FLO: The First Lunar Outpost (Space Exploration Initiative, Part I)

One of two landers for the First Lunar Outpost, this an unmanned one with an adapted Space Station module on top for use as a place to live during the mission. The astronauts would arrive at roughly the same time aboard a manned lander. This picture is somewhat incorrect in that the real lander would have had two large solar panels stretching to the right and left. Public domain image from NASA.

What is was: A 1992 benchmark mission for NASA to return to the Moon, using expendable launchers and a direct descent lander, and build a small periodically-inhabited lunar base on the Mare Smythii.

Details: Early during the presidency of George H. W. Bush, the White House directed NASA via Vice-President Dan Quayle to come up with a plan to go to Mars—a goal announced to the public as the Space Exploration Initiative (SEI). To say that NASA botched this opportunity is to put it mildly.

Their (admittedly non-mandatory) orders were that NASA should come up with a plan that could get to Mars relatively cheaply, probably using technology that had developed since the end of Apollo. Instead they put forward an obvious relative of von Braun’s 1969 Mars Expedition, ditching the nuclear rockets but otherwise following the path of building a big space station, a permanent Moon base, and then finally moving on to Mars. The total cost of the program was estimated to be about US$540 billion over about thirty years—or, to put it another way, a rough doubling of NASA’s annual budget through the next several presidential administrations. This was political suicide and the whole thing collapsed in acrimony almost the moment it was put forward. Richard Truly’s career as NASA administrator came to an end in large part because of the fiasco and he was replaced by Dan Goldin in 1992.

Goldin’s mantra for NASA was famously “faster, better, cheaper” and he arranged for another study that would attempt to recover the manned lunar exploration part of the SEI. It was explicitly to be based on new ideas from the so-called Stafford Report (properly known as America at the Threshold: Report of the Synthesis Group on America’s Space Exploration Initiative) from the previous year. Out of this study grew the First Lunar Outpost (FLO) proposal.

An artist’s rendition of the proposed HLV for the mission, referred to informally as Comet. Public Domain image from NASA.

The first step to the outpost was literally getting there. The initial SEI plan had foundered in part because of its allegiance to the Space Shuttle which, as it could lift only 25 tonnes to LEO, meant that NASA needed to build their Moon craft in Earth orbit; that in turn required a space station. FLO was based on a return to an expendable launch vehicle, and it would have been a monster: the core of the launcher would either be an all-new rocket or a stretched version of the Saturn V (to the extent that that program could be revived 20 years after its end); either would have been flanked with two boosters. Its resulting payload to LEO was to have been in the vicinity of 200 tonnes. Contrast that with the Saturn V at 118 tonnes, or 88 tonnes for the Energia.

This massive increase in capability was to be used in two ways: the Moon craft would not have to reconfigure itself in Earth orbit like the Apollo arrangement did, and it would land directly at its destination on the Moon rather than sending down a landing craft followed by a lunar orbit rendezvous before returning to Earth. As well as making the missions safer by allowing more ways to abort and opening up more of the lunar surface for exploration, this simplicity was believed to be the route to a cheaper mission despite the upfront cost of the rocket that launched it.

The FLO spacecraft on top of its TLI stage in Earth orbit. Public domain image from NASA.

Nuclear thermal engines were studied for the trans-lunar injection stage of the FLO spaceship, but it was assumed that it would probably use a J-2S LOX/LH2 engine—essentially the same as was used by the Apollo S-IVB injection stage, though slightly upgraded to use a de Laval nozzle. The lander itself would have used four RL-10s, repurposed from the tried-and-true Centaur.  Again, these choices were made with an eye to saving money by using what the American aerospace industry already had to offer.

The direct-descent/direct-return profile of the actual landing forced the lander to be quite different, though. Admittedly a scaled-up version of the Apollo CM was perched on top of it, where it would carry four astronauts in the relative comfort of 11.3 cubic meters—somewhat larger than the old CM and LM taken together. Below that, though, was a much bigger spacecraft.

It would have packed no less than ten propellant tanks, four smaller ones in an upper tier for the ascent stage, and six larger ones underneath for the lander itself. Sitting on a relatively robust landing truss and four very long legs the whole arrangement would have been 56.7 tonnes with propellant, which is more than four times the mass of the Apollo LM. It would have towered 14.1 meters above the lunar surface, and been 18.8 meters from landing-leg foot to landing-leg foot.

Another big change from the Apollo program was actually a return to what had been planned for the original Moon landings post-Apollo 20. A second, unmanned lander would have been sent prior to the manned one and landed within an easy Moon rover drive, no more than two kilometers. Its entire ascent stage would be swapped out and replaced with a 35-tonne habitation module made in the manner of a Space Station Freedom module with as few changes as possible—again as a nod towards cost.

A sketch of the interior of the FLO habitation module on top of the unmanned lander Note the solar panels. Public domain image from NASA.

This module would have been the actual base. The crew of the manned mission launched in tandem with it would live there for 45 days, exploring the region within 10 kilometers using the aforementioned rover driven by astronauts, and up to 100 kilometers driving it by remote control from the habitat. The explorers would then return home to Earth but the base would not be closed up permanently. Powered by two solar arrays that brought the width of the base craft to just over 41 meters, the intention was that further groups of astronauts could be landed nearby as often as every six months and would find themselves with usable living quarters right away.

Leaving the Moon in the Ascent/TEI stage, leaving behind the landing stage. Public domain image from NASA.

Once the lunar surface mission was over, the astronauts would return to their original landing craft. Its central stack would ignite a hypergolic N202/MMH engine (hydrogen being too tricky to hold on to for 45 days on the lunar surface) and head directly for home. The final twist on the Apollo mission design would have seen the FLO capsule land on dry land, rather than splash down into the ocean.

By sticking as much as possible to technology they already had, or at the very least were already developing, the cost of the project to the end of the first landing mission was estimated at US$25 billion, with the unmanned base touching down around 2000 and the manned follow-up soon after. Just over half of this money would be for the development of the launcher and building three rockets. Even making allowances for the inevitable cost and schedule overruns, it was a remarkably different result from the original SEI.

What happened to make it fail: George H. W. Bush lost the 1992 presidential election and the Clinton administration was noticeably less interested in manned space exploration for its own sake. NASA reoriented itself toward keeping people in LEO, primarily building what had now become the International Space Station, and unmanned space probes beyond Earth orbit.

Extended manned lunar missions did creep back onto the agenda over the next few years, particularly as part of George W. Bush’s “Vision of Space Exploration” which pictured them as a test-bed for an ultimate Mars mission. But the discovery of water ice at the Moon’s south pole by the Clementine satellite in 1994 changed the nature of all future Moon base proposals by slewing them heavily towards using that water. Despite its generally innovative approach to a lunar landing, the First Lunar Outpost turned out to be the last gasp of an older paradigm for exploring the Moon.

What was necessary for it to succeed: This one is more speculative than most, but it’s interesting to consider the First Lunar Outpost in terms of what happened to Space Station Alpha in the same time period. The station came perilously close to cancellation and was only saved by a foreign policy decision: to turn it into the International Space Station, specifically in partnership with Russia in an attempt to absorb the time and skills of the Russian space engineers freed up by the collapse of the Soviet Union.

If you were looking to start an American make-work project in 1993 that capitalized on Russian expertise, a space station made the most sense. After all, Mir was beyond anything the United States had ever accomplished. But it’s not too hard to picture the busy-work being fulfilled by a different major space program. Since a manned Mars mission was out of the question due to expense, the relatively cheap First Lunar Outpost might have been the choice if the Clinton White House had been more interested in the inspirational side of space exploration than its nuts and bolts. They wouldn’t have been the first administration to feel that way.

Project Horizon (Part II): The Minimal Orbital Station and the Orbital Return Vehicle

A “conceptual view” of the Minimal Orbital Station. Based on the mockup of the initial two-module station (linked below), the actual MOS would have looked somewhat different, but one module would be for human habitation and the rest would be gas tanks for fuelling the Moon ship and its injection stage, top. Another tanker is approaching, as it would take four fuellings in total to top up for a journey to the Moon. Image from Project Horizon: Volume I. Click for a larger view.

What it was: Project Horizon was the US Army’s full-blown proposal to put a man on the moon (and, in fact, start up a whole lunar base) by the end of 1966. While much of its focus was on the base itself, it also included extensive discussion of both the Earth-bound and orbital infrastructure they felt was necessary to reach their goal. The Minimal Orbital Station (MOS) was essentially a gas station in LEO for ships headed to the Moon, while the Orbital Return Vehicle was to be used to bring the gas station’s attendants back down to Earth when their tour of duty was done.

Details: In Project Horizon, Part I we discussed the US Army’s proposed launch facility on Christmas Island in the Pacific. Had it gone ahead, American soldiers and civilian experts would have been loaded on Saturn I rockets (or possibly a “Saturn II”, an early design of what would lead to the Saturn V) and launched into orbit.

Where would they go? To the space station, of course. The Project Horizon proposal blandly asserts “It is very likely that a previously constructed completely equipped space platform will be available in 1965 for use as housing facilities and for other support for the refueling operation.” It does then admit that it’s at least possible that 1965’s near-inevitable space station might not be suitable as a base for the Moon mission (by, for example, being in the wrong orbit). On the off chance that this happened, they proposed the Minimum Orbital Station.

A view of the MOS mockup shown in 1960. The bottom module is a Saturn stage converted for habitation. The cone at top is the ORV. Public domain image from NASA. Click for a larger view.

Building the station would start with a launch of a Saturn I with a payload of men in the nosecone. Once in a 640 kilometer equatorial orbit (a height selected so that the station would circle the Earth in an even fraction of a 24-hour period, making it easier to return to the launch point after the mission was over) the nosecone and the upper stage of the rocket would both reach orbit, at which point the two would disengage. The upper stage’s remaining propellant would be blown out, and the aft end of the nose cone would be mated to the top of the stage—or possibly the side if this variety of Saturn I was redesigned to have an airlock there. The astronauts could then enter the empty stage and fit it out as a living and working space; this “wet workshop” concept would appear again in the designs of the Manned Orbiting Laboratory and the original Skylab.

This basic MOS was enough to house the astronauts, but not to support a Moon mission. Project Horizon assumed that the lunar landing would be a direct descent, which implies a considerably heavier load of fuel than was needed for the Lunar Orbit Rendezvous approach that NASA came to favour in the years following the Army proposal. The Saturn I was completely incapable of lifting both a direct-descent landing craft and the necessary fuel at the same time, so the two had to go up separately. Once the MOS had one empty stage housing its crew, another Saturn I would be sent up, only this time it was carrying a full load of fuel instead of men. The fuel-laden tank would attach itself to the side of MOS, and then the process would repeat: the baseline lunar landing mission in the proposal suggested four tanker launches would be needed before enough fuel was in orbit. More missions might be sent up carrying men, depending on how many orbital personnel were deemed necessary for the next step: getting the lunar craft fuelled and underway.

One final Saturn I launch would loft an unfuelled direct descent ship (that’s six launches now, if you’re keeping count), which would rendezvous with the MOS. The station’s crew would get into their spacesuits, spacewalk out into LEO, and transfer the fuel from one to the other. Three crew would then get aboard the lander and head off to the Moon. The remainder would either re-board the station for the next mission (the pace of Project Horizon’s launches, as discussed in Part I, was downright frantic), or head back to Earth.

Those headed back to Earth would use the Orbital Return Vehicle. This is where the word “minimal” really comes into play, as it was essentially just a conical capsule roughly 7 meters long and 4 meters at its base. After detaching from the MOS, a small retrorocket would knock it out of orbit and its crew would ride down to the ground. Astonishingly, the Project Horizon report suggests that it would have carried anywhere from 10 to 16 men at a time—bear in mind that the actual Gemini capsule gave its two astronauts 5.7 x 3.05 meters to play with, and no-one ever described the Gemini as “roomy”. This feat was accomplished by dividing the interior into no less than three decks (four, if you count the equipment compartment in the nose). There would be no room for sitting or standing here, so the astronauts would lie prone for the entire trip. Here’s hoping they didn’t miss their initial de-orbit burn time and have to wait 90 minutes for the next.

An unfortunately blurry diagram of the ORV from Project Horizon: Volume II. Notice the number of astronauts depicted. Click for a larger view.

Ultimately, the plan was to turn the MOS into a destination in its own right, chaining together more and more Saturn stages converted for habitation and then eventually curving the chain back on itself to form a ring station that could be spun for artificial gravity.

What happened to make it fail: As mentioned in Part I, Project Horizon fell afoul of Eisenhower’s dislike of military activity in space. He’d already tried to pry manned space programs away from the Army, Air Force, and Navy by forming ARPA in February 1958. When that failed (ARPA then famously moving on to other projects like the development of the primitive Internet), he tried again and got them transferred to NASA.

In the particular case of the Horizon space station part of the larger Project Horizon. The Army’s main interest was militarizing the Moon, and the station was just a step toward that was made necessary by an EOR mission profile. When Eisenhower specifically took space exploration missions away from the services and gave them to NASA, the Army Moon program was dead and an Army space station to support it became superfluous.

What was necessary for it to succeed: The station was only going to go ahead if the Army had been given the green light on all of Project Horizon. Something like it might have been built if NASA had decided to use an EOR strategy for the Apollo program, but even that isn’t certain. The USSR considered a similar approach and felt that they didn’t need a station: their Moon ship would have fuelled up directly from the tanker rockets.

When NASA decided to go with a Lunar Orbit Rendezvous lunar landing in July 1962, the chances of seeing something like the MOS dropped from “maybe” to “none”. Space stations would be built in future, from Salyut to Skylab to Mir and the ISS, but none of them would serve the peculiar function of the MOS. Any similarity between them and the Horizon station was a function of position only, and not purpose.

As it was, the MOS and ORV made it to the mockup phase and no further; a diagram of one of these mockups can be found further up this page. Oddly enough it was put on display at the Daily Mail‘s 1960 Ideal Home Show in London, of all places. Somewhere between 150,000 and 200,000 visitors passed through it, and by all accounts it was one of the hits of the show.

Manned Venus Flyby: Apollo’s Hail Mary Pass (Apollo Applications Program, Part I)

A cutaway view of the Manned Venus Flyby spacecraft. Based on Apollo hardware, this remarkable proposal would have sent three astronauts on a year-long mission to Venus and back. Public domain image from the 1967 NASA document Manned Venus Flyby, via Wikimedia Commons. Click for a larger version.

What it was: A proposed post-Moon landing manned mission using Apollo hardware. It would have launched during a good alignment of Earth and Venus in November 1973 and taken three astronauts on a flyby of the planet Venus, returning to the Earth 13 months after launch.

A later variation of the mission ambitiously suggested using a better conjunction in 1977 to visit Venus and Mars on an outbound leg and Venus again on the Earth-return leg, however most of the work done considered the shorter Venus flyby.

Details: By the mid-1960s NASA was well aware that if they successfully completed the Apollo moon landings they would probably face a severe decline in budget for the manned space program. In the hopes of proving their ongoing worth they developed a few different post-Apollo proposals using evolutionary versions of the Apollo hardware, including plans for a manned lunar base, space stations, and planetary exploration. The latter two of these goals were at first grouped under the name Apollo X, and then became the Apollo Applications Program (AAP).

By far the most ambitious of the AAP missions was a manned flyby of the planet Venus. After two preliminary missions in Earth orbit to test the technology, a Saturn V launch would lift an Apollo Command Module into orbit. As in a typical mission, the first two stages of the rocket would be jettisoned. However the uppermost stage, the Saturn IVB, would be kept and drained of any remaining propellant. Using gear stored where the Lunar Landing Module would have been placed in a Moon mission, the astronauts would then rig it as a habitation module.

The resulting 33-meter-long spacecraft would leave Earth orbit on October 31, 1973 and travel towards Venus for 123 days. There would be a flyby on March 3, 1974. The craft would have been aimed to pass Venus as close as 6200 kilometers above the surface (one planet radius) very quickly—orbital mechanics would have it moving relative to Venus at a clip of 16,500 kilometers per hour—crossing the lit side of the planet. A sidescan radar would map the portion of the planet they could see as they flew by, and the astronauts would perform spectroscopic and photographic studies.

A series of probes was to be dropped by the spacecraft, and they were specifically enumerated in the proposal for the Triple Flyby variant of this mission that was mentioned earlier. Near closest approach the MVF would launch an orbiter and fourteen planetary probes; the probes would communicate with the orbiter, which would then beam the results back to Earth. Altogether the probes were:

• Six atmospheric probes, which would enter the atmosphere at six locations: the planet’s solar and anti-solar points, its terminator and equator, and the middle of the light and dark sides. They would drop in ballistically and try to determine how Venus’ atmosphere increased in density the closer one got to the surface.
• Four meteorological balloon probes. They would float in the atmosphere and try to learn how the Venusian atmosphere circulated as well as study smaller-scale winds.
• Two “crash-landing” probes that would try to photograph the surface on the way down, much like Rangers 7, 8, and 9 did with the Moon.
• Two soft-landers that would take surface photographs, examine the soil, and measure Venusian weather.

As well as acting as a communications hub, the orbiter would use X-band radar to map the planet.

The MVF’s trajectory. Detail from Manned Venus Flyby. Click for a larger view.

After that burst of activity the MVF craft would then return home, taking 273 days more to loop out to 1.24 AU from the Sun on a hyperbolic trajectory and eventually swing back to Earth. The astronauts’ landing on Earth would happen on December 1, 1974—total mission time would be 396 days. The Triple Flyby variant would have taken more than 800 days starting in 1977.

When not at Venus, the MVF astronauts would have studied the Sun and solar wind as well as making observations of Mercury, which would be only 0.3 AU away two weeks after the Venus flyby. To keep them occupied otherwise their habitation capsule would have been outfitted with a small movie screen (to show 2 kilograms of movies allowed), and a “viscous damper exercycle/g-conditioner”. The crew would also be allowed 1.5 kilograms of recorded music, 1 kilogram of games, and 9 kilograms of reading material. Hopefully they would choose wisely.

What happened to make it fail: The MVF was part of the Apollo Applications Program, and the AAP was killed dead on August 16, 1968 when the House of Representatives voted to cut its funding from US$455 million to US$122 million. President Johnson accepted this as part of a larger budget deal that kept NASA’s near-term goals safe, though even at that the agency’s entire budget dropped by 18% between 1968 and 1969. The only AAP mission to survive was Skylab.

What was necessary for it to succeed: It’s tough to get this one to work as it’s difficult to see any advantage to sending people on this mission. Mariner 5 had already flown by Venus in 1967 and NASA was able to send a robotic orbiter as part of the Pioneer 12 mission in 1978, just a few years after MVF would have flown.

Even the many probes that the MVF would leave behind at Venus had no obvious connection to the manned part of the mission; it would have been easier to send an unmanned bus of similar size and drop the probes that way. There would be no need then for heavy food, water, or air, or the space for people to move around. And unlike the manned mission there would be no need to bring the bus back, greatly reducing the mission’s difficulty. About all the manned mission had going for it was an opportunity to see what kind of effect a year in microgravity would have on humans, and that could just as easily be determined using a space station in low Earth orbit.

On that basis we also need to be aware that Congress asked hard questions about the purpose of NASA’s manned Mars mission plans in the late 1960s and were hostile to all of them. If Mars wasn’t going to get any money, it’s hard to see what could influence them to fund a mission to Venus.

Finally it needs to be pointed out that no matter even if the MVF launched, nature itself probably had this mission’s number. We didn’t have a very good understanding of the Sun at that time, having only observed one solar cycle from above the atmosphere when the flyby was proposed in 1967. While the launch window was deliberately chosen to be near a solar minimum, and the flyby craft was to have a radiation lifeboat in the equipment module, the mission would have run into an unforeseen natural event on the way back to Earth.

On July 5-6, 1974 the Earth was hit by a big coronal mass ejection (CME), a storm of electrons and protons thrown off of the Sun. People down on Earth were protected by the planet’s magnetic field, as usual, but the astronauts coming back from Venus wouldn’t have been so lucky. Their line to the Sun was several degrees off from the Earth’s (at the time they would have actually looped out past Earth as their trajectory slowly took them back home), but CMEs can cover quite a bit of space. Had the mission actually flown, the astronauts on-board may well have died of radiation sickness after being hit with more (and more energetic) solar protons than their spacecraft was built to handle.

The saving grace here is that coronal mass ejections were discovered in 1971, so the initial plan probably would have been called off rather than risk casualties, or at least be reconfigured to give the astronauts the protection the 1967 plan failed to give them.

An interesting simulation (using the program Orbiter) of how the MVF mission would have run can be seen on YouTube.