Earth from Space, 3rd Int. Conf., Dec. 4-7, 2007, Moscow, Russia > Dr. R. Sandau > 1 Small Satellites for Earth Observation Prospects & Limitations Rainer Sandau

Earth from Space, 3rd Int. Conf., Dec. 4-7, 2007, Moscow, Russia > Dr. R. Sandau > 2 OUTLINE 1. Why small satellites? 2. Small sat missions: Facts & Trends 3. Application requirements 4. Restrictions 5. Future of small satellite missions 6. Conclusions

Earth from Space, 3rd Int. Conf., Dec. 4-7, 2007, Moscow, Russia > Dr. R. Sandau > 3 1 M$10 M$100 M$ cost 1 yr2 yrs5 yrs response time examples CubeSat: 1 kg, ca. 2 yrs, 0.2 M$ ENVISAT: 8 t, 15+ yrs, 3 × 10 9 $ mass 1 kg10 kg100 kg kg PicoNanoMicroMini Small SatellitesLarge Satellites 1000 kg

Earth from Space, 3rd Int. Conf., Dec. 4-7, 2007, Moscow, Russia > Dr. R. Sandau > 4 Why Small Satellites Classification parameters Mass/Volume Costs Preparation time have large influence on Launch costs number of opportunities adoption of new applications temporal resolution (through constellations) reliability/continuity (replacement)

Earth from Space, 3rd Int. Conf., Dec. 4-7, 2007, Moscow, Russia > Dr. R. Sandau > 5 The advantages of small satellite missions are: more frequent mission opportunities and therefore faster return of science and for application data larger variety of missions and therefore also greater diversification of potential users more rapid expansion of the technical and/or scientific knowledge base greater involvement of local and small industry.

Earth from Space, 3rd Int. Conf., Dec. 4-7, 2007, Moscow, Russia > Dr. R. Sandau > 6 Small satellite missions are supported by several contemporary trends: Advances in electronic miniaturization and associated performance capability; The recent appearance on the market of new small launchers (e.g. through the use of modified military missiles to launch small satellites); The possibility of ‘independence’ in space (small satellites can provide an affordable way for many countries to achieve Earth Observation and/or defense capability, without relying on inputs from the major space-faring nations);

Earth from Space, 3rd Int. Conf., Dec. 4-7, 2007, Moscow, Russia > Dr. R. Sandau > 7 Earth Observation Request (1)

Earth from Space, 3rd Int. Conf., Dec. 4-7, 2007, Moscow, Russia > Dr. R. Sandau > 8 Earth Observation Request (2)

Earth from Space, 3rd Int. Conf., Dec. 4-7, 2007, Moscow, Russia > Dr. R. Sandau > 9 Increasing Example: Eros-B/ PIC-2 Launch Mass 350 kg GSD 0.82 m Increasing Example: Proba/ CHRIS Lauch Mass 149 kg Hyperspectral Imager Unique opportunity for affordable Constellation Example: DMC-1 Daily global coverage GSD 32 m Swath 600 km

Earth from Space, 3rd Int. Conf., Dec. 4-7, 2007, Moscow, Russia > Dr. R. Sandau > 10 Instrument & platform requirements Optical P/L High res imaging GSD opticsdownlink Stat.Dynam. constructionData rate & volume MTF radiometry MTF pointing Mass volume Antenna size power

Earth from Space, 3rd Int. Conf., Dec. 4-7, 2007, Moscow, Russia > Dr. R. Sandau > 11 Radiometric aspects Example orbit: H=600km, v ground  7km/s GSD = 10 m  t dwell  1.4 ms GSD = 1 m  t dwell  0.14 ms t dwell(1m) /t dwell(10m) =1/10 IFOV(1m)/IFOV(10m) = 1/100 For good signal and SNR - TDI with N stages  N signal, SNR (IKONOS, EROS-B) - Slow-down mode (EROS-A1)

Earth from Space, 3rd Int. Conf., Dec. 4-7, 2007, Moscow, Russia > Dr. R. Sandau > 12 Spatial Resolution MTF SR = MTF Optics MTF D MTF LM MTF J t int < 0.2 t dwell  J < 0.1 x MTF SR = MTF static/instrument MTF dynamic/platform

Earth from Space, 3rd Int. Conf., Dec. 4-7, 2007, Moscow, Russia > Dr. R. Sandau > 13 Spatial Resolution MTF: LM = 0.1, 1, 1.5 ∙ GSD MTF Detector, Jitter  = 0.1, 1 ∙ x MTF Detector, Sinus vibration a = 0.1, 1 ∙ x Total MTF with LM = 0.2 x,  = 0.1 x, a = 0.1 x, Detector-size x

Earth from Space, 3rd Int. Conf., Dec. 4-7, 2007, Moscow, Russia > Dr. R. Sandau > 14 Pointing stability From 600 km orbit, GSD = 1 m  IFOV  1.7  rad  0.3 arcsec Drift < 0.2 IFOV  2.4 mrad/s  8 arcmin/s For TDI with N = 96  25  rad/s !

Earth from Space, 3rd Int. Conf., Dec. 4-7, 2007, Moscow, Russia > Dr. R. Sandau > 15 Future of Small Sats for Remote Sensing New capabilities the convergence of data acquisition and data visualization technologies the ready availability of new small launchers and the rise of “space tourism” the development of smaller, lighter, lower power satellites that can act as a constellation or independently

Earth from Space, 3rd Int. Conf., Dec. 4-7, 2007, Moscow, Russia > Dr. R. Sandau > 16 Convergence of data acquisition and data visualization technologies Example: NASA’s “A Train” (Aqua, CloudSat, CALIPSO, PARASOL, Aura, and OCO) + NDVI small sat for crop yield forecasting in a particular region, Aerosol and cloud correction using data from the A Train.

Earth from Space, 3rd Int. Conf., Dec. 4-7, 2007, Moscow, Russia > Dr. R. Sandau > 17 Small launchers & „Space Tourism“ Getting into space is still a challenge and costly During the last 10 years more small launchers at prices reasonable compared to the cost of a small sat ( e.g.NASA/DLR GRACE constellation with EUROCKOT, SS-19 ICBM ) New impetus of „space tourism“ ( Oct.4th, 2004, Burt Rutan & Paul Allan win the AnsarX PRIZE) Looking back: At the turn of the last century, air travel was relatively risky and quite expensive. Now we fly e.g. apples half way around the world at prices that are competitive with local transport & production.

Earth from Space, 3rd Int. Conf., Dec. 4-7, 2007, Moscow, Russia > Dr. R. Sandau > 18 Conclusions Developing Small Satellites for Remote Sensing is within the means of many nations They provide enormous opportunities : To do more with less Address local and global needs Provides an affordable means to improve the temporal resolution Focus the development of the technical infrastructure of a country Reduce risk in the use of space

Earth from Space, 3rd Int. Conf., Dec. 4-7, 2007, Moscow, Russia > Dr. R. Sandau > 19 BIRD Payload Segment Mass of s/c: 94 kg Mass of p/l: 30.2 kg

Earth from Space, 3rd Int. Conf., Dec. 4-7, 2007, Moscow, Russia > Dr. R. Sandau > 20 Fire detection by MODIS and BIRD (Australia, January 5, 2002) MODIS: Fire mapBIRD: Fire map

Earth from Space, 3rd Int. Conf., Dec. 4-7, 2007, Moscow, Russia > Dr. R. Sandau > 21 F = 1.2 x = 10  m Nyquist frequency optics spatial frequency (cy/mm)