The design change that could save the Ares-1
January 18, 2010

Maybe it's due to the end of season sale, but also NASA has just recently started its end of season sales, selling off the last three (still working) Space Shuttles (that costed, at least, $3 billion each to build) for the modest amount of only $28.8 million each (already reduced from the previous price of $42 million each) also, it seems, they want (literally) giveaway the last (and never used) 17 SSMEs available (costed over $900 million, just two years ago) only for the price of the shipping charges!

In addition, with the forthcoming end of Space Shuttle flights (scheduled for late 2010 or 2011) NASA and its contractors have begun a mass layoff of their (highly experienced, trained and skilled) employees, technicians and engineers (as already happened at the end of the Apollo program, but not so many, of course) for a total number that could reach 12,500 people, that, from 2011, will be forced to search a new job and (if lucky) they will go to design vacuum cleaners, cooking mixers, bicycles, etc.

I do not know if all this (along with the dismantling of all production lines of the Space Shuttles' parts) has a political endorsement by the new U.S. administration or if it is an, independently taken, decision of the NASA officials, but, surely, that does not seem "just" an end of season sale, but, much more, a CLOSE OUT SALE of the "shop", the end of the NASA's human spaceflights, forever, and the suicide of the NASA itself.

The feeling is that NASA wants to close all its direct activities of human spaceflight, is reinforced by the fact that the "commercial space" will not be ready to send any cargo vehicle in space in the next 3-5 years and "could" be able to launch safely a crew in LEO not earlier than 6-8 years, also, no aerospace company ( or is (or will be) able to sell rockets to launch more than 24 tons of payload, while, every lunar mission, needs to launch over 200 tons in LEO.

Of course, none of the, existing or planned, rockets will be able to launch the Orion (that, in the lunar version and with a LAS, exceeds 32 tons of mass) and never can do that not even the Ares-1 (as explained my The Ares-1 can't fly article) as largely confirmed by the flight data of the Ares 1-X test (as explained in this article) then, the Ares-1 will never carry a so heavy Orion to LEO, not with the standard SRB nor with the new SRB-5, not in 2017 nor later, not even (really!) paying the (crazy) $35 billion price (that could become 40 or 50 with costs overrun!) that NASA wants, to complete the Ares-1 development.

As I explained in this article, the reason why the Ares-1 will never be able to launch the current (32 tons) Orion isn't due to a (small and simple) technical issue to be solved with some brilliant solutions, but to a basic problem of the SRB that wasn't born to fly alone, without the Shuttle, in fact, the 1-X test and its computer simulations (as written in the 1-X press kit) clearly show that an SRB, launched alone, can't (and does not) go over 35 km. of altitude before its burn-out, while, the altitude the Ares-1 1st stage should reach, must be of at least 55 km. otherwise, the 2nd stage power and the fuel, will be not able to carry the Orion to LEO.

The flight profile of an SRB booster, launched alone, depends almost entirely from its solid propellant's shape (an 11-points' star) so, great part of the propellant is burned in the early 80 seconds, giving MORE thrust than necessary, while, in the last 43 seconds, the SRB no longer has enough propellant to reach (at least) 45 km. of altitude (nor the 55 km. required by the Ares-1 flight profile) but it ends around 35 km. of altitude.

Also, NASA has not yet released the thrust vs. acceleration curve of the 1-X test, so, we do not know if the SRB's flight profile launched alone, is compatible with the human flight, or if, in the early 80 seconds of "excessive thrust", the acceleration reaches a too high level for the astronauts.

Time ago, a space forum has reported the rumor that, the 5-segment SRB would have a 12-point's star shaped propellant that would have worsened its flight profile since burning the propellant much more quickly, reaching a much lower altitude and with an higher acceleration for the astronauts in the early 80 seconds of the flight.

Then, later, ATK has abandoned this design change (maybe, after reading my article?) so (it seems) that, the ground-tested SRB-5, at the end of 2009 (to be used in the Ares-1) still had an 11-points' star propellant's shape (as the standard SRB) while, the article of the space forum that spoke about a 12-points' shape for the SRB-5, has been removed from the web...

Theoretically (and with considerable additional time and costs) we can change the SRB used for the Ares-1 so that it "could" reach (at least) the same altitude of a Shuttle's SRB (45 km.) at burn-out, with a more constant thrust and with a max acceleration compatible with the human flight.

To do that, we need to change the SRB's propellant shape, from its current (and sharp) 11-points' star to a (less points and less sharp) shape (as in the drawing below, that, however, is just an example of many possible shapes) have slightly more propellant in the SRB, burn it less quickly (with less thrust and less acceleration) in the early 80 seconds of the flight, leaving enough thrust to lift the SRB dry-mass and the upperstages to 45 km. of altitude or even more.

However, this change can't be applied to a 5-segment SRB, because, the 5th segment, adds more mass than thrust to the standard SRB, so, to work properly, it would, not only, need to change the geometric's shape of the solid propellant, but, also, to enlarge the diameter of the SRB rings and increase, in equal measure, the quantity and surface of the propellant, its dry-mass, but, also, the max thrust of the SRB-5.

A change of the diameter of the SRB rings (besides being extremely time consuming and expensive to implement) is not even possible, because, the company that produced the rings and even the machines used to make them, no longer exist from decades, in fact, for the Shuttle flights and the SRB tests (and even for the Ares-1 and the Ares-5) NASA always uses the same rings, just refurbished; about that, some time ago, I've read the figure "80" but I don't know if it refers to the total number of rings available (ie, enough to make 20 standard SRBs) or if it is the number of standards SRBs achievable with the available rings (so, 80 standard SRBs in total x 4 rings per SRB = 320 rings in total).

The propellent geometry's change of the SRB "could" work ONLY on an Ares-1 that uses a standard 4-segments SRB as 1st stage and a second stage made with an air-started SSME or two J-2X or an enhanced J-2Y or a single J-2X and a 30% lighter Orion.

Unfortunately, the downside of this solution is that needs very much time and money to develop, build, test, man-rate it; by comparison with the time and costs (three years and $3 billion) needed by ATK to (just) add a 5th segment to the standard SRB, change its nozzle and few other things, it could mean a delay of the first manned Orion/Ares-1 flight (scheduled for 2017) of, at least, three further years (thus, in 2020 or later) and additional R&D costs (over the $35 billion already evaluated) in the range of $5-10 billion, with the ONLY advantage to avoid a gigantic FLOP for the NASA rocket.


If you talk/discuss about this idea on forums, blogs, websites, magazines, newspapers
please acknowledge the source of the idea, putting a link to my article. Thank You.


Copyright Gaetano Marano - All rights reserved