The Stratospheric Observatory for Infrared Astronomy, also known as SOFIA, will conduct a series of science observations from Germany in February and March, 2021 after coming out of a specialized maintenance check conducted by Lufthansa Technik.
SOFIA is a joint project of NASA and the German Aerospace Center. NASA’s Ames Research Center in California’s Silicon Valley manages the SOFIA program, science, and mission operations in cooperation with the Universities Space Research Association (USRA), headquartered in Columbia, Maryland, and the German SOFIA Institute at the University of Stuttgart. The aircraft is maintained and operated by NASA’s Armstrong Flight Research Center Building 703, in Palmdale, California.
Recently, Lufthansa Technik completed scheduled maintenance on the aircraft and telescope upgrades at their facility in Hamburg, Germany. Lufthansa Technik has held a contract to maintain the aircraft for years.
The flying observatory is going to take advantage of its proximity to science teams at the Max Planck Institute of Radio Astronomy in Bonn and the University of Cologne, which operate the instrument called German Receiver at Terahertz Frequencies, or GREAT, to conduct research flights from the Cologne Bonn Airport.
“We’re taking advantage of SOFIA’s ability to observe from almost anywhere in the world to conduct compelling astronomical investigations,” said Paul Hertz, director of astrophysics at NASA Headquarters in Washington. “This observing campaign from Germany is an excellent example of the cooperation between NASA and DLR that has been the strength of the SOFIA program for over 25 years.”
Often SOFIA flies in the Southern Hemisphere out of Christchurch, New Zealand but is taking advantage of the trip into Hamburg to conduct about 20 overnight research flights that will focus on high-priority observations, including several large programs that were rescheduled from spring 2020 due to the COVID-19 pandemic. SOFIA will use its GREAT instrument to search for signatures of celestial molecules, ions and atoms that are key to unlocking some of the secrets of the universe, the groups say.
Infrared astronomy is a segment of the astronomy looking into a specific frequency or wavelength. The SOFIA project is managed and funded by the two national aerospace agencies, the U. S.’s NASA and Germany’s DLR. The aircraft is a highly modified Boeing 747 special performance (SP) aircraft with a 2.7 meter telescope on board, according to Michael Toberman, SOFIA operations director, NASA and Heinz Hammes, SOFIA project manager, German Aerospace Center (DLR) who spoke at a Zoom press conference in Hamburg as the work at Lufthansa Technik was being wrapped up. They stressed the 747 aircraft was chosen not because of the long range capabilities, but because of the ability to fly at very high altitudes.
The two experts explained that the advantage of having the observatory onboard an aircraft, rather than launching a satellite based observatory, is the ability to update and improve the observatory equipment on a regular basis as technology leaps forward. You can develop a new instrument and you can basically access the observatory, which is very difficult when the observatory is on a satellite. The aircraft was procured from United Airlines in 1997 and has been heavily modified with equipment and of course the telescope sensors. The primary mirror is 2.7 meters. But it is the pointing stability that is crucial. It has a pointing stability of 0.2 arc seconds.
“So what does that mean? How is it possible to have the world seeing things from a flying aircraft with all this rocking and rolling and shaking? To stabilize the telescope is definitely the hardest part of the whole story. So imagine a single one cent coin and the laser point. What would that mean with regard to the distance between the laser pointer and the coin? The, the answer is it’s a stunning 10 miles, 16 and a half kilometers. So you try to point at a coin with a laser pointer and at a distance of 16.5 kilometers. This is the precision that we achieve, and we achieve it while flying about 560 miles per hour at 45,000 feet with the door open. This is what we actually can do with Sophia,” Michael Hütwohl, SOFIA Telescope manager, Deutsches SOFIA Institut (DSI).
“Some prominent science results that we have achieved recently I think you all have heard about the detection of water on the sunlit surface of the moon, which was published late last year. This is definitely a very important and prominent observation for SOFIA. But also the detection of helium, which is supposed to be the first molecule that has ever been built in the universe. This was also a very prominent observation that we made,” said Hütwohl. See sidebar next page for more on the helium discovery and other major scientific discoveries by SOFIA.
Indeed, SOFIA provided “direct unambiguous evidence of water molecules on the Moon outside the permanent shadow at the Moon’s poles” NASA says. SOFIA succeeded in detecting the molecules in the southern hemisphere of the Moon with the FORCAST (Faint Object InfraRed CAmera for the SOFIA-Telescope) instrument. The results of that scientific research work were published in the scientific journal, Nature Astronomy on October 26, 2020.
“With SOFIA, we have finally been able to provide the long-awaited, unequivocal proof that water also exists on the warmer, sunlit lunar surface,” explains Bernhard Schulz, SOFIA Science Mission Operation deputy director of the University of Stuttgart. A team led by Casey Honniball from the Hawaiian Institute of Geophysics and Planetology had already observed the Moon with the FORCAST instrument on board SOFIA on August 30, 2018. They were able to detect the unique fingerprint of molecular water in the mid-infrared range (six micrometers wavelength) near the Clavius crater in the Moon’s southern hemisphere. Confirming water on the sunlit surface of the Moon indicates that water may be distributed across the lunar surface, and not limited to cold, shadowed places, NASA says, and could be relevant for deep space exploration.
NASA says SOFIA offered a new means of looking at the Moon. Flying at altitudes of up to 45,000 feet, the 747SP jetliner with the 106-inch diameter telescope reaches above 99% of the water vapor in Earth’s atmosphere to get a clearer view of the infrared universe. Using FORCAST for the Telescope, SOFIA was able to pick up the specific wavelength unique to water molecules, at 6.1 microns, and discovered a concentration of them in the sunlit Clavius Crater, according to NASA.
NASA says during the German missions happening now, they will be focusing on the following three research topics:
How Stars Affect Their Surroundings
In stellar nurseries like Cygnus X, newborn stars can destroy the clouds in which they’re born. Researchers will use SOFIA to create a map of ionized carbon, a gas the young stars are heating, to better understand this process. Ionized carbon’s chemical fingerprint can determine the speed of the gas at all positions across the celestial clouds. The signal is so strong that it reveals critical details that are otherwise hidden from view deep inside natal clouds. The data may also help explain the source of the mysterious bubble-like structures that were detected by the Herschel Space Observatory and Spitzer Space Telescope but have yet to be fully understood.
Searching for Clues About Cosmic Rays
The team will search for gases that can reveal the presence of cosmic rays, highly energetic charged particles that stream through our Milky Way galaxy. When a hydrogen atom combines with another element, such as argon or oxygen, simple molecules called hydrides are formed, some of which can be used to find cosmic rays. While cosmic rays can be detected directly within our solar system, astronomers know much less about their presence elsewhere in space. By measuring the concentration of hydride molecules, SOFIA’s observations will help researchers understand how common cosmic rays are in different parts of our galaxy, providing clues about the origin of these mysterious particles.
Understanding the Evolution of The Cigar Galaxy
SOFIA previously found that the Cigar galaxy’s powerful wind, driven by the galaxy’s high rate of star birth, is aligned along the magnetic field lines and transports a huge amount of material out of the galaxy. Now, researchers will study ionized carbon gas, which traces star formation, to learn how this intense star birth and wind are affecting the evolution of the galaxy.
Beyond Water on the Moon: Major Discoveries by SOFIA
The Universe’s First Type of Molecule Found
SOFIA found the first type of molecule to form in the universe, called helium hydride. It was first formed only 100,000 years after the Big Bang as the first step in cosmic evolution that eventually led to the complex universe we know today. The same kind of molecule should be present in parts of the modern universe, but it had never been detected outside of a laboratory until SOFIA found it in a planetary nebula called NGC 7027. Finding it in the modern universe confirms a key part of our basic understanding of the early universe.
• Newborn Star in Orion Nebula Prevents Birth of Stellar Siblings
The stellar wind from a newborn star in the Orion Nebula is preventing more new stars from forming nearby as it clears a bubble around it. Astronomers call these effects “feedback,” and they are key to understanding the stars we see today and those that may form in the future. Until this discovery, scientists thought that other processes, such as exploding stars called supernovas, were largely responsible for regulating the formation of stars.
• Weighing a Galactic Wind Provides Clues to the Evolution of Galaxies
SOFIA found that the wind flowing from the center of the Cigar Galaxy (M82) is aligned along a magnetic field and transports a huge amount of material. Magnetic fields are usually parallel to the plane of the galaxy, but the wind is dragging it so it’s perpendicular. The powerful wind, driven by the galaxy’s high rate of star birth, could be one of the mechanisms for material to escape the galaxy. Similar processes in the early universe would have affected the fundamental evolution of the first galaxies.
• Nearby Planetary System Similar to Our Own
The planetary system around the star Epsilon Eridani, or eps Eri for short, is the closest planetary system around a star similar to the early Sun. SOFIA studied the infrared glow from the warm dust, confirming that the system has an architecture remarkably similar to our solar system. Its material is arranged in at least one narrow belt near a Jupiter-sized planet.
• Magnetic Fields May Be Feeding Active Black Holes
Magnetic fields in the Cygnus A galaxy are feeding material into the galaxy’s central black hole. SOFIA revealed that the invisible forces, shown as streamlines in this illustration, are trapping material close to the center of the galaxy where it is close enough the be devoured by the hungry black hole. However, magnetic fields in other galaxies may be preventing black holes from consuming material.
• Magnetic Fields May Be Keeping Milky Way’s Black Hole Quiet
This image shows the ring of material around the black hole at the center of our Milky Way galaxy. SOFIA detected magnetic fields, shown as streamlines, that may be channeling the gas into an orbit around the black hole, rather than directly into it. This may explain why our galaxy’s black hole is relatively quiet, while those in other galaxies are actively consuming material.
• “Kitchen Smoke” Molecules in Nebula Offer Clues to Building Blocks of Life
SOFIA found that the organic, complex molecules in the nebula NGC 7023 evolve into larger, more complex molecules when hit with radiation from nearby stars. Researchers were surprised to find that the radiation helped these molecules grow instead of destroying them. The growth of these molecules is one of the steps that could lead to the emergence of life under the right circumstances.
• Dust Survives Obliteration in Supernova
SOFIA discovered that a supernova explosion can produce a substantial amount of the material from which planets like Earth can form. Infrared observations of a cloud produced by a supernova 10,000 years ago contains enough dust to make 7,000 Earths. Scientists now know that material created by the first outward shock wave can survive the subsequent inward “rebound” wave generated when the first collides with surrounding interstellar gas and dust.
• New View of Milky Way’s Center Reveals Birth of Massive Stars
SOFIA captured an extremely crisp infrared image of the center of the Milky Way Galaxy. Spanning a distance of more than 600 light-years, this panorama reveals details within the dense swirls of gas and dust in high resolution, opening the door to future research into how massive stars are forming and what’s feeding the supermassive black hole at our galaxy’s core.
• What Happens When Exoplanets Collide
Known as BD +20 307, this double-star system is more than 300 light years from Earth likely had an extreme collision between rocky. A decade ago, observations of this system gave the first hints of a collision when they found debris that was warmer than expected to be around mature stars that are at least one billion years old. SOFIA’s observations discovered the infrared brightness from the debris has increased by more than 10%, a sign that there is now even more warm dust and that a collision occurred relatively recently. A similar event in our own solar system may have formed our Moon.