NASA NIAC new phase 2 Kilometer Space Telescope (KST) project is a follow up to the 2006-2007 Space bubble phase 1 project. The goal of a kilometer space telescope would be to provide over three times the diameter and ten times the collecting area of the Arecibo ground based radio telescope with diffraction-limited performance at optical, infrared, and millimeter wavelengths.
• Webster Cash was joining to integrate the space bubble concept into both the New Worlds Imager and one additional mission concept to be called Maxim.
• Antoine Labeyrie has contributed suggestions for large space telescope applications that include the Hypertelescope.
• New Worlds Imager mission planning will be examined with the goal of incorporating low mass components to gain advantages that include:
o More star shades in one launch for increased search rate by looking in one direction while other shades are maneuvering.
o More Star shades for spares.
o More star shades to serve more telescopes to increase the search set.
o A lower mass, lower cost mission alternative.
o The technology can also make lower mass mirrors of any conical and some nonconical shapes.
• Web Cash has another mission called Maxim in the planning stages
This technology would enable payloads small enough to launch that can become self-contained orbital habitats, large buildings on planetary surfaces, or other large structures that require significant strength.
Features of the approach include:
1. Bubbles and foam with individual cell sizes up to 100 meters
2. Structural spans can exceed 10,000 kilometers in micro-g environments
3. Structural densities as low as 15 µg/cc
4. Foam densities tessellate volume in a structured way to maximize density in regions of stress
High Performance Solar Sails
With the fabrication of solar sails in space using rigidizable polymers, they project a sail loading of ~11 g/m2 for a sailcraft consisting of 100 kg spacecraft and 10 kg of sail hardware with an area of 10,000 square meters (100 meters by 100 meters).
An important parameter characterizing a solar sail propelled spacecraft is its acceleration, typically expressed in units of mm/s2. The relationship
between ideal acceleration and sail loading (in units of g/m2) is given by:
Acceleration (mm/s2) = 9.12 /sail loading (grams per square meter) where radiation pressure at approximately 1 AU (9.12 µN/m2) and a perfectly reflecting sail surface are assumed.
For the loading of ~11 g/m2 mentioned above with a space-fabricated, 0,000 square meters (100 meters by 100 meters) solar sail, the
acceleration will be ~0.83 mm/s2 for a sailcraft mass of 110 kg. With addition of three more sails, each with an area of 10000 square meters, the spacecraft mass would be 140 kg, the sail loading will be reduced to 3.5 g/m2, and the ideal acceleration increased to ~2.6 mm/s2. Assuming a realistic sail reflectance of 85%, the acceleration would be ~2.4 mm/s2. This is about 4 times the acceleration for the earth-fabricated L’Garde sailcraft (0.58 mm/s2 ), whose mass (140.7 kg) is very close to our sailcraft mass (140 kg). The calculations illustrate the performance advantages of the proposed ultra-lightweight solar sails fabricated in space.
Increasing the area or number of sails would the sail loading near the 1 gram per square meter and get acceleration up to about 8 millimeters per second per second. This acceleration would be increasing at 19 kilometers per second each month or about 630 meters per second per day.