Rocket Report: Hypersonics, Sentinel Silo Update, Next-Gen Cargo Trials
Stratolaunch Demonstrates Reusable Hypersonic Rocket Plane
Stratolaunch has put the world’s largest carrier aircraft to work on hypersonic flight testing. In two flights over the Pacific since December, the Scaled Composites-built Roc plane released the Talon-A test vehicle at 35,000 ft, accelerating it to Mach 5+ under rocket power before autonomously guiding it back for a powered touchdown at Vandenberg Space Force Base. Each Talon-A vehicle, with a dry mass of 1,500 kg and a composite-propellant tank loaded with 2,500 kg of solid fuel, is propelled by a clog-resistant, 25 kN thrust hybrid rocket motor built by Stratolaunch in partnership with Aerojet Rocketdyne. Zachary Krevor, CEO of Stratolaunch, said the goal is to ramp test flights to once per month by Q4 2025, a tempo enabled by rapid vehicle refurbishment and modular avionics.
“We’re essentially flying a 21st century X-15—no pilot on board, full autonomy throughout Mach 5 to Mach 7,” Krevor said. “That capability is foundational for future hypersonic weapon systems, particularly maneuvers beyond physiological limits.” Stratolaunch’s Talon-A is one of five vehicles under the Defense Department’s Hypersonic Air-breathing Weapon Concept (HAWC) program, feeding data back to DARPA, AFRL, and ONR on thermal protection, flight controls, and guidance algorithms.
Recent US Navy Conventional Prompt Strike Hypersonic Test
On April 25, the US Navy validated its Cold-Gas Ejection Launch System (CGELS) for the Conventional Prompt Strike (CPS) weapon, the Navy’s variant of the Army’s Long Range Hypersonic Weapon (LRHW). Launched from Cape Canaveral with a 5 m/s cold-gas push, the common hypersonic glide vehicle separated cleanly at 200 m above the deck, ignited its booster, and sustained flight above Mach 6 for a 1,000 km range. CGELS uses high-pressure nitrogen at 300 bar to eject the missile from Mark 41 Vertical Launch System tubes, ensuring safe distance from the ship’s superstructure prior to ignition—an innovation Army tests did not require.
Vice Adm. Johnny Wolfe Jr., director of Strategic Systems Programs, commented, “Successful CGELS demonstration proves we can deploy a conventional hypersonic strike from guided missile destroyers by 2028, complementing the Army’s Dark Eagle fielding in late 2025.” Both services will now integrate advanced seekers—dual-mode radar and infrared—to enable on-the-fly retargeting.
Sentinel ICBM Program Faces New Silo Design Challenges
The Air Force’s next-generation LGM-35A Sentinel ICBM is encountering unexpected issues in repurposing existing Minuteman III silos. Sentinel, developed by Northrop Grumman, is 18 m tall, 2 m in diameter, and weighs 42 metric tons fully fueled. Initial studies at Vandenberg Space Force Base revealed that the larger rocket and upgraded canister ejection system require a new silo bore of 4.5 m diameter and a depth increase of 3 m to accommodate the cold-landing shock absorbers and missile erector mechanisms.
According to sources at Defense News, retrofitting Minuteman III silos would have introduced unacceptable structural risks and delayed fielding beyond 2030. The program’s original $77.7 billion estimate ballooned to over $110 billion, triggering a critical Nunn-McCurdy breach in January 2024. While the Pentagon reaffirmed Sentinel’s importance to the nuclear triad, the requirement for ground-up silo construction adds another layer of cost and schedule pressure.
Gilmour Space’s Eris Orbital Launcher Nears Debut
Australia’s Gilmour Space Technologies has received Civil Aviation Safety Authority approval for its Eris three-stage orbital rocket. Standing 25 m tall with a 2 m diameter, Eris is powered by nine Aeon-1 engines on stage 1 (each generating 5.4 kN thrust with liquid oxygen and methane) and a vacuum-optimized Aeon Vac on stage 2. The third stage is a solid-motor kick stage capable of circularization burns. Launch is targeted from the Arnhem Space Centre in Queensland as early as May 15, pending final sign-off from the Australian Space Agency.
Engineering VP Dr. Simone Fuller noted, “We’ve performed full-duration hot fires, sonic boom predictions, and payload fairing acoustic tests. A successful debut would mark Australia’s first domestically built orbital launch and open up 300 kg payload capacity to sun-synchronous orbit.” A small launch team from the Gold Coast is en route to finalize vehicle integration after a four-week storage period.
Revisiting SpaceX’s 2016 Pad Explosion
A newly released FAA letter, obtained by Ars Technica, reveals that after the Sept. 1, 2016 Falcon 9 explosion at Cape Canaveral, SpaceX explored over 200 failure scenarios. Elon Musk even floated the unlikely “sniper shot” theory due to a brief flash seen near ULA’s Atlas V test stand 1 mile away. The FAA escalated the inquiry to the FBI, which concluded there was no evidence of sabotage or criminal activity.
SpaceX engineers ultimately traced the root cause to a sudden COPV (Composite Overwrapped Pressure Vessel) rupture in the second-stage helium pressurization system. The 3,500 psi tank’s carbon-fiber overwrap delaminated under cryogenic temperatures, leading to a catastrophic breach. Subsequent COPV redesigns and helium management logic updates have prevented recurrence in over 200 Falcon 9 flights since.
Eric Schmidt’s Vision for Space-Based Data Centers
Since acquiring Relativity Space in March 2025, former Google CEO Eric Schmidt has signaled his ambition to deploy orbital data centers. Speaking at a congressional AI hearing, Schmidt noted, “Plans are underway for 10 GW-scale data centers. On-Earth power and cooling won’t scale—space offers nearly infinite solar irradiance and vacuum-cooling through radiators.”
Relativity’s Terran R rocket (3.6 m diameter, 52 m tall, 25 Raptor 2 engines) could loft modular server racks clad in photovoltaic arrays and deploy heat‐pipe radiators to reject terawatts of waste heat. Still unclear are orbital slot bookings, laser communications backhaul architecture, and on-orbit assembly techniques. Analysis by the Secure World Foundation warns of orbital congestion and regulatory hurdles under the Outer Space Treaty if commercial data centers proliferate in LEO.
Rocket Lab’s Neutron Joins the Air Force Rocket Cargo Program
Rocket Lab’s 8-m-diameter Neutron launcher has been selected by the Air Force Research Laboratory for the Rocket Cargo experiment in 2026. Neutron uses nine Rutherford Mk 5 engines on its first stage (each producing 230 kN vacuum thrust with electric pump-fed kerosene/LOX) and a single vacuum-optimized Rutherford on stage 2. The AFRL mission will test a 2,000 kg cargo canister equipped with a guided reentry capsule, decelerated by a 60 m² hypersonic inflatable aerodynamic decelerator before parafoil deployment.
Founder Peter Beck said, “This experimental phase will validate rapid global logistics via space, potentially revolutionizing how materiel reaches remote theaters. If AFRL moves to full operational requirements, Neutron could regularly deliver tons of cargo anywhere on Earth within 12 hours.” SpaceX’s Starship is also contracted for Rocket Cargo, offering up to 100 t payload but with higher integration risk at Starbase.
FAA Unlocks Higher Starship Launch Cadence
The FAA has expanded SpaceX’s Starbase launch license from five to 25 Starship launches per year. The revised Environmental Assessment concluded incremental impacts on bird populations, noise levels, and coastal erosion are manageable. However, SpaceX must still resolve vehicle maturity issues: the latest two Starship upper stage failures off the Florida coast were traced to Raptor V combustion instability and thermal over‐cycling on the interstage welds.
Sources suggest SpaceX aims for a mid-May orbital attempt pending final static-fire of 33 Raptor engines and beach closure permits. The first full‐duration reflight of a booster would mark a critical step toward a 100-flight-per-year operational cadence.
SpaceX’s Starbase Voters Approve New Municipality
Residents near Boca Chica Beach in South Texas voted 97% in favor of incorporating a new city around SpaceX’s Starship facility. With just 218 ballots cast, two-thirds of eligible voters are SpaceX employees or contractors. The new city charter grants local authority over beach closures, property assessments, and public safety—areas Musk has long sought to control for future Starship flight expansions.
Next Three Launches
- May 10 2025: Falcon 9 | Starlink 15-3 | Vandenberg SFB, CA | 00:00 UTC
- May 10 2025: Falcon 9 | Starlink 6-91 | Cape Canaveral SFS, FL | 06:28 UTC
- May 11 2025: Falcon 9 | Starlink 6-83 | Kennedy Space Center, FL | 04:24 UTC
Deep Dive: Hypersonic Market Outlook
Analysts at Jane’s Defence estimate the global hypersonics market will exceed $100 billion by 2035, driven by demand from the US, China, Russia, and emerging players like India and Japan. Key growth areas include glide vehicle materials (ultra‐high temperature ceramics), advanced seekers (multi-spectral), and ground-based missile defenses (directed energy). Military contractors such as Lockheed Martin, Raytheon, and Aerojet Rocketdyne are pivoting resources from space launch to hypersonic R&D, betting that tactical conventional weapons will see more procurement than traditional orbital services.
Deep Dive: Economic Viability of Space-Based Data Centers
Space-based data centers promise unlimited solar power and radiative cooling, but high launch costs ($1,000–$2,000 per kg) and on-orbit servicing challenges remain barriers. A 2024 analysis by Morgan Stanley projected an breakeven capex of $30 billion for a 1 GW orbital data farm, assuming 50% reusable launch vehicles and in-situ assembly by robotic servicers. Thermal management studies indicate that a 10 m² radiator panel can reject up to 200 kW of heat, requiring radiators spanning several kilometers in total area for terawatt-scale operations.
Deep Dive: Strategic Implications of Sentinel Silo Redesign
Building new silos for the LGM-35A Sentinel extends construction timelines by 12–18 months per launch complex, potentially leaving garrison forces with fewer land-based ICBMs during the 2028–2032 window. Strategic analysts warn this could create a temporary triad gap, increasing reliance on submarine-launched ballistic missiles (SLBMs) and strategic bombers. To mitigate risk, the Air Force is exploring rapid-dig techniques using tunnel-boring machines and prefabricated silo modules, but these innovations have not yet been fully tested at scale.
Stephen Clark
Space Reporter
Source: Ars Technica