In a president George W. Bush-like moment NASA administrator Charles Bolden is reported to have said: “it is the uneasiest thing we could do”. Uneasiest? Don’t you mean it is one of the hardest things you could do?
And Bolden might not want to admit it but his allegedly executable non-Constellation programme is ultimately, in capabilities terms, just as challenging and probably unexecutable as Bush’s Constellation in technology and funding
Why? We now know that president Barack Obama’s plan for NASA is to work towards a 2025 asteroid rendezvous and a mid-2030s Mars mission that would not land. Constellation had Mars as an aspiration but its goal was to begin Moon missions from 2018 with a landing soon after and the slow build up of a permanent lunar base from the early 2020s
Surely they are very different? Look again
The asteroid mission is, so we’re told, going to take months of travel very likely beyond the Moon. It will need a crew vehicle to re-enter the Earth’s atmosphere, it will need a habitat module for the journey out to the asteroid. To go beyond lunar orbit and come back will require a large Earth departure stage and asteroid departure stage, or at least a large propellant tank. For mass savings the propellant will probably need to be cryogenic, requiring good insulation technology. It will need an in-space manouvering engine system to fly in formation with the asteroid. It will need RADAR or LIDAR for that formation flying and if the intention is to land the habitat, crew vehicle stack will need its own legs and an engine that acts as a “descent” and ascent thruster. Or this asteroid lander would have its own “descent” and ascent stages. Once on the surface or in close formation the stack will need good thermal management as it passes in and out of the harsh sunlight. If the plan is to land the asteroid is likely to tumble through space making landing more difficult. This will require some sort of automatic manouvering system to compensate for that multiple axes movement
To get this lander-habitat-crew vehicle stack beyond Moon orbit it will need to be launched into low Earth orbit as one spacecraft or assembled from its constituent parts in LEO. Its not this blog posts intention to detail the physical characteristics of these craft but to show what capabilities are needed. But it can be summised that the crew vehicle could probably be launched by a modified EELV-type booster but the departure stages for Earth and asteroid and the habitat, with its manouvering/descent/ascent engines and all their propellant tanks are going to be far larger. Perhaps they would need a heavy lift rocket, maybe the habitat and departures stages could be launched propellant empty and refuelled in orbit? This architectural issue will be address at the end of this blog post
For now, how is this asteroidship just like Constellation’s Orion crew exploration vehicle, Altair stack?
Orion was designed to go to the Moon ultimately for a seven month mission, it would enter lunar orbit and operate automaticaly while its crew descended to the surface in Altair. Initially the missons would be for a week or a gfew weeks operating form the lander. However the crew would ultimately live on the Moonbase once it has adequate accomodation
Like the asteroidship Constellation has a crew vehicle capable of long endurance in deep space and able to re-enter the Earth’s atmosphere. Like the asteroid ship a habitat, in this case called the Altair lunar lander, will be used and Altair’s pressurised section and life support systems would have laid the groundwork for technlogies for the Moonbase habitat modules, which were to be landed by Altair’s descent stage. To reach the Moon and return from it large Earth departure and lunar departure stages are needed. Constellation’s heavy lift Ares V cargo launch vehicle’s upper stage was to be the EDS and Altair was to have the LDS. For mass savings the propellant has already been decided to be cryogenic, requiring good insulation technology; just like the asteroidship.
Focusing on Altair, like the asteroidship it will need RADAR or LIDAR to land on the Moon and like the habitat-crew vehicle stack it will need its own legs and its own descent and ascent stages. Once on the surface Altair and/or the Moonbase habitat modules will need good thermal management as it passes in and out of the harsh sunlight during the lunar day or is permanently in sunlight. What Altair will not need is an automatic landing, real-time adaptive manouvering system that has to cope with a tumbling landing surface
Finally, Constellation’s Ares I crew launch vehicle was to launch Orion that would rendezvous with the EDS and Altair, which were orbited by Ares V
What can be seen is that the capabilities of Constellation’s Orion and Altair and Ares V upper stage are all directly useful for the asteroid mission. Call it what you like but something very much like Orion and very much like Altair and very much like the Ares V EDS will fly to an asteroid whether that path is flexible with few dates or has a cast iron schedule, as cast iron as any spaceflight programme can be
Having demonstrated that all the technologies and the crew vehicle capabilities and in-space systems developed and in development for Constellation are completely applicable to Bolden’s asteroid mission the next issue this blog post will deal with is, how to get into LEO
Do you use the Ares family or do you use other launch vehicles, launched multiple times, perhaps in tandem with in-orbit fuel resupply?
For the Ares family you are using a permanently manned spaceport with personnel and equipment specific to the Ares rockets. That workforce will launch two Ares Is and two Ares Vs every year
The other option is to use a modified existing booster for the crew vehicle. But for that booster to have a higher flight rate than Ares I, and therefore better economics, it will have to be able to launch a deep space crew vehicle although its primary commercial mission may be for smaller payloads.
If the EDS and habitat cum asteriod lander can be launched by the deep space crew vehicle’s booster all to the good. Perhaps this mystery universal booster can also launch the fuel depots? But now you are looking at three launches for the crew vehicle, habitat and EDS and another three, one would imagine, for three “fuel depot spacecraft” to launch the maximum possible propellant to resupply the aforementioned vehicles. Six launches instead of Constellation’s two and six LEO rendezvous - best of luck with that mission control!
Either way this universal rocket does not sound like a booster that already exists. A human rated vehicle that is probably going to have to put at least 45,000kg, the Altair’s mass, into LEO. This assumes for the asteroid mission that the larger beyond lunar orbit propellant assembly makes up the difference in mass where the habitat cum lander is not fuelled on launch (unlike Altair) but has on-orbit fuel resupply. The conclusion can only be that a new booster has to be designed and developed
The Ares V upper stage technologies are clearly already needed for the asteroidship, so isn’t it obvious that the Ares V first stage and solid rocket booster systems are too? Yet Bolden is prepared to wait another five years, to 2015, before making a decision for the glaringly obvious
One last point about the economics of all this. Much has been made that the Constellation programme was proposing only two flights a year to the Moon for crew transport for the permanent human presence of a research station, probably at a southern lunar pole (It should be said that many more Ares V launches for cargo bearing Altair’s would be needed but that was never part of the argument)
So what does Obama and Bolden’s plan have to say about this economic batch quantity of launches its proponents criticised Consetllation for? Their plan is proposing one mission, one flight to an asteroid, in 2025 after spending billions and using all the technology that would have been needed for Constellation anyway. And the only apparent advantage is that a multiple launch on-orbit rendezvous and fuel resupply architecture might make better use of ground infrastructure and launch personnel, if you can develop this universal rocket
With all that in mind what makes the Obama/Bolden plan so much better than Constellation? At the beginning of this blog post there is a chart that was used by Bolden’s deputy Lori Garver at a recent conference and it gives approximate dates for everything envisaged under the Bolden plan
What can be seen in the chart is that despite NASA’s budget increases being smaller than those recommended by the US human spaceflight review, Bolden’s plan will need to have all the Constellation systems for the asteroidship and launch it at the same time NASA would have been setting up a Moonbase; and fund the International Space Station extension to 2020 and beyond; have flagship, and “small”, technology demonstations; start commercial crew services; research exploration technology and send robotic precursor missions to, one assumes asteroids and Mars
Who is unexecutable now Mr Bolden?