SOFIA telescope recently completed a new set of observations of Venus to study the chemical composition of the planet's atmosphere. Observing Venus is particularly challenging to . Venus is located in an unobservable position in the sky and needs to be observed when the sun is about to set. For safety reasons, SOFIA can only turn on the telescope when the sun is above the horizon in very special circumstances. Care must be taken to avoid accidental observation of the sun by the telescope, causing damage to the telescope or aircraft.
Due to these special requirements, the flight planning and coordination of these observations requires extra care, discussion and special preparation.
The plan and preparation for observing Venus began more than two months before the flight. The pilots received special training from telescope engineers to understand the exact direction of flight before the sun sets to ensure safety. They carefully planned contingency measures and turns to ensure the safety of the telescopes and the aircraft.
Another challenge with these pre-sunset observations is to time each event in the flight plan. The exact time when the sun sets varies by altitude.
In addition, weather and air pressure can change the density of the atmosphere, which in turn will affect the refractive properties of the atmosphere. Refraction refers to the bending of the medium to light. Changes in atmosphere pressure, therefore its refractive capacity to sunlight, is a potential safety issue for observatory stations. SOFIA's flight planners designed and arranged detailed routes for Venus observations to ensure that SOFIA has no risk of accidental observation of the sun. Still, everyone in the flight carefully monitored the sky to see a green flash, a phenomenon that indicates that the sun has set on the horizon. Once the sun sets, the pilot turns the plane so that SOFIA can observe Venus.
SOFIA On the night before sunset, the rigid door on the upper layer was first opened so that SOFIA could observe Jupiter and prepare for Venus' instruments and telescopes. Jupiter is 90 degrees apart from the sunset in the sky, so SOFIA can safely observe the sun when it is above the horizon. In this brief observation of Jupiter, telescope operators and instrument scientists made the setup and calibrated as the sun continued to set. At this time, the plane turned and began to collect photos of Venus using the German terahertz frequency astronomical observation receiver (GREAT) instrument.
One of the purposes of this observation is to address recent reports on phosphine on Venus. Due to its high sensitivity, SOFIA and GREAT instruments will be able to set a strict upper limit on Venus' phosphine abundance. The ability to use GREAT to conduct multiple observations simultaneously. Venus Observation also studied hydrogen chloride and conducted the first search of atomic oxygen in Venus' atmosphere. Now that GREAT has observed Venus, the team of scientists who proposed these observations will begin to creatively reduce and analyze data.
