One common classifications of launchers is according to the mass they can throw to Low-Earth Orbit (LEO). This classification scheme breaks all launchers down into the mass of payload that they can deliver to LEO. Launchers can (and for now, all do) have multiple stages, some of which are aircraft-based first-stages. For those who are not familiar with the actual size of the launchers they see on television this might help demonstrate why there are some significant competitive differences between launchers. For those are more familiar with the launchers from the launch services market we’ll provide a meaningful segmentation of the launch market.
Much like the definition of celestial bodies (see the controversy over the definition of a planet - long live Pluto!), this classification is but one particular approach for classifying launchers into meaningful and comparable categories. There are certainly others, for example vertical vs horizontal launch, mode of re-usability, or NASA’s launch vehicle risk classification. The mass to LEO classification remains very relevant, however, as it remains a critical element of typical space-based activities now and for the foreseeable future.
The classification
The mass to LEO launcher classification is based upon a range of payload masses:
Small-Lift (also referred to as “Smallsat”): less than 2,000-kg to LEO
Medium-Lift: 2,000-kg to 20,000-kg to LEO
Heavy-Lift: 20,000-kg to 50,000-kg to LEO
Super-Heavy-Lift: greater than 50,000-kg to LEO
The classification is based on an earlier NASA standard; there may be other minor variations on it from other space agencies or analysts. Payload is the satellite, capsule, or other non-structural pieces that are delivered to LEO. Not included in that number are the second-stage, payload mount / dispenser, or aerodynamic fairing that covers the payload during launch. The payload amount is the maximum amount; Falcon 9, for example can achieve a Heavy-Lift classification, though often launches in a Medium-Lift capacity, to retain margin for booster return.
To help you reference what these numbers mean, the latest Block III GPS satellites are 3,880-kg, with the earlier Block IIF GPS satellites coming in at 1,630-kg. For a more domestic reference, a 2024 Chevrolet Suburban is approximately 3,400-kg, depending on the included options. The James Webb Space Telescope is 6,500 kg. The smallest 1U cubesats might be 2-kg, while a larger 3U cubesat might be 4-kg.
Ultimately, weight is not the only factor in what can fit onto a launcher. There will often be unused mass in a launcher’s payload, as the specific shape of a particular payload may or may not allow for the full mass available to be added to the payload mount or dispenser. Thus, the payload ranges should be seen as a maximum that can, but will not always, be reached. Similarly, the density of the payload may be such that a launcher can handle the mass, but not the volume. Likewise, the launcher classification is by mass to LEO; the same launcher may not be able to reach the same mass to another, higher, orbit, or reach the other orbit at all. The combination of payload mass, volume, and target orbit describes a more complex equation that won’t be treated in detail here. Launchers vary greatly in size, as the comparison below indicates; the six on the far right are all small-lift launchers.
Small-Lift (Smallsat)
Small-Lift encompasses everything from the smallest launcher that can take a payload to orbit, to everything up to 2,000-kg. This can include both dedicated launches of a single payload, or launches of multiple payloads together. This segment of launchers is often referred to as Smallsat launchers, as they often support the launch of smaller satellites on dedicated orbital insertions.
Thus, while a Small-Lift launcher can often support the mass of many payloads, it cannot often support the volume. For example, the typical Small-Lift launcher can support the mass of the Kepler Observatory (1,039-kg), yet they would not be able to handle the volume; Kepler is 2.7-m is diameter, while Alpha, for example, is only 1.82-m in diameter - even the enlarged fairing is only 2.2-m in diameter, insufficient to handle the payload. This is the reason why many Small-Lift launchers actually support a much lower mass - a mass that is commensurate with the volume they can support. Thus, there is another common sub-category called “Micro-Lift”, which is described as 500-kg to LEO; this ultimately encompasses many Small-Lift launchers with small volumes (as a natural limiting factor for mass).
Operational or retired launchers that fit into the Small-Lift classification as of June 2024 include:
There are a great many more launchers which also aspire to enter this launcher class:
RFA One from Rocket Factory Augsburg, 1,350-kg to LEO
Spectrum from Isar Aerospace, 1,000-kg to LEO
Eris from Gilmour Space Technologies, 305-kg to LEO
Nebula-1 from Deep Blue Aerospace, 200-kg to LEO
There are numerous others planned or under development. It is a common entry point to the launch services provider market.
A clear segmentation can be seen between the Micro-Lift launchers and the larger Small-Lift Launchers. It is entirely based upon diameter (micro are much smaller), and thus volume and mass. While a common entry point into the launch services provider market (see SpaceX, RocketLab, for example), it can nonetheless be a challenging segment commercially due to the heavy competition. A future post will talk more about the history and current status of that market segment.
Medium-Lift
Medium-Lift isn’t an exciting term, but describes an important sector of launchers that range all the way from 2,000-kg to 20,000-kg to LEO. Many well-known launchers are in this segment. Operational or retired launchers that fit into this classification as of June 2024 include:
Gravity-1 from Orienspace, 6,500-kg to LEO
Soyuz 2 from TsSKB-Progress, 8,200-kg to LEO
H-IIA from Mitsubishi Heavy Industries, 15,000-kg to LEO
Long March 2C from CALT, 3,850-kg to LEO
Long March 3A from CALT, 6,000 to LEO
Long March 2F from CALT, 8,400 to LEO
Launchers under development in this class include:
Ariane 6 from Arianspace, 10,350-kg to LEO
It might be easy to perceive rockets as unchanging vehicles, but many do in fact change. Falcon 9, for example, has evolved significantly since it was introduced. In 2011, for example the Falcon 9 launcher could only achieve 7,000-kg to LEO, classifying it as Medium-Lift. In 2024, it is classified as Heavy-Lift, now supporting 22,800-kg to LEO. Nonetheless, Falcon 9 often still flies a Medium-Lift profile to achieve booster return (again, speaking to the complexities of understanding the launcher landscape from just a single classification).
Heavy-Lift
Heavy-Lift describes the segment of launchers capable of delivering from 20,000-kg to 50,000-kg to LEO. There are several flagship launchers from the past and present here. These include Delta-IV Heavy - visually one of the most impressive launchers from the United States. Additionally, the new Vulcan-Centaur launcher is in this class, alongside other long-running launchers such as Long March 5, and the (still potential) New Glenn and Terran R launchers under development. These are the launchers which are launching the many of the larger national-interest and defense payloads for their respective nations, as well as many of the biggest and furthest-travelling scientific payloads. Such typical dedicated payloads are supported by their mass to orbit and fairing volumes.
Operational or retired launchers that fit into this classification as of June 2024 include:
Vulcan-Centaur from ULA, 25,000-kg
Delta-IV Heavy from ULA, 28,790 kg
Long March 5 from CALT, 25,000 kg
Launchers under development in this class include:
New Glenn from Blue Origin, 45,000 kg
Terran R from Relativity Space, 33,500 kg
This class of launchers is set to become competitive, similar to Small-Lift, once New Glenn and Terran R are in service. Unlike Small-Lift, the market in this launcher class is more limited at this time. As a result the introduction of new launchers in this class could put downward pressure on price, or lead to the failure of one of more launchers without additional payloads to fill their launch manifests.
Super-Heavy-Lift
As commercial launch services providers have grown, so have their ambitions, with both Chinese and US companies beginning to build-out ever-bigger launchers to support national interest and other non-commercial initiatives. While there are not substantive dedicated commercial payloads in this space, yet, there are companies such as space habitat manufacturer Vast that are pursuing classes of equipment that can only be launched by a Super-Heavy launcher. Similarly, SpaceX continues to intend to support a massive campaign of launches to Mars, part of which would be large commercial payloads. The Super-Heavy launcher class includes those launchers that can lift greater than 50,000-kg.
Operational or retired launchers that fit into this classification as of June 2024 include:
Falcon Heavy from SpaceX, 63,956-kg
Launchers under development in this class include:
Starship-SuperHeavy from SpaceX, 199,580
Long March 9 from CALT, 149,685
Long March 10 from CALT, 68,038-kg
Some of these launchers support very significant LEO payloads. While Falcon Heavy supports a substantial 63,956-kg to LEO, and SLS supports an additional 50% improvement on that to 95,000-kg to LEO - launchers in development, such as Long March 9 and Starship-SuperHeavy nominally support even more, in the form of 149,000-kg and 199,000-kg to LEO, respectively.
The expansion of this launcher class will be driven by the availability of a greater range of substantive payloads. To a certain extend, the demand involves a complicated feedback loop. Launchers such as Starship-SuperHeavy or Long March 9 completely change the mass equation for those considering larger-scale missions. Working groups have started forming to start imagine what sort of newer science missions could be done with Starship-SuperHeavy, for example, that before would have been impossible. For example, Starship is designed to deliver 100 tons of payload to the surface of Mars. That means you can take five D5 bulldozers (conceptually at least, they’d need different powerplants, of course). Over time, as imaginations no longer constrained by current capacity limits, the commercial market for this space may increase.
Sub-Orbital
Thought this one had been forgotten? What about New Shepard, doesn’t it take people to space? Virgin Galactic spaceplane flights?
The launcher classification outlined in this post covers orbital launchers, which deliver a payload to LEO. There are many other rockets which are sub-orbital, meaning that they do not travel a trajectory, or do not reach a speed, sufficient to reach LEO. These rockets may or may not reach space (beyond the Karman Line), and their trajectories may be directly up and down (such as with a sounding rocket), or may follow an arc which reaches the ground again before travelling around the Earth.
Historically, important sub-orbital launches include that of Alan Shepherd (Freedom 7), Gus Grissom ( Liberty Bell 7), and even Gagarin in Vostok 1 (Yes! While the Soviets were still the first to achieve a crewed mission to orbit, it was with Vostok 2, not Gagarin’s so-nearly-orbital flight). The first successful sub-orbital launch, while un-crewed, occurred with the German A-4 rocket (better known as the V-2) in 1944. These missions all date back to a time when engineers and scientists were still figuring out how to make rockets go up, and to get the first satellites and crew capsules into space at all. Today, suborbital rockets are used exclusively for research (sounding rockets) and space tourism.
While some companies have build lines of business around sub-orbital launchers (see Virgin Galactic and Blue Origin), others have used them as an intermediate engineering milestone as they figure out how to build engines, rocket bodies, and ground service equipment. The rest of this section will describe these types of launchers in some more detail, and provide some examples in the news.
Sounding rockets
Sounding rockets are very small launchers with one or more stages and very limited payload. They are typically used to study the upper atmosphere, or carry out temporary measurements from the upper atmosphere. They do not meet orbital speeds, and ultimately fall back to Earth. There are no crewed sounding rockets.
Launchers with a sub-orbital launch arc
There are several launchers today with a sub-orbital launch arc. Several of these launchers are human-rated and are focused on space tourism; they include:
A well-known launch system that follows a sub-orbital arc is Virgin Galactic’s White Knight - Spaceship Two launch system.
Blue Origin’s New Shepard single-stage launcher also follows a sub-orbital arc.
There are certainly other sub-orbital rockets in low-number production, but they won’t be itemized here.
While this launcher classification doesn’t provide a single overarching way in which to understand the wide variety of launchers across the industry, it provides an effective language which companies, journalists, space agencies, and the general public can use to refer to the launch capabilities of the many vehicles available. If you had not previously noticed this language in news articles, social media, and informational material, you will begin to. Watch the Small-Lift classification for new entrants into the market, and keep an eye on the Super-Heavy-Lift market for significant missions to come.
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