Lectures on Space Exploration

 

I planned my lectures pretty well keeping the need of M.A. and Ph.D students in mind. I was going to teach such a senior class and nothing should be missed. I prepared a document which dealt with the Art of Science, about missions in Space Science by NASA, about comets which are studied through the eyes of an Archaeologist and I took a case study of a very famous and experimental mission of NASA –The Deep Impact Mission which was destined to collide with a comet Tempel-1 in May June 2005. I also discussed with the curious lot of students about the Tsunami which had made a disastrous impact in coastal India.

For a full one year I delivered these lectures with Professor Pandey’s students, with students of the Engineering college of the University and with several other departments on the recommendation of professor Professor Pandey. Here are excerpts from what I discussed with the senior students of the University and how I designed it this by exploring NASA webpages and library.

 

Art of Science-

 

Thousands of years ago, on a small rocky planet orbiting a modest star in an ordinary spiral galaxy, our remote ancestors looked up and wondered about their place between Earth and sky. Today, we ask the same profound questions:

 

  • How did the universe begin and evolve?
  • How did we get here?
  • Where are we going?
  • Are we alone?

 

Today, after only the blink of an eye in cosmic time, we are beginning to answer these questions. Space probes and space observatories have played a central role in this process of discovery.

Our missions and research generate most of the coolest news coming out of NASA. We are responsible for all of NASA’s programs relating to astronomy, the solar system, and the sun and its interaction with Earth. Our science stretches from the middle levels of Earth’s atmosphere to the beginning of the universe, billions of light years away.

Our website serves our science community, educators, government decision-makers, and the public. We hope your visit is enjoyable. Thanks for stopping by!

 

Future Space Programs-

NASA’s Science Goals

The 2010 Science Mission Directorate Science Plan states that NASA’s goal in Planetary Science is to “ascertain the content, origin, and evolution of the solar system, and the potential for life elsewhere.”

NASA missions pursue this goal by seeking answers to fundamental science questions:

 

What is the inventory of solar system objects and what processes are active in and among them?

How did the Sun’s family of planets, satellites, and minor bodies originate and evolve?

What are the characteristics of the solar system that lead to habitable environments?

How and where could life begin and evolve in the solar system?

What are characteristics of small bodies and planetary environments that pose hazards and/or provide resources?

 

Discovery Program

 

NASA’s Discovery Program gives scientists the opportunity to dig deep into their imaginations and find innovative ways to unlock the mysteries of the solar system. It represents a breakthrough in the way NASA explores space, with lower-cost, highly focused planetary science investigations designed to enhance our understanding of the solar system.

 

Discovery Program Overview

 

NASA’s Discovery Program gives scientists the opportunity to dig deep into their imaginations and find innovative ways to unlock the mysteries of the solar system. When it began in 1992, this program represented a breakthrough in the way NASA explores space. For the first time, scientists and engineers were called on to assemble teams and design exciting, focused planetary science investigations that would deepen the knowledge about our solar system.

As a complement to NASA’s larger “flagship” planetary science explorations, the Discovery Program goal is to achieve outstanding results by launching many smaller missions using fewer resources and shorter development times. The main objective is to enhance our understanding of the solar system by exploring the planets, their moons, and small bodies such as comets and asteroids. The program also seeks to improve performance through the use of new technology and broaden university and industry participation in NASA missions

Discovery was among the first NASA programs to require a plan for education and public outreach, as NASA recognized the importance of communicating the excitement and meaning of space exploration to students and the public. Innovative methods that support national education initiatives are being developed to reach students of all ages.

All completed Discovery missions have achieved ground-breaking science, each taking a unique approach to space exploration, doing what’s never been done before, and driving new technology innovations that may also improve life on Earth.

 

Earth Science Enterprise

 

Studying Earth from space provides a unique global perspective on our home planet’s dynamic system of continents, oceans, atmosphere, ice and life. NASA’s Earth Science missions seek to understand how Earth is changing and the consequences to life on Earth.

 

 

EARTH

New Report: Responding to the Challenge of Climate and Environmental Change

NASA’s Plan for a Climate-Centric Architecture for Earth Observations and Applications from Space Earth is a complex, dynamic system we do not yet fully understand. The Earth system, like the human body, comprises diverse components that interact in complex ways. We need to understand the Earth’s atmosphere, lithosphere, hydrosphere, cryosphere, and biosphere as a single connected system. Our planet is changing on all spatial and temporal scales. The purpose of NASA’s Earth science program is to develop a scientific understanding of Earth’s system and its response to natural or human-induced changes, and to improve prediction of climate, weather, and natural hazards.

 

NASA recently completed deployment of the Earth Observing System, the world’s most advanced and comprehensive capability to measure global climate change. Over the coming decade, NASA and the Agency’s research partners will be analyzing EOS data to characterize, understand, and predict variability and trends in Earth’s system for both research and applications. Earth is the only planet we know to be capable of sustaining life. It is our lifeboat in the vast expanse of space. Over the past 50 years, world population has doubled, grain yields have tripled and economic output has grown sevenfold. Earth science research can ascertain whether and how the Earth can sustain this growth in the future. Also, over a third of the US economy – $3 trillion annually – is influenced by climate, weather, space weather, and natural hazards, providing economic incentive to study the Earth.

NASA Earth System Science conducts and sponsors research, collects new observations from space, develops technologies and extends science and technology education to learners of all ages. We work closely with our global partners in government, industry, and the public to enhance economic security, and environmental stewardship, benefiting society in many tangible ways. We conduct and sponsor research to answer fundamental science questions about the changes we see in climate, weather, and natural hazards, and deliver sound science that helps decision-makers make informed decisions. We inspire the next generation of explorers by providing opportunities for learners of all ages to investigate the Earth system using unique NASA resources, and our Earth System research is strengthening science, technology, engineering and mathematics education nationwide. This is a fundamental part of our mission because the leaders and citizens who will meet challenges of tomorrow are the students of today.

 

MISSIONS

 

In order to study the Earth as a whole system and understand how it is changing, NASA develops and supports a large number of Earth observing missions. These missions provide Earth science researchers the necessary data to address key questions about global climate change.

Missions begin with a study phase during which the key science objectives of the mission are identified, and designs for spacecraft and instruments are analyzed. Following a successful study phase, missions enter a development phase whereby all aspects of the mission are developed and tested to ensure that they meet the mission objectives. Operating missions are those missions that are currently active and providing science data to researchers. Operating missions may be in their primary operational phase or in an extended operational phase.

 

Senior Reviews for Earth Operating Missions:

 

  • 2009 Senior Review

o             Science Panel Report

o             National Interest Sub-Panel Report

o             Technical & Cost Sub-Panel Report (TBS)

 

  • 2007 Senior Review

 

o             2007 NASA Earth Science CoMRP Report

o             2007 NASA Earth Science Senior Review – Education/Public Outreach

o             2007 NASA Earth Science Senior Review Report

 

 

Exploration Systems Enterprise

 

Why Do We Explore?

From the time of our birth, humans have felt a primordial urge to explore — to blaze new trails, map new lands, and answer profound questions about ourselves and our universe.

The mission of NASA’s Exploration Systems Enterprise is to conduct safe, sustained and affordable human and robotic exploration of Earth’s Moon, Mars and beyond.

This new era in human exploration will leverage American ingenuity and propel the nation on a new journey of innovation and discovery. Groundbreaking new technologies will enable exploration of new worlds and increase our understanding of the Earth, our solar system and the universe beyond. Further collaborations on the International Space Station will increase NASA’s return on investment and provide an optimal test bed for space technology research and development. In order to place NASA’s focus on this forward-looking space enterprise, the President’s Budget Request proposes cancelling the Constellation Program.

NASA doesn’t intend to embark on this new journey alone. Commercial and international partnerships will benefit from a collective spirit of discovery and adventure, and will reduce the cost of space exploration by employing new business practices and leveraging common goals. NASA also invites citizen stakeholders to participate and share in the excitement of space exploration through upcoming initiatives designed to educate as well as glean new, creative ideas from standard and unconventional contributors.

We invite you to read below about the study teams that have been formed to develop strategies for the proposed new programs. Plans will continue to evolve with the next step of House and Senate appropriations.

NASA is pleased to release this summary of the agency’s recent work on future human space exploration capabilities and missions, largely performed by our Human Exploration Framework Team (HEFT).

The agency established the HEFT last year to analyze exploration and technology concepts and provide inputs to the agency’s senior leadership on the key components of a safe, sustainable, affordable and credible future human space exploration endeavor for the nation. The team’s work helps provide a context for the next stage of NASA’s diverse portfolio of activities and a basis for ongoing architecture analysis and program planning. HEFT’s analysis focused on affordability, cost, performance, schedule, technology, and partnership considerations, while also identifying capabilities and destinations for future exploration as we move out, step by step, into the solar system.

HEFT has found that the most robust path for NASA in human space flight is a capability-driven approach where evolving capabilities would enable increasingly complex human exploration missions over time. A capability-driven framework also provides increased flexibility, greater cost effectiveness, and sustainability. Our strategy will open up many potential destinations for human spaceflight throughout the solar system, including the moon, near Earth asteroids, and Mars.

 

In NASA’s framework, the four initial priorities are:

 

1) A human-rated Space Launch System, or heavy lift rocket;

 

2) A Multi-Purpose Crew Vehicle;

 

3) Commercial crew and cargo services to low Earth orbit, including the International Space Station; and

 

4) Mission-focused technologies to support expanded exploration capabilities in the future.

This summary provides information to facilitate discussions as the agency moves into the implementation phase of its new direction established in the NASA Authorization Act of 2010. Our intention is to provide effective assessment of the available information to support a roadmap that is affordable, sustainable and realistic. In line with future budget allocations and policy, we will continue to refine our strategic approach to short, mid and long term plans that will be leveraged by increasing capabilities and deepening partnerships with other nations. As we continue our analysis, NASA looks forward to working closely with the Congress and the public to build a space program that is forward thinking and also serves critical needs of the American people today.

 

Explorers Program

 

More than 70 spacecraft have been part of NASA’s Explorer Program, including America’s first artificial satellite – Explorer 1. The program’s goal is to provide frequent space flight opportunities with a series of low to moderate cost missions developed in a relatively short time frame.

 

Mars Exploration Program

 

NASA’s Mars Exploration Program sends robotic explorers to study the Red Planet roughly every two years. Current NASA Mars missions: Mars Global Surveyor, Mars 2001 Odyssey and the Mars Exploration Rovers (right), Spirit and Opportunity.

 

 

The Mars Exploration Program

 

Since our first close-up picture of Mars in 1965, spacecraft voyages to the Red Planet have revealed a world strangely familiar, yet different enough to challenge our perceptions of what makes a planet work. Every time we feel close to understanding Mars, new discoveries send us straight back to the drawing board to revise existing theories.

You’d think Mars would be easier to understand. Like Earth, Mars has polar ice caps and clouds in its atmosphere, seasonal weather patterns, volcanoes, canyons and other recognizable features. However, conditions on Mars vary wildly from what we know on our own planet.

Over the past three decades, spacecraft have shown us that Mars is rocky, cold, and sterile beneath its hazy, pink sky. We’ve discovered that today’s Martian wasteland hints at a formerly volatile world where volcanoes once raged, meteors plowed deep craters, and flash floods rushed over the land. And Mars continues to throw out new enticements with each landing or orbital pass made by our spacecraft.

 

The Defining Question for Mars Exploration: Life on Mars?

 

Among our discoveries about Mars, one stands out above all others: the possible presence of liquid water on Mars, either in its ancient past or preserved in the subsurface today. Water is key because almost everywhere we find water on Earth, we find life. If Mars once had liquid water, or still does today, it’s compelling to ask whether any microscopic life forms could have developed on its surface. Is there any evidence of life in the planet’s past? If so, could any of these tiny living creatures still exist today? Imagine how exciting it would be to answer, “Yes!!”

Even if Mars is devoid of past or present life, however, there’s still much excitement on the horizon. We ourselves might become the “life on Mars” should humans choose to travel there one day. Meanwhile, we still have a lot to learn about this amazing planet and its extreme environments.

 

Our Exploration Strategy: Follow the Water!

 

To discover the possibilities for life on Mars–past, present or our own in the future–the Mars Program has developed an exploration strategy known as “Follow the Water.”

Following the water begins with an understanding of the current environment on Mars. We want to explore observed features like dry riverbeds, ice in the polar caps and rock types that only form when water is present. We want to look for hot springs, hydrothermal vents or subsurface water reserves. We want to understand if ancient Mars once held a vast ocean in the northern hemisphere as some scientists believe and how Mars may have transitioned from a more watery environment to the dry and dusty climate it has today. Searching for these answers means delving into the planet’s geologic and climate history to find out how, when and why Mars underwent dramatic changes to become the forbidding, yet promising, planet we observe today.

 

Future Missions

 

To pursue these goals, all of our future missions will be driven by rigorous scientific questions that will continuously evolve as we make new discoveries.

Brand new technologies will enable us to explore Mars in ways we never have before, resulting in higher-resolution images, precision landings, longer-ranging surface mobility and even the return of Martian soil and rock samples for studies in laboratories here on Earth.

 

Human Space Flight

 

NASA’s Human Space Flight team has systematically developed the capability to live and work in space. Thousands of people work to keep astronauts living, working and researching in space aboard the International Space Station and Space Shuttle.

 

New Frontiers

 

Missions in NASA’s New Frontiers Program will tackle specific solar system exploration goals identified in the Decadal Solar System Exploration Survey conducted by the Space Studies Board of the National Research Council. Proposed targets include Pluto and the Kuiper Belt, Jupiter, Venus, and sample returns from the surface of a comet and Earth’s Moon. The program is designed enable high-quality planetary missions that require resources beyond those available in the lower-cost Discovery Program. The flight rate is expected to be about one mission every three years. The first New Frontiers mission is New Horizons.

 

New Millennium Program

 

The New Millennium Program tests breakthrough technologies in space before they become standard equipment on next-generation spacecraft. New Millennium solar system missions: Deep Space 1 and Deep Space 2.

NASA space science missions have ventured to the moon, explored other planets, traveled to the edges of our solar system, and peered back in time. They have also done what is sometimes even more difficult——studied our own planet, Earth.

These missions have provided astounding views of the universe and new knowledge of our solar system, but there is still so much more to “see” and learn. And, as missions become progressively more daring, and thus more difficult, more advanced capabilities are needed. However, before new, untried technologies are used for the first time on complex exploration missions, engineers and scientists want to make sure they will operate well, and safely, in the hazardous environment of space.

To accomplish this, NASA’s Office of Space Science (OSS) and Office of Earth Science jointly established the New Millennium Program (NMP) in 1995——an ambitious, exciting vision to speed up space exploration through the development and testing of leading-edge technologies. A unique program, managed by the Jet Propulsion Laboratory/California Institute of Technology, NMP provides a critical bridge from initial concept to exploration-mission use. Through NMP, selected technologies are demonstrated in the “laboratory” of space that can’t be replicated on Earth.

Since its inception over a decade ago, NMP has validated many innovative technologies for both Earth science and space science missions. Now funded and managed solely out of NASA’s newly formed Science Mission Directorate (SMD), the Program continues to demonstrate advanced technologies that will enable space science missions of the 21st century with significant (a several-generation leap) technical capabilities.

Highly advanced technologies are key to more capable, powerful, and efficient spacecraft and science instruments. They are also key to gathering new and exciting scientific knowledge of our solar system and of our universe.

 

Origins Program

 

NASA’s Origins Program seeks to answer questions that have endured since humans looked into the night sky: “Where did we come from?” and “Are we alone?” Origins scientists are from a wide range of scientific disciplines from astronomy, physics, and chemistry, to geology and paleontology, as well as micro- and evolutionary biology.

 

Project Prometheus

 

Project Prometheus was established in 2003 to develop technology in the areas of radioisotope power system and nuclear power and propulsion for exploration of the solar system. The project will develop the first reactor powered spacecraft and demonstrate that it can be operated safely and reliably on long duration space missions. The proposed Jupiter Icy Moons Orbiter will be the first space science mission to use the new technology.

 

 

Sounding Rockets

 

Wallops manages NASA’s Sounding Rocket Program and is responsible for all aspects of a mission, from the launch vehicle, to payload design and development and data retrieval. Scientific data are collected and returned to Earth by telemetry links, which transfer the data from the sounding rocket payload to the researchers on the ground. In most cases, the payload parachutes back to Earth, where it is recovered and reused.

 

Scientific Balloons

 

Balloons have been used for decades to conduct scientific studies. While the basics of ballooning have not changed, balloon size has increased and their dependability has improved greatly. The Wallops Flight Facility manages the NASA Balloon Program, which offers capabilities and benefits for scientific research that cannot be duplicated by other methods.

 

Structure and Evolution of the Universe

 

The Structure and Evolution of the Universe program seeks to explore and understand the dynamic transformations of energy in the Universe—the entire web of biological and physical interactions that determine the evolution of our cosmic habitat. This search for understanding will enrich the human spirit and inspire a new generation of explorers, scientists, and engineers.

 

Overview

 

The Astrophysics Science Division conducts a broad program of research in astronomy, astrophysics, and fundamental physics. Individual investigations address issues such as the nature of dark matter and dark energy, which planets outside our solar system may harbor life, and the nature of space, time, and matter at the edges of black holes.

Observing photons, particles, and gravitational waves enables researchers to probe astrophysical objects and processes. Researchers develop theoretical models, design experiments and hardware to test theories, interpret and evaluate the data, archive and disseminate the data, provide expert user support to the scientific community, and publish conclusions drawn from research. The Division also conducts education and public outreach programs about its projects and missions.

 

Sun-Earth Connection

 

The SEC Division investigates the physics of the Sun, the heliosphere, the local interstellar medium, and all planetary environments within the heliosphere. Taken together, these studies encompass the scientific disciplines of solar physics, heliospheric physics, magnetospheric physics, and aeronomy. They address problems such as solar variability, the responses of the planets to such variability, and the interaction of the heliosphere with the galaxy.

 

Near Earth Objects (NEO)—

 

History of Comets–

 

Comets are the remainders of material formed in the coldest part of our solar system. Impacts from comets played a major role in the evolution of the Earth, primarily during its early history billions of years ago. Some believe that they brought water and a variety of organic molecules to Earth. Take a look at what Ancient Cultures thought of comets.

Comets are visible for two reasons. Dust driven from a comet’s nucleus reflects sunlight as it travels through space. Secondly, certain gases, stimulated by the sun, give off light like fluorescent light bulbs. Over time a comet may become less active or even dormant.

Scientists are anxious to learn whether comets exhaust their supply of gas and ice to space or seal it into their interiors. What is the difference between the interior of a comet’s nucleus and its surface? Controlled cratering like that planned for Deep Impact allows a look deep into the interior of the comet. Investigators anticipate that a look inside comet Tempel 1 will unlock the treasures a comet has to offer.

Comet Tempel 1 was discovered in 1867. Although few physical data are available, it appears to be a comet with relatively little surface activity. Orbiting the sun every 5.5 years, it has probably made more than one hundred passages through the inner solar system. This makes it a good target to study evolutionary change in the mantle or upper crust of the comet.

Studies of brightness variations with time indicate that the comet rotates much more slowly than Earth. Its rotation will not take the impact crater out of the spacecraft’s field of view during the encounter period.

Comets in Ancient Cultures-Comets have inspired dread, fear, and awe in many different cultures and societies around the world and throughout time. They have been branded with such titles as “the Harbinger of Doom” and “the Menace of the Universe.”

 

They have been regarded both as omens of disaster and messengers of the gods. Why is it that comets are some of the most feared and venerated objects in the night sky? Why did so many cultures cringe at the sight of a comet?

When people living in ancient cultures looked up, comets were the most remarkable objects in the night sky. Comets were unlike any other object in the night sky. Whereas most celestial bodies travel across the skies at regular, predictable intervals, so regular that constellations could be mapped and predicted, comets’ movements have always seemed very erratic and unpredictable. This led people in many cultures to believe that the gods dictated their motions and were sending them as a message.

What were the gods trying to say? Some cultures read the message by the images that they saw upon looking at the comet. For example, to some cultures the tail of the comet gave it the appearance of the head of a woman, with long flowing hair behind her. This sorrowful symbol of mourning was understood to mean the gods that had sent the comet to earth were displeased.

Others thought that the elongated comet looked like a fiery sword blazing across the night sky, a traditional sign of war and death. Such a message from the gods could only mean that their wrath would soon be unleashed onto the people of the land. Such ideas struck fear into those who saw comets dart across the sky. The likeness of the comet, though, was not the only thing that inspired fear.

 

Ancient cultural legends also played a hand in inspiring a terrible dread of these celestial nomads. The Roman prophecies, the “Sibylline Oracles,” spoke of a “great conflagration from the sky, falling to earth,” while the most ancient known mythology, the Babylonian “Epic of Gilgamesh,” described fire, brimstone, and flood with the arrival of a comet.

Rabbi Moses Ben Nachman, a Jew living in Spain, wrote of God taking two stars from Khima and throwing them at the Eearth in order to begin the great flood. Yakut legend in ancient Mongolia called comets “the daughter of the devil,” and warned of destruction, storm and frost, whenever she approaches the earth. Stories associating comets with such terrible imagery are at the base of so many cultures on Earth, and fuel a dread that followed comet sightings throughout history.

Comets’ influence on cultures is not limited simply to tales of myth and legend, though. Comets throughout history have been blamed for some of history’s darkest times. In Switzerland, Halley’s Comet was blamed for earthquakes, illnesses, red rain, and even the births of two-headed animals.

The Romans recorded that a fiery comet marked the assassination of Julius Caesar, and another was blamed for the extreme bloodshed during the battle between Pompey and Caesar. In England, Halley’s Comet was blamed for bringing the Black Death. The Incas, in South America, even record a comet having foreshadowed Francisco Pizarro’s arrival just days before he brutally conquered them.

Comets and disaster became so intertwined that Pope Calixtus III even excommunicated Halley’s Comet as an instrument of the devil, and a meteorite, from a comet, became enshrined as one of the most venerated objects in all of Islam. Were it not for a Chinese affinity for meticulous record keeping, a true understanding of comets may never have been reached.

Unlike their Western counterparts, Chinese astronomers kept extensive records on the appearances, paths, and disappearances of hundreds of comets. Extensive comet atlases have been found dating back to the Han Dynasty, which describe comets as “long-tailed pheasant stars” or “broom stars” and associate the different cometary forms with different disasters.

 

Although the Chinese also regarded comets as “vile stars,” their extensive records allowed later astronomers to determine the true nature of comets.

Although most human beings no longer cringe at the sight of a comet, they still inspire fear everywhere around the globe, from Hollywood to doomsday cults. The United States even set up the Near Earth Asteroid Tracking (NEAT) program specifically to guard us from these “divine” dangers.” However, although they were once regarded as omens of disaster, and messengers of the god(s), today a scientific approach has helped allay such concerns.

It is science and reason that has led the fight against this fear since the days of the ancients. It is science and reason that has emboldened the human spirit enough to venture out and journey to a comet. It is science and reason that will unlock the secrets that they hold.

 

Deep Impact Mission–

 

What is deep inside a comet?

 

Comets are time capsules that hold clues about the formation and evolution of the solar system. They are composed of ice, gas and dust, primitive debris from the solar system’s distant and coldest regions that formed 4.5 billion years ago. Deep Impact, a NASA Discovery Mission, is the first space mission to probe beneath the surface of a comet and reveal the secrets of its interior.

On July 4, 2005, the Deep Impact spacecraft arrives at Comet Tempel 1 to impact it with a 370-kg (~820-lbs) mass. On impact, the crater produced is expected to range in size from that of a house to that of a football stadium, and two to fourteen stories deep. Ice and dust debris is ejected from the crater revealing fresh material beneath. Sunlight reflecting off the ejected material provides a dramatic brightening that fades slowly as the debris dissipates into space or falls back onto the comet. Images from cameras and a spectrometer are sent to Earth covering the approach, the impact and its aftermath. The effects of the collision with the comet will also be observable from certain locations on Earth and in some cases with smaller telescopes. The data is analyzed and combined with that of other NASA and international comet missions. Results from these missions will lead to a better understanding of both the solar system’s formation and implications of comets colliding with Earth.

 

The Mission

 

The Deep Impact mission lasts six years from start to finish. Planning and design for the mission took place from November 1999 through May 2001. The mission team is proceeding with the building and testing of the two-part spacecraft. The larger “flyby” spacecraft carries a smaller “impactor” spacecraft to Tempel 1 and releases it into the comet’s path for a planned collision.

In December 2004, a Delta II rocket launches the combined Deep Impact spacecraft which leaves Earth’s orbit and is directed toward the comet. The combined spacecraft approaches Tempel 1 and collects images of the comet before the impact. In early July 2005, 24 hours before impact, the flyby spacecraft points high-precision tracking telescopes at the comet and releases the impactor on a course to hit the comet’s sunlit side.

The impactor is a battery-powered spacecraft that operates independently of the flyby spacecraft for just one day. It is called a “smart” impactor because, after its release, it takes over its own navigation and manoeuvres into the path of the comet. A camera on the impactor captures and relays images of the comet’s nucleus just seconds before collision. The impact is not forceful enough to make an appreciable change in the comet’s orbital path around the Sun.

After release of the impactor, the flyby spacecraft manoeuvres to a new path that, at closest approach passes 500 km (300 miles) from the comet. The flyby spacecraft observes and records the impact, the ejected material blasted from the crater, and the structure and composition of the crater’s interior. After its shields protect it from the comet’s dust tail passing overhead, the flyby spacecraft turns to look at the comet again. The flyby spacecraft takes additional data from the other side of the nucleus and observes changes in the comet’s activity. While the flyby spacecraft and impactor do their jobs, professional and amateur astronomers at both large and small telescopes on Earth observe the impact and its aftermath, and results are broadcast over the Internet.

 

Comet Tempel 1

 

Comet Tempel 1 was discovered in 1867 by Ernst Tempel. The comet has made many passages through the inner solar system orbiting the Sun every 5.5 years. This makes Tempel 1 a good target to study evolutionary change in the mantle, or upper crust. Comets are visible for two reasons. First, dust driven from a comet’s nucleus reflects sunlight as it travels through space. Second, certain gases in the comet’s coma, stimulated by the Sun, give off light like a fluorescent bulb. Over time, a comet may become less active or even dormant. Scientists are eager to learn whether comets exhaust their supply of gas and dust to space or seal it into their interiors. They would also like to learn about the structure of a comet’s interior and how it is different from its surface. The controlled cratering experiment of this mission provides answers to these questions.

 

Technical Implementation

 

The flyby spacecraft carries a set of instruments and the smart impactor. Two instruments on the flyby spacecraft observe the impact, crater and debris with optical imaging and infrared spectral mapping. The flyby spacecraft uses an X-band radio antenna (transmission at about eight gigahertz) to communicate to Earth as it also listens to the impactor on a different frequency. For most of the mission, the flyby spacecraft communicates through the 34-meter antennae of NASA’s Deep Space Network. During the short period of encounter and impact, when there is an increase in volume of data, overlapping antennas around the world are used. Primary data is transmitted immediately and other data is transmitted over the following week. The impactor spacecraft is composed mainly of copper, which is not expected to appear in data from a comet’s composition. For its short period of operation, the impactor uses simpler versions of the flyby spacecraft’s hardware and software – and fewer backup systems.

 

The Team

 

The Deep Impact mission is a partnership among the University of Maryland (UMD), the California Institute of Technology’s Jet Propulsion Laboratory (JPL) and Ball Aerospace and Technology Corp. The scientific leadership of the mission is based at UMD. Engineers at Ball Aerospace and Technologies Corp. design and build the spacecraft under JPL’s management. Engineers at JPL control the spacecraft after launch and relay data to scientists for analysis. The entire team consists of more than 250 scientists, engineers, managers, and educators. Deep Impact is a NASA Discovery Mission, eighth in a series of low-cost, highly focused space science investigations. Deep Impact offers an extensive outreach program in partnership with other comet and asteroid missions and institutions to benefit the public, educational and scientific communities.

 

The Comet-Tempel-1

 

Discovery

 

Comet 9P/Tempel 1 was discovered on April 3, 1867 by Ernst Wilhelm Leberecht Tempel of Marseilles France while visually searching for comets. The comet was then 9th magnitude and described by Tempel as having an apparent diameter of 4 to 5 arcmin across. Later calculations revealed that the comet had been situated 0.71 AU from the Earth and 1.64 AU from the sun at that time.

 

Historical Highlights

 

The comet was very well placed for its 1867 discovery thanks to its closest approach to Earth (0.568 AU) and its perihelion (1.562 AU), which occurred on May 15 and May 24, respectively. Over the next five months after its initial detection, subsequent observations were frequently made. The comet was last detected on August 27, 1867 by Julius Schmidt, at which point the comet had become too faint for position measurements. At that time the comet was 1.30 AU from Earth and 1.81 AU from the sun.

The comet was first recognized as periodic in May of 1867 when C. Bruhns of Leipzig determined the orbital period to be 5.74 years. By the time the final observations had been made of the 1867 apparition, the orbital period had been re-calculated to be 5.68 years.

The comet was recovered on April 4, 1873 by E.J.M. Stephan of Marseilles, France. The comet remained under observation until July 1st of that year.

Predictions were made for an 1879 return, with the most ambitious being that of Raoul Gautier who computed definitive orbits from the two previous appearances before making his predictions for the upcoming return. Gautier’s predictions enabled Tempel to recover the comet on April 25, 1879. The comet was observed until its last detection on July 8.

 

In 1881, comet Tempel 1 passed 0.55 AU from Jupiter. Due to gravitational interactions, the comet’s orbital period was increased to 6.5 years and the perihelion distance was increased from 1.8 AU to 2.1 AU, making the comet an even fainter object. Subsequently, the comet was lost and it was not observed at its next expected return. Photographic attempts during 1898 and 1905 failed to recover the comet.

During 1963, B.G. Marsden conducted an investigation as to why comet Tempel 1 became lost. He found that further close approaches to Jupiter in 1941 (0.41 AU) and 1953 (0.77 AU) had decreased both the perihelion distance and the orbital period to values smaller than when the comet was initially discovered. These approaches moved Tempel 1 into its present libration around the 1:2 resonance with Jupiter. Subsequently, Marsden published predictions for the 1967 and 1972 returns in his paper On the Orbits of Some Long Lost Comets. (Courtesy of NASA Astrophysics Data System)

Despite an unfavorable 1967 return, Elizabeth Roemer of the Catalina Observatory took several photographs during 1967. Her initial inspections of these photographs revealed nothing. However, in late 1968 she re-examined the photographic plates and found that a single exposure taken on June 8, 1967 held the image of an 18th magnitude diffuse object very close to where Marsden had predicted the comet to be. Unfortunately, the single image did not provide definitive proof of the comet’s recovery.

During 1972, Marsden’s predictions allowed Roemer and L.M. Vaughn to recover the comet on January 11 from Steward Observatory. The comet became widely observed and reached a maximum brightness of magnitude 11 during May of that year. The comet was last seen on July 10. This apparition proved that the single image taken by Roemer in 1967 was indeed comet 9P/Tempel 1. Since that time the comet has been seen at every apparition.

 

Tempel 1 Before Its Discovery

 

Long term integrations of comet 9P/Tempel 1’s orbit suggest that the perihelion distance has been inside 10 AU for at least 3×105 years. The aphelion distance is much less well determined far in the past. The inclination of Tempel 1’s orbit has remained low for as far into the past as the integrations have been calculated.

 

Spacecraft and Instruments–

 

The Deep Impact Spacecraft

 

The flight system consists of two spacecraft: the flyby spacecraft and the impactor. Each spacecraft has its own instruments and capabilities to receive and transmit data.

The flyby spacecraft carries the primary imaging instruments (the HRI and MRI) and the impactor (with an ITS) to the vicinity of the comet nucleus.

It releases the impactor, receives impactor data, supports the instruments as they image the impact and resulting crater, and then transmits the science data back to Earth.

Image at Right: This illustration shows the Deep Impact two-part vehicle consisting of a flyby spacecraft and the impactor. Image credit: NASA

The impactor guides itself to hit the comet nucleus on the sunlit side. The energy from the impact will excavate a crater approximately 100m wide and 28m deep.

The instruments help guide both spacecrafts and then acquire the science data that will be analyzed by the science team.

 

The Boeing Delta II Launch Vehicle

 

Before the flight system can get to the comet, it has to be delivered into space.

The Deep Impact mission will be launched aboard a Boeing Delta II 2925 rocket with the dual spacecraft tucked within the Delta’s fairing.

The Delta II launch vehicles are descended from the Delta rockets that have been in use since the 1960s. They have carried aloft a number of NASA spacecraft like Deep Space 1, NEAR, Mars Climate Orbiter, Mars Polar Lander, STARDUST, FUSE, IMAGE and EO-1/SAC-C into space.

 

3.4.19-Feature of Spacecraft-

 

Technology – Flight System

11.19.04

 

The flight system consists of two spacecraft: the flyby spacecraft and the impactor. Each spacecraft has its own instruments and capabilities to receive and transmit data.

The flyby spacecraft carries the primary imaging instruments (the HRI and MRI) and the impactor (with an ITS) to the vicinity of the comet nucleus. It releases the impactor, receives impactor data, supports the instruments as they image the impact and resulting crater, and then transmits the science data back to Earth.

The impactor guides itself to hit the comet nucleus on the sunlit side. The energy from the impact will excavate a crater approximately 100m wide and 28m deep.

The instruments help guide both spacecrafts and then acquire the science data that will be analyzed by the science team.

 

Main Goals of the Flight System:

 

  • Hit nucleus of Tempel 1 with sufficient kinetic energy to form a crater with a depth > 20m
  • Observe nucleus for > 10 minutes following impact
  • Image nucleus impact, crater development and inside of crater
  • Obtain spectrometry of nucleus and inside of crater
  • Acquire, store, format, and downlink imagery and spectrometry data

 

Feature of Flyby Spacecraft

 

11.23.04

As part of Deep Impact’s Flight System, the flyby spacecraft is one of two vessels carrying the three science Instruments. Ball Aerospace & Technologies Corp. designed the spacecraft specifically for the Deep Impact mission.

 

The flyby spacecraft features a high throughput RAD750 CPU with 1553 data bus-based avionics architecture, and a high stability pointing control system. Spacecraft optical navigation and conventional ground-based navigation will facilitate maneuvering the flyby spacecraft as close as possible to the collision course with comet Tempel 1. When the impactor is released from its union with the flyby spacecraft, the flyby spacecraft will slow itself down and align itself to observe the impact, ejecta, crater development, and crater interior as it passes within 500 km of Tempel 1. It will also receive data from the impactor and transfer it to the Deep Space Network ground receivers.

The flyby spacecraft carries two of the three primary instruments, the High Resolution Instrument (HRI) and the Medium Resolution Instrument (MRI), for imaging, infrared spectroscopy, and optical navigation.

 

About the size of a Ford Explorer, the flyby spacecraft is three-axis stabilized and uses a fixed solar array and a small NiH2 battery for its power system. The structure is aluminium and aluminium honeycomb construction. Blankets, surface radiators, finishes, and heaters passively control the temperature. The propulsion system employs a simple blowdown hydrazine design that provides 190 m/s of delta V. The flyby spacecraft mass is 650 kg.

 

During the encounter phase, a high gain antenna transmits near-real-time images of the impact back to Earth. The flyby spacecraft uses X-band to communicate to Earth and S-band to communicate with the impactor after separation.

 

Debris shielding is a key part of the flyby S/C design. As the spacecraft passes through the inner coma of the comet it is in danger of being hit by small particles that could damage the control, imaging and communication systems. To minimize this potential damage the spacecraft is rotated before it passes through the inner coma allowing debris shielding to provide complete protection to the flyby spacecraft and instrument elements.

 

Payload Power: 92 W average during engagement

 

Payload Mass: 370 kg impactor, 90 kg instruments

 

Payload Total Data Volume: 309 Mbytes

 

Payload Data Downlinked: 309 Mbytes

 

Pointing Accuracy: 200 microradian

(inst. boresight orientation)

 

Pointing Knowledge: 65 microradian 3 axes 3-sigma

 

Telecom Band to Earth: X-band

 

Uplink/Downlink Rates: 125 bps/175 Kbps

(exclusive of Reed-Solomon encoding)

 

Telecom Band to Impactor: S-band

 

Data Rate to Impactor: 64 Kbps @ max range (8,700 km)

 

Propulsion/RCS: 190 m/s divert;

5000 N-s RCS total impulse

Deep Impact’s Impactor

 

The impactor separates from the flyby spacecraft 24 hours before it impacts the surface of Tempel 1’s nucleus. The impactor delivers 19 Gigajoules (that’s 4.8 tons of TNT) of kinetic energy to excavate the crater. This kinetic energy is generated by the combination of the mass of the impactor (370 kg; 816 lbs) and its velocity when it impacts (~10.2 km/s). Targeting and hitting the comet in a lit area is one of the mission’s greatest challenges since the impactor will be traveling at 10 km per second and it must hit an area less than 6 km (3.7 miles) in diameter from about 864,000 km (536,865 miles) away. To accomplish this feat, the impactor uses a high-precision star tracker, the Impactor Target Sensor (ITS), and Auto-Navigation algorithms (developed by Jet Propulsion Laboratory for the DS-1 mission) to guide it to the target. Minor trajectory corrections and attitude control are available by using the impactor’s small hydrazine propulsion system.

 

The impactor is made primarily of copper (49%) as opposed to aluminium (24%) because it minimizes corruption of spectral emission lines that are used to analyze the nucleus.

 

The impactor is mechanically and electrically attached to the flyby spacecraft for all but the last 24 hours of the mission. Only during the last 24 hours does the impactor run on internal battery power. The propulsion system uses hydrazine that can provide 25 m/s of delta-V for targeting.

 

System Requirement Specifications for the Impactor

 

Image Data Volume:    Approximately 17 Mbytes (about 35 images) total

 

Pointing Accuracy:    2 mrad 3-sigma (targeting sensor boresight orientation)

 

Pointing Knowledge:    150 microradian 3 axes 3-sigma

 

Targeting Accuracy:    300 m 3-sigma WRT nucleus center of brightness

 

Telecom Band:    S-Band

 

Data Rate to S/C:    64 Kbps @ max range (8,700 km)

 

Command Rate:    16 Kbps

 

Energy Storage:    2.8 Kw-hr for baseline 24 hr mission

 

Propulsion/RCS:    25 m/s divert; 1750 N-s RCS impulse

3.4.24-Technology – Instruments

Built by Ball Aerospace & Technologies Corp., the Deep Impact instruments have two purposes. They guide the flyby spacecraft and impactor onto a collision course with the comet and they take the science data before, during, and after the impact. The instruments are designed so that they satisfy the following science requirements:

Pre-impact Imaging Requirements:

Observe the comet and targeted impact site prior to impact, acquiring spatial and spectral data

Ejecta Imaging Requirements:

Observe the ejecta and track the movement of the ejecta curtain from crater to coma

Crater Evolution Data Requirements:

Observe the crater and surface evolution

Pristine Crater Data Requirements: Observe the exposed pristine crater surface features via spectral imagers with increasing resolution

Modular Design Requirements:

Have opto-mechanically interchangeable focal plane modules

 

The primary instruments on the flyby spacecraft are the High Resolution Instrument (HRI) and the Medium Resolution Instrument (MRI). The HRI, one of the largest space-based instruments built specifically for planetary science, is the main science camera for Deep Impact. It provides the highest resolution images via a combined visible camera, an infrared spectrometer, and a special imaging module. The HRI is optimally suited to observe the comet’s nucleus. The MRI serves as the functional backup for the HRI, and is slightly better at navigation for the last 10 days of travel before impact due its wider field of view, which allows it to observe more stars around the comet. The difference between the two is the telescope, which sets the field of view (FOV) and the resolution of each. .

 

The ITS on the impactor is nearly identical to the MRI as it uses the same type of telescope as the MRI as well as the same type of CCD that is in the MRI’s Multi Spectral CCD Camera but differs only in that it lacks the filter wheel.

Technology – Instruments

Built by Ball Aerospace & Technologies Corp., the Deep Impact instruments have two purposes. They guide the flyby spacecraft and impactor onto a collision course with the comet and they take the science data before, during, and after the impact. The instruments are designed so that they satisfy the following science requirements:

Pre-impact Imaging Requirements:

Observe the comet and targeted impact site prior to impact, acquiring spatial and spectral data

Ejecta Imaging Requirements:

Observe the ejecta and track the movement of the ejecta curtain from crater to coma

Crater Evolution Data Requirements:

Observe the crater and surface evolution

Pristine Crater Data Requirements:

Observe the exposed pristine crater surface features via spectral imagers with increasing resolution

Modular Design Requirements:

Have opto-mechanically interchangeable focal plane modules

 

 

The primary instruments on the flyby spacecraft are the High Resolution Instrument (HRI) and the Medium Resolution Instrument (MRI). The HRI, one of the largest space-based instruments built specifically for planetary science, is the main science camera for Deep Impact. It provides the highest resolution images via a combined visible camera, an infrared spectrometer, and a special imaging module. The HRI is optimally suited to observe the comet’s nucleus. The MRI serves as the functional backup for the HRI, and is slightly better at navigation for the last 10 days of travel before impact due its wider field of view, which allows it to observe more stars around the comet. The difference between the two is the telescope, which sets the field of view (FOV) and the resolution of each.

 

The ITS on the impactor is nearly identical to the MRI as it uses the same type of telescope as the MRI as well as the same type of CCD that is in the MRI’s Multi Spectral CCD Camera but differs only in that it lacks the filter wheel.

 

Views: 13

Comment

You need to be a member of Global Ethics Network to add comments!

Join Global Ethics Network

Carnegie Council

Climate Change and the Power to Act: An Ethical Approach for Practical Progress

We are already living with climate change; and although countries have pledged to limit global warming to 2 °C, success seems highly unlikely. This panel explores how to advance ethical leadership on climate justice globally, nationally, and locally in the years ahead. Topics include the Paris Agreement and commitments going forward, geoengineering governance, the problems in California, and the creative ways the Seychelles are coping.

Greed, Movies, and Capitalism with Ethicist John Paul Rollert

Every capitalist economy struggles with how to come to terms with greed, says John Paul Rollert, an expert on the intellectual history of capitalism. He describes how our perspective has changed from the Christian view of greed as an unalloyed sin, to the 18th century idea that it could bring positive benefits, to the unabashed "Greed is good" ethos in the movie "Wall Street." Where do we stand now? How can we rehabilitate capitalism?

Global Ethics Forum Preview: Plutopia: Nuclear Families in Atomic Cities, with Kate Brown

Next time on Global Ethics Forum, University of Maryland Baltimore County's Professor Kate Brown details the ethical, social, and health costs of nuclear power since World War II. In this excerpt Brown, author of "Plutopia," and journalist Stephanie Sy discuss the little-known Cold War era nuclear production plants in the Soviet Union and Washington State.

SUBSCRIBE TODAY

E&IA Journal

GEO-GOVERNANCE MATTERS

© 2018   Created by Carnegie Council.   Powered by

Badges  |  Report an Issue  |  Terms of Service