Optical Payloads for Space Missions

Shen-En Qian

• Publisher: Wiley
• Year: 2015
• Print ISBN: 9781118945148
• eBook ISBN: 9781118945278
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Mechanical Engineering
• Index: Technology & Engineering

Optical Payloads for Space Missions is a comprehensive collection of optical spacecraft payloads with contributions by leading international rocket-scientists and instrument builders.

• Covers various applications, including earth observation, communications, navigation, weather, and science satellites and deep space exploration
• Each chapter covers one or more specific optical payload
• Contains a review chapter which provides readers with an overview on the background, current status, trends, and future prospects of the optical payloads
• Provides information on the principles of the optical spacecraft payloads, missions' background, motivation and challenges, as well as the scientific returns, benefits and applications

Part One
Overview

1
Review of Spaceborne Optical Payloads

Shen-En Qian

1.1 Introduction

The objectives of a space mission are accomplished by the hardware (i.e., instruments) and software, which are referred to as payloads, onboard the platform of a spacecraft. Payloads sense or interact with the subject, are typically unique to each mission, and are the fundamental reason that the spacecraft is flown. The purpose of the rest of the subsystems is to keep the payloads healthy, happy, and pointed in the right direction. The payloads largely determine the mission’s cost, complexity, and effectiveness. A critical part of a mission analysis and design is to understand what drives a particular set of payloads so that these demands can become part of the overall system trade process designed to meet mission objectives at minimum cost and risk.

Payloads of space missions can be roughly classified into two categories in terms of the wavelength of their operating: optical and microwave. Optical payloads, or sensors, measure reflective light in wavelength range from ultraviolet, visible, to infrared (including near infrared, intermediate infrared, thermal infrared), while microwave sensors measure microwaves whose wavelength is longer than visible light and infrared (IR) rays. Microwaves are radio waves with wavelengths ranging from as long as 1 m to as short as 1 mm, or equivalently, with frequencies between 300 MHz (0.3 GHz) and 300 GHz. The observation of microwave sensors is not affected by day, night, or weather. Radar sensors and synthetic aperture radar (SAR) sensors are the typical microwave sensors.

There are two types of observation methods for both optical and microwave payloads: passive and active. Passive payloads detect and measure natural radiation that is emitted or reflected by the objects or surrounding area being observed. Reflected sunlight is the most common source of radiation measured by passive sensors. Active sensors, on the other hand, emit energy in order to scan the area of objects and then detect and measure the radiation that is reflected or backscattered from the objects. Radar and lidar sensors are active sensors, where the time delay between emission and return is measured, establishing the location, height, speed, and direction of an object.

The focus of this book is optical payloads for space missions. Radar payloads are beyond the scope of this book.

Optical payloads can be roughly classified into following six types based on their functions:

1. Panchromatic sensors
2. Multispectral sensors
3. Imaging spectroscopy sensors
4. Fourier transform spectroscopy sensors
5. Light detection and ranging (lidar) sensors
6. Spectrometers and radiometers

This book consists of eight parts (Part One – Part Eight) and covers all these six types of optical payloads. Part One (Chapter 1) is the overview of spaceborne optical sensors. Parts Two through Six each describe one type of optical sensors except for the panchromatic sensors, which are included in Part Two or Part Three together with their hyperspectral or multispectral sensors onboard the same platform. Part Seven describes spaceborne optical sensors other than these six types. Part Eight describes optical sensors onboard microsatellites and nanosatellites.

1.1.1 Panchromatic Sensors

Panchromatic refers to black and white imagery exposed by all visible light. However, a spaceborne panchromatic sensor often acquires visible light within a wavelength range typically between 0.50 and 0.80 μm using a minus blue filter to reduce the scattering that occurs in the blue wavelengths. A panchromatic sensor produces images with a much finer ground footprint size (or spatial resolution) than those produced by the multispectral sensor or hyperspectral sensor onboard the same satellite. For example, the QuickBird satellite produces panchromatic imagery having a ground footprint size of 0.6 m × 0.6 m, while the multispectral pixels represent an area of 2.4 m × 2.4 m.

1.1.2 Multispectral Sensors

Unlike a panchromatic sensor that records the total intensity of radiation falling on each pixel and generates only a panchromatic image, a multispectral sensor acquires multiple images of the scene simultaneously at specific spectral bands, or wavelength ranges. Multispectral images acquired by multispectral sensors are the main type of remote sensing images. Usually, a multispectral sensor has three or more spectral imagers (Landsat 7 has seven). Each one is a scene image in a band of visible spectra, ranging from 0.4 μm to 0.7 μm, called red (635–700 nm), green (490–560 nm), and blue (450–490 nm) (RGB) region, and going to IR wavelengths of 0.8 μm to 10 μm or longer, classified as near infrared (NIR), middle infrared (MIR), and far infrared (FIR or thermal). In the case of Landsat 7, the acquired images comprise seven-band multispectral images. A list of spaceborne multispectral sensors together with their satellite platforms and detailed technical information can be found in Table 1.1 of Reference 1.

Table 1.1 Summary of Optical payloads collected in the book

No.	Ch.	Payload Type	Payload name	Acronym name	Platform or Mission	Launch year	Active? (in Dec. 2014)	Country
1	2	Imaging Spectroscopy Sensor	Hyperspectral Imager for the Coastal Ocean	HICO	International Space Station	2009	until Sept. 2014	DoD, USA
2	3		Moderate Resolution Imaging Spectroradiometer	MODIS	Terra, Aqua	1999, 2002	Yes	NASA, USA
3	4		Medium Resolution Imaging Spectrometer for Ocean Color	MERIS	ENVISAT	2002	Until 2012	ESA
4	5		Visible and Near-infrared Imaging Spectrometer	VNIS	Chang’E 3	2013	Yes	China
5	6		Hyperspectral Imager HySI	HySI	IMS-1	2008	Yes	India
6	7		Environmental Mapping and Analysis Program	EnMap	EnMap	2018	–	Germany
7	8		PRecursore IperSpettrale della Missione Applicativa	PRISMA	PRISMA	2017	–	Italy
8	9		Hyperspectral Imager Suite	HISUI	HISUI	2018	–	Japan
9	10		Ocean and Land Color Imager	OLCI	Sentinel–3	2015	–	ESA
10	11		Spaceborne Hyperspectral Applicative Land and Ocean Mission	SHALOM	SHALOM	2020	–	Israel
11	12		Hyperspectral and Luminescence Observer	HALO	Mars Rover	–	–	Canada
12	13	Multispectral Sensor	Infrared Scanner	IRS	HJ-1-B	2008	Yes	China
13	14		MUX Multispectral Camera	MUXCAM	CBERS 4	2014	Yes	Brazil
14	15		Multispectral camera MX	MX	IMS-1	2008	Yes	India
15	16		WFI Wide Field Imager	WFICAM	CBERS 4	2014	Yes	Brazil
16	17		Remote Sensing Instrument	RSI	FORMOSAT-2	2004	Yes	ROC (Taiwan)
17	18	Fourier Transform Spectrometer	WIND Imaging Interferometer	WINDII	NASA UARS	1991	Until 2003	Canada
18	19		Atmospheric Chemistry Experiment - Fourier Transform Spectrometer	ACE-FTS	SCISAT	2003	Yes	Canada
19	20		Cross-track Infrared Sounder	CrIS	Suomi NPP/JPSS	2011	Yes	NOAA, USA
20	21		Thermal And Near infrared Sensor for carbon Observation Fourier Transform Spectrometer	TANSO-FTS	GOSAT	2009	Yes	Japan
21	22		Geostatio...

Table of contents

• Cover
• Title Page
• Table of Contents
• Contributors List
• Preface
• Part One: Overview
• Part Two: Imaging Spectrometers
• Part Three: Multispectral Sensors
• Part Four: Fourier Transform Spectrometers
• Part Five: Lidar and Active Sensors
• Part Six: Spectrometers and Radiometers
• Part Seven: Other Types of Optical Sensors
• Part Eight: Nanosatellites and Microsatellites
• Index
• End User License Agreement