TheAsteroid Impact and Deflection Assessment (AIDA) missions are a proposed pair ofspace probes which will study and demonstrate the kinetic effects of crashing an impactor spacecraft into anasteroid moon. The mission is intended to test and validate impact models of whether a spacecraft could successfullydeflect an asteroid on a collision course withEarth.[8]
The original plan called for a European spacecraft, the Asteroid Impact Mission (AIM), to operate in synergy with a large NASA impactor calledDouble Asteroid Redirection Test (DART) and observe the immediate effects of the impact.AIM was cancelled in 2016 when Germany was unable to fund its portion, and after some backlash withinEuropean Space Agency (ESA),AIM was replaced in 2018 with a smaller spacecraft calledHera that launched three years afterDART to orbit and study the crater on the asteroid. Hera will also deploy two European CubeSats in deep space for close-up asteroid surveying: Juventas and Milani.[9]
DART impactedDimorphos, the asteroid moonlet of65803 Didymos, on 26 September 2022.[10]Hera will arrive at Didymos in December 2026, four years and three months afterDART's impact.[11]
Infographic showing the effect of DART's impact on the orbit of Didymos B with deployment of LICIACube
Initially,Hera's role was to be realized by a much larger spacecraft calledAsteroid Impact Mission (AIM),[12] that would have observed the plume, the crater, and the freshly exposed material to provide unique information for asteroid deflection, science and mining communities. In December 2016, theEuropean Space Agency (ESA) cancelled the development of the AIM spacecraft after Germany decided to fund theExoMars project only.[13] Germany offered to cover only 35 million of the 60 million needed for the AIM portion to continue,[13] and this was not enough to continue development.[14] Had AIM been developed, its notional requirements in 2012 were:[15][16]
an asteroid lander (based on the GermanMASCOT heritage) for in-situ measurements
a thermal infrared imager to discriminate different surface properties like rocks or granular surfaces
a monostatic high frequency radar to obtain information on the structure of the asteroid's surface
a bistatic low frequency radar (on the orbiter and on the lander) to allow a view inside the asteroid and obtain data on its inner structure
Under the original proposal, AIM would have launched in October 2020, and DART in July 2021. AIM would have orbited the larger asteroid and studied the composition of it and its moon. DART would then impact the asteroid's moon in October 2022, during a close approach to Earth.[19] AIM would have studied the asteroid's strength, surface physical properties and internal structure, as well as measured the effect on the asteroid moon's orbit around the larger asteroid.
Nevertheless, NASA has continued development of the DART mission to65803 Didymos and plans to measure the effects of the impact from ground-based telescopes,[20][21] and from an Italian CubeSat DART will bring along. Following AIM's cancellation, ESA directorJan Wörner stated his intentions to revive the European mission in some form.[20]Etienne Schneider,Luxembourg's deputy prime minister, expressed regret at AIM's cancellation, and commented that his country would continue to advocate for the realization of the mission.[22]
By March 2018,Hera proposal was in Phase B1, where the preliminary design was being drawn up. On 7 January 2019, theHera team announced the selection of twoCubeSats to piggyback on the mission:APEX andJuventas.[23] ESA officials approvedHera in November 2019 for a 2024 launch.[24] In September 2020 ESA awarded a contract covering the detailed design, manufacturing, and testing of Hera.[9] In this occasion theAPEX CubeSat is also substituted by theMilani one, named after the late Andrea Milani,[25][26] distinguished professor and leading asteroid scientist.
TheItalian Space Agency (ASI) decided in 2018 to contribute to NASA a secondary spacecraft calledLICIACube (Light Italian CubeSat for Imaging of Asteroids), a 6-unit CubeSat that piggybacked with DART and separated 15 days before impact on 11 September 2022 to acquire images of the ejecta as it drifts past the asteroid.[27][28][29][30] LICIACube is equipped with two optical science cameras, dubbed LUKE and LEIA.
The miniaturelidar instrument on boardHera will be provided by a consortium of teams from Portugal, Poland, and Ireland.[6] Two CubeSats will be deployed byHera while at Didymos:[31] TheMilani CubeSat is being developed by Italy,Czech Republic, and Finland.[32][33] TheJuventas CubeSat is being developed byGomSpace andGMV's Romanian division.[34]
Along with surveyingDART's impact crater,Hera may also carry a Japanese impactor that would be a replica of the Small Carry-on Impactor (SCI), on board theHayabusa2 asteroid sample return mission.[12] NASA'sDART brought a 6U flyby CubeSat along with it, called LICIACube, which was developed by theItalian Space Agency (ASI) to image the ejecta plume.[27][28][29]
Illustration of the DART impactor spacecraft and LICIACube approachingDimorphos.
DART orDouble Asteroid Redirection Test was a 500 kg (1,100 lb) impactor that hosted a single camera, Didymos Reconnaissance and Asteroid Camera for Optical Navigation (DRACO), derived fromLORRI camera aboardNew Horizons, to support autonomous guiding to impact the center of the moon ofDidymos B.[35] It also carried an Italian-built cubesat called LICIACube that was released pre-impact on 11 September 2022 to image the event.[36] It is estimated that the impact of the 500 kg (1,100 lb)[37] DART at 6 km/s (3.7 mi/s)[21] will produce a velocity change on the order of 0.4 mm/s, which leads to a small change in the orbit of Didymos B, but over time, a large change in the orbital position (or orbital phase).[15][19][16] DART impacted Dimorphos on 26 September 2022.[10]
DART Mission animated video from launch to impact along with separation of LICIACube
DART in launch configuration
LICIACube, a companion satellite of the DART probe
Hera is the European component of the ESA–NASA AIDA mission. TheHera spacecraft, approved on 29 November 2019,[24] will focus on key measurements to validate impact and asteroid deflection models, such as the detailed characterisation of the impact crater made by theDART impactor.[38]Hera will also measure the DART impact outcome, such as change in the binary system orbit,[38] and will enable detailed characterisation of the Dimorphos volume and surface properties, as well as measure the volume and morphology of theDART impact crater.[39]
The baseline payload ofHera includes a camera, a miniaturizedlidar and twoCubeSats dedicated to asteroid characterisation. The spacecraft design allows for 40 kilograms (88 lb) of additional payload mass, including the Small Carry-on Impactor (SCI) proposed by Japan's space agencyJAXA. Other options, such as a small lander, are being considered.[38]Hera was launched on aFalcon 9 on 7 October 2024.[4]
Milani is a 6-unitCubeSat carrying the ASPECT visual and near-IR imaging spectrometer and VISTA for dust characterization. Milani will study the binary system surface composition, and perform technology demonstration experiments related to the Inter-Satellite Link (ISL) and autonomous optical navigation. The CubeSat will operate for 3–6 months in the vicinity of the system.[41]
Juventas is a 6-unitCubeSat carrying a camera and a low-frequency radar (JuRa), for determining the internal structure of Dimorphos.[42][43] It will operate for 3–6 months near the asteroid.[7] At the end of its mission, it will attempt a landing on the surface of Dimorphos to obtain close-up data.[7]
This section needs to beupdated. Please help update this article to reflect recent events or newly available information.(March 2024)
Schematic showing the progress of the mission. In the current proposalAIM is replaced withHera, there is no MASCOT, and the CubeSats are now envisioned to be 6U instead of 3U
AIDA will target65803 Didymos, abinary asteroid system in which one asteroid is orbited by a smaller one. The primary asteroid is about 800 metres (2,600 ft) in diameter; its small satellite is about 150 metres (490 ft) in diameter in an orbit about 1.1 km (0.68 mi) from the primary. Didymos is not anEarth-crossing asteroid, and there is no possibility that the deflection experiment could create an impact hazard to Earth.[16]
The impact of the 300 kilograms (660 lb)DART spacecraft at 6.25 km/s will produce a velocity change on the order of 0.4 mm/s, which leads to a significant change in the mutual orbit of these two objects, but only a minimal change in theheliocentric orbit of the system.[15][19][16] AIDA will provide a great benefit obtaining the size of the resulting impact crater in addition to the momentum transfer measurement, as the effects of porosity and strength of the target are needed to calculate themomentum transfer efficiency.[19][16]
DART impacted the small moon of the asteroidDidymos on 26 September 2022, whileHera would arrive at Didymos in 2027, five years afterDART's impact. To maximize scientific outcome, the AIDA team had proposed to delayDART's launch so thatHera would arrive at the asteroid first, enabling it to studyDART's impact, the plume, the crater, and the freshly exposed material.[12] While most of the initial objectives of AIDA would still be met ifHera arrives afterDART, as a drawback, data from direct observation of the impact and ejecta will not be obtained.[12]
^abKretschmar, Peter; Küppers, Michael (20 December 2018)."The CubeSat Revolution"(PDF).ESA. Retrieved24 January 2019.
^abDouble Asteroid Redirection Test: The Earth Strikes Back. Elena Adams; Daniel O'Shaughnessy; Matthew Reinhart, etal. 2019 IEEE Aerospace Conference; 2–9 March 2019.doi:10.1109/AERO.2019.8742007 Quote: "In addition, DART is carrying a 6U CubeSat provided by Agenzia Spaziale Italiana (ASI). The CubeSat will provide imagery documentation of the impact, as well as in situ observation of the impact site and resultant ejecta plume".
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