The Flight of Orion

A milestone in the program to develop a new human spaceflight system is set to occur this week, as the first unmanned flight of the new Orion spacecraft lifts off from Cape Canaveral’s Launch Complex 37 on Thursday. This mission will test the overall flight qualities of the new Orion spacecraft. Many systems are still to be developed, with pieces of the spacecraft needed for human occupation replaced on this flight by instrumentation. The tests are designed to observe the vehicle’s responses to the dynamic environments of launch, orbit, high-speed re-entry and splashdown. Such flight test articles are called “boilerplate” vehicles.

The flight profile of Thursday’s test is similar in scope to the first test flights of the Apollo boilerplates. The general concerns are to monitor aerodynamic stresses during the key flight phases of launch and re-entry to assure that hull integrity is maintained and that operations in space are as expected. It is a test flight with limited objectives and expectations. But as the only human spaceflight event of any future significance in the calendar year, it has ramped up media interest and their coverage about the significance and potential of Orion.

Contrary to some articles, Orion is not a “replacement” for the Space Shuttle, which had capabilities and features that no planned future vehicle will possess. The Shuttle could transport as many as seven people to and from low Earth orbit (but could not journey beyond LEO). In addition, it could carry up to 24 metric tons of cargo in its payload bay. It could stay in orbit about two weeks, limited primarily by the amount of hydrogen and oxygen needed to generate electrical power from its fuel cells. The massive stable platform of the Shuttle payload bay, in conjunction with its dexterous robotic Canada arm, could grapple recalcitrant satellites, temporarily install them in holding cradles for repair and service, and then release them back into space. The Shuttle also had an airlock, through which astronauts conducting an EVA could exit and enter the spacecraft without depressurizing the entire vehicle.

The new Orion spacecraft can take up to seven people into space and back, but it is not designed to carry cargo or to service on-orbit satellites. It has no airlock, so the entire crew will have to be fully suited during EVA. Because the Orion has solar panels, it can stay somewhat longer in space, up to a few weeks, but has much less total electrical power available (about 6 kW) than did the Shuttle (21 kW continuous, 36 kW peak). Orion is designed for missions beyond LEO, i.e., human expeditions to destinations in deep space. NASA describes Orion as the “first piece” of the system needed to attain their long-term goal – a human Mars mission.

Put more accurately, Orion represents a small piece of an envisioned human Mars mission system. Its principal role will be to serve as the re-entry and splashdown vehicle for crew return. With a habitable volume of only about 9 cubic meters (for four people), it is too small to support even a skeleton crew on a three-year mission to Mars and back. For comparison, a typical Recreational Vehicle (RV) contains about 28 cubic meters of habitable volume per person. Imagine living inside the nine-cubic meter Orion spacecraft (about the volume of a small, walk-in closet) for three years, with the bulk of that time being the transit flight between Earth and Mars. When you listen carefully to agency people talk about Mars missions, you will hear about something called a “habitation module.” This would be the actual living quarters of the crew during such a mission, most probably some derivative of an International Space Station (ISS) module. This vehicle does not now exist, even in conceptual form. Beyond this, there is also the requirement for a yet-to-be-designed lander and ascent vehicle for the actual Mars excursion.

In short, any reports you may read about Orion being NASA’s “Mars spacecraft” are misleading at best and/or downright false, at worst. The Orion is actually a spacecraft optimized for cislunar spaceflight, missions which traverse the bounds of Earth-Moon space for a duration of a few weeks at most. This fact should come as no real revelation as Orion is the remnant of Project Constellation, the architecture that the agency chose to implement the Vision for Space Exploration (VSE), which President Obama cancelled in his 2010 budget submission. That system consisted of four pieces – the Orion spacecraft, a lunar lander called Altair, and the Ares I and Ares V launch vehicles. Our re-tooled human space program consists only of Orion and the Space Launch System rocket, a scaled-down version of the scrapped Ares V launch vehicle.

The main problem with Orion is not the spacecraft or its specific design, but its mission. It doesn’t have one. We will need multiple pieces of technology and knowledge in order to conduct a Mars mission, in addition to several hundreds of billions of dollars, none of which are on tap now or are likely to be in the near future. Moreover, the Orion spacecraft occupies an uncomfortable niche, being significantly over-designed for trips to and from LEO and the ISS, and significantly under-designed for human Mars missions. It remains what it was designed for when first conceived in the 2005 Exploration Systems Architecture Study – a vehicle for cislunar missions.

Given its abilities and limitations, what might Orion do and where might it go? NASA has embraced a proposal coming out of a 2012 Keck Institute workshop, in which an unmanned spacecraft (yet to be designed) is sent to a small (yet to be identified) asteroid in space, where it is bagged and then coaxed back into orbit around the Moon. Once in lunar orbit, a human crew using the Orion spacecraft can visit it. That, in short, is the “Asteroid Retrieval Mission” (ARM). This mission, while technically feasible, is of highly questionable value, both operationally and scientifically. There is a widespread perception in the space community that this mission is merely a “make-work” project, flown not to achieve any new capability or exploration objectives, but simply to conduct a mission – call it the mission, as there needs to be something other than the programmatic vacuum we’re in. Even more telling are recent reports that this mission could not be flown before 2025, a full decade from now. It’s one thing to wait a decade for the establishment of a lunar base – it’s quite another to wait a decade for a proposed mission of questionable value.

Another possibility is that Orion could be sent to Earth-Moon L-2, a point in space about 60,000 km above the far side of the Moon. From that stationary vantage point, astronauts in the Orion could control a teleoperated robotic rover on the lunar surface, collecting samples from the floor of the South Pole-Aitken basin, the largest (and probably oldest) impact feature on the Moon. Like the ARM, this mission would require additional hardware, in this case a rover to be delivered separately to the lunar surface as well as a small Earth-return vehicle to bring back lunar samples. In terms of both complexity and cost, the ARM and L-2 missions are probably comparable.

The real issue is not which of these missions is best, but rather, why are we considering either of them? We are stuck with a new human spaceflight vehicle that is optimized for a mission that cannot even be acknowledged (lunar return) and thus, we are forced to improvise mission scenarios of dubious value to justify the program.

Let’s hope the test flight of Orion goes well this week. No doubt anomalies will be found and technical issues will be dealt with – this happens with all new spacecraft developments. But for now, Orion and SLS are what currently remain of our national civil human space program – starkly representing its uncertain future. Can we end up doing anything of lasting value with them? It will take clear-eyed leadership to navigate us out of this bind.

Paul D. Spudis | READ MORE

Paul D. Spudis (1952-2018) was a senior staff scientist at the Lunar and Planetary Institute in Houston, Texas, and a prolific author on the subject of the moon. His books include The Value of the Moon: How to Explore, Live, and Prosper in Space Using the Moon's Resources.