- 3243 - ASTRONOMY - using broader frequency coverage? With our eyes alone we have very limited coverage of everything that is out there . Telescopes have made a huge jump in all we can learn with bigger eyes. Telescopes developed technology to “see” far beyond the limited range our eyes can see, even through the traditional telescope.
------------- 3243 - ASTRONOMY - using broader frequency coverage?
- What’s possible when Earth and space-based telescopes work together to combine the range to see more of the universe at the same time? Scientists are exploring the potential benefits of coordinating ground, orbital and “in situ” based observations of objects. “ in situ” refers to planet formation.
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- The full electromagnetic spectrum with the different sub-bands has the different wavelengths contained in the electromagnetic spectrum, which is it important to capture the full width of to truly understand some transient phenomena.
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- The electromagnetic spectrum is extremely large. It includes all types of light, such as radio, infrared, x-rays, ultraviolet and visible light. There is no one single sensor that can collect data in all of those different wavelengths at the same time.
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- Therefore, scientists have developed a plethora of instruments that are extremely good at collecting data in one specific spectrum, such as radio (ALMA), or mid-range infrared (James Webb telescope).
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- The down side of this specialization is that those instruments are blind in other spectral ranges. If a scientific team is only observing in one type of light, there is a chance that they could miss important aspects of a phenomena they are studying that are only visible in a different spectral band.
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- Much of the planetary science data collected is the result of spacecraft that are sent to a planetary system to perform in situ observations. However, due to the high cost of developing space-based systems and then launching them into orbit, mission planners for these in situ missions must be very selective about what types of instruments they allow on board their spacecraft. What this normally means is that they are not able to bring imagers that are capable of covering the entire electromagnetic spectrum.
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- That is where coordination with ground and near-earth-orbit based telescopes comes in. There are many telescopes in those locations, such as the Atacama desert or Hawaii’s Mauna Kea, that are extremely large, and can provide very high resolution images in specific spectral bands, such as radio, microwaves, or infrared. Infrared is particularly useful as there is a lot of physical data points that can be obtained in a single measurement, such as pressure, temperature, and molecular abundances.
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- If a mission planner of a planetary exploration spacecraft mission can coordinate observations with these much larger, specialized observatories, they will no longer need to include them on their own spacecraft.
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- Another advantage that earth-based observatories have over their “in situ” counterparts is their ability to image a whole planet at once. Many orbiter or fly by missions are only capable of measuring part of their subject at a single point in time. This results in a loss of contextual understanding, as dynamic phenomena that might be observed in a single place by the in situ spacecraft might not be present over the entire surface of the planet or moon. Support from earth-based telescopes, whether on the ground or in space, could provide that larger context that the spacecraft itself lacks.
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- This sort of coordination to cover all of the spectral frequencies has already been accomplished with one in situ planetary mission: the “Juno spacecraft” currently in orbit around Jupiter. The resulting coordination between the Juno spacecraft and a series of earth-based observatories resulted in over 40 papers that used data from more than one observational source of the Jupiter system during that time.
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- Recording simultaneous parts of Jupiter in three different wavelengths shows that some features that particularly interesting are only visible on one wavelength. Images were taken in visible light, in mid-infrared, and at a different wavelength of infrared. Each image shows important features that can only been seen in one spectral band while remaining invisible in the other two.
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- Mars is of particular interest, as it is the most studied planet outside of Earth, and the only one with active rovers physically on its surface. Scientists interested in understanding where the methane from Mars’ atmosphere comes from would certainly benefit from a coordinated observational campaign between several of the orbiters around Mars (TGO and MAVEN), and earth-based telescopes the Infrared Telescope Facility in Hawaii.
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- The orbiters around Mars provide excellent two-dimensional slices of spectral data as they are passing over a specific strip of the planet. However, observatories closer to Earth can provide data on the entire hemisphere of the planet that is facing them, and add a layer of depth that would allow scientists to piece together a three-dimensional picture that would be impossible using only data from the orbiters.
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- There are still some limitations to earth-based observations, such as the fact that methane is present in Earth’s atmosphere as well, which could skew the data when looking at Mars.
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- To get around this problem, scientists came up with an ingenious method of only observing Mars while it is moving away from (or toward) Earth at more than 13 kilometers a second. This differential speed red- (or blue-) shifts the spectral signature of the Martian methane enough that it can be differentiated from that simply present in Earth’s atmosphere.
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- Another particularly interesting target of joint observations is Titan, the largest moon of Saturn, has been the subject of intense scrutiny in recent years due to its hydrocarbon lakes, and its methane/ethane based hydrological cycle.
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- The moon is so interesting it is about to receive it’s own in situ visitor in the form of the “Dragonfly” mission. When Dragonfly lands in 2034, many Earth-based telescopes will turn their eyes toward Titan, as the data collected from the surface can then be coordinated with more remote observations.
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- Dragonfly will be equipped a mass spectrometer, which allows the detection of molecules which are impossible to see remotely, and reveals the full composition of the atmosphere. Earth-based observation could in turn provide context for these measurements.
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- Dragonfly's lander will be the first to reach Titan's surface, and can provide local data to any coordinated observation program. Those combined observations will focus on the organic chemistry that is taking place on the moon.
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- An Earth-based tool is ALMA, the observatory is a series of radio telescopes, which are particularly good at observing organic compounds and making detailed maps of its observational subjects. Both capabilities would be particularly helping the Dragonfly mission.
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- Studying Titan and the evolution of its atmosphere, revealing dynamic processes, and leading to improved understanding of the moon. Unfortunately, it also revealed Titan is actively changing, making it less suitable as a flux calibration target. The ALMA team then switched to using a pulsar for future calibrations.
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- Unless the data on a given object was collected simultaneously by more than one observatory, the benefits of coordination are lost as transient phenomena would not be present in both those sets of data. There might be some simultaneous data of an object collected by more than one observational platform buried in their data archives.
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- Coordinating future observational efforts is much more likely to result in new discoveries rather than trawling through old data. Concerted observations may reveal phenomena that wouldn’t be visible without combining the datasets, revealing new and exciting glimpses into foreign worlds.
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- August 5, 2021 ASTRONOMY - using broader frequency coverage? 3243
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