Family: Atlas
Atlas V 551
Launch statistics
- 23
- Launches (as of July 27, 2026)
- 4
- Successes
- 0
- Failures
- 100.0 %
- Success rate
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The Atlas V 551 is the most powerful faired configuration of the Atlas V, not a separate rocket. Atlas V is an expendable launch system, the fifth major version of the Atlas family, developed by Lockheed Martin and operated since 2006 by United Launch Alliance. Each vehicle has two main stages: a first stage, the Common Core Booster, powered by a single Russian RD-180 engine burning kerosene and liquid oxygen, and a Centaur upper stage with one or two RL10 engines burning liquid hydrogen and liquid oxygen. Each configuration is identified by three digits. The first indicates the payload fairing diameter, the second the number of solid rocket boosters, and the third the number of Centaur engines. The 551 is therefore the variant with a 5.4-metre fairing, five solid rocket boosters — the maximum possible — and a single-engine Centaur. It is the most capable configuration of the faired series: about 18,814 kg to low Earth orbit and 8,900 kg to geostationary transfer orbit, with an advertised base price of US$153 million, the highest in the Atlas V catalogue. That capability made it the choice for the programme's most demanding missions: interplanetary probes such as New Horizons and Juno, MUOS and AEHF military communications satellites, and, in its final years, Amazon's internet constellation deployments. Atlas V is being retired; the 551 configuration flew for the last time on 2 July 2026, after 23 launches.
History
Origins of Atlas V
Lockheed Martin Commercial Launch Services developed the Atlas V under the U.S. Air Force EELV programme. The family's inaugural flight took place on 21 August 2002 with the Hot Bird 6 satellite. The vehicle abandoned the pressure-stabilised stainless-steel 'balloon' construction of earlier Atlas rockets in favour of isogrid aluminium tanks that are structurally stable unpressurised, and incorporated attachment points for parallel stages.
Debut of the 551 configuration
The five-booster variant debuted on 19 January 2006 with the launch of the New Horizons probe toward Pluto and the Kuiper Belt. That flight was doubly notable: the first mission of an Atlas V 551 and the first Atlas V fitted with a third stage, added to raise heliocentric escape speed.
Two decades of demanding missions
The 551 established itself as the configuration for the heaviest payloads. On 5 August 2011 it launched the Juno probe toward Jupiter. Between 2012 and 2016 it orbited all five MUOS military communications satellites, and between 2018 and 2020 the AEHF-4, AEHF-5 and AEHF-6. It also flew classified missions for the National Reconnaissance Office and, in July 2024, USSF-51, the first ULA launch under the National Security Space Launch programme, whose payload was transferred from Vulcan Centaur to Atlas V.
Retirement
In August 2021 ULA announced that Atlas V would be retired and that all remaining launches had been sold; production ended in 2024. The final phase of the 551's career was dominated by internet constellations: 27 Kuiper satellites in April, June and September 2025, and batches of up to 29 Amazon Leo satellites in 2026. On 14 November 2025 it launched ViaSat-3 Flight 2, the programme's last geostationary communications satellite. The final flight came on 2 July 2026 with the LA-08 mission, closing out the 551 configuration, the 5-metre fairing, the Single Engine Centaur III and the GEM-63 strap-on boosters on Atlas V.
Launch timeline
| Date | Launch site | Outcome | Payload |
|---|---|---|---|
| Jul 2, 2026, 4:30 AM | Space Launch Complex 41 | Success | Amazon Leo, formerly known as Project Kuiper, is a mega constellation of satellites in Low Earth Orbit that will offer broadband internet access, this constellation will be managed by Kuiper Systems LLC, a subsidiary of Amazon. This constellation is planned to be composed of 3,276 satellites. The satellites are projected to be placed in 98 orbital planes in three orbital layers, one at 590 km, 610 km and 630 km altitude. 29 satellites are carried on this launch. |
| May 29, 2026, 11:53 PM | Space Launch Complex 41 | Success | Amazon Leo, formerly known as Project Kuiper, is a mega constellation of satellites in Low Earth Orbit that will offer broadband internet access, this constellation will be managed by Kuiper Systems LLC, a subsidiary of Amazon. This constellation is planned to be composed of 3,276 satellites. The satellites are projected to be placed in 98 orbital planes in three orbital layers, one at 590 km, 610 km and 630 km altitude. 29 satellites are carried on this launch. |
| Apr 28, 2026, 12:53 AM | Space Launch Complex 41 | Success | Amazon Leo, formerly known as Project Kuiper, is a mega constellation of satellites in Low Earth Orbit that will offer broadband internet access, this constellation will be managed by Kuiper Systems LLC, a subsidiary of Amazon. This constellation is planned to be composed of 3,276 satellites. The satellites are projected to be placed in 98 orbital planes in three orbital layers, one at 590 km, 610 km and 630 km altitude. 29 satellites are carried on this launch. |
| Apr 4, 2026, 5:46 AM | Space Launch Complex 41 | Success | Amazon Leo, formerly known as Project Kuiper, is a mega constellation of satellites in Low Earth Orbit that will offer broadband internet access, this constellation will be managed by Kuiper Systems LLC, a subsidiary of Amazon. This constellation is planned to be composed of 3,276 satellites. The satellites are projected to be placed in 98 orbital planes in three orbital layers, one at 590 km, 610 km and 630 km altitude. 29 satellites are carried on this launch. |
Versions
| Atlas V 551 (two-stage) | Atlas V 551 with Star 48B third stage | |
|---|---|---|
| First launch | January 19, 2006 | January 19, 2006 |
| Last launch | — | January 19, 2006 |
| Height | 58.3 m Best value in this row | 58.3 m Best value in this row |
| Diameter | 3.8 m Best value in this row | 3.8 m Best value in this row |
| Mass | 590,000 kg | — |
| Stages | 2 Best value in this row | 3 |
| LEO capacity | 18,814 kg | — |
| Reusable | No | No |
Images