Roundup: Reusable rocket vehicles

Significant progress is being made towards space transportation systems that operate repeatedly rather than just fly once and then discarded. Reusable rocket powered vehicles will eventually lower the cost of access to space by orders of magnitude from expendables when the vehicles can fly  hundreds of times with only brief refurbishment between flights.

While the Space Shuttle program aimed for cost-effective reusablity, the extensive refurbishment, if not rebuilding, after each flight prevented the Shuttles from making any progress towards lower cost space access.

The multiple recoveries and reuses of SpaceX Falcon 9 first stages have proven that lower cost launch can be attained even with partial reuse. The per kilogram to orbit cost is about $2000, which is roughly a factor of 10 lower than conventional expendables were when the program started.

Below are updates on the SpaceX vehicles as well as several other reusable rocket systems in development including suborbital and long distance point-to-point vehicles.

Liftoff for the first test flight of a Starship with Booster B7 and upper stage SN24 on April 20, 2023. Credits: SpaceX

** SpaceX StarshipSecond orbital flight test soon.

[ Update Nov.21.2023: SpaceX released a statement summarizing the second flight tests: Starship’s Second Test Flight – SpaceX – Nov.21.2023.

The statement basically restates the same positive and negative aspects of the flight listed in the update below. However, one difference is that the destruction of the booster was due to “a rapid unscheduled disassembly“, i.e. an explosion in the vehicle’s systems, rather than a deliberate detonation by the flight termination system. The upper stage, on the other hand,  was definitely destroyed by the FTS:

The flight test’s conclusion came when telemetry was lost near the end of second stage burn prior to engine cutoff after more than eight minutes of flight. The team verified a safe command destruct was appropriately triggered based on available vehicle performance data.

The statement provides no information or speculation on what might have led to the destruction of the stages.

Update Nov.20.2023: The second flight test lifted off on Nov.18th within a tight 20 minute window. The test demonstrated that the major issues that afflicted the first flight in April had been resolved.

  • No significant damage to the launch pad. The steel plate and water deluge system worked to protect the launch mount and the ground area beneath it. Elon Musk: “Just inspected the Starship launch pad and it is in great condition! No refurbishment needed to the water-cooled steel plate for next launch…
  • No engine failures or engine compartment fires this time on the Super Heavy Booster. All 33 engines performed well from launch till staging.
  • Hot staging, a major design change implemented since the first test, appeared to work well.
  • The six engines on the Starship upper stage started up at staging and powered the stage to 148 kilometers, thus reaching space.

There were, however, two significant shortcoming to the test:

  • After separation, the booster began maneuvering for the boostback burn, which would have led to a soft landing on the waters of the Gulf of Mexico. However, the flight termination system soon destroyed the vehicle. SpaceX has not yet reported what led to  the abort. It’s possible that the hot staging resulted in sloshing of propellants, which could have caused one or more of the engines to shut down.
  • After the upper stage engines burned for 6 minutes of the planned 6.5 minute thrust time, the flight termination system destroyed the stage. SpaceX has not yet indicated what caused the abort just 30 seconds before scheduled engine cutoff.

Both of these problems will probably have straight-forward fixes and won’t significantly delay the next test flight. The most important component of the Starship system yet to be tested is the heat shielding on the upper stage. This test flight would have had the upper stage reach just short of orbital velocity and reenter near Hawaii. Hopefully, the next flight will achieve this goal.

Elon Musk has indicated that a Starship for the next test flight could be ready in 3 to 4 weeks. However, before a FAA license can be approved, SpaceX must show that it understands the problems with this flight and has implemented solutions.

See also:

Some videos of the launch:


SpaceX has designed Starship for recovery of both stages after each mission and re-flight after a rapid turnaround. If this goal is achieved,  Starships should allow the cost of access to orbit to drop by another factor of 10 over the Falcon 9. The cost could go even lower if the flight rate can rise to a very high level.

A series of test flights are planned to achieve the operational goals for the vehicle. Meanwhile, the factories at Boca Chica Beach, Texas are churning out boosters and upper stages for the tests.

As of the time of this post, the second Starship flight test is set for November 18th. Beyond simply testing as many components and systems as possible, the end goal is to send the upper stage nearly  into orbit and have it reenter the atmosphere over the Pacific and survive the tremendous heating during reentry. It will splashdown in waters near Hawaii. For this test there will be no attempt at a powered landing. The booster, however,  will attempt a soft landing onto the waters of the Gulf of Mexico. Presumably, the stage will be retrieved if it floats.

The first orbital test flight on April 20, 2023 succeeded in testing many systems in the first stage booster and it showed in a rather spectacular manner that major fixes and improvements were needed for many of those systems. Most notably, the launch mount and its ground substructure were badly damaged, with debris and dust hurled over a wide area. There were also Raptor engine failures as well as fires in the engine compartment that eventually severed control of the booster and prevented separation of the stages. Thus there was essentially no testing at all of the Starship upper stage.

SpaceX has spent the past several months implementing those fixes and improvements. The launch mount has undergone a major overall that included the installation of metal flooring that implements a water deluge system to handle the enormous heat and blast produced by 33 Raptors firing at liftoff. The engine compartment was also modified to better prevent fires and to isolate a fire if one does occur. Using electric actuators instead of hydraulics to power the thrust vector control for the 13  inner engines (i.e. change the angle of the thrust) will eliminate a common source of problems and significantly reduce TVC related hardware.

A major design change to the vehicle will also get its first test on this flight. A vented ring was added between the stages to  allow engines on the Starship to start firing while the stages are still connected. This “hot staging” should increase the payload capability by about 10%. This technique has been used on Soviet/Russian launch systems but never before on America launchers.

The Starship program is attracting massive coverage from a wide array of professional and volunteer reporters. Here are links to some articles of interest and video report sites.

See also the SpaceX Starship report, which is published by NewSpace Global and for which I was the primary author. The initial version came out in March 2023 and then we updated it in May to include coverage of the first flight test.


** SpaceX Falcon 9Currently aiming for 20 flights per booster

The Falcon 9 (F9) has become one of the most successful launch systems ever developed. As of the date of this posting, there have been 282 total F9 launches starting with the first flight in 2010. F9 and the Super Heavy have flown 83 times so far in 2023 and may reach close to 100 for the year. The goal for 2024 is 144 flights, or 12 per month.

Reusability has played a big role in its success. In those 282 launches, the booster has landed 245  times and 217 used a first stage booster that had flown previously.

So far, a F9 booster has achieved 18 flights and should fly at least 20. SpaceX appears to have followed a pattern in which after achieving each additional set of five flights, a  deep examination of the vehicles is made to check for any signs of fatigue and degradation in the structures and components. Whether booster reuse will extend beyond 20 will depend on another such evaluation.

A Falcon 9 first stage booster landed on the A Shortfall of Gravitas droneship following the launch of Starlink satellites on Nov.3.2023. This was the 18th launch and landing of the booster. Credits: SpaceX

A F9 payload is protected during launch by a nosecone composed of two fairings that split and fall away shortly after stage separation. The F9 fairings are now routinely recovered and reused after parachuting back to the sea. Initially, SpaceX aimed to catch fairings in a large net extended above a ship but this turned out to be more difficult than hoped. Fortunately, fairings recovered after floating on the sea showed far less damage from salt water than expected. After some design modifications to fully eliminate water effects, fairings are now routinely recovered from the ocean, refurbished and reused, saving several million dollars over construction of a new set of fairings.

SpaceX recovery vessel Doug retrieves a fairing half from Atlantic waters following a launch of Starlink satellites on Nov.3, 2023. The fairing was on its 13th mission. Credits: SpaceX

Note also that Dragon Crew/Cargo space capsules have also been reused. The current Dragon II capsules have been designed to re-fly up to 15 times.

** Stoke SpaceSecond stage prototype successfully hops.

Stoke is developing an fully reusable two stage vehicle called Nova that will carry 7 ton payloads to LEO. Though much smaller than Starship, the goal is to achieve low cost to orbit via 24 hour turnaround and a high number of flights per vehicle. To accomplish this goal, their vehicle design uses an innovative approach to the most difficult challenge of full reusability: a second stage that can take a substantial payload to orbit and then reenter the atmosphere and execute a powered soft landing.

A space capsule like a SpaceX Dragon uses a heat shield over its “bottom” to protect the vehicle from the high temperatures generated as it is slowed by atmospheric drag. The capsule’s gumdrop shape and low center of mass keep the shield facing forward and no dynamic piloting is required. Eventually the capsule slows to the point that it simply falls through the lower portion of the atmosphere. The capsule deploys parachutes for the final phase of the descent and landing. (The Shuttles similarly used heat shields but employed their aerodynamic surfaces, i.e. the wings, to help reduce speed and glide to a landing.)

The Stoke second stage also uses a capsule-like heat shield during re-entry. Unlike the ablative materials typically used for capsule shields, the Nova upper stage will use an actively cooled metallic shield. In addition, rather than deploying parachutes for the final phase of speed reduction and landing, the vehicle is slowed and landed via the thrust of an array of combustion chambers set along the outer rim of the shield. During ascent, these same thrusters fire to send the upper stage into orbit after it separates from the first stage booster.

Stoke recently carried out a successful test vertical-takeoff, vertical landing (VTVL) “hop” of a second stage prototype: Update on Hopper2: The Hopper Has Landed | Stoke Space – Sept.17.2023.

And the company subsequently obtained a substantial investment that will enable development of the first stage of Nova: Stoke Space Announces $100 Million in New Investment | Stoke Space – Oct.4.2023.

The goal for the debut of Nova is 2025: Stoke Space hops its upper stage, leaping toward a fully reusable rocket | Ars Technica – Sept.18.2023.


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** Relativity Space –  Terran-R with reusable first stage to fly in 2026

Relativity Space aims to begin launching the mid-lift Terran R from Launch Complex 16 at Cape Canaveral in 2026. The vehicle design resembles the Falcon 9 with a reusable first stage that lands downrange on a sea platform and an expendable upper stage. Initial goal is 20 flights per first stage unit. The vehicle will take as much as 23,500 kg to Low Earth Orbit (LEO).

On left stands a stacked Terran R rocket with both stages and nosecone fairings. On left is the reusable first stage alone. Credits: Relativity Space

A September update marked  the following milestones :

Broke new ground at the A-2 test stand
Completed our fifth Aeon R thrust chamber assembly campaign, bringing us to 43 hot fires to date.
Shipped and mounted our Aeon R powerpack: the first integrated test article that will be hot-fired on our new dual bay stand.

** Rocket LabElectron first stage recovered from launch; Neuron development underway

Rocket Lab is pursuing two reusability projects. They are progressing with a reusable first stage for the Electron small payload launch system while in parallel they are developing the reusable Neutron launch system for larger payloads.

Initially, Rocket Lab intended for a helicopter to use a hook to grab the parachute of an Electron booster and return it to land, preventing any contact with the sea. One attempt to do this briefly succeeded in snagging a booster’s parachute but it was then quickly detached due to signs of excessive stress. The booster went into the ocean but it floated and was recovered. Similar to the SpaceX experience with fairings, Rocket Lab found little sea water damage to stages and decided to eliminate the helicopter snag and let the boosters fall softly into the water. In July of 2023, Rocket Lab successfully recovered an Electron rocket booster after it was deliberately landed onto the sea.

See this video for a description of a Electron booster’s return and recovery.

So far, no booster has re-flown but they did successfully reuse an engine from a recovered booster.

Progress on development of the reusable Neutron rocket vehicle is proceeding well according to the company. The Neutron has a reusable first stage with an alligator style nosecone with hinged fairings that open to release the payload.  An expendable second stage is attached to the payload for reaching orbit. The hinges close and the stage returns for a powered landing. The Neutron will place up to 13,000 kg into LEO.

An artist rendering of a Neutron rocket first stage deploying a payload attached to a propulsion stage to reach orbit. Credits: Rocket Lab

Rocket Lab will use a former Virgin Orbit facility in Long Beach, California to build the Neuron rockets.

First launch of Neutron could be as early as 2024: Peter Beck pushes toward a Neutron debut in 2024, but acknowledges challenges | Ars Technica – Aug.18.2023.

** Blue Origin New GlennLots of work underway at the Cape

Blue Origin seldom provides updates on the progress in development of the heavy-lift New Glenn launch system. However, outside observers (e.g. here) have reported that a great amount of activity has been happening this year at the Blue Origin facilities at Cape Canaveral. These facilities include a large factory complex, testing sites, and Launch Complex 36 (LC-36).

The first-generation NG will consists of a reusable booster and an expendable upper stage. For the longer term, a reusable upper stage is in development. The seven-meter diameter and 98-meter height will make it one of the largest rockets ever built. The first stage is powered by seven BE-4 engines burning liquid natural gas and oxygen propellants. BE-4 engines also power the ULA Vulcan rocket’s first stage. The NG booster will land on a ocean platform.

The upper stage has two BE-3U engines, which are vacuum optimized variants of the BE-3 engines used on the suborbital New Shepard vehicle (see below). These engines use liquid hydrogen and oxygen propellants.

It’s believed that Blue is aiming to fly the first New Glenn by late 2024 but this obviously could slip.

** Sierra SpaceAssembly of first Dream Chaser cargo vehicle completed

The first of the reusable Dream Chaser lifting-body vehicles has been assembled and will soon “ship to NASA’s Neil A. Armstrong Test Facility in Ohio for environmental testing“: Today Sierra Space Introduces Tenacity | Sierra Space – Nov.2.2023

A Dream Chaser will launch atop an expendable ULA Vulcan rocket for missions to low earth orbit (LEO). After servicing the ISS or carrying out other tasks, the Dream Chaser will return in a manner similar to the Space Shuttles:

Harnessing cutting-edge technology, Dream Chaser showcases its mettle by safely withstanding temperatures exceeding 3,000 degrees during re-entry, all while being cool to the touch mere minutes after landing. The incorporation of the most advanced autonomous flight system, ensuring a minimum 15-mission lifespan, marks a monumental leap forward in space transportation.

The company currently has a contract with NASA for 7 cargo resupply missions. These include carrying experiment materials, waste, and other items back to earth.

Development of crew capable versions of Dream Chasers, referred to by the generic name DC-200, appears to be a long term priority for Sierra. These could carrying people to and from the ISS as well as commercial space stations such as Orbital Reef, for which Sierra is a co-developer.

See also

** Suborbital space tourismVirgin Galactic and Blue Origin updates

There are currently two reusable suborbital rocket systems that have flown paying “spaceflight participants“.

*** Virgin Galactic on November 2, 2023 flew the VSS Unity reusable rocket plane on its fifth operational commercial flight: Virgin Galactic Completes Sixth Successful Spaceflight in Six Months | Virgin Galactic – Nov.2.2023.

The flight carried three paying participants, two pilots and an “Astronaut Instructor”. Two of the participants, Alan Stern and Kellie Gerardi, were scientists who each carried out some experiments during the 3 minutes of weightlessness.  See Stern’s reports about the project and the flight. This article describes the tests they did: Virgin Galactic Flies Science Experiments to the Edge of Space | Universe Today – Nov.15.2023.

Such flights begin with the White Knight vehicle carrying the space plane to an altitude of about 16 kilometers and then releasing it. The space plane fires its hybrid rocket motor, which can send the vehicle to an altitude of 85 to 90 kilometers. This exceeds the 80 km border to space as defined by the USAF.

Previously, the company had said it would fly Unity monthly while developing in parallel the next-generation Delta class vehicles. However, the company recently announced that it would phase out the current flight program in 2024 and focus its limited manpower and resources on development of the Delta-class vehicles. About 15% of the workforce was laid off. The  much higher flight rate enabled by the Delta vehicles is essential if the company is to remain financially viable.

The Delta-class vehicles can carry up to six customers, fly twice per week, and require lower maintenance costs than the current vehicle. The company is aiming for flight operations by 2026.

*** Blue Origin developed the New Shepard rocket to learn how to do vertical takeoff and landings and to use it for suborbital tourism and science missions. The vehicle includes a capsule atop a booster stage, which is powered by the liquid hydrogen/liquid oxygen BE-3 engine. The booster’s engine fires for about 110 seconds and then the booster and capsule separate at around 40 kilometers in height. Both continue upwards  and exceed 100 kilometers before they begin to fall back to earth. The booster restarts its engine and makes a powered soft landing. The capsule returns for a soft landing with parachutes. A solid rocket fires just before touching down to soften the impact.

Following a series of test flights over several years, the first crewed flight happened on July 20, 2021. This was followed by an uncrewed flight with commercial payloads aboard and then there were 5 flights with paying passengers by August 4, 2022.

A New Shepard booster failed during a flight on Sept. 12, 2022 . The capsule payload included a set of experiments but no people. The capsule successfully fired its abort motor to separate from the booster and then landed safely with its parachutes. Blue Origin announced in March 2023 that the failure had been traced to a structural fatigue flaw in the nozzle of the New Shepard’s engine. They were implementing a fix and  expected “to return to flight soon, with a re-flight of the NS-23 payloads“.

However, as of November 2023, flights have not resumed. No explanation for the delay has been given and there is speculation that the company may discontinue the service to focus its manpower and resources on development of the orbital New Glenn rocket: How long will Jeff Bezos continue to subsidize his New Shepard rocket? | Ars Technica – Nov.3.2023.

** PLD Space – Successful suborbital test flight

The PLD Space Miura-1 suborbital lifts off on Oct.7.2023. Image credits: PLD Space.

This Spanish company has been developing a reusable launch system for several years. On October 7, 2023 the company carried out their first successful test flight of the  prototype suborbital rocket,  MIURA 1. The rocket flew the planned trajectory to an apogee of 46 kilometers. (Range safety issues led to lowering the apogee from a previous goal of 80 km.) A payload of memorabilia items was released and the rocket’s parachute opened as planned. The vehicle reached the sea service in one piece but high lateral winds caused the vehicle to hit the water at an excessive speed that “caused one of the two main tanks to rupture, filling with water and sinking the vehicle“.

Based on lessons learned from this test, the company will proceed with development of MIURA 5, “which will make its first flight in 2025 from the European spaceport CSG, in Kourou (French Guiana), and will place satellites of up to 500 kg in polar orbit and up to one ton in equatorial orbit“. The first stage of Miura 5 will be recovered via parachute return and be reused. Commercial operations will then begin in 2026 and their goal is to average 30 launches per year subsequently.

More details at

Below is a video of the launch and a press conference.

** Pangea AerospaceDeveloping aerospike engines

Pangea is a Spanish company developing reusable aerospike propulsion systems. Aerospike engines can provide stable, efficient thrust at full atmospheric pressure and in vacuum while conventional engines need different nozzles for the two regimes. So theoretically aerospike engines would be ideal for single-stage-to-orbit vehicles but this has yet to be proven in practice.

Pangea has demonstrated a Methane-Liquid Oxygen aerospike engine:

Check out their collection of videos providing an introduction to aerospace propulsion.

** Jess SponableRLV history and a new P-2-P hypersonic rocket vehicle project

Jess Sponable discussed the history and current state of reusable rocket vehicles on a recent episode of The Space Show. While with the Air Force, DARPA, and other organizations, Sponable participated in several reusable rocket vehicle projects including the DC-X, X-33, and X-34.

Sponable also discussed his recent work with New Frontier Aerospace (NFAero), a startup company developing a rocket powered lifting body vehicle for long distance, point-to-point flights at Mach 8. The vehicle takes off and lands vertically and can reach any place on earth within two hours. It will be powered by the Mjölnir, a “3D-printed, full-flow staged combustion engine“.

Mojlnir full flow staged combustion engine. Credits: NFAero and PRLog

More about Mjölnir amd MFAero:

** Venus Aerospace Hypersonic flight with rotating detonation rocket engine

Venus is another company pursuing global hypersonic transportation. They say their Stargazer would reach anywhere in the world in one hour. It would be powered by a rotating detonation rocket engine (RDRE) currently in development.

Stargazer will take off from a primary airport with jet engines, then when away from city-center, our rocket engine will propel passengers gently to 170,000 feet and Mach 9, crossing 5000 miles in 1 hour. San Francisco to Japan. Houston To London. All with a 2-hour turn-around.

The company has raised more than $20M and investors include Airbus, Draper Associates, and several other firms.

See this video for a good intro to RDRE: How NASA Reinvented the Rocket EngineReal Engineering.

** Astrobotic Zodiac flies again.

Astrobotic acquired Masten Space last year after it ran into a cash flow crisis that resulted in bankruptcy: Astrobotic Acquires Masten Space Systems | Astrobotic – Sept.13.2022.

Astrobotic promise to

continue to offer and develop [Masten’s] unique test capabilities, including providing VTVL test flights for commercial and government customers. Astrobotic plans to expand these test flight offerings with the development of the next-generation Xogdor rocket, which will offer higher altitudes, longer missions, and supersonic flight for suborbital payload testing.

NASA’s Flight Opportunities has sponsored a number of projects that took advantage of VTVL flights for applications such as testing lunar landing sensors and guidance systems. In October the first flight campaign since the Astrobotic acquisition was successfully carried out with the Xodiac rocket, which has flown over 150 times. The flight test experiments were funded by NASA.

Astrobotic, a leader in vertical-takeoff, vertical-landing (VTVL) reusable rockets, successfully completed a flight test campaign for the University of Central Florida (UCF) last week at the company’s facility in Mojave, CA. The campaign consisted of four flights aboard Astrobotic’s Xodiac VTVL rocket to test UCF’s Ejecta STORM laser sensor, which was developed by Dr. Phil Metzger to study plume-surface interactions (PSI) between a rocket plume and lunar regolith. This test campaign will provide valuable data for researchers, including Dr. Metzger, as they seek to better understand PSI for humanity’s return to the Moon under NASA’s Artemis program.

Here is a  video of the test.

University of Central Florida researchers tested an instrument designed to measure the size and speed of surface particles kicked up by the exhaust from a rocket-powered lander on the Moon or Mars. The four tethered flights on Astrobotic’s Xodiac rocket-powered lander took place in Mojave, California, from Sept. 12 through Oct. 4, 2023. Researchers tested the Ejecta STORM technology’s integration with a lander and operation in flight conditions that simulated the plume effects of a lunar lander.

** Exos AerospaceTests engine for suborbital vehicle to fly in 2024

Exos Aerospace, a descendant of John Carmack’s Armadillo Aerospace, continues to develop reusable suborbital vehicles. The company is based in Greenville, Texas and recently test fired an ethanol engine mounted in a tethered rocket. A Purdue student group collaborated in the test:

Exos Aerospace BLK3 Engine Tests with Purdue University Sept 13 2023:
“Exos Aerospace, a Greenville-based company, tested an engine for a rocket as they prepare for a launch in 2024.”

“a team from Purdue University was on hand for the rocket test Wednesday, performing a lunar lander thermal experiment as part of the test.”

““This is a reduced throttle run,” said John Quinn, co-founder and CEO of Exos Aerospace, according to NBC 5 DFW. “It’ll be 60% throttle on the first test and 70% on the second test”

North Texas commercial spaceflight tests rocket engine (Article and video)…

Other Exos news items:

Exos Aerospace BLK3 Hold Down Test and Hover Test.
0:01 BLK3 Tether Test
0:45 BLK3 Hover Test

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** Chinese RLV development iSpace Hyperbola-2 rocket does vertical takeoff and landing flight

The Chinese government program and several Chinese companies are pursuing rocket reusability. Some of these projects include:

On November 2nd, iSpace flew its Hyperbola-2 methane fueled test stage to 178 meters and then came back down for a soft landing: China’s iSpace launches and lands rocket test stage – SpaceNews. Such VTVL tests were flown by the DC-X in the early 1990s, by Masten and Armadillo in the 2000s, and by SpaceX with the Grasshopper vehicle to master vertical takeoffs and landings.

The company is aiming for a SpaceX Falcon 9 type of system with a reusable first stage and expendable upper stage.

** Other reusable rocket related projects:

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