By: Rob Coppinger, SPACE.com Contributor
Published: 10/30/2012 05:12 PM EDT on SPACE.com
NASA is contemplating space journeys far beyond a near-Earth asteroid, the moon or Mars for its new heavy-lift rocket in development. The Space Launch System (SLS), as it is called, could instead visit the moon of Pluto or return samples from other outer planets.
An unmanned flyby mission to Pluto's Charon, sample return missions to Jupiter's moon Europa or Saturn's Titan, or a sample-gathering flight through Jupiter's atmosphere or the ice water jets of Saturn's Enceladus — all are said to be possible with the 286,000-pound (130,000 kilograms) launch capabilities of the Space Launch System.
The first launch of SLS is planned for 2017, but it will not have an upper stage and will be able to put only 154,000 pounds (70,000 kg) into low-Earth orbit. Beginning in 2022, however, the rocket is expected to have more powerful boosters and an upper stage to give it an ability to deliver 286,000 pounds to Earth orbit.
Such large cargos will be transported under a nose-cone fairing that will have a diameter of about 30 feet (10 meters), giving the Space Launch System a useful payload volume of about 38,846 cubic feet (1,100 cubic meters). The rocket itself has a diameter of about 25 feet (8.4 meters). [Photos: NASA's Space Launch System for Deep Space Flights]
It is this combination of a very large lift capability and nose-cone volume that is expected to enable ambitious missions such as sample return from the outer planets.
"Most of the science community hasn't thought beyond current lift capability. Scientists haven't thought about what mass and volume they need to use," Kenneth Bruce Morris, a Booz Allen Hamilton senior associate, said at the 63rd annual International Astronautical Congress in Naples, Italy, on Oct 5. Morris' presentation was co-authored with the Marshall Space Flight Center. Before joining Booz Allen Hamilton, Morris was NASA's lead for Ares V utilization planning under the now-canceled Constellation program.
Because of the SLS payload capability, future science spacecraft will be able to carry large propulsion systems and more fuel, enabling them to reduce their mission time and carry more instruments. To reach the outer planets, previous spacecraft have had to make multiple gravity-assist maneuvers around the inner planets to reach the velocity needed, costing valuable time. The SLS could increase mission time by years, since its larger propulsion systems would enable more direct trajectories.
Another advantage of SLS is the potential to reduce the number of separate launches complex missions will require. For example, with existing boosters, an outer planet sample mission would require many launches to assemble the spacecraft. With SLS, however, the mission could be achieved with fewer launches, or even just one, reducing complexity.
In addition to sample return, such large scientific spacecraft could deliver multiple rovers to the surface of Venus or carry the substantial shielding needed for operating long term in the harsh radiation environment of the Jupiter system.
"We've been talking with the science community. Most of our focus has been on targeted one-on-one interactions between SLS and high-priority science missions in the coming decades, discussing mutually beneficial options," Stephen Creech, SLS strategic development manager for NASA's Marshall Space Flight Center, told SPACE.com.
On July 25, the SLS program passed two key reviews, for combined system definition and system requirements, to move toward its preliminary design review, scheduled for late 2013. The SLS critical design review is scheduled for early 2014. These various checkpoints pave the way for the finished design of SLS to begin construction in earnest.
As well as missions to the outer planets, the SLS could launch space telescopes that operate at the thermally stable second sun-Earth Lagrange point, a spot in space where gravity from the sun and Earth balance each other out. Designed to observe ultraviolet, visible and near-infrared light, these space telescopes would use huge mirrors with diameters from about 24 feet to 52 feet (16 meters). A 52-foot mirror telescope could find and characterize alien planets around other stars.
Such large imaging systems would also be useful for the U.S. government's National Reconnaissance Office satellites and other Department of Defense spacecraft. Launching large robotic spacecraft capable of traveling to geostationary orbit to service telecommunication satellites is another possible use for SLS. [Video: SLS — Leaving Low-Earth Orbit Behind]
Because the Space Launch System would be able to deliver very large structures with a few launches, it could also put into orbit, for assembly, the component parts of a space-based solar power system. Such a solar satellite could be a commercial venture.
Private space stations
Another commercial venture the SLS could help launch is a Bigelow Aerospace space station. NASA's Creech has confirmed to SPACE.com that the space agency has spoken to Bigelow.
The company has proposed a private space station, leased by governments and corporations for research, which would consist of four of Bigelow's inflatable BA330 modules, a docking node and a propulsion unit. Each BA330 has a total volume of 11,653 cubic feet (330 cubic meters). The first BA330 is to be launched on a Space Exploration Technologies (SpaceX) Falcon 9 rocket in 2015.
The SLS could also enable Lagrange point gateway architecture for manned exploration, said Jim Chilton, Boeing's space exploration vice president and Space Launch System stages program manager. Speaking at the astronautical congress, Chilton's presentation showed how two SLS launches, using 15-foot-long nose cones capable of fitting 154,000 pounds inside, would be able to deliver the modules for a Lagrange point platform. Located at the Earth-moon L2 Lagrange point, beyond our natural satellite's orbit, the platform would be a waypoint for refueling.
Under NASA's exploration plans, the manned Orion Multi-Purpose Crew Vehicle, launching atop an SLS rocket, would go to an asteroid after a trip around the moon and back in 2021. The asteroid mission would be a deep-space trip for the astronauts; an intermediate test mission could see the crew go to such a platform at the L2 Lagrange point.
Lockheed, the primary Orion contractor, is also considering alternate missions for the space capsule. Josh Hopkins, Lockheed Martin Space Systems' space exploration architect, described to SPACE.com an in-orbit experiment to create a centrifugal force onboard Orion that would give astronauts a gravity-like experience.
"We've been looking at an artificial gravity test where you put an Orion in a tether with a mass and spin them up and Orion is not designed to be spun up and so we're working on that, we're interested in it," he told SPACE.com.