L‘Garde Programs - INFLATABLE ANTENNA EXPERIMENT
ISP Solar Sail
Solar sails reflect photons streaming from the sun and convert some of the energy into thrust. This thrust, though small, is continuous
and acts for the life of the mission without the need for propellant. Recent advances in sail materials and ultra-low mass structures have
enabled a host of useful missions utilizing solar sail propulsion. The team of L'Garde, Jet Propulsion Laboratories, Ball Aerospace,
and Langley Research Center, under the direction of NASA, has been developing a solar sail configuration to address NASA's
future space propulsion needs.
As future phases of this program will require test articles of a specific configuration, a baseline mission was selected around which to optimize
the design. The Solar Sentinel or Geostorm mission was selected as a likely candidate for future missions. This scenario takes advantage of the
constant thrust available from the solar sail to place a payload in a solar orbit inside of a Lagrange Point (L1) point, yet remain in the same
period as the Earth's. This position provides an excellent vantage point for solar observation and warning of adverse solar activity.
Satellites can station keep at the L1 Lagrange point without the need for additional propulsion, see figure 2. This point is about 230
Earth radii (Re) from the Earth toward the sun along the Earth-sun line. Using the constant thrust from the sail it is possible to descend to
a closer orbit to the sun yet remain in the same period as the Earth, and remain on the Earth-sun line. An orbital analysis shows that the baseline
sail design can descend an additional 520 Re closer to the sun. This location can provide information of solar activity with a lead-time 3 times
greater than current solar observing missions.
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The booms are designed in an iso-grid configuration. Longitudinal uni-directional fibers are oriented to absorb the compressive
loads in the booms, while the lateral fibers absorb the inflation loads and stabilize the longitudinal fibers and the cross section. |
| The booms are not sized to withstand the bending generated by the solar flux alone. A tensioned truss or spreader system is used
to increase the moment of inertia of the boom to absorb the bending. The spreader system consists of lightweight rigid spreader bars
mounted to rigid rings integrated into the boom |
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The Space Segment consists of all items released from the upper stage. This includes the sailcraft and the carrier shown toward the
bottom. After deployment of the sail, the carrier is jettisoned to free the sailcraft from all non-flight required components and mass.
The payload envelope is visible toward the center of the sailcraft portion, and all of the spacecraft specific elements are shown toward
the top of the configuration. The stowed solar arrays and communication antennas are visible toward the top. |
| The space segment fits well inside of the Delta payload fairing. With a sufficient payload interface fixture,
it may be possible to fit two space segments on a single launch. |
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You can view a deployemnt animation of the solar sail. And you don't have to wait for anything to download. This link requires at least a
low speed broadband connection and RealPlayer. If you don't have a broadband connection, you can download the video and then play it.
There are some other system requirements to play this video. If this link does not work for you, download the free RealPlayer by clicking
in this button:
This 134 second movie shows the deployment of the solar sail at five-times normal speed.
Play deployment right now for dual-ISDN connection.
Download deployment to disk for later. (1.8 M)
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See how another L'Garde solar sail will help
power the Team Encounter spacecraft. |
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