Aerocube decay study

0802-EX-ST-2006 Text Documents

Aerospace Corporation, THE

2006-10-25ELS_78516

AeroCube 1 Drag Augmentation Study for the AeroCube-2 Mission Alan B. Jenkin Brenda E. Eichel August 31, 2006 THE AEROSPACE A.B. Jenkin, B.E. Eichel CORPORATION Astrodynamics Department

Background 2 • The AeroCube-2 CubeSat will be launched with a variety of other satellites and CubeSats along with the primary payload, the EgyptSat satellite, on a Dnepr launch vehicle • The Federal Communications Commission (FCC) requires that post- mission orbital lifetime for low Earth orbit satellites be less than 25 years • AeroCube-2 by itself will not satisfy this requirement due to high altitude of the mission orbit • Study objective – Determine size of drag augmentation device needed to achieve various target orbital lifetimes THE AEROSPACE A.B. Jenkin, B.E. Eichel CORPORATION Astrodynamics Department

Study Analysts 3 • Alan Jenkin (Astrodynamics Department) – Generation of cases for sizing of drag augmentation device – Analysis of atmospheric pressure on drag augmentation device and resulting unrigidized Mylar balloon motion • Brenda Eichel (Astrodynamics Department) – Orbital decay propagations and lifetime analysis THE AEROSPACE A.B. Jenkin, B.E. Eichel CORPORATION Astrodynamics Department

Methodology 4 • Used long-term orbit decay modeling code LIFETIME – Developed by Aerospace (C.C. Chao) – MSISE-90 atmosphere model – Gravity model J2 through J3 • Considered 5, 50, and 95 percentile level of solar flux (F10.7) and geomagnetic index (Ap) – NOAA predictions for jettison epoch THE AEROSPACE A.B. Jenkin, B.E. Eichel CORPORATION Astrodynamics Department

Study Assumptions and Ground Rules 5 • Launch on December 1, 2006 • Injection orbit: – Apogee altitude: 803 km – Perigee altitude: 658.5 km – Inclination: 97.43 deg (taken from AeroCube-1 mission) – RAAN: 88.07 deg (taken from AeroCube-1 mission) • Aerocube-2 mass: 0.825 kg (taken from AeroCube-1) • Assumed AeroCube-2 tumbles randomly during decay – CubeSat with 10-cm side will have an average projected area of 150 cm2 • Assumed drag augmentation device is approximately spherical – Inflatable Mylar balloon inside Aluminum foil – Aluminum foil retains shape after balloon loses pressure THE AEROSPACE A.B. Jenkin, B.E. Eichel CORPORATION Astrodynamics Department

AeroCube-2 Orbital Lifetime Without Drag Augmentation 6 • 50-percentile (median) solar activity : 30.4 years • 95-percentile (extreme high) solar activity : 14.9 years • 5-percentile (extreme low) solar activity: 107 years • Based on 50-percentile result, FCC requirement is not met THE AEROSPACE A.B. Jenkin, B.E. Eichel CORPORATION Astrodynamics Department

Balloon Diameter for Specific Orbital Lifetimes 7 • 50-percentile solar cycle case Projected cross- Orbital lifetime Balloon diameter sectional area 2 Years cm cm in 25 208.5 16.3 6.4 20 295.5 19.4 7.6 10 754.1 31.0 12.2 5 1307.0 40.8 16.1 THE AEROSPACE A.B. Jenkin, B.E. Eichel CORPORATION Astrodynamics Department

Altitude Decay of AeroCube-2 With Drag Augmentation (50- percentile case) 8 • Plot shows decay profile for 10, 20, and 30-inch diameter balloons (50-percentile solar cycle case) 900 800 Apogee/perigee altitude (km) 700 600 500 400 20-inch balloon No drag 300 10-inch balloon augmentation diameter diameter 200 30-inch balloon 100 diameter 0 0 5 10 15 20 25 30 35 Time (years) THE AEROSPACE A.B. Jenkin, B.E. Eichel CORPORATION Astrodynamics Department

Conclusions 9 • A drag augmentation device with a spherical diameter of 10 inches or higher will adequately reduce orbital lifetime to meet the FCC requirement as long as the balloon remains effective (does not collapse or separate) for a sufficiently long time • A 30-inch diameter is recommended for a drag augmentation device that is expected to survive two years or longer THE AEROSPACE A.B. Jenkin, B.E. Eichel CORPORATION Astrodynamics Department


Document Created: 2006-10-25 11:15:02
Document Modified: 2006-10-25 11:15:02
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