Launch Roundup: Delta IV Heavy swan song, Falcon 9 and Soyuz launches on tap for last week of March

by Justin Davenport

A trio of Falcon 9 Starlink launches, a Falcon 9 non-Starlink launch involving an Eutelsat communications satellite, a Chinese launch, and a Russian Soyuz launch with a Resurs Earth observation satellite were scheduled for this week.

However, the launch that will likely get the most attention is the final launch ever of a Delta family rocket, a family that dates back to near the beginning of the space age, but now it will be delayed to April after a faulty gaseous nitrogen pump on the ground support equipment failed.

Starlink 6-46 started the launch week off on Monday, from the Cape Canaveral Space Force Station (CCSFS). A launch from China, which had been thought to be a Chang Zheng 6C, but was in fact a CZ-6A variant, occurred on Tuesday.

Starlink 7-18 was to follow up from Vandenberg Space Force Base (VSFB) on the West Coast on Friday evening in the United States, with NROL-70 making the last Delta 4 Heavy — and Delta family — launch from SLC-37B at CCSFS earlier on Friday.

However, the NROL-70 launch date has been pushed to April and Starlink 7-18 finally launched on April 1. Starlink 6-45 from Florida and the Falcon 9 Eutelsat 36D flight successfully launched on Saturday. A Soyuz 2.1b with the Resurs-P No. 4 rounded out the launch week.

Starlink v2 Mini satellites prior to deployment (Credit: SpaceX)

Starlink v2 Mini satellites prior to deployment. (Credit: SpaceX)

SpaceX Falcon 9 | Starlink 6-46

The first launch for this week was a Starlink launch from SLC-40, on the heels of a cargo Dragon launch from that same pad. A Falcon 9 flew successfully on Monday, March 25 at 7:42 PM EDT (23:42 UTC), in the middle of a four-hour and 31-minute launch window. Several Starlink launches have made use of these extended windows to be able to fly on the scheduled launch date, and this one did as well.

The booster for this launch, B1078-8, carried a batch of Starlink v2 Mini satellites to continue building up the 6,000-unit strong satellite constellation and its reach to up to 2.6 million users worldwide. Like all Group 6 launches, this flight flew to the southeast on a trajectory, with a spectacular “jellyfish” visible after stage separation, inclined 43 degrees to the Equator. After stage separation, the booster landed safely on A Shortfall of Gravitas out in the Atlantic.

This flight was the 29th SpaceX orbital launch — and Falcon 9 flight — of 2024 as well as the 10th Falcon 9 launch in March. To put this in perspective, 2017 was the first year that SpaceX reached double digits in launch cadence, with 18 flights for the whole year. There is a possibility of 12 Falcon 9 launches this month if the rest of this week’s flights happen as scheduled, as the company continues to attempt to reach its stated goal of 148 launches this year. 

Chang Zheng 6A | Yunhai 3-02

A Chang Zheng 6A launched from Taiyuan Satellite Launch Center in northern China on Tuesday, March 26, at 22:51 UTC from the LC-9A pad. The rocket launched the Yunhai 3-02 Earth atmospheric and oceanic observation satellite, and the flight path was to a sun-synchronous orbit as per published notices. Sun-synchronous polar orbits are frequently used by Earth observation satellites as they allow the spacecraft to image a given location in the same lighting conditions every day.

This is the first launch of a CZ-6A this year and the 14th flight of 2024 for China. This flight will also be the 12th launch of a CZ-6 family rocket and the fifth of the 50-meter-high CZ-6A variant. This variant, capable of launching 4,500 kilograms to a sun-synchronous orbit, features two RP-1 kerosene-fueled YF-100 engines on the first stage, four strap-on solid rocket boosters, and an RP-1 kerosene-fueled YF-115 on the second stage. Both stages use liquid oxygen as the oxidizer.

The CZ-6A is comparable to the Antares and Soyuz-2 launch vehicles in performance, and was designed as a modern launcher for medium-sized commercial, military, and civilian satellites to low-Earth orbits. This dual-engine variant, developed to launch heavier payloads than other rockets in the CZ-6 family, has two stages, unlike other CZ-6 variants with one YF-100 engine on the first stage.

SpaceX Falcon 9 | Eutelsat 36D

The first of three Falcon 9 flights of Saturday lifted off from Pad 39A at the Kennedy Space Center with a non-Starlink payload, the Eutelsat 36D geostationary communications satellite.  A successsful launch took place at 5:52 PM EDT (21:52 UTC) on Saturday, March 30 at the beginning of a two-hour, 39-minute window.

After launch, the Falcon 9 flew due east to launch the Eutelsat payload into a geostationary transfer orbit. B1076-12 successfully landed downrange on SpaceX’s Just Read the Instructions drone ship for SpaceX’s 289th landing success and 300th landing attempt. Eutelsat 36D will end up at the 36 degrees East longitude orbital slot to serve Europe, Africa, and Russia, and will succeed the earlier Eutelsat 36B satellite.

Eutelsat 36D prior to shipment aboard an Airbus Beluga cargo jet to Florida. (Credit: Airbus)

Eutelsat 36D, massing 5,000 kilograms at launch, is based on the Eurostar-Neo platform. This satellite features 70 Ku-band transponders over five downlink beams, a steerable antenna, an 18-kilowatt power generation capability, and an electric orbit-raising ability. It is designed to serve for up to 15 years and will service a key Eutelsat direct-to-home TV and government services orbital slot.

The Eutelsat 36D flight was the 11th of March for the Falcon 9, setting a new monthly launch record, and it will also be the 30th Falcon 9 launch of this year, nearly matching the entire 2021 launch total for the type in just three months. SpaceX is currently on track to fly around 120 times this year with the Falcon family of rockets, not accounting for an increased cadence in the latter half of the year. Taking this into account, Falcon is expected to reach roughly 140 flights.

SpaceX Falcon 9 | Starlink 6-45

A second Starlink launch happened this week. A Falcon 9 successfully launched Saturday, March 30 from CCSFS SLC-40 at 9:30 PM EDT (01:30 UTC on March 31). This flight carried 23 Starlink v2 Mini satellites on a southeast trajectory like all other Group 6 Starlink launches, to an orbit inclined 43 degrees to the Equator.

After stage separation, B1067-18 landed safely on the drone ship A Shortfall of Gravitas out in the Atlantic. This flight was the 12th Falcon 9 launch in March 2024, and the 31st mission of this year. This has matched 2021’s entire yearly launch output for the Falcon 9.

Video capture from a Falcon 9 flight showing Starlink v2 Mini satellites being deployed. (Credit: SpaceX)

SpaceX Falcon 9 | Starlink 7-18

Another batch of Starlink v2 Mini satellites is scheduled to fly but this time from the West Coast. A Falcon 9 had been scheduled to launch from SLC-4E at VSFB on Saturday, March 30 at 11:30 PM PDT (06:30 UTC on Sunday, March 31), but finally launched on Monday, April 1, at 7:30 PM PDT (02:30 UTC on Tuesday, April 2). Weather in the area had been unfavorable for the last few days in March.

Once Starlink 7-18 got off the ground, the vehicle flew on a southeast trajectory with a minimal “dogleg” maneuver required to get its batch of satellites into an orbit inclined 53 degrees to the Equator. The booster supporting this mission is B1071-15, which last flew 48 days ago on the Starlink Group 7-13 mission. After stage separation, it landed downrange on the drone ship Of Course I Still Love You after a spectacular sunset launch and descent. This particular drone ship is based out of Long Beach, California for VSFB flights and is the only one assigned to the Pacific at present.

This flight was the 32nd Falcon 9 launch of 2024. SpaceX’s 32 orbital flights this year — not counting Starship IFT-3, which also took place in March — now exceeds the 2021 total of 31 launches for the whole year and would exceed the total number of launches for the company for any given year before that. 

The Soyuz 2.1b on the launch pad at Baikonur following rollout for a previous flight. (Credit: Glavkosmos)

RKK Energia Soyuz 2.1b | Resurs-P No.4

A Soyuz 2.1b launched successfully from Site 31/6 in Baikonur, Kazakhstan with the Resurs-P No.4 Earth observation satellite on board. The launch happened on Sunday, March 31 at 09:36 UTC, just over one week after Soyuz MS-25 flew atop a Soyuz 2.1a. The flight sent the 6,570-kilogram Resurs-P satellite into a sun-synchronous orbit.

The Resurs-P family of satellites, operated by Roscosmos, is capable of obtaining imagery at 1-meter resolution. The Resurs-P is a replacement for the Resurs-DK No.1 satellite, and the imagery has government and commercial applications. The three prior Resurs-P satellites are no longer in orbit, so Resurs-P No.4 will fill a gap in Russian imaging capability while the follow-on Resurs-PM family is under development.

This flight is the second mission for this Soyuz variant this year and just the fifth orbital launch for Russia in 2024. The Soyuz family has flown much higher yearly cadences in the past, especially in the 1970s and 1980s, but the current funding situation for spaceflight in Russia has forced a decrease in activity.

The Delta IV Heavy center core for the NROL-70 mission rolls through Cape Canaveral on May 11, 2023. (Credit: Max Evans for NSF)

ULA Delta IV Heavy | NROL-70

The Delta family of rockets started its service in May 1960 with the first launch of what was then known as the Thor-Delta, based on the Thor intermediate-range ballistic missile. Following a scrub at T-3:58 on Thursday, the very last launch of the Delta family is now no earlier than April 1 at 1:25 PM EDT (17:25 UTC) — as per an FAA advisory — from SLC-37B after a ground support issue. This flight is a classified mission for the National Reconnaissance Office (NRO).

The Delta IV Heavy, the heaviest-lifting variant of the Delta IV family with a Common Booster Core (CBC) stage and two CBC stages mounted as boosters, has been the final variant of the Delta IV family to continue flying. While medium-capacity Delta IV variants have been retired since 2019, the NRO had heavier payloads that required the Heavy variant’s capabilities and that needed to fly before new vehicles were fully available.

The NROL-70 payload being mated to the Delta IV Heavy. (Credit: ULA)

The NRO’s Delta IV Heavy flights out of CCSFS have flown spacecraft thought to be signals intelligence satellites to geostationary orbits, as opposed to the electro-optical reconnaissance payloads from SLC-6 at VSFB. If this flight follows form, NROL-70 will be taking its payload on a due east trajectory out of CCSFS into a geostationary orbit.

The Delta IV Heavy, capable of launching up to 13,810 kilograms to a geostationary transfer orbit, is making its first and only flight of 2024, its 16th overall flight, and the second flight this year for the United Launch Alliance. NROL-70 will also be the very last of 389 Delta family rockets that have flown since the dawn of the space age, with a 95 percent success rate.

(Lead image: Delta IV Heavy being prepared for its final flight on NROL-70. Credit: ULA)

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