atlas v, ula

Lucy | Atlas V 401

Lift Off Time
October 16, 2021 – 09:34 UTC | 05:34 EDT
Mission Name
Launch Provider
(What rocket company launched it?)
United Launch Alliance (ULA)
(Who paid for this?)
National Aeronautics and Space Administration (NASA)
Atlas V 401 AV-096
Launch Location
SLC-41, Cape Canaveral Space Force Station, Florida, USA
Payload mass
1,550 kg wet mass (3,417 lb)
Where is the spacecraft going?
The spacecraft will visit seven Trojan asteroids
Did they attempt to recover the first stage?
No, the Atlas V is not capable of recovery
Where did the first stage land?
It crashed into the Atlantic Ocean
Did they attempt to recover the fairings?
No, the Atlas V is not capable of recovery
Were these fairings new?
This was the:
– 40th launch of an Atlas V launch vehicle in the 401 configuration
– 89th launch of an Atlas V launch vehicle
– 146th mission for United Launch Alliance
– 99th orbital launch attempt of 2021
Where to watch
Official Replay

How did it go?

United Launch Alliance (ULA) successfully launched the Lucy Trojan Explorer mission atop an Atlas V to the Trojan asteroid belt. The Atlas V lifted off from Space Launch Complex 41, at the Cape Canaveral Space Force Station, in Florida, in its 401 configuration: a 4 meter fairing, 0 solid rocket motors (SRMs), and one RL-10 on the second stage. Lucy is a planned 12-year mission that will explore the Trojan asteroid belt, which is located around Jupiter.

After payload deployment, Lucy successfully deployed all instruments and one of its solar panels. The second solar panel was not fully deployed, but is producing 75-95% of the expected power. Teams are working the issue, but this problem would not pose a risk to the spacecraft’s mission.

What is the Lucy mission?

Lucy will be the first mission of its kind, and is set to explore seven asteroids around Jupiter’s L4 and L5 Lagrange points and one asteroid in the main asteroid belt. The spacecraft will be used to study the formation of the solar system, as it is believed that the Trojan asteroids are remnants of the primordial material that formed the outer planets in the solar system.

The Lucy spacecraft will has several main instruments. Lucy’s LOng Range Reconnaissance Imager (L’LORRI) is a high spatial resolution visible imager that will provide highly detailed images of the Trojan asteroid surfaces. It is similar to the LORRI instrument used on the New Horizons spacecraft.

Lucy is also equipped with a way to detect and measure radiation; Lucy’s Thermal Emission Spectrometer (L’TES) will be used to detect radiation from each asteroid, which helps scientists learn more about their composition and how they formed. The L’TES instrument is based off of the thermal emission spectrometer that flew on OSIRIS-REx.

L’Ralph is the final instrument on Lucy and consists of two parts: the Multispectral Visible Imaging Camera (MVIC), a visible imager, and the Linear Etalon Imaging Spectral Array (LEISA), an infrared spectrometer. Once again, this instrument is based off of one that was flown on the New Horizons mission.

Additionally, Lucy is equipped with radio telecommunication hardware and a high-gain antenna, which in addition to being used for communication will use Doppler shift to attempt to determine the mass of the asteroids. This, along with the trio of instruments, will be used to give scientists the best understanding of how the outer solar system formed.

A diagram showing the Earth gravity assists and the location of the asteroid clusters (Credit: NASA)

L4 Cluster

Following launch, the Lucy spacecraft will perform two Earth gravity assists, which will help raise its orbit to Jupiter’s L4 Lagrange point. During these gravity assists, Lucy will visit its first asteroid: 52246 Donaldjohanson on April 20, 2025. The 52246 asteroid has a radius of roughly 2 km and is found in the main asteroid belt. Lucy will use this asteroid as a way to practice what it’ll do when it gets to the Trojan asteroids in 2027.

Lucy will reach the L4 cluster of asteroids in 2027; the Trojan asteroid belt is made up of two large clusters of asteroids that are roughly near the L4 and L5 Lagrange points. Once in the L4 cluster of asteroids, Lucy will fly by asteroid 3548 Eurybates on August 12, 2027. Asteroid 3458 is a 32 km radius C-type asteroid. A C-type asteroid is an asteroid with a large amount of carbon in it, leading to a very low albedo. Approximately 75% of all asteroids are C-type.

Around a month later, on September 15, 2027, Lucy will then go fly by asteroid 15094 Polymele, which at 10.5 km in radius will be the smallest Trojan asteroid ever visited. Polymele is a P-type asteroid. On April 18, 2028 Lucy will visit the 11341 Leucus asteroid, which is a D-type asteroid that has a radius of 17 km. D-type asteroids also have an extremely low albedo and have a reddish spectrum. This causes them to be one of the hardest types of object to observe. This asteroid is of particular interest to scientists, as it has an abnormally slow rotation rate: it rotates once every 466 hours, which is a lot lower than most other asteroids. Lucy will then visit one last asteroid in the L4 cluster: 21900 Orus. This 25.5 km radius D-class asteroid will be passed by Lucy on November 11, 2028.

L5 Cluster

Having completed its observation of all of the asteroids in the L4 cluster, Lucy will exit the cluster and coast back to Earth to perform another gravity assist in 2030. Lucy will then fly by a binary pair of asteroids: 617 Patroclus and Menoetius. The 56.5 km and 52 km radius asteroids are both P-type asteroids. P-type asteroids are similar to D-type, having an extremely low albedo and a reddish glow. It is expected that Lucy will fly past these asteroids on March 2, 2033. This will conclude the original mission, although it is probably that the mission will be extended.

The Lucy mission targets
An artist’s rendering of the seven Trojan asteroids that Lucy will visit (Credit: NASA)

What is the Atlas V?

The Atlas V is an expendable medium lift launch system and member of the Atlas rocket family. The rocket has two stages. The first is a Common Core Booster (CCB), which is powered by a single RD-180 engine that burns kerosene (RP-1) and liquid oxygen (LOx). This is accompanied by up to five strap-on solid rocket boosters. The second stage is the Centaur upper stage, which is powered by one or two RL10 engines and burns liquid hydrogen (LH2) and liquid oxygen (LOx).

What does 401 mean?

Atlas V rockets have a three number configuration code. The first number represents the fairing diameter size in meters The second number denotes the number of solid rocket motors (SRMs), which attach to the base of the rocket. The number of SRms for a 4 meter fairing can range from 0 – 3. However, the 5 meter fairing Atlas V can support up to 5 SRMs, due to the different aerodynamic properties of the fairing. For the Lucy mission, there will be 0 SRBs attached to the center core. The third number shows the number of engines on the Centaur Upper Stage.

rocket white srb atlas v fairing fuel engine
A diagram of the entire Atlas V family with the SRM placement for each number shown. (Credit: NASA)

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