SpaceX Falcon 9 Block 5 - DART - Launched November 23/24, 2021
Screenshot from SpaceX Webcast of the launch of DART - Purging of LOX gas from the TEL lines
Mission Rundown: SpaceX Falcon 9 Block 5 - DART
Written: August 3, 2022
Pillow Fight in outer space. Who wins?
Tuesday, November 23 at 10:21 p.m. PST, Falcon 9 launched NASA’s Double Asteroid Redirection Test (DART) mission to an interplanetary transfer orbit from Space Launch Complex 4 East (SLC-4E) at Vandenberg Space Force Base in California.
DART is humanity’s first planetary defense test mission to see if intentionally crashing a spacecraft into an asteroid is an effective way to change its course, should an Earth-threatening asteroid be discovered in the future. This was SpaceX’s first interplanetary mission.
SpaceX successfully launched the Double Asteroid Redirection Test (DART) spacecraft on a Falcon 9 Block 5 B1063-3, which lifted off from Space Launch Complex 4 East (SLC-4E), at the Vandenberg Space Force Base, in California. DART is the first-ever kinetic impactor, meaning the spacecraft will attempt to demonstrate the ability to deflect the asteroid Didymos B by colliding with it at a high speed (approximately 6.6 km/s).
Static fire test was performed November 19, 2021 Friday morning on SLC-4.
Upon successfully landing on Of Course I Still Love You, B1063-3 will have made its third flight after launching the following previous missions:
The Falcon 9 lifted off on a southbound trajectory, with stage separation occurring some two minutes and thirty seconds into flight. The first stage then aimed for a landing on the drone ship ‘Of Course I Still Love You', stationed off the coast of Baja California.
Meanwhile, the second stage performed a small “dogleg” maneuver to place itself and DART into a 200×300 km 64.7-degree inclined parking orbit. The two fairing halves will later be recovered from an area south of the drone ship.
After a short coast period, the second stage engine reignited to send DART onto an escape trajectory away from the Earth. This set up DART to intercept the asteroid Didymos and its moon Dimorphous 10 months from now.
The payload adapter, a new smaller design that made its first flight, then released DART following the cutoff of the second stage. Measuring just 24 inches in diameter, this is the first time that this small size adapter is being used. Usually the Geostationary satellites are mounted on 4-6 foot adaptor rings on the Payload Adapter Fitting, PAF.
The team then mated the electrical connectors between the spacecraft and the adapter. Finally, the integrated stack of spacecraft and adapter was secured to the payload attach fitting to the second stage. The mate process took about a day to complete.
Final closeouts will occur over the next two weeks in preparation for launch aboard a SpaceX Falcon 9 rocket from Vandenberg during a launch window that opens at 10:21 p.m. PST, Nov. 23 (1:21 a.m. EST, Nov. 24). DART will be encapsulated in the payload fairing and attached to the Falcon 9 rocket to prepare for rollout to the launch pad.
Released in space, the spacecraft will deploy its two 27.9-foot long ROSA solar arrays, enabling the spacecraft to become power-positive, a critical step that must happen soon after spacecraft separation. The ROSA solar arrays are two rolls of solar cells each with two low pressure inflated tubes, that stiffens and secures the arrays structural shape.
I can imagine using a hot resin rich gas inflating the almost airtight tubes, that will absorb the resin gas, which will harden and become semi rigid tubes.
DART will test several new technologies during its cruise to the asteroid and its moon. This includes the NEXT-C ion engine based on the engine Dawn used to fly to the asteroids Vesta and Ceres. DART will also trial a new compact high-gain antenna called the Radial Line Slot Array to send and receive data.
The Science Payload
The DART spacecraft is an impactor and contains no scientific payloads. The spacecraft is roughly a cylinder that is 12.5 meters tall and 2.4 meters wide. DART had a mass of 670 kg at launch, but will only have a mass of 500 kg during impact.
The satellite is equipped with a sun sensor, a star tracker, and an aperture camera, all of which will be used to navigate to Didymos B. The spacecraft will navigate to the asteroid autonomously, and is expected to arrive in September of 2022. DART is powered by the NASA Evolutionary Xenon Thruster (NEXT), which is an ion thruster that runs on Xenon.
Dimorphos is approximately 170 meters in diameter, similar in size to a football stadium, and falls within the size of objects that would pose the most threat to Earth. Its parent body’s diameter is approximately 780 meters.
DART will impact the asteroid Didymos B at a speed of 6.6 km/s (4.1 mi/s), which is expected to produce a change in velocity on the order of 0.4 mm/s. While a tiny change, this velocity change will cause a drastic change in the object’s orbit. The orbital period is expected to be reduced by approximately 10 minutes.
DART’s primary mission is to test one technique for modifying an asteroid’s orbital path. This spacecraft will be autonomously maneuvered to a direct impact of the moonlet Dimorphos. The kinetic impact is meant to change the velocity and path of the moonlet’s orbit around Didymos.
Dimorphos currently orbits Didymos with a period of 11 hours and 55 minutes. DART’s collision into Dimorphos is expected to change its orbital time to 11 hours and 45 minutes. However, as this is the first time a solar system body would have purposely had its orbit altered by a spacecraft impact, the actual effects of the impact will be studied by multiple methods and could differ from preflight projections.
Ten days before the kinetic impact, DART will release an Italian-built CubeSat known as LICIACube, which will image the impact and the far side of Dimorphos. Sixty minutes before impact, DART’s single instrument, a camera called DRACO (Didymos Reconnaissance and Asteroid Camera for Optical Navigation), will see Dimorphos as a tiny dot. At this point, its final approach will start.
DART will autonomously guide itself to the impact with Dimorphos using its SMART NAV system and the images from DRACO. These images will be used to characterize Dimorphos’ surface, which could be anything from a rubble pile to solid rock.
Two minutes before impact, the spacecraft maneuvering will be finished. Twenty seconds prior to impact, Dimorphos will fill the camera’s field of view, and the images will continue to be transmitted until the collision.
LICIACube will image the debris resulting from the impact, which will be a measure of how forceful the event was. Ground-based telescopes will also be used to measure how much Dimorphos’ orbit around Didymos was changed. Didymos itself is not expected to be hit by any debris from the collision due to the trajectory chosen by the DART team.
In this corner we have micro featherweight Buzz Bye aka. DART the Farter.
Waiting for DART in the other corner of the Solar system we have ‘the flying mountain’ Dimorphous and his tiny twin brother Didymos running around.
DART will fly straight down Didymos belly button hoping to change the course, speed and direction of Didymos while ‘the flying mountain’ Dimorphous shakes his head.
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