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DIRECT v3.0 - Jupiter Launch Vehicle[1] [2]
FunctionPartially re-usable launch vehicle system
ManufacturerNone
Country of originUnited States
Size
Height75.1–79.0 m (246.4–259.2 ft)
Diameter8.41 m (27.6 ft) (identical to Shuttle External Tank)
Mass2,061,689–2,176,772 kg (4,545,246–4,798,961 lb)
StagesOne core stage with optional Jupiter Upper Stage (similar to Earth Departure Stage (EDS))
Capacity
Payload to LEO64,293–91,670 kg (141,742–202,098 lb) (to 100nmi and 130nmi orbits, respectively)
Launch history
StatusProposal
Launch sitesLC-39, Kennedy Space Center
Type of passengers/cargoOrion
EDS
LSAM
Boosters - Shuttle SRB
No. boosters2
Engines1 solid rocket per booster
Thrust25,774–27,955 kN (5,794,000–6,285,000 lbf) (sea level - vacuum; both boosters combined)
Specific impulse237.0 - 269.1 sec (sea level - vacuum)
Burn time123.8 sec
Propellantsolid
First stage (Jupiter-130 Variant) - Core Stage
based on Shuttle External Tank
Engines(3 SSME-Block-2 regeneratively-cooled)
Thrust5,524–6,550 kN (1,242,000–1,472,000 lbf) (sea level - vacuum; three engines combined)
Specific impulse361.4 - 452.2 sec (sea level - vacuum)
Burn time524.5 sec
PropellantLOX/LH2
First stage (Jupiter-246 Variant) - Core Stage
based on Shuttle External Tank
Engines(4 SSME-Block-2 regeneratively-cooled)
Thrust6,981–8,734 kN (1,569,000–1,963,000 lbf) (sea level - vacuum; four engines combined)
Specific impulse361.4 - 452.2 sec (sea level - vacuum)
Burn time384.1 sec
PropellantLOX/LH2
Second stage (Jupiter-246 Variant) J-246 Jupiter Upper Stage
Engines6 RL-10B-2
Thrust661 kN (149,000 lbf) (vacuum; six engines combined)
Specific impulse459.0 sec (vacuum)
Burn time609.9 sec
PropellantLOX/LH2
[edit on Wikidata]

DIRECT is a proposal outlining an alternative architecture for supporting the Vision for Space Exploration. The cornerstone of the proposal consists of replacing the two new Ares I and Ares V launch vehicles with a single "Jupiter" launch system. The Jupiter system would have greater commonality with the existing Space Shuttle systems, thereby reducing costs, shortening schedules, and simplifying technical requirements.

As of September 2008, the DIRECT Team consists of 69 members[3], 62 of whom are NASA engineers, NASA-contractor engineers, and managers from the Constellation Program volunteering their expertise in their spare time, along with 7 non-NASA "front men" who provide the public face of the group.

The project name "DIRECT" refers to the use of components with a more direct heritage to the existing Space Shuttle designs. The Jupiter launch vehicle is sometimes referenced in media reports as the DIRECT v2.0 rocket, although "DIRECT" refers to the larger-scope architecture.[4]

Overview

Some of the many configurations possible with the Jupiter Launch Vehicle Family.

The DIRECT architecture proposes that the twin Ares I and Ares V launchers be replaced with a single launch family named "Jupiter". Instead of using two very different rockets to perform the duties of crew and cargo launch, two similar rockets (single-stage or two-stage with nearly identical aerodynamic characteristics) would perform all of the same missions.

All Jupiters share a common core stage consisting of a tank structure based closely on the existing External Tank with a pair of Space Shuttle Solid Rocket Boosters mounted exactly as used on the Space Shuttle. Space Shuttle Main Engines are mounted to the bottom of the tank while crew and cargo are mounted on top.

There are many different theoretical configurations of Jupiter possible, but the DIRECT v3.0 proposal centers around two primary configurations; the Jupiter-130, capable of lifting over 60 metric tons to circular orbit,[1] and the Jupiter-246, capable of lifting over 90 t to circular orbit.[2]

Naming Convention

According to DIRECT spokesperson Stephen Metschan, "The Jupiter named used by the Wernher von Braun team was their internal name. The official name for the rocket that launched Explorer 1 was changed to Juno. We choose Jupiter so that America would finally acknowledge their accomplishment with the name they chose."

Proposed Jupiter launch vehicle configurations are prefixed with a J- followed by a three-digit code, such as J-130 or J-246.[5] The first digit refers to the number of inline stages, while the second, third, and (potentially) fourth digits refer to the number of rocket engines for each respective stage. For example, a J-246 would imply a 2-stage rocket with 4 engines on the first/core stage and 6 engines on the second/upper stage. A final zero is added as filler for single-stage rockets such as the J-130.

Shuttle Solid Rocket Booster Motors are assumed for all Jupiter vehicles and are not reflected in the type designation. Engines that are part of the launch vehicle's payload, e. g., Earth Departure Stage engines, are not considered in this simplified scheme.

Proposed Configurations

The recommended DIRECT v3.0 vehicles share a common core stage, based on existing Space Shuttle hardware. The two four-segment Space Shuttle Solid Rocket Boosters are retained, attached to a heavily modified External Tank (ET) which is plumbed for up to four Space Shuttle Main Engines (SSME) attached inline upon the bottom of the ET. In configurations where an SSME is omitted, the plumbing remains, and a cover plate is attached in place of the engine.

The Jupiter-130 (1 cryogenic stage, 3 core-stage SSME engines, 0 upper-stage engines) is the first proposed configuration. It is intended to be relatively simple to develop in order to quickly become fully operational after the retirement of the Space Shuttle. J-130 consists of the core vehicle alone, fitted with three SSMEs and a large payload fairing on top. This configuration can lift over 60 t of payload to a 100 nmi (190 km), 29° inclined, circular_orbit. In addition to the Orion spacecraft and crew, the J-130 could accommodate substantial cargo. Compared to the Space Shuttle, crew safety would be enhanced as any cargo would be positioned between the ET and the crew spacecraft. In the event of an emergency, the Launch Abort System would pull the crew capsule to safety.

The Jupiter-246 (2 cryogenic stages, 4 core-stage SSME engines, 6 upper-stage RL-10B-2 engines) would lift over 90 t of cargo to a stable 130 nmi (240 km) 29° inclined, circular orbit. Combined with the J-130, the J-246 is designed to return humans to the surface of the Moon, and to support the first human exploration of Mars and possibly other destinations beyond.

Crew Safety

The Jupiter launch vehicles have five main safety features:

  • The Jupiter design re-uses the proven method of Space Shuttle to safely attach the SRB's, avoiding all of the severe vibration problems which the Ares I design is experiencing in the form of thrust oscillation[6].
  • The Jupiter's main engines are ignited on the ground. Any start-sequence problems can then be detected before committing to the launch.
  • With multiple engines on all stages, one of the engines can be safely shut down after a non-catastrophic failure without aborting the mission. Some Jupiter flight configurations offer the ability to survive engine-out situations starting as early as 45 seconds after launch.
  • Located at the top of a large payload fairing, just like the Saturn V, the Orion spacecraft is always at least 10 meters (33ft) further away from the stages filled with fuel than it would be on an Ares I. This provides an additional "buffer space" between an exploding vehicle and the crew in any catastrophic failure situations.
  • The excess cargo capacity of the single-stage Jupiter allows additional protective hardware inside the payload fairing, mounted below the spacecraft. Options include flying with a composite panel made from boron-carbide and Kevlar, designed to create a light-weight "bullet proof vest" between the spacecraft and the stages below. Another option is to fit a full-width tank filled with water, which could act as a shield to protect the spacecraft from high-velocity shrapnel during a disaster.

The currently baselined Ares V configuration, with 6 RS-68B main engines and 5.5segment SRB's has a Loss of Mission (LOM) risk factor below 1 in 90 and a Loss of Crew (LOC) risk factor below 1 in 850. The ESAS Report specified that an LOC of 1 in 1,000 (a figure estimated to be at least five times higher than the Space Shuttle today, even accounting for the latest safety upgrades) would be the minimum required to be acceptable for human use for any new systems, using this issue to dismiss vehicles from consideration such as the Atlas V. Because Ares V will not meet NASA's targets regarding human safety all Ares-based missions will be forced to utilize an Ares I, incurring all of its associated costs for every mission type. However, being considerably smaller and with fewer engines, even the larger Jupiter variant, the now superseded DIRECT v2.0 Jupiter-232, was expected to comfortably exceed these targets with an LOC of 1 in 1,162. If the DIRECT v3.0 vehicles have similar safety margins, the DIRECT system could offer considerable mission flexibility. Lunar missions could be flown with a pair of powerful two-stage Jupiters instead of one single-stage crew vehicle and one two-stage cargo vehicle.

Program Risk

Proponents of DIRECT contend that the high costs and continually growing schedule for both Ares I and Ares V are leading the current efforts towards cancellation. Parallels are drawn between Ares and the many previous NASA programs which have been cancelled, such as the X-33/Venture Star development, the Orbital Space Plane, the First Lunar Outpost, the Space Launch Initiative and even the premature termination of the historically successful, but brief, Apollo Program - all terminated due to high costs and/or severe delays to their schedules.

One of the strongest programmatic criticisms with the current Ares I and Ares V architecture is the high cost for both developing two new launchers and for operating two concurrent programs. The cost concerns have been cited in GAO Reports to Congress[7] noting that the Ares I alone is expected to cost up to $14.4 billion to develop. Former NASA Administrator Michael D. Griffin confirmed that the total cost for developing both Ares launchers would be $32 billion, clearly indicating that the Ares V will be even more expensive to develop than the Ares I.

The schedule for the simpler Ares I launcher continues to slip. From the original intent in the Exploration Systems Architecture Study (ESAS) Report proposing crewed CEV flights as early as mid-2011, the schedule has been pushed-back by more than a year for every year of work so far done on the system. Three years later, the current NASA schedule has slipped by more than 4 years with a 65% confidence that the very first flight of Orion 2 (the first manned flight with the Orion spacecraft) will occur as early as September 2015[8] meaning that the first fully operational flight - Orion 4 - will not now occur until March 2016[9] at the soonest.

DIRECT contends that the requirement to develop so much new hardware for Ares I in order to fly the first Orion is directly responsible for the delays and that this is driving up the development costs. Specifically, the requirement to develop the brand-new 5-segment version of the Space Shuttle SRB, a brand-new J-2X engine, a brand-new Upper Stage, all-new manufacturing at the Michoud Assembly Facility and new launch facilities at Kennedy Space Center are all contributing to the slippage.

Comparatively, to fly the Orion sooner, DIRECT proposes to reuse the existing 4-segment Space Shuttle Solid Rocket Booster and Space Shuttle Main Engine which are already fully qualified for human use and reuse existing manufacturing to build a modified variant of the existing Space Shuttle External Tank. Only moderate modifications are required at Kennedy Space Center to enable launches. All DIRECT variants share a common footprint which allows flexibility in final assembly and choice of launch site.

The key program risk, according to DIRECT, is that NASA's Ares I is already over-budget, late and is lacking in performance, so when serious funding is required for the much larger and more expensive Ares V, Congress is not likely to be impressed. The risk is that Congress may pull the budgetary plug on the Heavy Lift effort before it is complete. This would leave NASA with a very expensive, yet small, Ares I launcher and no heavy-lift capability to enable any Lunar or Martian exploration programs in the future. NASA would then be locked into small missions incapable of venturing beyond Low Earth Orbit, and would have a small launch system comparable in performance to the Delta-IV Heavy EELV, but costing four or five times as much to operate each year.

DIRECT’s proposal for a single launch vehicle entirely removes the program risks associated with the possible cancellation of any second launcher. The brand-new J-2X is still needed to go to the Moon around 2017, but is not required to support the initial Orion crew flights to the International Space Station (ISS) around 2013.

Schedule

The critical activity of Ares I development is currently the schedule for the J-2X Upper Stage engine. Second is the development of the 5-segment version of the SRB, after that, the third major item driving the schedule is the constant revisions needed to the Orion spacecraft to get it light enough to fit within the Ares I's performance envelope while strengthening it due to the Thrust Oscillation concerns. These two factors have resulted in the contractor, Lockheed Martin, requesting that NASA fix the Ares I to stop impeding their design progress[10]. Latest information indicates this process has resulted in setting back the entire Orion program, from a relatively complete Cycle-3 [citation needed] effort, back to the beginning of a brand-new Cycle-2 effort in order to try to change the primary structure of the Crew Module from Aluminum-Lithium to a lighter-weight composite material[11]. This change has already pushed the Preliminary Design Review (PDR) milestone date back by more than a year to February 2010 and promises to add a considerable amount of additional development cost and production costs to an already-over-budget Orion Project.

DIRECT's Jupiter launchers avoid all these delays by firstly not requiring the J-2X at all on the first generation of the Jupiter-130 vehicle, by not requiring the 5-segment SRB at all and by providing more than 60 t of lift performance allowing the Orion design to be solidified today and go straight on to PDR unhindered.

In addition, by removing the parallel development of the Ares V booster, DIRECT removes a complete layer of high development costs from the budget requirements. Most of this money would be reused to speed development work of the other elements, Orion, Jupiter-130, launch facility modifications and all associated systems. A significant cash injection is expected to allow the schedules of all those elements to be significantly trimmed allowing an initial crew launch to occur in 2012 [citation needed] and full operational capability of an Orion/Jupiter-130 system to perform 6-person crew rotations and cargo deliveries at the ISS in early 2013 - three years ahead of the current Ares I schedule.

Workforce

Artists impression of an Orion spacecraft taking a DIRECT Space Shuttle Payload Delivery Module (SSPDM) to the International Space Station in 2013, carrying an airlock, the $1.5bn AMS Experiment and some other cargo - all which could be launched on a single Jupiter-120.

An additional aspect of the DIRECT proposal is to utilize some of the funds made available by removing the need for a second launcher, to fund additional projects intended to make use of the extra performance of the Jupiter-120. The 20 t of extra payload capability of the Jupiter-120 allows for a range of additional cargo payloads to be flown with each Orion crew, a capability which is not possible with the Ares I. The DIRECT Team have suggested a number of extra missions which would be enabled by Jupiter in their proposal[12], including:-

  • New ISS resupply missions delivering the 3 Italian-built Multi-Purpose Logistics Modules in 2012, 2013 and 2014
  • Performing even more Hubble Space Telescope Servicing Missions with Orion crews around 2015
  • Launching massive new space telescopes over 8 meters in diameter (twice the diameter and 4 times the resolution of Hubble)
  • Perform NASA's Mars Sample Return[13] mission on a single Jupiter launcher, to land on Mars and return a sample of its soil back to Earth for study as early as 2013
  • Launching a human crew to fly around the moon as early as 2013

This wide range of new missions can be planned and afforded if only one new launcher is being developed instead of two. The new missions and payloads would all require new contracts, providing useful employment for many of the experienced people who will otherwise be laid-off at the end of the Space Shuttle Program in 2010. Instead of being released, thousands of these knowledgeable and skilled people would be required for building, preparing and processing all the additional payloads. And such employment would keep those valuable skills and knowledge within the agency until the Lunar phase is ready to pick up their contracts around 2016-2018 to support the new Lunar base and Lunar Lander projects. Essentially this approach provides a “bridge” to help transition the thousands of experienced staff across the gap and avoid a devastating repeat of the Apollo Program to Space Shuttle "brain-drain" which occurred in the 1975-1981 period.

Missions

Because DIRECT relies heavily on technology derived from the Space Shuttle, much of the planned missions in Project Constellation will move significantly earlier in schedule. The first crewed CEV will fly in December 2012. The first ISS rotation will take place in September 2013. The first crewed Lunar flyby will take place in December 2013. A possible fifth Hubble Space Telescope service mission can fly in December 2014. The first manned Lunar mission can take place on December 2017 and the first manned Mars mission can take place in 2031.[14]

Origins

A 1978 image of a Morton Thiokol-proposed In-Line Shuttle Derived Launch Vehicle concept - Note the "white" tanking

The basic concept behind DIRECT has been around since the inception of the Space Shuttle Program. Drawings and artwork of an In-Line Shuttle stack configuration date back to 1978 – 3 years before the first Shuttle flight.

The first official trade study was conducted in 1986 by NASA's Marshall Space Flight Center in the aftermath of the Space Shuttle Challenger disaster[15]. It was promoted as one of the most logical alternatives for launching unmanned cargo and would have potentially allowed a re-started Apollo spacecraft program as well. There were, however, no funds available to NASA for building any new vehicles while the Space Shuttle Program continued. The idea was shelved and NASA concentrated on fixing and operating the Space Shuttle instead.

Of all the previous studies and development efforts, DIRECT bears the strongest relationship to the 1991 National Launch System[1] effort. Proposed jointly by NASA and the Department of Defense as an alternative to the Titan IV, the design was based on the same SRB’s as Shuttle and the same core tanking, but it had four inexpensive engines and considerably lower performance than the original concept. But again, Congress did not appropriate funding for the development while Shuttle continued to be operated, so the work never proceeded beyond the design phase. A great deal of reference material exists in the public domain regarding NLS[16][17][18][19].

Then in 2005, NASA's Exploration Systems Architecture Study (ESAS) included a very similar design, but with three of the Space Shuttle Main Engines (SSME). Known as LV-24 in Crew launch form, and LV-25 in Cargo configuration, the idea was dismissed because it did not have sufficient performance for the proposed lunar program - however the concept was not considered using an Earth Departure Stage (EDS) and no versions were investigated powered by the less costly, but higher thrust RS-68 engines.

DIRECT v1.0

According to its proponents, DIRECT v1.0 was the product of a three-month grass-roots study produced by more than a dozen NASA engineers and managers working purely in their free time, and a small group of dedicated enthusiasts. DIRECT takes the final ESAS recommendation of using the EDS during the ascent phase of the flight to gain additional launch performance on the Cargo LV, and applies this same methodology to the LV-24/25.

The next change in DIRECT's development was in response to NASA dropping the Space Shuttle Main Engine on their Cargo LV design. This was due to the high manufacturing cost of the SSME engines, and the difficulty in producing the required number of units per year with existing manufacturing facilities. So NASA chose to replace them with five RS-68 engines to make the Ares V Cargo LV. This same change was also applied to DIRECT's concept. Analysis showed, however, that the number of engines required for this particular vehicle could be reduced to just two of the basic RS-68 engines. Additional performance and Initial Mass in Low Earth Orbit (IMLEO) could be provided by upgrading the main engines with the Regenerative Cooling Nozzles to improve their efficiency. It should be noted, however, that the analysis also demonstrated that this improvement, while desirable, is not required in order to accomplish the basic missions of both the crew and cargo programs.

The proposal was submitted on October 25 2006 to NASA's Administrator, Michael D. Griffin, and a wide range of industry, political and advocacy groups involved in the current development plans. v2.0 of the proposal is a 9 month refinement study which was announced on September 19 2007 at the AIAA "Space 2007" Conference in Long Beach, CA.

Criticism and Changes

The original DIRECT v1.0 proposal created a wave of discussion within both professional NASA/aerospace circles and within the broader community of NASA supporters and enthusiasts. Approximately 2,000 posts about DIRECT v1.0 appeared on the public forum at NASASpaceflight.com over a 7 month period.

In late 2006, head of the ESAS Study, Dr. Doug Stanley, declared that the DIRECT v1.0 proposal could not work as it relied on overly-optimistic and speculative performance specifications for an upgraded RS-68 Regen engine. Dr. Stanley produced official specifications from Rocketdyne about the RS-68 Regen upgrades to prove his point. Later evidence from Rocketdyne confirmed that DIRECT v1.0's “overly-optimistic” RS-68 variant was in fact technically achievable, although it would be expensive and time-consuming to develop.

DIRECT v2.0

On May 10 2007, a revised DIRECT v2.0 proposal was released by the same volunteer group to meet peer-reviewed critiques of the initial proposal. To address criticism of relying on engine studies rather than working engines, DIRECT v2.0 uses only man-rated versions of the standard performance RS-68 as flown on existing Delta IV launchers, with no performance upgrades at all and the lower of two specifications of J-2X engine which Rocketdyne were currently developing for NASA's Ares launchers. DIRECT v2.0 introduced a scalable, modular family of Shuttle-derived launch vehicles, starting with the DIRECT Jupiter-120 and DIRECT Jupiter-232.

The Jupiter-232 heavy launch vehicle in the revised DIRECT v2.0 proposal differs from the original proposal primarily by specifying the use of two existing J-2 engines on the Earth Departure Stage (EDS) instead of one new J-2X, and 3 human-rated ablative nozzle RS-68 main engines instead of 2 new Regenerative Cooling Nozzle RS-68 main engines. The Jupiter-120 Crew LV in the revised DIRECT v2.0 proposal specifies the use of 2 existing man-rated ablative nozzle RS-68 main engines instead of 2 new Regenerative Cooling Nozzle RS-68 main engines.[20]

DIRECT v2.0 was further expanded in September 2007 with a 9-month study culminating in a 131 page exploration architecture study released at the AIAA "Space 2007" Conference in Long Beach, CA. The 131 page paper detailed specifically how the launch vehicles were a single part of a much wider-reaching architecture designed to enable the US to maintain the ISS, progress on to the moon with even larger missions than Ares I and Ares V could perform, and presented the wide range of additional capabilities available to evolve the program using Jupiter launchers to achieve the goals of the future Mars program which will follow eventually. The paper also considered many other options which are enabled by DIRECT, such as Lagrangian point staging architecture options and mission architectures for visiting Near-Earth object destinations.[21].

DIRECT v3.0

On 29 May 2009, DIRECT spokesperson Stephen Metschan gave a presentation to the 28th Annual International Space Development Conference entitled, "Direct 3.0: Landing Twice the Mass on the Moon at Half the Cost."[22] In April of 2009, following NASA trade studies comparing use of the Space Shuttle Main Engine (SSME) to the originally planned RS-68 engine for Ares V, the DIRECT Team announced that future DIRECT proposals would recommend SSME as the core-stage engine.[23] The DIRECT team worries that the intense heat of the Space Shuttle SRBs will be too much for the ablatively-cooled RS-68. Additionally with the Space Shuttle retirement nearing, DIRECT reasons that the extra expense of the regeneratively-cooled SSME will be offset by the expense and time of man-rating the RS-68. Similarly, for the upper stage, the DIRECT team recommends using six RL-10B-2 engines as a proven, man-rated alternative to the still-in-development J-2X.

On 17 June 2009, Stephen Metschan presented the DIRECT concept to the Review of U.S. Human Space Flight Plans Committee[24] chaired by Norman R. Augustine.

Advantages and disadvantages

Proponents of DIRECT also argue that this proposal will enable NASA to fulfill the mandate of the Vision for Space Exploration faster, safer, and sooner than the planned Ares I and Ares V, at a much lower cost and with far less programmatic risk. Unlike the budget plans for Ares I and Ares V, DIRECT will still allow NASA sufficient room in its current budgets beyond launch vehicle development and operations to continue funding other missions such as the International Space Station beyond 2016, while being better able to withstand the unpredictability of future annual congressional/administration budget allocations.

The DIRECT proposal calls for NASA to use the massive development-cost and fixed-cost savings from DIRECT to accelerate the VSE's schedule for returning to the moon, to continue to fly missions to support the International Space Station, and to potentially fly other missions such as servicing missions to the Hubble Space Telescope. Like NASA's official Constellation plans, the DIRECT proposal calls for ensuring that the existing NASA Space Shuttle industrial base and workforce at sites around the U.S. would be retained (which is important from both the standpoint of maintaining Congressional support and maintaining the skills and know-how of this workforce). However, compared to Constellation, the much shorter gap in manned U.S. space flight under DIRECT would prevent the type of knowledge-loss that NASA suffered in the gap between Apollo and the Shuttle in the late 1970s and the related localized economic hardship in Florida's Space Coast that was seen during the same time period.

Opponents of DIRECT argue that the safety factor of this proposal is not as good as that of the original ESAS Crew LV proposal. DIRECT's proponents counter that the Jupiter-120 Crew LV has much greater safety margins than NASA's current plans for an Ares I Crew LV, which is a significantly different vehicle from the originally selected ESAS Crew LV. Opponents also contend that, as a plan developed outside of official NASA channels (NIH), DIRECT stands little chance of being implemented.

David King, director of NASA's Marshall Space Flight Center said that NASA has considered DIRECT as well as many other rocket proposals, and that the Ares family is the right set of rockets for the mission.[25] "DIRECT v2.0 falls significantly short of the lunar lander performance requirement for exploration missions as specifically outlined in Constellation Program ground rules. The concept also overshoots the requirements for early missions to the International Space Station in the coming decade. These shortcomings would necessitate rushed development of a more expensive launch system with too little capability in the long run, and would actually increase the gap between space shuttle retirement and development of a new vehicle. Even more importantly, the Ares approach offers a much greater margin of crew safety - paramount to every mission NASA puts into space."

On May 18th, 2009, the DIRECT team released a comprehensive rebuttal to the charges raised by NASA.[26][27] "NASA’s October 2007 analysis of DIRECT, on the surface, appears to be a carefully executed analysis of the DIRECT architecture and its central launch vehicle, Jupiter. However, a closer examination of the document reveals significant flaws in the evaluation of DIRECT that set up a scenario where DIRECT would inevitably look inferior when compared to Ares. The errors are so numerous that the only conclusion possible is that this document cannot be used to properly assess the value of the DIRECT alternative."

Design

Exploded Diagram of the Jupiter-120 configuration

The DIRECT launch vehicle concept consists of a core stage, based on many existing elements of the current External Tank with either two or three Pratt & Whitney/Rocketdyne RS-68 main engines mounted directly underneath, and a pair of Alliant Techsystems 4-segment Solid Rocket Boosters (SRBs) unchanged from the Space Shuttle today. According to its proponents, initial performance to Low Earth Orbit (LEO) [specifically to 42x120nm, 28.5-degree inclination initial orbit] for this initial variant of the DIRECT Crew LV is conservatively expected to be at least 46,635kg (102,812lb), which is 250% of Ares I's 19,300kg (42,500lb) maximum performance. This means that an Orion spacecraft could be launched on top of the vehicle, along with 24,600kg (54,000lb) of additional cargo on every flight - a useful capability that is impossible with the Ares I.[28]

An optional upper stage, known as the Earth Departure Stage (EDS), powered by two Pratt & Whitney/Rocketdyne J-2XD engines would be used to increase payload capacity for certain missions. Payload performance to LEO increases to at least 103,342kg (227,829lb).

Exploded Diagram of the Jupiter-232 configuration

Gross performance for the two Ares I and Ares V launchers required for every Lunar mission is expected to be no more than 150,900kg (333,000lb). By comparison, two DIRECT J-232 vehicle, one launching Crew and spacecraft and the other launching mostly propellant, are capable of launching in excess of 220,000kg (485,000lb), including greater performance margin reserves.

To speed development of DIRECT, the RS-68 engines on the core stage would be man-rated versions of those used successfully on the current Delta IV program. DIRECT explicitly plans not to require performance upgrades, even rejecting the 6% additional performance NASA requires from the RS-68 for use on the Ares V instead opting to operate the engines at the lower performance levels being used today to gain the maximum possible reliability and safety.

Unlike NASA's Ares I, DIRECT does not require any new engines to be developed for the first vehicle, designated J-120, in order to fly the first manned Orion spacecraft. This removes the greatest cost and schedule impacts that Ares I faces. J-2XD engines are only required by DIRECT on the optional upper stage for the later lunar missions. Even then DIRECT would only require the lower-thrust, less-costly J-2X "Development" variant. DIRECT does not require the additional performance of the fully upgraded J-2X engine needed by both Ares I and Ares V.

Similarly, DIRECT does not require the very expensive development of new 5-segment Solid Rocket Boosters as needed by Ares I and Ares V. The existing fully man-rated 4-segment Shuttle SRB's provide adequate thrust for DIRECT while helping to reduce costs.

Finally, DIRECT's Core Stage uses the existing 8.41m diameter of the Shuttle's External Tank. Unlike Ares V with its 10.06m diameter Core Stage, this allows DIRECT to re-use the existing manufacturing tooling for the External Tank at the Michoud Assembly Facility, the existing Pegasus barge used to transport the tank from Michoud to Kennedy Space Center, the existing work platforms in the Vehicle Assembly Building, the existing Mobile Launcher Platforms and Crawler-Transporters, and much of the structure of the existing Fixed Service Structure and Flame Trenches at Launch Complex 39.

While DIRECT does not require any of the upgraded hardware needed by the Ares launchers, should additional performance be required in the future DIRECT can take advantage of these enhancements to increase performance - but they are not requirements in the critical path to success and the additional capital investment is not required.

Integrated Approach

Once the basic vehicle was pinned down, more NASA engineers and managers started to support the concept and offer their time to flesh out the concept from a wider perspective. These professionals contributed to creating a complete cost analysis comparison, a detailed series of evaluations for supporting facilities such as data on the existing manufacturing facilities for the External Tank at the Michoud Assembly Facility and the various launch-processing facilities currently at the Kennedy Space Center.

From these contributions, a clear difference in cost, schedule, maintenance, manufacturing & launch processing flow became apparent between the Ares and DIRECT approaches. DIRECT would re-use almost all of the existing facilities, whereas Ares I and Ares V each required seriously overhauled or completely replaced facilities – and each required its own set. This impacts almost every aspect of the operation from cost to design, development, testing, evaluation, implementation, schedule, risk mitigation, workforce retention and safety.

A fully integrated assessment of all these factors, under the outlines of the political requirements NASA must operate within, and a detailed analysis of the wider range of Lunar mission procedures which DIRECT can offer, resulted in the complete DIRECT Launch Vehicle Proposal.

References

  1. ^ a b "DIRECT v3 - Jupiter-130 - LEO Crew Launch Vehicle Configuration" (PDF). 2009-06-06. Retrieved 2009-06-12.
  2. ^ a b "DIRECT v3 - Jupiter-246 - Lunar EDS Launch Vehicle Configuration" (PDF). 2009-06-06. Retrieved 2009-06-12.
  3. ^ "End Run - A small band of rogue rocketeers takes on the NASA establishment". Air & Space Magazine \ publisher = Smithsonian Institution. September 29, 2008. Retrieved 2008-10-19. {{cite web}}: Missing pipe in: |work= (help)
  4. ^ "NASA remains silent on rocket that could rescue the Cape". Orlando Sentinel. June 22, 2008. Retrieved 2008-06-25.
  5. ^ Tierney, Ross. "NASA Space Flight Forum - NASA CEV / CLV / CaLV / MTV / Alternatives - DIRECT v2.0 - Thread 3". Retrieved 2009-04-09.
  6. ^ Mark Carreau (19 January 2008). "Severe vibration problem plagues moon rocket design". Houston Chronicle.
  7. ^ "Agency Has Taken Steps Toward Making Sound Investment Decisions for Ares I but Still Faces Challenging Knowledge Gaps, Report to the Chairman, Committee on Science and Technology, House of Representatives, #GAO-08-51" (PDF). Government Accountability Office. October 2007.
  8. ^ "Hanley's confidence over the gap - Orion 4 scheduled for March, 2016". NASA Space Flight .com, Chris Bergin. 24 June 2008.
  9. ^ "Constellation confirm IOC slip to Orion schedule". NASA Space Flight .com, Chris Bergin. 11 August 2008.
  10. ^ "Orion's plea to Ares I: Stop adversely hindering our design process". NASA Space Flight .com, Chris Bergin. 15 September 2008.
  11. ^ "Orion PDR delay could stretch into 2010". NASA Space Flight .com, Chris Bergin. 30 September 2008.
  12. ^ "DIRECT Presentation". The DIRECT Team. 3 July 2008.
  13. ^ "Missions to Mars - Mars Sample Return".
  14. ^ http://www.directlauncher.com/documents/DIRECT_Analysis_Rebuttal_Final_090518.pdf
  15. ^ http://www.orlandosentinel.com/news/space/orl-rocket2208jun22,0,6150021
  16. ^ "Cycle 0(CY1991) NLS trade studies and analyses report. Book 1: Structures and core vehicle". NASA Technical Reports Server (NTRS). 20 October 2008.
  17. ^ "Cycle O (CY 1991) NLS trade studies and analyses, book 2. Part 1: Avionics and systems". NASA Technical Reports Server (NTRS). 20 October 2008.
  18. ^ "Cycle O(CY1991) NLS trade studies and analyses report. Book 2, part 2: Propulsion". NASA Technical Reports Server (NTRS). 20 October 2008.
  19. ^ "88 Search Results for "NLS"". NASA Technical Reports Server (NTRS). 20 October 2008.
  20. ^ "DIRECT Space Transportation System Derivative;The Jupiter Launch Vehicle Family" (PDF). DIRECT Team. Retrieved 2008-06-15.
  21. ^ "Achieving the Vision for Space Exploration on Time and Within Budget" (PDF). AIAA Houston. Retrieved 2008-06-15.
  22. ^ Metschan, Stephen (2009-05-29). "DIRECT - Safer, Simpler and Sooner than Ares" (PDF). Retrieved 2009-06-12.
  23. ^ Tierney, Ross. "NASA Space Flight Forum - NASA CEV / CLV / CaLV / MTV / Alternatives - DIRECT v2.0 - Thread 3". Retrieved 2009-04-01.
  24. ^ "NASA - Review of U.S. Human Space Flight Plans Committee". 2009-06-17. Retrieved 2009-06-17.
  25. ^ "Ares remains the answer for-ew frontiers". The Huntsville Times. June 29, 2008. Retrieved 2008-06-29.
  26. ^ "DIRECT issue rebuttal over NASA analysis of Jupiter launch vehicle". NASA Spaceflight. May 18, 2009. Retrieved 2009-05-21.
  27. ^ "Rebuttal of NASA's October 2007 DIRECT 2.0 Analysis Findings" (PDF). DIRECT Team. May 18, 2009. Retrieved 2009-05-21.
  28. ^ "Horizons - A Direct Approach" (PDF). AIAA Houston. Retrieved 2008-06-15.
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