

• Science Investigations 2019.4 lbs. / 916 kg
• Crew Supplies 485 lbs. / 220 kg
• Vehicle Hardware 747.4 lbs. / 339 kg
• Spacewalk Equipment 66.1 lbs. / 30 kg
• Computer Resources 116.8 lbs. / 53 kg

UNPRESSURIZED 2773.4 lbs. / 1258 kg
• Cosmic-Ray Energetics and Mass (CREAM) 2773.4 lbs. / 1258 kg

The CREAM instrument from the University of Maryland will be stowed for launch inside the Dragon’s unpressurized trunk. Astronauts will use the stations robotic arm to pluck it from the trunk and attach it to the exposed porch of the Japanese Experiment Module (JEM).

The Cosmic-Ray Energetics and Mass investigation (CREAM) instrument from the University of Maryland, College Park involves placing a balloon-borne instrument aboard the International Space Station to measure the charges of cosmic rays over a period of three years. CREAM will be attached to the Japanese Experiment Module Exposed Facility. Existing CREAM hardware used for balloon flights. Credit: NASA

Here is a NASA description of CREAM:

The Cosmic Ray Energetics and Mass (CREAM) instrument, attached to the Japanese Experiment Module Exposed Facility, measures the charges of cosmic rays ranging from hydrogen to iron nuclei. The data collected from the CREAM instrument will be used to address fundamental science questions on the origins and history of cosmic rays. CREAM’s three-year mission will help the scientific community build a stronger understanding of the fundamental structure of the universe.

The LRRK2 experiment seeks to grow larger crystals of the protein to investigate Parkinson’s disease and help develop new therapies:

Here is a NASA description of LRRK2:

Crystallization of Leucine-rich repeat kinase 2 (LRRK2) under Microgravity Conditions (CASIS PCG 7) will use the orbiting laboratory’s microgravity environment to grow larger versions of this important protein, implicated in Parkinson’s disease. Developed by the Michael J. Fox Foundation, Anatrace and Com-Pac International, researchers will look to take advantage of the station’s microgravity environment which allows protein crystals to grow larger and in more perfect shapes than earth-grown crystals, allowing them to be better analyzed on Earth. Defining the exact shape and morphology of LRRK2 would help scientists to better understand the pathology of Parkinson’s and aid in the development of therapies against this target.

Watch this Michael J. Fox video describing the LRRK2 crystallization experiment:

Video Caption: ISS National Lab SpaceX CRS-12 Payload Overview: Michael J. Fox Foundation. The Michael J. Fox Foundation is sending an experiment to the ISS National Lab to investigate the LRRK2 protein, a key target in identifying the makeup of Parkinson’s disease.

Watch for Ken’s continuing onsite CRS-12, TRDS-M, and ORS 5 and NASA mission reports direct from the Kennedy Space Center and Cape Canaveral Air Force Station, Florida.

Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.

Ken Kremer


Learn more about the upcoming SpaceX Dragon CRS-12 resupply launch to ISS on Aug. 14, ULA Atlas TDRS-M NASA comsat on Aug. 18, 2017 Solar Eclipse, NASA missions and more at Ken’s upcoming outreach events at Kennedy Space Center Quality Inn, Titusville, FL:

Aug 12-14: “SpaceX CRS-12 resupply launches to the ISS, Intelsat35e, BulgariaSat 1 and NRO Spysat, SLS, Orion, Commercial crew capsules from Boeing and SpaceX , Heroes and Legends at KSCVC, ULA Atlas/John Glenn Cygnus launch to ISS, SBIRS GEO 3 launch, GOES-R weather satellite launch, OSIRIS-Rex, Juno at Jupiter, InSight Mars lander, SpaceX and Orbital ATK cargo missions to the ISS, ULA Delta 4 Heavy spy satellite, Curiosity and Opportunity explore Mars, Pluto and more,” Kennedy Space Center Quality Inn, Titusville, FL, evenings

Up close view of SpaceX Dragon CRS-11 resupply vessel atop Falcon 9 rocket and delivering 3 tons of science and supplies to the International Space Station (ISS) for NASA. Liftoff occurred 3 June 2017. Credit: Ken Kremer/

Inside the Astrotech payload processing facility in Titusville, FL,NASA’s massive, insect like Tracking and Data Relay Satellite, or TDRS-M, spacecraft is undergoing preflight processing during media visit on 13 July 2017. TDRS-M will transmit critical science data gathered by the ISS, Hubble and numerous NASA Earth science missions. It is being prepared for encapsulation inside its payload fairing prior to being transported to Launch Complex 41 at Cape Canaveral Air Force Station for launch on a United Launch Alliance (ULA) Atlas V rocket on 3 August 2017. Credit: Ken Kremer/

Cancer Risk for a Human Mars Mission Just Got a Lot Worse

Astronauts hoping to take part in a crewed mission to Mars might want to pack some additional rad tablets! Long before NASA announced their proposal for a “Journey to Mars“, which envisions putting boots on the Red Planet by the 2030s, mission planners have been aware that one of the greatest risks for such a mission has to do with the threat posed by cosmic and solar radiation.

But according to a new study from the University of Nevada, Las Vegas, this threat is even worse than previously thought. Using a predictive model, this study indicates that astronauts that are the surface of Mars for extended periods of time could experience cell damage from cosmic rays, and that this damage will extend to other healthy cells – effectively doubling the risk of cancer!

The study, which was led by UNLV scientist Dr. Francis Cucinotta, was published in the May issue of Scientific Reports – under the title of Non-Targeted Effects Models Predict Significantly Higher Mars Mission Cancer Risk than Targeted Effects Models“. Building on conventional models that predict that DNA damage caused by radiation leads to cancer, their model looked at how such damage could spread throughout the body.

At one time, Mars had a magnetic field similar to Earth, which prevented its atmosphere from being stripped away. Credit: NASA

Galactic cosmic rays (GCRs) are one of the greatest hazards posed by space exploration. These particles, which originate from beyond our Solar System, are basically atomic nuclei that have been stripped of their surrounding electrons, thanks to their high-speed journey through space. In the cases of iron and titanium atoms, these have been known to cause heavy damage to cells because of their very high rates of ionization.

Here on Earth, we are protected from these rays and other sources of radiation thanks to our protective magnetosphere. But with missions that would take astronauts well beyond Earth, they become a much greater threat. And given the long-term nature of a mission to Mars, mitigation procedures and shielding are being investigated quite thoroughly. As Cucinotta explained in a UNLV press statement:

“Exploring Mars will require missions of 900 days or longer and includes more than one year in deep space where exposures to all energies of galactic cosmic ray heavy ions are unavoidable. Current levels of radiation shielding would, at best, modestly decrease the exposure risks.”

Previous studies have indicated that the effects of prolonged exposure to cosmic rays include cancer, central nervous system effects, cataracts, circulatory diseases and acute radiation syndromes. However, until now, the damage these rays cause was thought to be confined to those cells that they actually traverse – which was based on models that deal with the targeted effects of radiation. 

Artist’s impression of astronauts exploring the surface of Mars. Credit: NASA/JSC/Pat Rawlings, SAIC

For the sake of their study, Dr. Cucinotta and Dr. Eliedonna Cacao (a Chemical Engineer at UNLV) consulted the mouse Harderian gland tumor experiment. This is the only extensive data-set to date that deals with the non-targeted effects (NTEs) of radiation for a variety of particles. Using this model, they tracked the effects of chronic exposure to GCRs, and determined that the risks would be twice as high as those predicted by targeted effects models.

“Galactic cosmic ray exposure can devastate a cell’s nucleus and cause mutations that can result in cancers,” Cucinotta explained. “We learned the damaged cells send signals to the surrounding, unaffected cells and likely modify the tissues’ microenvironments. Those signals seem to inspire the healthy cells to mutate, thereby causing additional tumors or cancers.”

Naturally, any indication that there could be an elevated risk calls for additional research. As Cucinotta and Cacao indicated in their study, “The scarcity of data with animal models for tissues that dominate human radiation cancer risk, including lung, colon, breast, liver, and stomach, suggest that studies of NTEs in other tissues are urgently needed prior to long-term space missions outside the protection of the Earth’s geomagnetic sphere.”

These studies will of course need to happen before any long-term space missions are mounted beyond Earth’s magnetosphere. In addition, the findings also raise undeniable ethical issues, such as whether or not these risks could (or should) be waived by space agencies and astronauts. If in fact we cannot mitigate or protect against the hazards associated with long-term missions, is it even right to ask or allow astronauts to take part in them?

In the meantime, NASA may want to have another look at the mission components for the Journey to Mars, and maybe contemplate adding an additional layer or two of lead shielding. Better to be prepared for the worst, right?

Further Reading: UNLV, Nature

Space Station-Based Experiment Might Have Found Evidence of Dark Matter Destroying Itself

Since it was first proposed in the 1960s to account for all the “missing mass” in the Universe, scientists have been trying to find evidence of dark matter. This mysterious, invisible mass theoretically accounts for 26.8% of the baryonic matter (aka. visible matter) out there. And yet, despite almost fifty years of ongoing research and exploration, scientists have not found any direct evidence of this missing mass.

However, according to two new research papers that were recently published in the journal Physical Review Letters, we may have gotten our first glimpse of dark matter thanks to an experiment aboard the International Space Station. Known as the Alpha Magnetic Spectrometer (AMS-02), this a state-of-the-art particle physics detector has been recording cosmic rays since 2011 – which some theorize are produced by the annihilation of dark matter particles.

Like its predecessor (the AMS), the AMS-02 is the result of collaborative work and testing by an international team composed of 56 institutes from 16 countries. With sponsorship from the US Department of Energy (DOE) and overseen by the Johnson Space Center’s AMS Project Office, the AMS-02 was delivered to the ISS aboard the Space Shuttle Endeavour on May 16th, 2011.

Artist’s impression of the AMS-02 instrument. Credit: NASA/JSC

Ostensibly, the AMS-02 is designed to monitor cosmic rays to see how much in the way of antiprotons are falling to Earth. But for the sake of their research, the two science teams also been consulted the data it has been collecting to test theories about dark matter. To break it down, the WIMPs theory of dark matter states that it is made up of Weakly-Interacted Massive Particles (WIMPS), protons and antiprotons are the result of WIMPs colliding.

By monitoring the number of antiprotons that interact with the AMS-02, two science teams (who were working independently of each other) hoped to infer whether or not any of the antiprotons being detected could be caused by WIMP collisions. The difficulty in this, however, is knowing what would constitute an indication, as cosmic rays have many sources and the properties of WIMPs are not entirely defined.

To do this, the two teams developed mathematical models to predict the cosmic ray background, and thus isolate the number of antiprotons that AMS-02 would detect. They further incorporated fine-tuned estimates of the expected mass of the WIMPs, until it fit with the AMS-02 data. One team, led by Alessandro Cuoco, was made up of researchers from the Institute for Theoretical Particle Physics and Cosmology.

Using computer simulations, Cuoco and his colleagues examined the AMS-02 data based on two scenarios – one which accounted for dark matter and one which did not. As they indicate in their study, they not only concluded that the presence of antiprotons created by WIMP collisions better fit the data, but they were also able to constrain the mass of dark matter to about 80 GeV (about 85 times the mass of a single proton or antiproton).

According to supersymmetry, dark-matter particles known as WIMPs annihilate each other, creating a cascade of particles and radiation. Credit: Sky & Telescope / Gregg Dinderman.

As they state in their paper:

“[T]he very accurate recent measurement of the CR antiproton flux by the AMS-02 experiment allows [us] to achieve unprecedented sensitivity to possible DM signals, a factor ~4 stronger than the limits from gamma-ray observations of dwarf galaxies. Further, we find an intriguing indication for a DM signal in the antiproton flux, compatible with the DM interpretation of the Galactic center gamma-ray excess.”

The other team was made up of researchers from the Chinese Academy of Sciences, Nanjing University, the University of Science and Technology of China, and the National Center for Theoretical Sciences. Led by Ming-Yang Cui of Nanjing University, this team made estimates of the background parameters for cosmic rays by using prior data from previous boron-to-carbon ratio and proton measurements.

These measurements, which determine the rate at which boron decays into carbon, can be used to guage the distance that boron molecules travel through space. In this case, they were combined with proton measurements to determine background levels for cosmic rays. They incorporated this data into a Bayesian Analysis framework (i.e. a statistical model used to determine probabilities) to see how many antiprotons could be attributed to WIMP collisions.

The results, as they state it in their paper were quite favorable and produced similar mass estimates to the study led by Cuoco’s team. “Compared with the astrophysical background only hypothesis, we find that a dark matter signal is favored,” they write. “The rest mass of the dark matter particles is ?20 – 80 GeV.”


The AMS being delivered to the ISS by the Space Shuttle Endeavour in 2011. Credit: NASA

What’s more, both scientific teams obtained similar estimates when it came to cross-section measurements of dark matter – i.e. the likelihood of collisions happening based on how densely dark matter is distributed. For example, Cuoco’s team obtained a cross-section estimate of 3 x 10-26 per cm³ while Cui’s team obtained an estimate that ranged from 0.2 5 × 10-26 per cm³.

The fact that two scientific teams, which were operating independently of each other, came to very similar conclusions based on the same data is highly encouraging. While it is not definitive proof of dark matter, it is certainly a step in the right direction. At best, it shows that we are getting closer to creating a detailed picture of what dark matter looks like.

And in the meantime, both teams acknowledge that further work is necessary. Cuoco and his team also suggest what further steps should be taken. “Confirmation of the signal will require a more accurate study of the systematic uncertainties,” they write, “i.e., the antiproton production cross-section, and the modeling of the effect of solar modulation.”

While scientists have attempted to find evidence of dark matter by monitoring cosmic rays in the past, the AMS-02 stands apart because of its extreme sensitivity. As of May 8th, the spectrometer has conducted measurements on 100 billion particles. As of the penning of this article, that number has increased to over 100,523,550,000!

Further Reading: PBS Nova Next, Ars Technica, Physical Review Letters, (2)