In 1992 we found our first exoplanets. We have discovered many thousands more. The first steps in identifying other worlds that could have life were taken.
planetary scientists want to study exoplanet atmospheres.
ARIEL will be a powerful tool.
ARIEL is a name for a large-survey. The European Space Agency has a Cosmic Vision Program. ARIEL wants to examine the atmospheres of about 1,000 previously-confirmed exoplanets. It will study the composition of the atmospheres.
ARIEL is still in the design study phase, and its tentative launch date isn't until 2028. Some of the mission's critical details are still being worked on. Automatic scheduling is one of the details, and a new paper looks at how the mission might work.
Ariel mission planning involves scheduling the survey of a thousand exoplanets. The author is a researcher at theInstitut de Ciencies de l'Espai in Barcelona, Spain. The paper can be found at the pre-press site.
NASA designed missions to find exoplanets. ARIEL is focused on studying exoplanets. Rather than looking at the sky for more, it will look at known exoplanets.
ARIEL will answer questions in exoplanet science. It will look at the composition of exoplanets, the formation and evolution of planetary systems, and the physical processes that shape exoplanet atmospheres.
We are used to thinking about the planets in our own Solar System. The compositions of exoplanets can vary greatly. ARIEL will help us understand them better. The theoretical internal structure of the exoplanet GJ 3470 b is shown in this artist's illustration. It is not like any other planet in the Solar System. The planet is less massive than Neptune. Unlike Neptune, which is 3 billion miles from the Sun, GJ 3470 b may have formed very close to its red dwarf star as a dry, rocky object. It pulled in hydrogen and helium gas from a circumstellar disk. The planet stopped growing after the disk dissipated. The system may have looked at the disk long ago. The composition of GJ 3470 b's very clear and deep atmosphere has been analyzed by NASA's Hubble and Spitzer space telescopes. There are many planets of this mass in our universe. The image is from NASA.
Detailed knowledge of exoplanet atmospheres tells scientists how they formed. Planets form in disks of gas and dust around young stars. When scientists know about the composition of the atmosphere and its thermal structure, they can better understand how quickly a planet formed.
Other questions can be addressed by science results from ARIEL. How life got started on Earth is one of the questions.
Earth is the same as exoplanets in that it formed from a disk. Evidence for life's beginnings is long gone from Earth's geological record. The question of life's origins can be answered by observing exoplanets. If ARIEL can show us how physical and chemical environments on planets similar to Earth evolved, we can get a glimpse of early Earth.
ARIEL has to use its time wisely to accomplish this. That is what the new paper explores.
Automatic scheduling techniques are becoming a crucial tool for the efficient planning of large surveys.
The previous missions were surveys. They looked for transit signals in the sky. ARIEL is different. It will not watch a preset area of the sky but a list of targets. When mission designers know where those targets are, they can schedule the mission more precisely and efficiently. Since the mission isn't based on passive observations, there are some stringent constraints on the planning.
The difference between transits and occultations can be seen in this graphic. When a planet passes in front of a star, it makes the star faint. A transit is a phenomenon. The light from the planet is obscured by the star for a short time when the planet passes behind it. This is a phenomenon. Credit is given to the European Space Agency.
The ARIEL mission will last four years. The authors conclude that the mission will be able to fulfill the scientific objectives, with a total exposure time of about 75%.
ARIEL will watch some exoplanets. As the planets circle their stars, it will watch their spectrum. Phase curves give a more detailed picture of an exoplanet's atmosphere than transits and occultations can.
The physical processes that drive the transport of heat from the hot day side to the cooler night side are shown in the changes in starlight reflected by a planet. The phase curves reveal details of the planet's atmosphere, including the presence of clouds, and possibly even hints of the cloud composition. The image is from the European Space Agency.
ARIEL must balance more than transits. The scheduling equation includes operations like maintaining the spacecraft. ARIEL needs periodic recalibration to observe bright G-type stars. About 3% of the mission takes up 300 hours per year to calibrate. Station-keeping operations take about four hours per month or 50 hours per year. That adds up to less than 1% of the mission.
The factors put limitations on scheduling. In their paper, the authors talk about other topics beyond the scope of the article. Their scheduling method uses a combination of Evolutionary Computation, Genetic Algorithms, Evolutionary Algorithms, and a subset of EC called SWARM intelligence. Readers can look into the paper in more detail.
ARIEL has a list of targets. The MRS is a combination of known exoplanet targets and targets that are yet to be found by TESS. The targets were divided into tiers based on the type of observations they wanted to do with them. Tier one targets include all of the planets in the MRS at low resolution, and tier two includes a subset of the whole MRS at medium resolution. 50 of the most interesting exoplanets are around bright stars that will be observed longer to get the best resolution.
Tier 2 targets have a higher priority than tier 1 targets. It is easy to see how complicated the scheduling can get, and why mission designers use artificial intelligence and related methods to guarantee the most science results. It is even more complicated because the mission designers hope to complete other observations outside of the MRS.
ARIEL has potential targets in three tiers. It is beneficial to have targets scattered across the sky. The credit is given to the authors of 2019.
Outside of the MRS, tier 4 planets are extremely desirable scientific targets. Scientists want ARIEL to observe their phase curves. If it won't affect the mission's core science objectives, they'll be scheduled in. There are 43 targets in tier 4 that are further divided into three levels of priority.
There are back-up targets in case ARIEL can't observe some of the planets. There are back-up planets.
Most of us don't spend a lot of time thinking about mission scheduling, but this paper gives an interesting behind the scenes look. It is important that a mission has precise and effective scheduling. The ARIEL mission can be scheduled effectively enough to meet almost all of its science goals, according to simulations by the team. Problems, delays, and unexpected difficulties can be found in every mission.
The team writes that the main conclusion of the different simulations is that almost all the targets in the core sample can be observed as requested while meeting all mission and system requirements and constraints. The scheduler can be used to easily identify targets that are observable few times.
Some inactive time slots are inevitable due to the complexity of the scheduling and the hard and soft mission constraints. The time slots can still be maximized by re-serving some targets. It is possible to increase the number of well-characterized targets in the tier 3 subsample by a factor of? 2.5, or to survey several more Neptune and Earth-like planets considered as back-up targets.
The exoplanet is about 50 light years away. It is a potentially rocky world that is larger than Earth. It is an interesting target because of its composition and dense atmosphere. It is a red dwarf that is cooler and dimmer than our Sun. The image is from NASA.
ARIEL will take the science further than it is now. ARIEL project scientist Theresa Lueftinger talked about some of the expectations for the ARIEL mission in an interview with Innovation News Network. We will find things we had not expected or imagined. That happens frequently in science. This field of science is so exciting because of this.
ARIEL is one of three missions. There are known exoplanets in the vicinity of bright stars that are being focused on by Cheops. It is looking at planets in the size range. It wants to make high-precision observations of these planets to determine their bulk density.
ThePLAnetary Transits and Oscillations of stars will launch in 2026 and will search up to one million stars for exoplanet transits. PLATO wants to discover rocky exoplanets around stars like our Sun. There are Earth-like planets around their stars that might have liquid water on their surfaces.
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