That's the thing. I asked that question because I want to design a space station for my Japan-like country soon, and I'm not sure whether or not I want it to look like the ISS.
And yay, the first Japanese person to walk on the Moon!
And yay, the first Japanese person to walk on the Moon!
ISS is the result of a wide collection of studies that converged on the current truss--mostly ones driven by far larger, expansive trusses like these where a massive truss for mounting external experiments was most of the reason for the design. In that sense, the final truss is almost vestigial.
In this TL, with similar design goals and designers, we had a similar-to-ISS design come out the tail end of the design process, but there's no reason you can't mess around with alternatives to give your station a more distinct feel. I hope Michel won't mind me linking this alternate "Starlab"/"Pre-freedom" proposal he sent to Workable Goblin and me back in early Part II--it shows yet a third different way of doing a large station with large arrays, in addition to Freedom/ISS or TTL's Mir design we came up with, and I'm sort of sorry we never found a use for it.
Apparently the "far larger, expansive trusses" of that version of Space Station Freedom were there because of this:
"In March 1986, the System Requirements Review modified the configuration to the 'Dual-Keel' design, which moved the modules to the central truss—placing them at the center of gravity, providing a better microgravity environment. However, the desire to maintain tidal alignment led to the use of increased truss structure, with two large 'keels'."
Michel's concept is an interesting design.
"In March 1986, the System Requirements Review modified the configuration to the 'Dual-Keel' design, which moved the modules to the central truss—placing them at the center of gravity, providing a better microgravity environment. However, the desire to maintain tidal alignment led to the use of increased truss structure, with two large 'keels'."
Michel's concept is an interesting design.
It was addressed a bit indirectly, so no harm in repeating it.The crew live in the CSM and ascent module cabin, which is about the same size as the MM used for LEO missions on Block IV and V (and larger than the Block III+ MM variant).
In short, the Lander ascent stage really *does* function as a Mission Module as much as it does a ride down to and up from the lunar surface. I realize it hibernates during the lunar stay, but it will still need some robust life support for four people for all that. But I see that there's no easy alternative, unless one wants to go to a four launch architecture, or radically re-conceive the entire program.
Sorry I missed the previous reference on that.
In other news, I see that the administration has opted for the most likely outcome - extending Artemis for a handful of more missions, while it kicks the ball down the road about what comes after.
In a way, the way forward for the lunar program (if it continues at all) seems more obvious - the gradual shift to a man-tended base, once a suitable location is identified - than does the future of LEO operations. It seems unlikely that NASA will simply opt for a Freedom II, and not just because of the cost while lunar missions are underway. Assuming that Freedom has a robustness of design comparable to ISS, I'm guessing they might make it to the 2015 timeframe with the station, so they have some time to play with - but not all that much. So I'll be every bit as curious to see where you go with post-Freedom LEO plans as I will lunar plans.
Yes, the ascent module comes all the way back to Earth, being discarded shortly before atmospheric interface along with the capsule's service module. There's two major things that could be dumped: the engines/trust structure and the propellant tanks. All told, jettisoning both would be quite complex, and reduce the return dry mass by less than 10%. We decided to just hang onto them and save a critical mission event.
Not quite! It is a joke, but that's not the reference. Anyone else have a guess? A hint: it has to do with the post he was introduced in.
Morning all. This week's illustration is the fulfillment of a long-term request from e of pi, so it's with great pleasure I present MOK-2.
Indeed! I'm of an age where Skylab was a thing I remember from childhood--indeed, I got a look at it in its shroud in the VAB from a boat passing by, and so until the Shuttle was launched when I was in high school it was practically the last word in the American space program. I guess I never noticed the relative smallness of Shuttle-lifted ISS modules because at the time ISS was actually being established at last, I was distracted rather heavily from following space news.
It raises a question though:
In addition to the in retrospect obviously Utopian notion that STS was going to cheapen spaceflight by rapid turnarounds and high volume of use, there were supposed to be other advantages to going that route. One of them was that the launch and possible return of objects into space would be a smoother and gentler ride than sitting on top of a stack of rocket stages, therefore cargoes could ride the STS that could not tolerate being launched on say a Saturn V or 1B. There was also a related idea that between the gentler ride and the prospect of Orbiter crew members performing final preparations on orbital payloads, that the various spacecraft could be designed more cheaply and simply, and thus offset the obvious inefficiency of using Saturn V level rockets and propellant to achieve Saturn 1B type payloads.
In the ATL of ETS, have there been occasions when you as authors know the people were constrained by the nature of the disposable multi-stage traditional rockets used from doing things that OTL were indeed more easily done because of NASA's OTL commitment to STS? Looking at nice big "modules" that come close to being full space stations in their own right shows us the upside of this world--an upside we all enjoy and appreciate. But now that the case has been well and truly made that STS was a big mistake--candidly, do you the authors ever miss it? And if so, for what?
Obviously, when there is a real felt need for something (rationally based or not) in your ATL as in OTL life, someone bestirs themselves to do something about it, so I would guess some of these regrets, if you have any, would relate to needs that will be or already have been addressed. So since STS was a child of the '70s that came on line in the '80s, perhaps I'm asking you to cast your minds back to TTL's 1980s. What could not be done, of any significance to you, in TTL's 1980s that could be done OTL? In what respects is the glass half empty instead of 207% full?
Well, they're not that much smaller than Skylab. Skylab was 290 cubic meters, the sort of "generic" ISS module is about 160 cubic meters--4.5m in diameter by 10 or so long. There's about seven of those in the USOS--Node 1, Node 2, Node 3, the US lab, Columbus, the JEM, and the PMM. So it's not exactly dinky--Freedom ITTL just consists of fewer modules.
Downmass is the major one. There's very little extra room inside crew rotation Apollos, and even once we had the European Minotaur available, we lacked the experiment/hardware return capability of Shuttle IOTL. For instance, in the post from two weeks ago, the pump failure is based on the OTL failures of the same unit. IOTL, the failed pump modules were returned to Earth in the Shuttle cargo bay for inspection. ITTL...no dice.
The other big one is Hubble--the sole major example of ongoing upkeep and maintenance of orbital satellites with Shuttle (not the only one, but the others were one-time and mostly about demonstrating retrieval/relaunch than orbital servicing). ITTL, without that (and with an on-time launch in 1985) Hubble reaches the end of its service life by 1995 and has to be decommissioned. We had plans for an special MM variant or something based at Freedom for satellite servicing, but the funding profile and delta-v for rendezvous just never made sense.
I'm sure Workable Goblin could name a few more I've forgotten.
All that is true, though 160 vs. 290 is still a noteworthy difference, especially in diameter. More to the point, this difference doesn't capture fully the size and mass limitations of STS, since Skylab a) had a lot of unused space in the waste tank (which you corrected with Spacelab), and b) did not make full use of the lifting capability of the Saturn V (it being merely a modified S-IVB stage), as you have also pointed out. The Challenger module of Freedom, on the other hand, does, and as a result permits larger crew and, therefore, much more science, than is the case with ISS. Your Freedom Centrifuge module is another example of taking advantage of the capabilities of Saturn multi-body.
Also, you can't do this sort of thing in an ISS module:
That said, the downmass capability of the Shuttle is not to be dismissed. On the whole, however, it is (as I think we all agree) a very worthwhile tradeoff.
We could've gotten those wide-diameter modules in Shuttle-sized payload bays with the use of inflatable technology, but NASA's work on TransHab was banned by Congress for some reason. So now, Bigelow Aerospace is trying to work on that kind of module.
But having a larger-diameter rocket & fairing still gives the advantage of having larger-diameter rigid station modules which can have six sides of experiment racks (instead of four sides on modules in the US orbital segment of the ISS), as well as equipment that cannot be packed in a deflated state, such as this centrifuge (OTL's cancelled Centrifuge Accommodations Module would've only had a 2.5 m-diameter centrifuge)
But how are docking ports (or at least, what looks like docking ports) being used in TTL's Freedom, instead of berthing ports? In OTL, while an APAS docking port has an internal diameter of 800 mm, a Common Berthing Mechanism has a diameter of 1270 mm. The ISS's International Standard Payload Rack can only fit through CBMs.
But having a larger-diameter rocket & fairing still gives the advantage of having larger-diameter rigid station modules which can have six sides of experiment racks (instead of four sides on modules in the US orbital segment of the ISS), as well as equipment that cannot be packed in a deflated state, such as this centrifuge (OTL's cancelled Centrifuge Accommodations Module would've only had a 2.5 m-diameter centrifuge)
But how are docking ports (or at least, what looks like docking ports) being used in TTL's Freedom, instead of berthing ports? In OTL, while an APAS docking port has an internal diameter of 800 mm, a Common Berthing Mechanism has a diameter of 1270 mm. The ISS's International Standard Payload Rack can only fit through CBMs.
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We explained this a long, long, long time ago, back at the beginning of Part II. As part of the design effort for Freedom, NASA designed a new docking port they called the Common Androgynous Docking System (CADS; originally it was called the Androgynous International Docking System, but for obvious reasons that was soon changed...) which was designed to have a larger internal diameter than the probe-and-drogue, be androgynous (obviously), and work as both a docking and berthing port. The Block IV (and V) Apollo utilize CADS ports at the outward end of their mission modules, with the probe-and-drogue relegated only to the connection between the mission module and command module. It was designed to be large enough to fit quite large payloads (and those payloads were of course designed to fit through it).
Indeed. Basically, instead of developing CBM as IOTL, they develop a CBM-sized androgynous system, CADS.
Thus, there's currently three systems in use by the US and international partners:
(1) Apollo probe/drogue, which is just between the CSM and the MM or the Artemis ascent stage and the CSM
(2) CADS, which is in use between Freedom modules and between Freedom and visiting vehicles like the Apollo MM and the European Minotaur
(3) LPAS (Large Payload Attach System), which is a CADS port with an augmented ring, which is used to dock the Artemis crew lander to the Pegasus EDS in orbit. The CADS is used for docking, then on retraction an outer, wide-diameter ring adds additional strength for transferring the larger forces of the Pegasus RL-10s
Part IV, Post 8: US unmanned probes in the early noughties
Good evening everyone! It's that time once again, and while we've spent the last two weeks focused heavily on the fate of manned space exploration, both in Earth orbit and on the Moon, that's certainly not the only exploration occurring. However, the budget isn't infinite, which has certain implications...
Eyes Turned Skyward, Part IV: Post #8
With the selection of MACO behind them, the University of Washington and their industry partners at Boeing-Grumman immediately began work on the spacecraft, translating the designs they had developed for the Pioneer selection into an actual vehicle. In a striking contrast to previous Mars spacecraft, it would face stringent cost and time caps, with launch already scheduled for July, 2003, the next feasible window for Mars transfer. While NEAL and Barnard had also been built to schedule and under budget, they had also been built by NASA’s own field centers, groups with lengthy experience in building and operating spacecraft. It was hardly certain whether a university team would be able to do as well, even partnered with a firm with as much experience as Boeing-Grumman.
Fortunately, Headquarters had chosen well when it had selected MACO to go ahead. Boeing-Grumman had cut its teeth building the Orbiting Astronomical Observatories and, later, the Hubble Space Telescope, and the recent purchase of Hughes from Ford had brought possibly the world’s greatest concentration of satellite-building experience into the corporate fold, along with a heritage base that reached back to the first Pioneer probes in the 1960s. As an orbiter with only a few instruments on board, MACO was similar to dozens of previous probes and Earth-orbiting spacecraft, and simple enough to pose relatively little challenge for Boeing-Grumman’s engineers, and manufacturing proceeded largely on schedule. Based on one of Boeing-Grumman’s latest three-axis stabilized communications satellite designs,
Back in Washington, however, those charged with planning and executing NASA’s robotic exploration program were much less sanguine about the future. Although the Pioneer Program seemed to be growing into a solid, continuing budget line, Congress was still reluctant to authorize funding for new, larger missions. The new President’s proposal to extend Artemis by four missions had faced less opposition than it might have, given that it left NASA budgets relatively constant, but it had still faced opposition, and it had still consumed much of the attention of Congressional space advocates to achieve even that. With Headquarters equally focused on the human spaceflight program and a lack of Congressional advocates outside of the California delegation for robotic spaceflight, it had simply been left in the cold.
While this was bad enough in of itself, what was even worse was the division among planetary scientists about which mission to fly next. As in the previous decade, there were three major lobbies, one pushing for Mars sample return, one for a Europa orbiter mission, and one for an ice giants mission, but with the realization that getting even one of them to fly was going to be an uphill battle came an additional degree of vitriolic bitterness to this internecine struggle. Spreading from journals to the halls of funding agencies and finally to the offices and labs of the researchers themselves, this vicious war divided the planetary science community against itself, splintering it into a series of opposing camps. The united lobbying effort that would have been needed to overcome Congressional indifference and reluctance to allocate more funding was hardly possibly in such an environment, forming a great contrast to the more unified astronomical community’s success in repeatedly obtaining support for missions just as expensive and abstruse as any Cornerstone-class effort.
Matters were not helped by the fact that one of the few headline missions still in development, the Asteroid Sample Return mission originally planned to cap off the Pioneer program’s first mission set, was disintegrating. Although the teams developing the mission continued to struggle onwards as best they could, by the beginning of 2001 the schedule had again slipped, this time more than a year, while the required budget was ballooning as the American effort to replicate and adapt the Fobos Together bus for the mission was running into serious technical issues. Although in theory a well-proven design whose development costs had already been paid, in practice the technical demands of a rendezvous with a near-Earth asteroid were substantially different than those associated with a Mars orbiter mission, and significant, costly modifications were needed to enable it to carry out the mission. Almost as bad, while Fobos Together had been a Cornerstone-class mission with an enormous budget, Pioneer missions like ASR by definition had to make do with much less, adding further problems as the design had to be modified to be cheaper to produce and launch than Fobos Together had been. With no chance of it meeting many of its original objectives, it was clear that continuing ASR development was a waste of effort, and after intense discussions with CNES and a failed attempt to turn the project around NASA opted to terminate funding in July. Shortly afterwards the French, unable to find support at ESA for a European version of the mission, terminated further work on the lander/sample collection vehicle, sending ASR to an early and undistinguished grave.
Fortunately, not all news for the planetary science community was so poor. While MACO was progressing relatively smoothly and NEAL and its Sojourner-class rover were exploring Nereus, back in Washington scientists were preparing for the next Pioneer selection round. Although intense interest had surrounded the first Pioneer competition, those hoping for lightning to strike again were disappointed. The original selection, after all, had benefited from a combination of being unexpected and coming as prospects for further larger missions had dropped to zero. Many of the proposals in 2000 had been hardly serious, with little technical detail, excessively complex mission designs, or overly difficult destinations like Io or even Pluto, and most of those who had not at least made the earlier longlist declined to try again. Among those that were ready to try again, however, significant effort was being put into refining them and applying lessons learned from the previous competition to make them even more likely to succeed.
Among the most prominent of these was Hermes, named after the messenger of the Greek gods, famed for his speed and cunning, and the counterpart to the Roman Mercury. By orbiting the planet of its namesake, it would, if all went as planned, finally subject it to the kind of attention that its terrestrial counterparts had received over the past fifty years, supplanting the brief flybys of Mariner 10 as the best source of information on the innermost planet. Although Mercury orbiters had been studied off and on since the 1960s, the closest planet to the Sun is surprisingly difficult to reach, similar in some respects to the most distant planets in requiring relatively enormous changes in spacecraft velocity to rendezvous or orbit, and forcing the mission to rely on either large, expensive launch vehicles and in-space braking stages or complex, expensive electric propulsion and high-temperature solar cells to successfully reach the planet. Thus, each burst of interest in Mercury orbiter missions had ultimately perished when the sheer cost of such a flight was revealed, and scientists had decided that, after all, another Mars or near-Earth object mission would be productive enough. What had changed to shift the Mercury orbiter mission from the Cornerstone to the Pioneer class was the development of more sophisticated computers during the 1970s, 1980s, and 1990s, and with them the development of more sophisticated gravity assist models. No longer bound by the limitations of flesh and blood, or even the computers of the 1960s, lengthy calculations could be carried out, studying concatenations of multiple Venus and Mercury flybys to gradually brake the would-be orbiter into a Mercury-rendezvous trajectory. By doing so, the size and cost of the spacecraft could be greatly reduced, all without requiring advanced technology beyond that needed for the Mercury mission itself.
Going into the 2000 competition, the scientific case for Hermes had been undeniable, with only technical issues related to long-term, high-temperature operations in Mercury orbit putting it behind MACO. With three extra years for mission planners to refine and study the problem, Hermes was almost universally regarded the favorite for the 2003 selection. By the time the final selection, confirming that Hermes had indeed been chosen, was announced in late June, the impending launch date for MACO had overwhelmed all interest in Hermes, at least for the moment. Instead, the attention of the press and public was focused on the usual drama of space launch, on whether or not MACO’s launch vehicle would succeed--as most did and do--or fail and send the spacecraft plunging into the Atlantic.
As a bookie would have predicted, it succeeded, and by the beginning of 2004 MACO was settling into orbit around the red planet just as work on Hermes was beginning to pick up steam. While the trio of instruments aboard MACO did not include a camera, the first time an American Mars orbiter would omit the device since Pioneer Mars in 1979, they were finely tailored to provide more subtle information on the composition and structure of the Martian atmosphere and how it changed over time, cataloguing even rare and unusual compounds, their distribution, and how they traveled through the atmosphere. Although data on a wide range of molecules was obtained during MACO’s mission, the most prominent discovery was that detectable quantities of methane were present in the Martian atmosphere, a major surprise given that ordinarily carbon dioxide would be expected to quickly react with and destroy any methane in the atmosphere. Something was clearly happening that was releasing methane on a regular basis, whether the decomposition of carbonaceous meteorites on the surface or volcanic activity deep underground.
All of this, however, had certain implications that Mars scientists, or at least Mars scientists who were concerned about their careers, had rarely spoken about in public since the perceived failure of the Viking missions in 1976. At the time, scientists had widely expected that bacterial spores might be found near the Martian surface, and when the Vikings--despite some equivocal results--failed to find evidence of this life, there had been something of a backlash against Mars exploration by the public. Few scientists were willing to go on record speaking about Mars life afterwards, and with little evidence behind it in any case the focus of later Mars missions shifted to geological and atmospheric studies, like those Pioneer Mars, Mars Reconnaissance Pioneer, and now MACO had carried out. If Mars was still active enough to release methane, however, there was a distinct possibility that something like the communities of bacteria that live around volcanic vents or deep underground on Earth, feeding off of gases released by geological activity, could exist on Mars as well. Even more tantalizingly, there are many species of bacteria on Earth that release methane as a by-product of their metabolism, much as humans exhale carbon dioxide. If a few communities of similar bacteria existed on Mars, they could easily account for the detected emissions, and it was possible that MACO had, in fact, discovered life on Mars.
Naturally, this possibility, rather than more likely explanations, was the one that grabbed the headlines, with certain segments of the popular press claiming MACO’s result as definitive proof that Mars was, in fact, not dead. The mission’s scientists were, of course, more careful, but began to acknowledge the possibility in public, stating only that their results could be interpreted to support the existence of life on Mars. Outside of the University of Washington, a few more voices could be heard expressing cautious optimism for life on Mars, but by and large Mars scientists were focused on potential physical explanations for the curious amount of methane present, and beginning to draw up plans to further study the issue.
With two open selections completed on schedule and on budget and the first launched, many teams began planning proposals for the next Pioneer selection, widely expected for 2006, soon after Hermes itself had been selected in 2003. The success of Hermes had shown that missions with well-developed scientific goals and thoroughly developed technical plans were far more likely to make it through the new competitive bid process, and with no money forthcoming for non-Pioneer missions there certainly was no ready alternative for scientists eager to continue exploring the planets. By starting early, often using whatever funding they could scrape up to have at least one or two graduate students slowly developing their proposals, every interested competitor hoped to get an edge on the others and see their mission selected for flight. Thus, by the middle of 2005 all of the most serious mission teams, with the most fleshed-out missions, had invested tens of thousands of dollars in developing their proposals. Although they were aware at the back of their minds that only one of their number could be chosen, each were sure that they had prepared as thoroughly as possible for the selection, and that they would, in the end, be the one to make it through.
Then the rug was pulled out from under them. Although NASA had sent out a formal request for proposals earlier in the year, normally the first step of the Pioneer selection process, no further information was forthcoming from the agency by the beginning of October and the next federal fiscal year, by which time the agency had previously indicated that it was studying any proposals that had been submitted. The major shock, however, came in January of 2006, when there was not a single mention of the Pioneer program or future Pioneer missions from NASA. With no explanation for the omission, and a by this point long and feared history of cuts to planetary missions, planetary scientists across the country immediately jumped to the conclusion that the Pioneer program, and therefore all future NASA planetary missions, had been quietly canceled, sending them into fits of rage, depression, or apoplexy, depending on the scientist in question.
By the end of February, however, a reaction was brewing among planetary scientists, especially as the head of the Department of Astronomy at Cornell University finished drafting and sending an open letter inviting his colleagues to an informal meeting in Ithaca to ‘discuss the planetary science response to the recent end of the Pioneer Program’...
Eyes Turned Skyward, Part IV: Post #8
With the selection of MACO behind them, the University of Washington and their industry partners at Boeing-Grumman immediately began work on the spacecraft, translating the designs they had developed for the Pioneer selection into an actual vehicle. In a striking contrast to previous Mars spacecraft, it would face stringent cost and time caps, with launch already scheduled for July, 2003, the next feasible window for Mars transfer. While NEAL and Barnard had also been built to schedule and under budget, they had also been built by NASA’s own field centers, groups with lengthy experience in building and operating spacecraft. It was hardly certain whether a university team would be able to do as well, even partnered with a firm with as much experience as Boeing-Grumman.
Fortunately, Headquarters had chosen well when it had selected MACO to go ahead. Boeing-Grumman had cut its teeth building the Orbiting Astronomical Observatories and, later, the Hubble Space Telescope, and the recent purchase of Hughes from Ford had brought possibly the world’s greatest concentration of satellite-building experience into the corporate fold, along with a heritage base that reached back to the first Pioneer probes in the 1960s. As an orbiter with only a few instruments on board, MACO was similar to dozens of previous probes and Earth-orbiting spacecraft, and simple enough to pose relatively little challenge for Boeing-Grumman’s engineers, and manufacturing proceeded largely on schedule. Based on one of Boeing-Grumman’s latest three-axis stabilized communications satellite designs,
Back in Washington, however, those charged with planning and executing NASA’s robotic exploration program were much less sanguine about the future. Although the Pioneer Program seemed to be growing into a solid, continuing budget line, Congress was still reluctant to authorize funding for new, larger missions. The new President’s proposal to extend Artemis by four missions had faced less opposition than it might have, given that it left NASA budgets relatively constant, but it had still faced opposition, and it had still consumed much of the attention of Congressional space advocates to achieve even that. With Headquarters equally focused on the human spaceflight program and a lack of Congressional advocates outside of the California delegation for robotic spaceflight, it had simply been left in the cold.
While this was bad enough in of itself, what was even worse was the division among planetary scientists about which mission to fly next. As in the previous decade, there were three major lobbies, one pushing for Mars sample return, one for a Europa orbiter mission, and one for an ice giants mission, but with the realization that getting even one of them to fly was going to be an uphill battle came an additional degree of vitriolic bitterness to this internecine struggle. Spreading from journals to the halls of funding agencies and finally to the offices and labs of the researchers themselves, this vicious war divided the planetary science community against itself, splintering it into a series of opposing camps. The united lobbying effort that would have been needed to overcome Congressional indifference and reluctance to allocate more funding was hardly possibly in such an environment, forming a great contrast to the more unified astronomical community’s success in repeatedly obtaining support for missions just as expensive and abstruse as any Cornerstone-class effort.
Matters were not helped by the fact that one of the few headline missions still in development, the Asteroid Sample Return mission originally planned to cap off the Pioneer program’s first mission set, was disintegrating. Although the teams developing the mission continued to struggle onwards as best they could, by the beginning of 2001 the schedule had again slipped, this time more than a year, while the required budget was ballooning as the American effort to replicate and adapt the Fobos Together bus for the mission was running into serious technical issues. Although in theory a well-proven design whose development costs had already been paid, in practice the technical demands of a rendezvous with a near-Earth asteroid were substantially different than those associated with a Mars orbiter mission, and significant, costly modifications were needed to enable it to carry out the mission. Almost as bad, while Fobos Together had been a Cornerstone-class mission with an enormous budget, Pioneer missions like ASR by definition had to make do with much less, adding further problems as the design had to be modified to be cheaper to produce and launch than Fobos Together had been. With no chance of it meeting many of its original objectives, it was clear that continuing ASR development was a waste of effort, and after intense discussions with CNES and a failed attempt to turn the project around NASA opted to terminate funding in July. Shortly afterwards the French, unable to find support at ESA for a European version of the mission, terminated further work on the lander/sample collection vehicle, sending ASR to an early and undistinguished grave.
Fortunately, not all news for the planetary science community was so poor. While MACO was progressing relatively smoothly and NEAL and its Sojourner-class rover were exploring Nereus, back in Washington scientists were preparing for the next Pioneer selection round. Although intense interest had surrounded the first Pioneer competition, those hoping for lightning to strike again were disappointed. The original selection, after all, had benefited from a combination of being unexpected and coming as prospects for further larger missions had dropped to zero. Many of the proposals in 2000 had been hardly serious, with little technical detail, excessively complex mission designs, or overly difficult destinations like Io or even Pluto, and most of those who had not at least made the earlier longlist declined to try again. Among those that were ready to try again, however, significant effort was being put into refining them and applying lessons learned from the previous competition to make them even more likely to succeed.
Among the most prominent of these was Hermes, named after the messenger of the Greek gods, famed for his speed and cunning, and the counterpart to the Roman Mercury. By orbiting the planet of its namesake, it would, if all went as planned, finally subject it to the kind of attention that its terrestrial counterparts had received over the past fifty years, supplanting the brief flybys of Mariner 10 as the best source of information on the innermost planet. Although Mercury orbiters had been studied off and on since the 1960s, the closest planet to the Sun is surprisingly difficult to reach, similar in some respects to the most distant planets in requiring relatively enormous changes in spacecraft velocity to rendezvous or orbit, and forcing the mission to rely on either large, expensive launch vehicles and in-space braking stages or complex, expensive electric propulsion and high-temperature solar cells to successfully reach the planet. Thus, each burst of interest in Mercury orbiter missions had ultimately perished when the sheer cost of such a flight was revealed, and scientists had decided that, after all, another Mars or near-Earth object mission would be productive enough. What had changed to shift the Mercury orbiter mission from the Cornerstone to the Pioneer class was the development of more sophisticated computers during the 1970s, 1980s, and 1990s, and with them the development of more sophisticated gravity assist models. No longer bound by the limitations of flesh and blood, or even the computers of the 1960s, lengthy calculations could be carried out, studying concatenations of multiple Venus and Mercury flybys to gradually brake the would-be orbiter into a Mercury-rendezvous trajectory. By doing so, the size and cost of the spacecraft could be greatly reduced, all without requiring advanced technology beyond that needed for the Mercury mission itself.
Going into the 2000 competition, the scientific case for Hermes had been undeniable, with only technical issues related to long-term, high-temperature operations in Mercury orbit putting it behind MACO. With three extra years for mission planners to refine and study the problem, Hermes was almost universally regarded the favorite for the 2003 selection. By the time the final selection, confirming that Hermes had indeed been chosen, was announced in late June, the impending launch date for MACO had overwhelmed all interest in Hermes, at least for the moment. Instead, the attention of the press and public was focused on the usual drama of space launch, on whether or not MACO’s launch vehicle would succeed--as most did and do--or fail and send the spacecraft plunging into the Atlantic.
As a bookie would have predicted, it succeeded, and by the beginning of 2004 MACO was settling into orbit around the red planet just as work on Hermes was beginning to pick up steam. While the trio of instruments aboard MACO did not include a camera, the first time an American Mars orbiter would omit the device since Pioneer Mars in 1979, they were finely tailored to provide more subtle information on the composition and structure of the Martian atmosphere and how it changed over time, cataloguing even rare and unusual compounds, their distribution, and how they traveled through the atmosphere. Although data on a wide range of molecules was obtained during MACO’s mission, the most prominent discovery was that detectable quantities of methane were present in the Martian atmosphere, a major surprise given that ordinarily carbon dioxide would be expected to quickly react with and destroy any methane in the atmosphere. Something was clearly happening that was releasing methane on a regular basis, whether the decomposition of carbonaceous meteorites on the surface or volcanic activity deep underground.
All of this, however, had certain implications that Mars scientists, or at least Mars scientists who were concerned about their careers, had rarely spoken about in public since the perceived failure of the Viking missions in 1976. At the time, scientists had widely expected that bacterial spores might be found near the Martian surface, and when the Vikings--despite some equivocal results--failed to find evidence of this life, there had been something of a backlash against Mars exploration by the public. Few scientists were willing to go on record speaking about Mars life afterwards, and with little evidence behind it in any case the focus of later Mars missions shifted to geological and atmospheric studies, like those Pioneer Mars, Mars Reconnaissance Pioneer, and now MACO had carried out. If Mars was still active enough to release methane, however, there was a distinct possibility that something like the communities of bacteria that live around volcanic vents or deep underground on Earth, feeding off of gases released by geological activity, could exist on Mars as well. Even more tantalizingly, there are many species of bacteria on Earth that release methane as a by-product of their metabolism, much as humans exhale carbon dioxide. If a few communities of similar bacteria existed on Mars, they could easily account for the detected emissions, and it was possible that MACO had, in fact, discovered life on Mars.
Naturally, this possibility, rather than more likely explanations, was the one that grabbed the headlines, with certain segments of the popular press claiming MACO’s result as definitive proof that Mars was, in fact, not dead. The mission’s scientists were, of course, more careful, but began to acknowledge the possibility in public, stating only that their results could be interpreted to support the existence of life on Mars. Outside of the University of Washington, a few more voices could be heard expressing cautious optimism for life on Mars, but by and large Mars scientists were focused on potential physical explanations for the curious amount of methane present, and beginning to draw up plans to further study the issue.
With two open selections completed on schedule and on budget and the first launched, many teams began planning proposals for the next Pioneer selection, widely expected for 2006, soon after Hermes itself had been selected in 2003. The success of Hermes had shown that missions with well-developed scientific goals and thoroughly developed technical plans were far more likely to make it through the new competitive bid process, and with no money forthcoming for non-Pioneer missions there certainly was no ready alternative for scientists eager to continue exploring the planets. By starting early, often using whatever funding they could scrape up to have at least one or two graduate students slowly developing their proposals, every interested competitor hoped to get an edge on the others and see their mission selected for flight. Thus, by the middle of 2005 all of the most serious mission teams, with the most fleshed-out missions, had invested tens of thousands of dollars in developing their proposals. Although they were aware at the back of their minds that only one of their number could be chosen, each were sure that they had prepared as thoroughly as possible for the selection, and that they would, in the end, be the one to make it through.
Then the rug was pulled out from under them. Although NASA had sent out a formal request for proposals earlier in the year, normally the first step of the Pioneer selection process, no further information was forthcoming from the agency by the beginning of October and the next federal fiscal year, by which time the agency had previously indicated that it was studying any proposals that had been submitted. The major shock, however, came in January of 2006, when there was not a single mention of the Pioneer program or future Pioneer missions from NASA. With no explanation for the omission, and a by this point long and feared history of cuts to planetary missions, planetary scientists across the country immediately jumped to the conclusion that the Pioneer program, and therefore all future NASA planetary missions, had been quietly canceled, sending them into fits of rage, depression, or apoplexy, depending on the scientist in question.
By the end of February, however, a reaction was brewing among planetary scientists, especially as the head of the Department of Astronomy at Cornell University finished drafting and sending an open letter inviting his colleagues to an informal meeting in Ithaca to ‘discuss the planetary science response to the recent end of the Pioneer Program’...