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Astronomers keep being brief when they study "normal" matter, the material that makes up galaxies, stars, and planets. A new NASA-commissioned CubeSat mission called HaloSat, deployed from the International Space Station on July 13, will help scientists search for the missing matter of the universe by studying the X-rays of the hot gas that surrounds the Milky Way [19659002] (CMB) is the oldest light in the universe, radiation dating back 400,000 years. Calculations based on CMB observations indicate that the universe contains: 5% protons of normal matter, neutrons, and other subatomic particles; 25 percent dark matter, a substance that remains unknown; and 70% black energy, a negative pressure accelerating the expansion of the universe.
As the universe expanded and cooled, normal matter turned into gas, dust, planets, stars, and galaxies. But when astronomers calculate the estimated masses of these objects, they represent only about half of what cosmologists say to be present.
"We should have everything we had today when the universe was 400,000 years old," Philip Kaaret, principal investigator of HaloSat at the University of Iowa (UI ), who directs the mission. "The answer to this question can help us learn how we went from the CMB's state of uniformity to the large-scale structures we see today."
The researchers believe that the missing material may be in hot gas located either in the space between galaxies or in galactic halos, extended components surrounding individual galaxies.
HaloSat will study gas in the Milky Way halo that is around 2 million degrees Celsius (3.6 million degrees Fahrenheit). At such high temperatures, oxygen loses most of its eight electrons and produces the X-rays measured by HaloSat.
Other X-ray telescopes, such as the Neutron Star of the NASA Interior Composition Explorer and the Chandra X Observatory, study individual sources. looking at the little spots of the sky. HaloSat will look at the entire sky, 100 square degrees at a time, which will help determine if the diffuse galactic halo is more shaped fried egg or sphere.
"If you think of the galactic halo in the model fried egg, it will have a different distribution of brightness when looking directly from the Earth than when looking at wider angles," Keith said. Jahoda, co-investigator HaloSat and astrophysicist at NASA's Goddard Space Flight Center in Greenbelt, Maryland "If it's almost spherical in shape, compared to the dimensions of the galaxy, then we're expecting it to be the same." it is more or less the same in all directions. "
The shape of the halo will determine its mass, which will help scientists to understand if the missing matter of the universe is in galactic halos or elsewhere.
HaloSat will be the first astrophysics mission that minimizes the effects of X-rays produced by the solar wind load exchange.This emission occurs when the solar wind, a stream of highly charged particles from the Sun, interacts with uncharged atoms like those in the Earth's atmosphere. Particles in the solar wind pick up the electrons of uncharged atoms and emit X-rays. These emissions have a spectrum similar to what scientists expect to see in the galactic halo.
"Every observation we make has to a certain extent this solar wind emission, but it varies with the weather and the solar wind," says Kuntz. , a HaloSat co-researcher at Johns Hopkins University in Baltimore. "The variations are so hard to calculate that many people mention it and then ignore it in their observations."
In order to minimize these solar rays, HaloSat will collect most of its data for 45 minutes at night. half of its 90-minute orbit around the Earth. On the side of the day, the satellite will recharge with its solar panels and transmit data to the NASA Wallops Flight Facility in Virginia, which will relay data to the Mission Operations Control Center in Blue Canyon. Technologies in Boulder, Colorado
a wonderful opportunity to get your hands on an instrument, to work on the complexities of something happening in the space, and to plan all the problems that arise from it, which is very fun, "said Daniel LaRocca, a graduate student in the mission team
HaloSat measures 4 x 8 x 12 inches (about 10 x 20 x 30 centimeters) and weighs about 26 pounds (12 kilograms). This is the first CubeSat mission of scientific astrophysics, but a CubeSat called the arcsecond space telescope enabling astrophysical research (ASTERIA), conducted by NASA's Jet Propulsion Laboratory in Pasadena, California, launched in 2017 to demonstrate astrophysical technology. CubeSat missions typically take about three years to develop, through the launch and start of data collection, the optimal time for undergraduate or graduate students to involve from start to finish.
"HaloSat has definitely shaped my future out," said Hannah Gulick, an undergraduate student of the UI working on the mission. "I hope to be an astrophysicist who builds instruments and then uses the observations of these instruments to make my own discoveries. "
HaloSat is a NASA CubeSat mission conducted by the University of Iowa at Iowa City.S NASA's Goddard Space Flight Center at Greenbelt, Maryland, NASA's Wallops Flight Facility in Wallops Island, Virginia, Blue Canyon Technologies in Boulder, Colorado, Johns Hopkins University in Baltimore, and major contributions from partners in France. NASA's CubeSat Launch Initiative as part of the 23rd edition of the Nanosatellites Educational Launch Mission
