On November 1st, NASA’s Lucy spacecraft flew by the small asteroid Dinkinesh. The spacecraft’s preliminary photos of this diminutive 0.4-mile-wide world have already illustrated the capabilities of its instrument suite. Excessive-resolution photos reveal that Dinkinesh’s floor is strewn with boulders and that it’s orbited by a small moon. Dinkinesh’s companion, in flip, is a contact binary comprised of two asteroids which had been fused collectively throughout a delicate collision. The encounter was a significant milestone in its personal proper, as each asteroid which we discover with a spacecraft has the potential to show us extra in regards to the substances which shaped the planets. Nonetheless, this preliminary flyby was only a foretaste of the information which the Lucy spacecraft will return over the approaching decade. Together with Dinkinesh, Lucy will examine eleven completely different planetesimals over the course of its mission.
Lucy is the 13th mission in NASA’s Discovery Program. This program permits scientists to design and suggest novel small planetary science missions to NASA. So far as interplanetary spacecraft are involved, Discovery missions are cheap, with growth budgets of $500 million or much less. These frequent, inexpensive flight alternatives steadiness out bigger Flagship missions and permit NASA to discover quite a lot of locations concurrently. Prior Discovery missions included the Mars Pathfinder lander, the Stardust comet pattern return mission, and the Daybreak mission to orbit the dwarf planet Ceres.
Lucy was pitched as the primary mission to Jupiter’s Trojan asteroids. The Trojans are a household of small our bodies which had been gravitationally rearranged by Jupiter through the early historical past of the Photo voltaic System. They’re trapped in clusters which orbit two of Jupiter’s Lagrange factors. At these areas, the gravitational forces of Jupiter and the Solar are balanced; these forces can maintain smaller objects in place indefinitely. Jupiter’s Trojans lead and path the planet in its orbit by 60 levels.
Whereas planetary scientists haven’t decided the origin of the Trojan asteroids, the purple tint of a few of these objects means that they could have been captured from the Kuiper belt. This broad zone of particles is situated past the orbit of Neptune, and Pluto is its largest and most well-known member. If this concept is appropriate, the Trojans is likely to be wealthy in water ice and natural compounds. Together with carbonaceous asteroids akin to OSIRIS-REx’s goal, Bennu, they could have performed a necessary position in delivering the substances for all times to Earth. Over the course of its mission, Lucy will fly by eight Trojans and map their surfaces to check the speculation that they’re captured Kuiper Belt Objects.
Dinkinesh was not initially on Lucy’s itinerary. Nonetheless, the science group wished to check the spacecraft’s devices and software program by observing a major belt asteroid earlier than gathering very important knowledge on the Trojans. In January of 2023, astronomer Raphael Marschall calculated that Lucy would cross simply 40,000 miles from a small asteroid, then referred to as 1999 VD57. By conducting a small burn of the spacecraft’s thrusters, the group was capable of tweak its trajectory to strategy the asteroid at a decreased distance of 280 miles. They named their mission’s first goal Dinkinesh, which is the Ethiopian title for the fossil of the early hominid Lucy. The mission’s namesake was one of many early ancestors of contemporary people.
The first objectives of the flyby had been to calibrate Lucy’s three devices and to substantiate that there are not any errors within the software program used to manage them. The probe carries a telescopic digital camera (L’LORRI), a visual and near-infrared spectrometer (L’Ralph), and a thermal emission spectrometer (L’TES). Collectively, they permit planetary scientists to know an asteroid’s composition, form, and inside construction. The devices are mounted on a scan platform, which is able to level them in direction of their goal whereas the spacecraft stays stationary. The scan platform and its monitoring cameras are a number of the most revolutionary items of {hardware} on the spacecraft. The Dinkinesh flyby was meant to exhibit that the scan platform can hold a small asteroid centered within the L’LORRI digital camera’s slim area of view. Provided that Lucy has already returned high-resolution images of the asteroid to Earth, it seems that this check was profitable.
Nonetheless, Lucy’s photos of Dinkinesh are additionally invaluable in their very own proper. The primary belt of asteroids, situated between Mars and Jupiter, is a particles area left over from the formation of the Photo voltaic System. As we study extra about this area, it’s changing into obvious that this group of asteroids aren’t homogenous. As a substitute, they’re an eclectic assortment of stony, carbonaceous, icy, and metallic asteroids shepherded into their present orbits by the migration of the large planets 3.9 billion years in the past. Dinkinesh is the smallest major belt asteroid ever explored by a spacecraft. Due to this fact, Lucy’s flyby of this object will permit scientists to check and distinction it to bigger major belt asteroids explored by different spacecraft and examine whether or not there’s a hyperlink between the properties of an asteroid and its measurement.
When the Lucy science group acquired the primary high-resolution photos from Lucy two days after the flyby, they had been in for a shock. Dinkinesh just isn’t one asteroid, however three. The very best-resolution L’LORRI picture revealed that the 0.4-mile-wide asteroid is accompanied by a moon which is half its measurement. The surfaces of each asteroids are strewn with boulders. This suggests that they is likely to be “rubble pile” asteroids, that are collections of smaller rocks held collectively by their collective weak gravitational area. Nonetheless, this concept can solely be examined by measuring the density of Dinkinesh.
Lucy venture scientist Keith Noll famous that there are some similarities between the Dinkinesh system and the near-Earth asteroid Didymos, which was the goal of the DART impactor. Dimorphos is orbited by a satellite tv for pc named Dimorphos, and in each programs, the diameter of the primary asteroid is roughly double that of its moon. DART’s remaining photos additionally present that Dimorphos is clearly a rubble pile. Nonetheless, Noll additionally identified that “there are some actually attention-grabbing variations that we are going to be investigating.” [1]
Decrease-resolution L’LORRI photos captured from a distinct angle enabled one other surprising discovery. Dinkinesh’s moon is comprised of two smaller asteroids which have been fused collectively. This peanut-shaped configuration is named a contact binary, and it’s comparatively widespread among the many small, icy our bodies of the Kuiper Belt. Probably the most well-known instance is Arrokoth, which was visited by the New Horizons spacecraft in 2019. Contact binaries type when two objects in close by orbits are progressively drawn collectively by weak gravitational interactions. They ultimately collide at a strolling tempo, which leaves each objects comparatively intact.
Contact binaries are scientifically intriguing as a result of they will solely type when the dad or mum our bodies are in concentric, round orbits. This was true of most Kuiper Belt Objects previous to the migration of the large planets. Nonetheless, Dinkinesh’s moon is the primary contact binary which we’ve noticed within the asteroid belt. This raises a number of new questions. Did the contact binary type early within the historical past of the Photo voltaic System, and was it subsequently captured into orbit round Dinkinesh? Or did the asteroid initially have two moons, which gently collided? Is that this configuration widespread amongst small asteroids, or are contact binaries comparatively scarce? Extra evaluation of the information from Lucy might be required to distinguish between these hypotheses and some other theories which come up.
Over the approaching days, spectra of Dinkinesh may even be returned to Earth. These knowledge require extra processing than the L’LORRI photos, so the outcomes of those observations won’t be launched for a number of months. Nonetheless, scientists have already got a speculation in regards to the asteroid’s composition primarily based on telescopic knowledge. The main concept is that Dinkinesh is a S-type stony asteroid. These asteroids are wealthy in silicate minerals, akin to olivine and feldspar, they usually had been seemingly the first constructing blocks of Earth’s mantle. Lucy’s flyby of the asteroid Dinkinesh was wildly profitable. Preliminary photos from the spacecraft’s L’LORRI telescope have already revealed that the asteroid is accompanied by a novel binary moon. Picture processing will undoubtedly expose extra particulars in regards to the floor and inside construction of the asteroid. Lucy’s subsequent asteroid flyby is slated for April 20th, 2025. The spacecraft will discover a bigger major belt asteroid named after Donald Johansen, the discoverer of the Lucy fossil.
