Fuel Conservation in Space - Aerocapture

[Waspie_Dwarf]

For Fuel Conservation in Space, NASA Engineers Prescribe Aerocapture

With gas prices sky-high, conserving fuel has become a national obsession. Accelerate slowly. Stop gently. Allow ample time to reach your destination. But what if you want to conserve fuel and still get there in a hurry? For a team of NASA engineers, the answer is aerocapture.

Aerocapture technology is a flight maneuver that inserts a spacecraft into orbit around a planet or moon by using the destination's atmosphere like a "brake." The dense atmosphere creates friction, which is used to slow down a craft, transferring the energy associated with the vehicle's high speed into heat. This allows for a quick orbital capture without the need for a heavy load of on-board propellant, which increases launch cost.

Aerocapture is part of a unique family of "aeroassist" technologies being developed by NASA for science missions to any planetary body with an appreciable atmosphere. These destinations could include Mars, Venus and Saturn's moon Titan, along with the outer planets.


Image above: Artist concept of aerocapture entering Mars orbit.
Credit: NASA

There are several alternative vehicle designs that can be used for aerocapture. One option is enveloping spacecraft in a capsule with heat shielding applied to the external surfaces. This type of “aeroshell” isn’t new. It was used in the 1960s and 1970s to bring astronauts home from our moon during the Apollo Program, in 1997 for the Mars Pathfinder mission, and in 2003 during the entry, descent and landing of the two Mars Exploration Rovers, Spirit and Opportunity.

Rigid aeroshell designs, which encase a spacecraft in a hard, protective shell, are among those being studied. For rigid aeroshell aerocapture, a thermal protection system is needed to shield the spacecraft from the high heat it experiences when it enters the atmosphere of a moon or planet. NASA scientists and engineers are already "hot" on the trail. Testing is under way on several new thermal protection systems specially suited for rigid aeroshell aerocapture systems.

Two companies currently are developing advanced thermal protection system technologies for aerocapture. The companies' work is led by NASA's In-Space Propulsion Technology Program, which is managed by the In-Space Propulsion Technology Project at NASA's Marshall Space Flight Center in Huntsville, Ala.

Applied Research Associates of Denver, Colo., currently is conducting tests of a family of new thermal protection systems at the National Solar Thermal Test Facility at Sandia National Labs in Albuquerque, N.M. The facility uses a common household item to perform the testing -- mirrors, and lots of them. The test facility’s solar tower uses 212 large mirrors to track the sun and focus sunlight on a target, simulating the high heat encountered during an aerocapture maneuver.

Lockheed Martin, also in Denver, is currently testing an advanced technology aeroshell system that absorbs heat as a spacecraft enters an atmosphere. These tests are being done at the NASA Ames Research Center at Moffett Field, Calif., and at the Lockheed facilities in Denver.

Along with the rigid aeroshell system, NASA is also considering inflatable deployed systems that decelerate a spacecraft by providing a large drag area. One such system is an inflatable, trailing "ballute," a combination balloon and parachute made of thin, durable material that deploys and trails behind a spacecraft to slow it down. Ball Aerospace in Boulder, Colo., is designing and testing a trailing ballute system at ILC Dover in Frederica, Del., and in the wind tunnels at the NASA Langley Research Center in Hampton, Va. Ball also is also developing a ballute system that is attached to the aft body of the spacecraft and acts like an inflatable "skirt" to decelerate the incoming spacecraft. An inflatable rigid aeroshell option is also being developed by the team at Lockheed Martin in Denver.

Aerocapture technology is being considered for a broad range of future mission objectives. Although the orbit capture maneuver has never been flight tested, ablative and non-ablative entry capsules have been used throughout the U.S. space program, providing plenty of relevant experience. This includes the Apollo return capsule, used between 1963 and 1972 to return humans from the moon and Earth orbits, and the Galileo Probe, launched in 1989 on a 14-year mission to explore the planet Jupiter and its surrounding moons.

Many other aerocapture component technologies already exist, or have evolved from other aeroentry applications. The aeroshell and thermal protection systems have heritage to those developed for past Earth, Venus, Mars and Jupiter missions. The ability to guide and control a blunt body design was human-rated -- tested on the ground by human test subjects -- for the capsule used during the Apollo era to return astronauts to Earth. These tests were part of a weather contingency plan but were never used or tested during space flight.

Aerocapture could open the door to destinations throughout our solar system, making possible near and mid-term space science missions that are keys to NASA's exploration goals.

For more information about advanced propulsion technologies being developed by NASA, visit:

http://www.nasa.gov/

For more information about aerocapture technology development and other in-space propulsion technologies, visit:

http://www.inspacepropulsion.com/

Contact:
Steve Roy, Marshall Space Flight Center
256.544.0034

Source: NASA - Exploring The Universe

[MID]

Another Arthur C. Clarke concept beginning to see fruition.

He called it aero-braking, and was featured in 2010:Odyssey Two (1982), when the Chinese ship, Tsien, used it to enter orbit around Jupiter, and then, when the Leonov did the same thing a few weeks later.

Maybe, by the actual 2010, the concept will actually begin to bear fruit!

[Waspie_Dwarf]

Another Arthur C. Clarke concept beginning to see fruition.

He called it aero-braking

NASA also use the term aero-breaking. I think that aero-breaking is a general term used for the process of slowing a spacecraft by using a planet's (or satellite's) atmosphere. Aero-capture is a specific type of aero-braking and is when the atmosphere is used to slow a spacecraft down so that it can enter orbit from it's interplanetary cruise.

NASA has used aero-braking (but not aero-capture) on several of it's Mars missions to lower and circularise the initially highly elliptical orbit. The spacecraft skims the outer layer of the atmosphere at an altitude where the air is thin enough to slightly slow the spacecraft but is not thick enough to heat the spacecraft. Indeed the Mars Reconnaissance Orbiter is undergoing these maneuvers now, see this post in the Exploration of Mars thread.

[ROGER]

As stated this is an old idea being up dated. Though some wonderful heat resistant materials have come out of making the Shuttles reentry tiles , I have all ways wondered why a larger drag shut was not use to slow the shuttle down before reentry. I am guessing fuel and weight makes it impractical. Though I do remember reading an old research paper that stated it just was not a popular idea at the time.

[Waspie_Dwarf]

NASA Meets Key Objective in Developing New Propulsion Method

Steve Roy
Marshall Space Flight Center, Huntsville, Ala.
(Phone: 256.544.0034)

News Release: 06-141

A test of thermal protection system panel Tapping the power of 1,500 suns, scientists at NASA's Marshall Space Flight Center have met a critical milestone in the development of aerocapture technology, a maneuver that primarily uses a planet's atmosphere to capture a spacecraft and place it in the desired orbit.

The In-Space Propulsion Technology Project at NASA's Marshall Space Flight Center in Huntsville, Ala., has successfully tested a series of 12-inch-square thermal protection panels. The tests focused on a type of spacecraft shielding material called an advanced charring ablator.

"The tests exposed ablators to solar power levels up to 150 watts per square centimeter -- approximately 1,500 times the intensity of the sun on Earth on a clear day," said Bonnie James, aerocapture technology manager at the Marshall Center. "This helped us simulate the high temperatures encountered by a space vehicle using aerocapture to complete a hypersonic flight through a planet's atmosphere."

The tests were part of a larger effort by NASA and technology developers from partnering institutions to place space vehicles into long-duration orbits around distant planets and other bodies throughout the solar system without heavy, on-board fuel loads. Instead, the nearly propellant-less method uses friction to slow a spacecraft entering the atmosphere of its destination planet. The thermal protection system shields the spacecraft from heat produced by the friction.

The tests were conducted at the Sandia National Laboratories in Albuquerque, N.M. Located on Kirtland Air Force base, Sandia's National Solar Thermal Test Facility is a nine-acre test site with a 200-foot-tall solar tower, 212 computer-controlled mirrors called heliostats and a separate five-story control tower. The heliostats harness the power of the sun and direct it to a test sample mounted on top of the solar tower. With the total mirror area exceeding 84,000 square feet, the facility can subject specimens to up to 260 watts of thermal energy per square centimeter -- about 2,600 times the intensity of the sun on Earth.

"Data from the tests are helping us determine the overall suitability of advanced thermal protection systems, adhesives and structure combinations for a future rigid aeroshell system," said James. Aeroshells are protective "shells" that surround the spacecraft. The aeroshell and thermal protection systems under study have similar characteristics to those developed for past missions to Venus, Mars and Jupiter, along with missions to return spacecraft from the moon to Earth.

During the last three years, NASA and its partnering organizations have conducted more than 100 similar tests on samples ranging from 5-inch-diameter heat shield components to panels up to 24 inches square.

The tests also advance the technology readiness level of ablator families funded by the In-Space Propulsion Technology Program. With lower densities, higher performance and better insulative properties than current state-of-the-art technologies, these ablators have the potential to round out NASA's current thermal protection system portfolio for aerocapture and planetary entry.

Aerocapture technology development is funded by NASA's In-Space Propulsion Technology Program.

Source: NASA Marshall Space Flight Center - News

[Waspie_Dwarf]

NASA Meets Key Objective in Developing New Propulsion Method

(Images to accompany the news story)

An artist concept illustrates how aerocapture might be used to enter the orbit of Mars. Aerocapture technology is a flight maneuver that inserts a spacecraft into orbit around a planet or moon by using the destination's atmosphere like a "brake." The dense atmosphere creates friction, which is used to slow down a craft, transferring the energy associated with the vehicle's high speed into heat. This allows for a quick orbital capture without the need for a heavy load of on-board propellant, which increases launch cost.

Aerocapture is part of a unique family of "aeroassist" technologies being developed by NASA for science missions to any planetary body with an appreciable atmosphere. Along with Mars, these destinations could include Venus and Saturn's moon Titan, along with the outer planets. (NASA)

A panel of an innovative thermal protection system reacts as sunlight, focused by large mirror arrays, heats up the target during testing at the National Solar Thermal Test Facility at Sandia National Labs in Albuquerque, N.M. The tests were conducted by the In-Space Propulsion Technology Project at NASA’s Marshall Space Flight Center in Huntsville, Ala. The test series is part of efforts to develop advanced thermal protection systems for future spacecraft. (NASA/MSFC/S. Moon)

Located on Kirtland Air Force Base at Albuquerque, N.M., the National Solar Thermal Test Facility is a nine-acre test site at Sandia National Laboratories. The facility consists of a 200-foot-tall solar tower, 212 computer-controlled mirrors called heliostats, and a separate five-story control tower. These heliostats harness the power of the sun and direct it to a test sample mounted near the peak of the 200-foot-tall solar tower. (NASA/MSFC/S. Moon)

Located on Kirtland Air Force Base at Albuquerque, N.M., the National Solar Thermal Test Facility is a nine-acre test site at Sandia National Laboratories. The facility consists of a 200-foot-tall solar tower, 212 computer-controlled mirrors called heliostats, and a separate five-story control tower. These heliostats harness the power of the sun and direct it to a test sample mounted near the peak of the 200-foot-tall solar tower. (NASA/MSFC/S. Moon)

Source: NASA Marshall Space Flight Center - News