AIDA (mission)

The Asteroid Impact and Deflection Assessment (AIDA) missions are a proposed pair of space probes which will study and demonstrate the kinetic effects of crashing an impactor spacecraft into an asteroid moon. The mission is intended to test and validate impact models of whether a spacecraft could successfully deflect an asteroid on a collision course with Earth.

The original plan called for a European spacecraft, the Asteroid Impact Mission (AIM), to operate in synergy with a large NASA impactor called Double 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 within European Space Agency (ESA), ''AIM'' was replaced in 2018 with a smaller spacecraft called '' Hera'' that will launch five years after ''DART'' 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.

''DART'' impacted Dimorphos, the asteroid moonlet of 65803 Didymos, on 26 September 2022. ''Hera'' will arrive at Didymos in December 2026, four years and three months after ''DART'' impact.

History

Initially, ''Hera'' role was to be realized by a much larger spacecraft called Asteroid Impact Mission (AIM), 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, the European Space Agency (ESA) cancelled the development of the AIM spacecraft after Germany decided to fund the ExoMars project only.ExoMars Rover Gets Funding Despite Schiaparelli Mars Lander Crash
Alixandra Caole Vila, ''Nature World News'' 7 December 2016 Germany offered to cover only 35 million of the 60 million needed for the AIM portion to continue, and this was not enough to continue development.NASA presses ahead with asteroid mission despite ESA funding decision
Jeff Foust, ''Space News'' 13 December 2016 Had AIM been developed, its notional requirements in 2012 were:
* an asteroid lander (based on the German MASCOT 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
* two interplanetary CubeSats
* deep-space optical communication.

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.Asteroid Impact & Deflection Assessment (AIDA) study
. 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 to 65803 Didymos and plans to measure the effects of the impact from ground-based telescopes, and from an Italian CubeSat DART will bring along. Following AIM's cancellation, ESA director Jan Wörner stated his intentions to revive the European mission in some form. 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.

Status

By March 2018, ''Hera'' proposal was in Phase B1, where the preliminary design was being drawn up. On 7 January 2019, the ''Hera'' team announced the selection of two CubeSats to piggyback on the mission: ''APEX'' and ''Juventas''. ESA officials approved ''Hera'' in November 2019 for a 2024 launch. In September 2020 ESA awarded a contract covering the detailed design, manufacturing, and testing of Hera. In this occasion the ''APEX'' CubeSat is also substituted by the ''Milani'' one, named after the late Andrea Milani, distinguished professor and leading asteroid scientist.

The Italian Space Agency (ASI) decided in 2018 to contribute to NASA a secondary spacecraft called LICIACube (''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. LICIACube is equipped with two optical science cameras, dubbed LUKE and LEIA.

Collaboration

The AIDA mission is a joint international collaboration of the European Space Agency (ESA), the German Aerospace Center (DLR), Côte d'Azur Observatory (OCA), NASA, and Johns Hopkins University Applied Physics Laboratory (JHU/APL).

The miniature lidar instrument on board ''Hera'' will be provided by a consortium of teams from Portugal, Poland, and Ireland. Two CubeSats will be deployed by ''Hera'' while at Didymos: The ''Milani'' CubeSat is being developed by Italy, Czech Republic, Finland. The ''Juventas'' CubeSat is being developed by GomSpace and GMV's Romanian division.

Along with surveying ''DART'' impact crater, ''Hera'' may also carry a Japanese impactor that would be a replica of the Small Carry-on Impactor (SCI), on board the '' Hayabusa2'' asteroid sample return mission. NASA's ''DART'' brought a 6U flyby CubeSat along with it, called LICIACube, which was developed by the Italian Space Agency (ASI) to image the ejecta plume.

DART and LICIACube

DART or Double Asteroid Redirection Test was a impactor that hosted a single camera, Didymos Reconnaissance and Asteroid Camera for Optical Navigation (DRACO), derived from LORRI camera aboard New Horizons, to support autonomous guiding to impact the center of the moon of Didymos B. It also carried an Italian-built cubesat called LICIACube that was released pre-impact on 11 September 2022 to image the event. It is estimated that the impact of the DART impacted Dimorphos on 26 September 2022.

File:DART AnimatedSequence-2020 from launch to impact along with separation of LICIACube.webm, DART Mission animated video from launch to impact along with separation of LICIACube
File:51619406234 b05ef2464f o Dart Spacecraft Launch Configuration.jpg, DART in launch configuration
File:LICIACube CubeSat a companion satellite of Dart Spacecraft.jpg, LICIACube, a companion satellite of the DART probe

''Hera''

''Hera'' is the European component of the ESA–NASA AIDA mission. The ''Hera'' spacecraft, approved on 29 November 2019,''Hera'' mission is approved as ESA receives biggest ever budget.
Kerry Hebden, ''Room Space Journal''. 29 November 2019. will focus on key measurements to validate impact and asteroid deflection models such as the detailed characterisation of the impact crater made by the ''DART'' impactor.The ''Hera'' mission: European component of the ESA-NASA AIDA mission to a binary asteroid
Michel, Patrick; Küppers, Michael; Carnelli, Ian. 42nd COSPAR Scientific Assembly. Held 14–22 July 2018, in Pasadena, California, USA, Abstract id. B1.1-42-18 ''Hera'' will also measure the DART impact outcome, such as change in the binary system orbit, and will enable detailed characterisation of the Dimorphos volume and surface properties, as well as measure the volume and morphology of the ''DART'' impact crater.

The baseline payload of ''Hera'' includes a camera, a miniaturized lidar and two CubeSats dedicated to asteroid characterisation. The spacecraft design allows for of additional payload mass, including the Small Carry-on Impactor (SCI) proposed by Japan's space agency JAXA. Other options, such as a small lander, are being considered. ''Hera'' will be launched on an Falcon 9 in 2024.

Proposed payload

The notional payloads on ''Hera'' are:
* Asteroid Framing Camera to obtain information on the dynamics of a binary asteroid and physical characteristics.
* Lidar laser altimeter to measure the shapes of the two bodies and constrain the mass of the asteroid's moon.
* Thermal imager
* Milani is a 6-unit CubeSat 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.
* Juventas is a 6-unit CubeSat carrying a camera and a low-frequency radar (JuRa), for determining the internal structure of Dimorphos.A Low Frequency Radar to Fathom Asteroids from Juventas Cubesat on HERA.
Alain Herique, Dirk Plettemeier, Wlodek Kofman, Yves Rogez, Christopher Buck, and Hannah Goldberg. EPSC Abstracts. Vol. 13, EPSC-DPS2019-807-2, 2019. EPSC-DPS Joint Meeting 2019.
Alain Herique, Dirk Plettemeier, Hannah Goldberg, Wlodek Kofman, and the JuRa Team. EPSC Abstracts. Vol.14, EPSC2020-595. . It will operate for 3–6 months near the asteroid. At the end of its mission, it will attempt a landing on the surface of Dimorphos to obtain close-up data.
* An optional impactor may also be carried by ''Hera''. It would be a replica of the Japan's Small Carry-on Impactor (SCI) on board the '' Hayabusa2'' asteroid sample return mission. By performing a secondary impact (the primary impact being ''DART''), a comparison of the effects posed by two collisions of different nature on the same asteroid can be realized, helping validate numerical impact algorithms and scaling laws.

Mission design

AIDA will target 65803 Didymos, a binary asteroid system in which one asteroid is orbited by a smaller one. The primary asteroid is about in diameter; its small satellite is about in diameter in an orbit about from the primary. Didymos is not an Earth-crossing asteroid, and there is no possibility that the deflection experiment could create an impact hazard to Earth.

The impact of the ''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 the heliocentric orbit of the system. 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 the momentum transfer efficiency.

''DART'' impacted the small moon of the asteroid Didymos on 26 September 2022, while ''Hera'' would arrive at Didymos in 2027, five years after ''DART'' impact. To maximize scientific outcome, the AIDA team had proposed to delay ''DART'' launch so that ''Hera'' would arrive at the asteroid first, enabling it to study ''DART'' impact, the plume, the crater, and the freshly exposed material. While most of the initial objectives of AIDA would still be met if ''Hera'' arrives after ''DART'', as a drawback, data from direct observation of the impact and ejecta will not be obtained.

AIDA mission architecture

See also

* Asteroid impact avoidance
* B612 Foundation
* Don Quijote, AIDA's predecessor proposal
* The Spaceguard Foundation

References

External links

ESA Hera page

Hera community page



Sciency Words: Didymoon
* Video
5 min presentation of AIDA
at YouTube.
* Video
4 min presentation of Hera
at YouTube

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