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Why NASA chose Senegal to observe a frozen world beyond Pluto

Salma Sylla Mbaye, is the first Ph.D. student in Astronomy in Senegal. She is in her second year at Cheikh Anta Diop university in Dakar. Mbaye was part of two dozen Senegalese astronomers and scientists that accompanied NASA’s New Horizons team to observe the flyby of an ancient object called the Ultima Thule (beyond the known world) orbiting just beyond Pluto. The views expressed in this commentary are solely hers.

Dakar, Senegal (CNN)On a night in August, an object called 2014 MU69 passed in front of a star and blocked its light. This phenomenon, called a stellar occultation, lasted just a second and was visible only in certain regions in Africa (more exactly in Senegal, Mali and Algeria) and in South America in Colombia.

MU69 is an icy object of the Kuiper Belt, (informally named Ultima Thule) which was discovered in June 2014 with the Hubble Space Telescope.
NASA is pursuing this object to learn more about the origins of our solar system.
Senegal was chosen to observe this occultation, because of its political stability, and the existence of a community of amateur astronomers and scientists.
The choice of Senegal was made despite the challenging climatic conditions in August (rainy season), which offered a probability of success of only 50%.
The observations organized by NASA in collaboration with Senegal will help with precious data for the preparation of the New Horizon spacecraft’s flyby of MU69, which will take place on the 1st of January 2019. It will help to confirm its shape, speed and position.
This information is critical to make a successful approach of a small object at a distance a billion miles away from us.

Most distant world ever explored

MU69 is about 6.5 billions kilometers away from the sun. This is the most distant and most primitive world ever explored by spacecraft. The team behind NASA’s New Horizons, after successful exploration of the dwarf planet Pluto and its moons in July 2015, decided to extend the mission further.
Considering the possibilities offered by the current trajectory of the New Horizons probe, MU69 was chosen as the next target for a close flyby. In order to collect data for this object, the New Horizons team took advantage of a stellar occultation on July, 3, 2017, visible in Argentina and South Africa.
The results from these observations suggested that the object has an elongated shape or could consist of two objects rotating around each other.
For the observation in August 2018, approximately 21 Senegalese scientists actively participated in the preparation by choosing possible location sites across the country in a region extending from Thiès to Saint-Louis.
They marked the observing sites, and this work was critical as NASA participants had to reach the observation sites, often in rural areas, by night. Then, the Senegalese scientists were trained to use the telescope and acquisition systems, to be fully operational during the night of observation.
The goal of the training was to be able to set the telescope and acquisition system, point the telescope to the field of the view of the occulted start and acquire data for 10 to 20 minutes.
Each of the teams included one Senegalese scientist (either a postgraduate, a PhD student or a professor) and two astronomers from NASA or France (French planetary scientists also participated in the experiments).
During the occultation observed in Senegal we have collected data using telescopes pointed in 21 different sites. These data are photometric measurements, which allow an accurate record of the time when MU69 passes in front of the star and blocks its light.
Since it was rainy season in Senegal, we were not able to collect data in all of the 21 sites. In total, three sites acquired useful data.
But, given the weather during the occultation night, we were really relieved that the occultation had been observed.

Origins of our solar system

In Senegal, astronomy is not taught at university level. However the Senegalese government is building a planetarium and an astronomical observatory.
For the new generation, Senegal would like to focus on research areas where it can contribute, based on available equipment, expertise and financial means.
This includes the monitoring of meteoroid impacts on the Moon or giant planets, the survey of variable stars, the search of observation of exoplanets, or the monitoring of the atmosphere of giant planets.
The exploration of MU69 by New Horizons will allows to us understand more about the origins of our solar system.
The flyby will reveal an unknown world. As for Pluto, the knowledge about this object will change from a ‘tiny dot’ to high resolution images of mysterious landscapes.
The recent geological activity of Pluto, the existence of the largest 1,000 kilometer wide heart shaped nitrogen glacier in the solar system, and the blue color of its atmosphere were among the top 10 unexpected discoveries as a result of the New Horizons flyby of Pluto. Who can tell what will be found at MU69?
The future of this collaboration is also in our hands, by developing research projects in our country and at African level for example the Africa Initiative for Planetary and Space Science and maintaining the links that were established with NASA scientists on this occasion.
Ideas, such as organizing a future workshop of planetary atmospheres, have been raised. We learn a lot by comparing our planet with other planets, and in the context of climate change, such a workshop about planetary atmospheres in Senegal would really make sense.

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