The ISS National Lab is an outpost on the frontier of space. It is a point from which we can peer out into the undiscovered vastness of the universe to discover who we are, how we got here, and where we are going. From this outpost for observation and innovation in space, it is possible to conduct research off of Earth for the benefit of life on Earth.
The research on the ISS is diverse and spans many fields—including rodent research aimed at elucidating the mechanisms behind disease; protein crystallization seeking to improve drug design; understanding gravity’s effects on plant growth to enhance crops on Earth; testing materials and technologies in space to improve products on the ground; and studies of our planet, its ecosystems, and climate from the vantage point of low Earth orbit.
But not all research on the ISS is focused on Earth—some researchers have turned their gaze outward and are utilizing the ISS National Lab to gain a better understanding of the universe around us.
Three such outward-looking projects include:
- Project Meteor, which is examining meteors as they burn through Earth’s atmosphere to learn more about asteroids and comets—some of the oldest bodies in our solar system.
- A project to test a new type of technology called a charge injection device that can be used to directly image exoplanets (planets outside our solar system) around distant stars.
- The Alpha Magnetic Spectrometer-02 project, an international collaboration searching for evidence of dark matter and primordial antimatter to better understand the origin and composition of our universe
Studying Meteors to Uncover Clues About the Early Solar System
For thousands of years, humans have looked up in awe at the beauty of meteors streaking brightly across the night sky. Now, from the vantage point of the ISS, researchers are able look at meteors in a new way—they can look down and observe meteors from above as they enter Earth’s atmosphere.
Project Meteor, which launched on Orbital ATK CRS-6 in March 2016, will spend two years collecting images of meteors crossing the Earth’s atmosphere using a high-definition camera positioned in the Window Observational Research Facility (WORF) in the Destiny module of the ISS. The project is a collaboration between researchers at the Southwest Research Institute in San Antonio and Japan’s Planetary Exploration Research Center at the Chiba Institute of Technology.By analyzing these images, researchers can obtain information about the physical and chemical properties of meteoroids (rock and dust particles from space that enter Earth’s atmosphere), such as their size, density, and chemical composition. Most meteoroids come from known comets and asteroids. By studying the rock particles as they burn through the atmosphere, scientists can learn more about these parent bodies, said project Meteor payload developer Michael Fortenberry, principal engineer at the Southwest Research Institute.
“In essence, meteors are just little pieces of dust and rock that are entering the atmosphere and burning up, which is what you see from the ground,” Fortenberry said. “But ultimately, that dust and rock is coming from something else far out in the solar system that has been traveling around the sun for millions of years, and we’re basically getting to catch a little piece of it as it comes to the Earth.”
Comets and asteroids are some of the oldest objects in our solar system. By studying their composition and properties, scientists get a glimpse of what the early solar system was like before the planets formed, which helps them better understand the origin of our solar system, Fortenberry said. “There have been several space missions out to comets and asteroids, but this is a way of doing it a little closer to Earth and a lot cheaper.”
The biggest advantage of observing meteors from space is being above Earth’s atmosphere and atmospheric elements such as clouds, which block the view, Fortenberry said. Ground observations of meteors are also limited to short periods of time and small portions of the atmosphere.
Project Meteor will allow researchers to monitor meteors passing through Earth’s atmosphere over longer periods of time without the limitations of atmospheric interference.
The project Meteor camera records continuous video during each night pass as the ISS orbits the Earth. The camera’s lens is designed with a wide aperture, allowing it to capture high-resolution images in low light that enable the detection of even small meteors.
The project is already generating large amounts of data, currently filling a 750-GB hard drive each week. The team has received some of the data for analysis by downlink, but for the rest they must wait until the hard drives return to Earth on SpaceX CRS-10, which launched to the ISS earlier this month.
Testing New Technology to Directly Image Distant Planets
One of the biggest ideas humans have pondered is the possible existence of life elsewhere in the universe. Is the Earth one-of-a-kind, or are there other planets like ours? Are we alone, or does other life exist somewhere else out there?
Scientists have now found conclusive evidence of exoplanets orbiting distant stars, bringing us closer to answering these fundamental questions. Scientists can discover exoplanets by observing the gravitational effects they have on the stars they orbit or by observing the change in starlight when the orbiting planet passes in front of its star. However, Earth-size exoplanets still remain largely invisible to us and cannot yet be studied directly. These exoplanets are billions of times dimmer than their host stars and are incredibly close to the stars, thus imaging them is a significant challenge.
Researchers at the Florida Institute of Technology are aiming to change this by utilizing the ISS National Lab to test a new technology called a charge injection device (CID) that will allow scientists to directly image planets around distant stars. For a typical camera, this is difficult because the star is so bright that it saturates the image, washing out the faint light from the planet. The CID, however, does not have this problem due to its design, said principal investigator Daniel Batcheldor, professor at the Florida Institute of Technology.
“It’s been very interesting seeing all of these new results coming out about the plurality of worlds around other stars,” Batcheldor said. “The CID is a type of sensor that in the future, if mounted on the right type of telescope, will be able to take direct images of distant planets—rather than just seeing the gravitational effects of a planet or the light blocked during a transit, which is what we can do now.”
The CID is unique in that it can read light from each pixel independently. This allows the very bright pixels to be read quickly without affecting the pixels around the bright object that are much fainter. This allows researchers to directly image faint objects next to very bright objects within the same frame—such as the faint light of a planet next to a very bright star.
The team tested the CID using a small ground-based telescope at the Florida Institute of Technology, and the results were published in the January 2016 issue of the Publications of the Astronomical Society of the Pacific. The team found that the CID imaged several small stars (never before catalogued) around the brightest star in the night sky, Sirius. The faintest of these stars was 70 million times dimmer than Sirius itself. Although these ground-based results are exciting, the ideal location for astronomical observations is not on the ground, but in space, Batcheldor said.
To ensure that the technology works as it should in space, the team will be testing the CID onboard the ISS National Lab, and the payload launched to the ISS on SpaceX-10 earlier this month. However, for this mission, the team will not be trying to image planets and stars; instead, the CID will observe a special test pattern inside a box positioned on the NanoRacks external platform outside the ISS. The test pattern is designed to test the extreme contrast ratio ability of the CID. From space, the team expects the CID to achieve a contrast ratio in which the faint object is one billion times fainter than the bright object—the same contrast ratio as between an Earth-like planet and a sun-like star.
The ability to directly image planets around distant stars will help scientists learn more about other planets that may be similar to Earth in size and composition. “The science is massively exciting,” Batcheldor said. “An understanding of planets around other stars is going to lead toward the question of whether we are alone in the universe and whether or not there’s actually life on some of these other planets.”
Searching For Signs of Dark Matter and Primordial Antimatter
The Big Bang model postulates that the universe began from a tiny, hot, dense point and quickly expanded outward—still expanding today. To better understand the origin and composition of the universe, scientists are asking two key questions: Is there evidence of primordial antimatter (original antimatter from the early universe) existing somewhere in the universe? And is there evidence of dark matter?
Researchers working on AMS-02 are seeking to answer both of these questions. The Alpha Magnetic Spectrometer collaboration is searching for evidence of dark matter and primordial antimatter using a large magnet and six particle detectors onboard the ISS National Lab to measure cosmic rays (high-energy particles) passing through our solar system.
AMS-02 is the most sensitive particle detector to ever operate in space, and it allows researchers on Earth to measure the mass, momentum, speed, and charge of particles that pass through the space-based detectors. AMS-02 was launched to the ISS on the Space Shuttle Endeavour in May 2011 and has measured more than 90 billion particles to date.
What is Antimatter?
For each type of matter particle, there is a corresponding antimatter particle. The antimatter particle has the same mass as the matter particle but the opposite charge. For example, a proton has a positive charge, and an antiproton has a negative charge. When matter and antimatter interact, they annihilate into energy.
According to the Big Bang model, there should have been equal amounts of matter and antimatter at the beginning of the universe. In the lab, scientists have detected antimatter particles produced from high-energy collisions of matter particles, but no one has ever detected primordial antimatter.
This has led scientists to the question Where is all the antimatter left over from the Big Bang? Because primordial antimatter has never been detected, the current prevailing theory is that there was an imbalance, or asymmetry, of matter and antimatter at the beginning of the universe that resulted in the annihilation of all the antimatter. If evidence of primordial antimatter were found, it would overturn this theory.
AMS-02 is searching for evidence of primordial antimatter by looking for antihelium nuclei. Collisions of particles in space often produce antiprotons and positrons (the antimatter partner of the electron). However, it is highly unlikely that particle collisions would produce an antimatter particle of an element, such as an antihelium nucleus. It is more likely that an antihelium nucleus would be primordial antimatter left over from the Big Bang. For this reason, detection of antihelium nuclei would strongly suggest the existence of primordial antimatter in the universe.
Previous experiments have indicated that if primordial antimatter exists, it is rare, said AMS-02 deputy spokesperson Michael Capell of the Massachusetts Institute of Technology. In order to confirm the existence of primordial antimatter in a statistically significant way, AMS-02 would need to detect not just one or two antihelium nuclei, but several. This would take a long time and would require a lot of data.
“If you examined millions of helium-like cosmic rays, you wouldn’t find that one was actually antihelium—so AMS-02 is extending this search to the level of billions,” Capell said. “However, even with an experiment as large as AMS-02, it takes years of continuous operations to collect these billions of cosmic rays, and each must be examined in detail to figure out if it is or is not antihelium.”
What is Dark Matter?
Dark matter, an invisible form of matter that does not reflect, absorb, or emit light, is believed to be prevalent in the universe. Scientists postulate dark matter exists because of a gravitational effect observed in galaxies.
As a galaxy rotates, gravity holds together all of the matter in the galaxy, keeping it from being flung apart as it spins. However, scientists have found that galaxies appear to be rotating at speeds faster than they should be based on the amount of matter that can be observed in the galaxies. In other words, the amount of matter that can be observed in the galaxies does not provide enough mass for gravity to be able to hold the galaxies together at the speeds at which they are rotating.
The fact that galaxies are not being flung apart led scientists to believe that there must be some form of invisible matter that we cannot directly detect that is providing more mass, and thus more gravity to hold the galaxies together. Scientists termed this invisible matter “dark matter.” Because dark matter cannot be directly detected, AMS-02 is looking for evidence of dark matter interactions with matter or other dark matter.
The AMS-02 collaboration has had eight major papers published in Physical Review Letters and has repeatedly made measurements that existing theories cannot explain—redefining high energy physics. Several AMS-02 results hint at the existence of dark matter; however, more data is needed to confirm evidence of its existence.
“While the AMS-02 measurements hint at the existence and nature of dark matter, we can’t yet pin it down,” Capell said. “However, if the AMS-02 measurements continue the trend they have shown so far, we should be able to determine the mass of dark matter.”
By utilizing the ISS National Lab to look outward into space, we are learning more about the universe around us. We can study meteors to get a glimpse of what our early solar system was like, we can use new technology to directly image distant Earth-like exoplanets that could potentially harbor life, and we can use cutting-edge particle detectors to gain a better understanding of the origin and composition of our universe.