The intent of this claim is to argue that human travel to Mars is feasible using smaller spacecraft. If validated, this implies that the supporting launch infrastructure can be scaled for smaller vehicles, lowering its capital cost.

At one end of the spectrum of possibilities is a single, large monolithic spacecraft. At the other end is a large fleet of smaller spacecraft containing either a single person or just cargo. There are many possibilities at intermediate points along the spectrum.

At the large, monolithic spacecraft end of the spectrum, the "fleet" benefits from the square-cube law. The total mass of the fleet can be organized so that the crew is better shielded from space radiation within a centralized spherical shell of supplies, provisions, and propellant. A single, integrated spacecraft also allows the crew to share common systems such as environmental control and life support, restrooms, sleeping quarters, and exercise equipment. Specialists, including medical personnel and technical experts, have easy access to all onboard systems. The entire crew can also interact freely, making use of shared common areas and maintaining a cohesive social and operational environment, leading to better behavioral health.

At the other end of the spectrum—a fleet of many small, single-occupant spacecraft—cost and reliability improve through mass production of spacecraft and repeated reuse of launch infrastructure. A critical failure, such as a meteoroid puncture, affects only the individual vehicle and does not jeopardize the mission as a whole. Entry, descent, and landing may also be simpler: smaller spacecraft benefit from higher surface-area-to-mass ratios and can use reasonably sized parachutes, representing an evolution of the EDL techniques validated by earlier robotic missions rather than a major redesign.

This approach also provides substantial operational flexibility. Some spacecraft can remain on Mars while others return to Earth; individual units can be repurposed as rovers, habitats, or storage modules; and the fleet can disperse across the surface for wider exploration or development. If the Mars campaign instead relies on a large central base—using a hub-and-spoke pattern in which crews conduct out-and-back excursions in all directions—the scope of exploration is naturally limited by travel time and range. A distributed fleet, by contrast, can establish many smaller outposts connected by rovers, allowing more terrain to be studied and potentially enabling more science and development within the same mission resources.

An intermediate solution involves lots of small, individually launched spacecraft that are designed to "aggregate" to gain some of the benefits associated with having fewer large spacecraft. Different types of aggregation are possible.

"Digital aggregation" requires that the spacecraft in the fleet are close enough together that real-time communications between crew members in different spacecraft are possible. With modern VR headsets, crewmembers could socialize with each other inside virtual environments. All of the crew could share a digital resource, such as real-time access to a powerful AI or access to a high-bandwidth communications relay that would connect them to Earth or Mars.

"Material aggregation" would add the ability for small autonomous courier drone spacecraft to carry essential supplies between ships in the fleet. This way, the mass needed for spare parts and medicines could be distributed across the fleet without excessive redundancy.

"Emergency aggregation" would permit one spacecraft to travel to and dock with another in an emergency. In such a case, one of these spacecraft would likely use up the propellant that it needed to land safely, and therefore, some mission supplies may be lost, but this strategy might prevent the loss of crew in case of a critical system failure or serious medical condition.

"Partial aggregation" would allow some of the spacecraft in the fleet to rendezvous and dock with each other after launch, while on the way to Mars. This might be easiest among the spacecraft that were all launched on the same day, as these spacecraft would be closest to each other. For example, with partial aggregation, three crewed spacecraft could physically dock with each other while a fourth cargo-only spacecraft could be connected to the first three by a long tether. Then the system could be set spinning so that the crew would have artificial gravity on during their journey.

"Full aggregation" would require all of the spacecraft in the fleet to be able to rendezvous and dock with each other. Full aggregation would enable many of the benefits of a single monolithic spacecraft, such as allowing mission specialists full access to all systems within the fleet, and allowing the crew to interact in the interests of good behavioral health. It would allow the fleet's mass to be arranged to better shield internal spaces from space radiation. It also preserves some of the benefits of having a fleet comprised of many smaller spacecraft, such as more easily repurposing spacecraft upon arrival and executing a more decentralized Martian exploration strategy.

The difficulty of an aggregation strategy depends on the separation distances and the amount of mass that is aggregated. For spacecraft that are launched back-to-back, with 5 minutes of each other, the separation distance will be the hyperbolic trajectory's excess velocity times the separation time. So, if four spacecraft are launched back-to-back, and they can correct, during endoatmospheric flight, the small differences in departure angle due to the Earth's spin, then the distance between successive spacecraft will be

$$d_{sep} \approxeq v_∞ (5 )(60) = 2,943 m/s * 300s = 882,900 \space m$$

The first and fourth spacecraft in a set of four can rendezvous by each doing a 10 m/s burn towards each other and then waiting until they coast together. Assuming that they are travelling along the same trajectory and are far from Earth

$$v_{closing}=2*10=20 \space m/s$$ $$d_{traversed}=3*d_{sep}=3(882900)=2648700 \space m$$ $$t_{closing} = d_{traversed}/v_{closing} = 2648700 / 20 = 132435s \approx 1.5 \space days$$

The second and third spacecraft would take less time to rendezvous, roughly 0.5 days. Conceptually, to avoid the need for deceleration burns and save propellant, spacecraft could fire magnetic grapplers at each other to affect a catch. If that catch fails, then a burn could still be executed as a backup.

Another propellant-saving method would be to deploy an autonomous courier drone between successive spacecraft. The drone could trail a fine tether or wire, which, once captured, could be reeled in to draw the two spacecraft together without relying on their onboard propellant. A fine wire that is 882,900 m in length and 5.08e-5 m in diameter would have a mass of

$$m = l \pi r^2 \rho = 882,900 * \pi * (5.08e-5/2)^2 (8000kg/m^3) = 14 \space kg$$

A rendezvous of two groups of spacecraft that are separated by a day is significantly more difficult, as the separation distance is much greater. Either much higher delta-v burns would be needed to bring them together, or, if the tethering approach was used, the mass of wire needed would increase by a factor of $24*60/5=288$ (which is a first-order estimate).

If the entire fleet of spacecraft was launched over 14 days, then the separation between the first and last spacecraft would be approximately

$$d \approxeq v_∞ (14)(24)(3600) = 2,943 m/s * 1209600s = 3,559,852,800 \space m$$

The worst-case communication delay over this distance would be

$$t=3,559,852,800/299,800,000 m/s = 11.9 \space s$$

If commanders and mission specialists are located in the middle of the fleet, then their worst-case communication delay would be half that.

Taken together, these considerations show that human travel to Mars does not require a single, large spacecraft. A mission architecture based on many smaller vehicles, optionally augmented through digital, material, or physical aggregation, can capture many of the advantages traditionally associated with large monolithic designs while retaining the cost, reliability, and operational flexibility of a distributed fleet. If such architectures are viable, then the launch infrastructure that supports them can be correspondingly smaller and more affordable, making human missions to Mars achievable with far lower capital expenditure than would otherwise be required.