[7][8][9] DART's success in deflecting Dimorphos was due to the momentum transfer associated with the recoil of the ejected debris, which was substantially larger than that caused by the impact itself.

[11] NASA and the European Space Agency (ESA) started with individual plans for missions to test asteroid deflection strategies, but by 2015, they struck a collaboration called AIDA (Asteroid Impact and Deflection Assessment) involving two separate spacecraft launches that would work in synergy.

[13] The AIM orbiter was however canceled, then replaced by Hera which plans to start observing the asteroid four years after the DART impact.

[20] The DART spacecraft was an impactor with a mass of 610 kilograms (1,340 lb)[21] that hosted no scientific payload and had sensors only for navigation.

DRACO was based on the Long Range Reconnaissance Imager (LORRI) onboard New Horizons spacecraft, and supported autonomous navigation to impact the asteroid's moon at its center.

[25] Fed into an onboard computer with software descended from anti-missile technology, the DRACO images helped DART autonomously guide itself to its crash.

The fabricated antenna in a flat and compact shape exceeded the given requirements and was tested through environments resulting in a TRL-6 design.

[31] Early tests of the ion thruster revealed a reset mode that induced higher current (100 A) in the spacecraft structure than expected (25 A).

Obtaining accurate measurements of that effect was one of the mission's main goals and will help refine models of future impacts on asteroids.

[40] The DART impact excavated surface/subsurface materials of Dimorphos, leading to the formation of a crater and/or some magnitude of reshaping (i.e., shape change without significant mass loss).

If the kinetic energy delivered to its surface was high enough, reshaping may have also occurred in Didymos, given its near-rotational-breakup spin rate.

[46] DART's mission science depends on careful Earth-based monitoring of the orbit of Dimorphos over the subsequent days and months.

The impact was planned for a moment when the distance between Didymos and Earth is at a minimum, permitting many telescopes to make observations from many locations.

[47] The change in Dimorphos's orbit around Didymos was detected by optical telescopes watching mutual eclipses of the two bodies through photometry on the Dimorphos-Didymos pair.

[10] In a collaborating project, the European Space Agency has developed Hera, a spacecraft that was launched to Didymos in October 2024[34][49][50] and planned to arrive in 2026[51][52] to do a detailed reconnaissance and assessment.

[60] On 4 October 2022, Didymos made an Earth approach of 10.6 astronomical units (4,100 lunar distances; 1.59 billion kilometres; 990 million miles).

Two days later, the team received the green light to fill DART's fuel tank with roughly 50 kilograms (110 lb) of hydrazine propellant for spacecraft maneuvers and attitude control.

[63] Starting on 10 November 2021, engineers mated the spacecraft to the adapter that stacks on top of the SpaceX Falcon 9 launch vehicle.

Early planning suggested that DART was to be deployed into a high-altitude, high-eccentricity Earth orbit designed to avoid the Moon.

[68] On 27 May 2022, DART observed the bright star Vega with DRACO to test the camera's optics with scattered light.

[69] On 1 July and 2 August 2022, DART's DRACO imager observed Jupiter and its moon Europa emerging from behind the planet, as a performance test for the SMART Nav tracking system to prepare for the Dimorphos impact.

[71] Four hours before impact, some 90,000 kilometres (0.23 LD; 56,000 mi) away, DART began to operate in complete autonomy under control of its SMART Nav guidance system.

[72] When DART was 24,000 kilometres (0.062 LD; 15,000 mi) away Dimorphos became discernible (1.4 pixels) through the DRACO camera which then continued to capture images of the asteroid's surface and transmit them in real-time.

[47] The measured momentum enhancement factor (called beta) of DART's impact of Dimorphos was 3.6, which means that the impact transferred roughly 3.6 times greater momentum than if the asteroid had simply absorbed the spacecraft and produced no ejecta at all – indicating the ejecta contributed more to moving the asteroid than the spacecraft did.

The goal is to use these results and modeling to infer what beta could be for another asteroid by observing its surface and possibly measuring its bulk density.

Scientists estimate that DART's impact displaced over 1,000,000 kilograms (2,200,000 lb) of dusty ejecta into space – enough to fill six or seven rail cars.

Researchers found the impact caused an instantaneous slowing in Dimorphos' speed along its orbit of about 2.7 millimeters per second — again indicating the recoil from ejecta played a major role in amplifying the momentum change directly imparted to the asteroid by the spacecraft.