Experiment on the space station to investigate the origins of components

"We're made of star stuff." said astronomer Carl Sagan. The atoms that make up our bodies' chemistry did not originate on Earth; they originated from distant space. The great bang generated hydrogen, helium, and a trace of lithium, but heavier elements, which are required for life, originated via star-related processes. Scientists can now delve further deeper. Particular stellar processes generate which elements? And who are the celebrities involved?


TIGERISS, a novel experiment envisioned for the International Space Station, tries to find out. The latest NASA Astrophysics Pioneers mission, TIGERISS, has been selected. Pioneers are small-scale astrophysics missions that allow for novel studies of cosmic events. Experiments meant to travel on tiny satellites, research balloons, the space station, and payloads that may orbit or land on the Moon could be among them. Earlier this year, the four prior Pioneers mission designs, chosen in January 2021, were given the go-ahead to begin building and would fly later this decade.


The Pioneer missions, according to Mark Clampin, director of the astrophysics division at NASA Headquarters in Washington, are an invaluable opportunity for early- to mid-career scientists to conduct compelling astrophysics investigations while gaining real-world experience in building space-based instrumentation. The Pioneers extend their reach to the space station with TIGERISS, which provides a unique platform for studying the universe.


Brian Rauch, research associate professor of physics at Washington University in St. Louis, has been studying elemental origins and high-energy particles since he was an undergraduate there. Rauch spent nearly three years in college working on a particle detector known as the Trans-Iron Galactic Element Recorder, or TIGER. The experiment had its maiden balloon flight in 1995, and long-duration balloon flights from Antarctica launched a version of TIGER from 2001 to 2002 and 2003 to 2004.


Rauch's research career grew, and he assisted in the evolution of TIGER into the more advanced SuperTIGER. SuperTIGER took out from Antarctica on its maiden flight on December 8, 2012, travelling at an average altitude of 125,000 feet and setting a new record for the longest research balloon flight of 55 days. From December 2019 to January 2020, SuperTIGER flew for 32 days. The experiment assessed the abundance of elements on the periodic table up to and including barium (atomic number 56).

The TIGER instrument family will reach new heights aboard the International Space Station. The TIGERISS experiment will be able to do higher-resolution measurements and collect heavy particles that a research balloon would not be able to do. A perch on the space station will also enable a bigger physical experiment 3.2 feet (1 meter) on a side than could fit on a tiny satellite, potentially expanding the size of the detector. And, in comparison to a balloon ride, the experiment may endure more than a year. Individual elements as heavy as lead, atomic number 82, will be able to be measured by researchers.


All stars exist in a delicate equilibrium; they must emit enough energy to counterbalance their own gravitational pull. That energy is created by fusing elements together to create heavier ones, such as carbon, nitrogen, and oxygen, all of which are essential for life as we know it. However, when a large star attempts to fuse iron atoms, the process does not provide enough energy to overcome gravity, and the star's core collapses. This causes a supernova explosion, in which shock waves expel all of the heavy elements created in the center of the star. The explosion itself produces heavy components and speeds them to near-light speed particles known as "cosmic rays."


However, this is not the only way heavy atoms may arise. When a neutron star, a superdense relic of a supernova, collides with another neutron star, the catastrophic merger produces heavy metals.


According to Rauch, TIGERISS will not be able to pinpoint specific supernovae or neutron star collisions but will provide context for how these fast-moving components are propelled and transported around the galaxy.


So, how much do supernovae and neutron star mergers contribute to the production of heavy elements?


That, according to Rauch, is the most intriguing question we can hope to answer.


TIGERISS observations are critical to understanding how our galaxy generates and distributes stuff, according to John Krizmanic, TIGERISS's deputy principal investigator stationed at NASA's Goddard Space Flight Center in Greenbelt, Maryland.


TIGERISS will also provide data on the overall amount of cosmic rays, which pose a risk to astronauts.

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