Search

The CORSAIR (COmet Rendezvous, Sample Acquisition, Investigation, and Return) mission was a proposal for the NASA New Frontiers program. It belongs to the Comet Surface Sample Return mission theme which focuses on acquiring and returning to Earth a macroscopic sample from the surface of a comet nucleus. CORSAIR uses a harpoon-based Sample Acquisition System (SAS) with the spacecraft hovering several meters above the comet surface. This stand-off strategy overcomes disadvantages of other systems such as drills. Since comets are low gravity objects, those techniques would require anchoring before sampling, which is not necessary here. Moreover, the harpoon-based system allows for acquiring several samples from different locations on the comet maximizing the scientific output of the mission. Each SAS assembly consists of a pyro-driven launcher, a Sample Acquisition and Retrieval Projectile (SARP) and a retraction system using a deployable composite boom structure. In order to collect enough cometary material, the launcher has to provide the required kinetic energy to the SARP. Due to high energy densities, pyrotechnically actuated devices ultimately reduce the overall system mass and dimensions. First, the scientific and technological background of the CORSAIR mission is explained. Then, an overview of the development, design and testing of the launcher is given. Finally, the launcher theory is introduced explaining the entire reaction chain: initiation → gas dynamics → SARP motion.

The Rosetta mission arrived at comet 67 P/Churyumov-Gerasimenko in Summer 2014, after more than 10 years in space. All previous mission encounters with a comet have provided a snapshot of the cometary activity at a given heliocentric distance. In contrast, Rosetta has escorted the comet nucleus for an extended period (>2 years) at a large range of cometo-centric and heliocentric distances, which has provided exceptional and unprecedented observing conditions to study, analyse and monitor 67 P during its passage to, through and away from perihelion. One of the biggest challenges of this mission is the development of an observation plan that adequately addresses the mission's science objectives while coping with a largely unknown and continuously evolving environment that constantly modifies the planning constraints. The Rosetta Science Ground Segment (RSGS), in support of the Project Scientist and the Science Working Team, is in charge of translating the high level mission science objectives into a low level pointing and operations plan. We present here the high-level science planning process adopted during the comet escort phase. We describe the main science objectives addressed along the mission lifetime, the different groups involved in the science planning, and the approach followed to translate those requirements into a viable and scientifically valid operations plan. Finally, we describe how the science planning scheme has evolved since arrival at the comet to react to the unexpected environment, largely reducing the planning lead times.

The ROLIS, CIVA-P and OSIRIS instruments on-board the Philae lander and the Rosetta orbiter acquired high-resolution images during the lander׳s descent towards the targeted landing site Agilkia, during its unexpected rebounds and at the final landing site Abydos on comet 67P/Churyumov–Gerasimenko. We, exploited these images, using robotic vision techniques, to locate the first touchdown on the surface of the comet nucleus, to reconstruct the lander׳s 3D trajectory during the descent and at the beginning of the first rebound, and to create local digital terrain models and depth maps of Agilkia and Abydos sites. Using the ROLIS close-up images we could also determine the actual movements of the lander between the beginning and the end of the First Science Sequence and we propose a new lander׳s bubble movement command meant to increase the probability for a successful drilling during a hypothetical future Long Term Science phase.

The International Rosetta Mission of the European Space Agency (ESA) was launched on 2nd March 2004 on its 10 year journey to comet Churyumov-Gerasimenko and has reached it early August 2014. The main mission objectives were to perform close observations of the comet nucleus throughout its orbit around the Sun and deliver the lander Philae to its surface. This paper describers the activities at mission operations level that allowed the landing of Philae. The landing preparation phase was mainly characterised by the definition of the landing selection process, to which several parties contributed, and by the definition of the strategy for comet characterisation, the orbital strategy for lander delivery, and the definition and validation of the operations timeline. The definition of the landing site selection process involved almost all components of the mission team; Rosetta has been the first, and so far only mission, that could not rely on data collected by previous missions for the landing site selection. This forced the teams to include an intensive observation campaign as a mandatory part of the process; several science teams actively contributed to this campaign thus making results from science observations part of the mandatory operational products. The time allocated to the comet characterisation phase was in the order of a few weeks and all the processes, tools, and interfaces required an extensive planning an validation. Being the descent of Philae purely ballistic, the main driver for the orbital strategy was the capability to accurately control the position and velocity of Rosetta at Philae’s separation. The resulting operations timeline had to merge this need of frequent orbit determination and control with the complexity of the ground segment and the inherent risk of problems when doing critical activities in short times. This paper describes the contribution of the Mission Control Centre (MOC) at the European Space Operations Centre (ESOC) to this mission phase and the lessons learned that can be derived from this experience.

The International Rosetta Mission, cornerstone of the European Space Agency Scientific Programme, was launched on 2 March 2004 on its 10 years journey towards a rendezvous with comet Churyumov–Gerasimenko. Rosetta will reach the comet nucleus in summer 2014, orbit it for about 1.5 years down to distances of a few kilometres and deliver the lander Philae onto its surface. After its successful Asteroid fly-by in September 2008, Rosetta is coming back to Earth, for the last gravity acceleration towards its longest heliocentric orbit, up to a distance of 5.3 AU, never reached before by a solar generator-powered spacecraft. This revolution around the Sun will last several years, during which the spacecraft will have to be spun-up and put into hibernation mode, with most of the systems deactivated, to minimise power consumption. This paper presents the preparation and implementation of the deep space phase of the Rosetta mission. Differences between operations performed until now, at moderate distances to Earth and Sun, and the upcoming ones, involving distances up to 800 million km from the Sun and almost 1 billion km from Earth, are analysed and their impact on the operational concept described. The ground tools required in support of the operations are presented.

The International Rosetta Mission, a cornerstone mission of the European Space Agency Scientific Programme, was launched on 2 March 2004 on its 10 years journey towards a rendezvous with comet Churyumov-Gerasimenko. Once reached the comet nucleus in summer 2014, Rosetta will orbit it for about 1.5 years down to distances of a few kilometres and deliver a lander onto its surface. In the long cruise to its target, Rosetta performs four gravity assist manoeuvres, three times with Earth and once with Mars. During this flight Rosetta will cross twice the main asteroid belt, and in both occasions its trajectory is designed and controlled to flyby an asteroid at close distance. On 5 September 2008 the first of the two asteroid flybys has been conducted, with the spacecraft approaching asteroid 2867-Steins at a minimum distance of about 800 km, and a relative velocity of 8.6 km/s. Steins is an E-type asteroid with a diameter of about 5 km. This paper continues the period reporting of the operational experience from the Rosetta mission operations. Preparation and execution of the flyby activities are described including the first experience in optical navigation that will prove of utmost importance for the next asteroid flyby and for the comet approach phase.

The International Rosetta Mission, a cornerstone mission of the European Space Agency Scientific Programme, was launched on 2nd March 2004 on its 10 years journey towards a rendezvous with comet Churyumov–Gerasimenko. Once reached the comet nucleus in summer 2014, Rosetta will orbit it for about 1.5 years down to distances of a few kilometres and deliver a Lander, named Philae, onto its surface. In the long cruise to its target, Rosetta performs four gravity assist manoeuvres, three times with Earth and once with Mars. After the first successful Earth swing-by in March 2005, the year 2007 started with a highly critical Mars swing-by, carried out in February at a target altitude over the planet's surface of only 250 km. This manoeuvre re-oriented the spacecraft trajectory towards the second Earth swing-by, planned for November 2007. During both swing-by phases the payload was operated to achieve a variety of scientific and calibration objectives. This paper continues the periodic reporting of the operational experience from the Rosetta mission operations. Preparation and execution of the swing-by activities are described. As derived from the lessons learned in this phase, a generic approach to be adopted for planning and execution of planets swing-by phases, including those of future missions like BepiColombo, is presented.

We describe laboratory tests to investigate and demonstrate the acquisition and encapsulation of a subsurface sample from a comet analogue using a coring penetrator. The penetrator imbeds itself in the target, coring out a sample during the impact itself. Mechanisms seal the sample in a canister and the canister is spring-ejected from the rear of the penetrator where it can be retrieved in free-flight by a mother spacecraft, which thus need not perform a landing. We describe the penetrator vehicle, sample preparation and testing technique using the large airgun at the University of Arizona, and the performance results which indicate the technique is an attractive option for comet nucleus sample return.

The International Rosetta Mission, a cornerstone mission of the European Space Agency Scientific Programme, was launched on 2nd March 2004 on its 10 years journey towards a rendezvous with comet Churyumov–Gerasimenko. Once reached the comet nucleus in summer 2014, Rosetta will orbit it for about 1.5 years down to distances of a few kilometers and deliver a Lander, named Philae, onto its surface. In its first year of flight, the spacecraft and its payloads have gone through an extensive commissioning exercise, several trajectory correction manoeuvres, the first Earth gravity assist manoeuvre (1 year after launch), and some important scientific operations. The spacecraft has finally entered its first Passive Cruise phase end of July 2005. This paper describes the mission operations experiences collected during the first year of routine flight, after completion of the commissioning activities mid-October 2004. The two main mission events that occurred during this period are described: the first Earth swing-by in March 2005 and the scientific Deep Impact observation campaign in July 2005. An overview of the major in-flight anomalies is given and lessons learnt are presented.

“Rosetta” is a Cornerstone Mission of the Horizon 2000 ESA Programme. Its goal is to rendezvous with a comet and to study its nucleus and coma using an orbiting spacecraft and a landed platform. The latter is called Philae; the Rosetta Lander has been designed to land softly on the comet nucleus and is equipped with 10 scientific instruments to perform in situ studies of cometary material. The Lander system is provided by international consortium with the participation of Germany, France, Italy, United Kingdom, Finland, Ireland, Hungary and Austria. The original Rosetta mission was planned to launch in January 2003 to reach comet 47P/Wirtanen in 2011 at a heliocentric distance of about 3 AU. Due to uncertainties regarding the reliability of the Ariane 5 launcher (after a catastrophic failure in December 2002) the Rosetta launch was postponed and a new mission studied. Changed mission characteristics (e.g. in launcher capacity; no swing-by at Venus) strongly limited the number of possible alternatives. After careful investigation, a decision was taken for a mission to comet 67/P Churyumov-Gerasimenko with a launch date in February 2004 and rendezvous in 2014. This new mission scenario has significant consequences for the Rosetta Lander, because the nucleus of P/Churyumov-Gerasimenko is expected to be considerably larger than that of P/Wirtanen. Current best estimates assume a radius of about 2.0 km and, thus, a mass which is about two orders of magnitude larger than that of the original target comet. This impacts strongly on the Lander separation, descent and landing scenario. Analysis of the increased landing risk on P/Churyumov-Gerasimenko has led to modifications of the landing gear to cope with the increased impact velocities expected.

The Comet Nucleus Tour (CONTOUR) is a NASA Discovery mission to study the diversity of comet nuclei. Top level mission goals include imaging the nuclei of several comets at resolutions up to 4 m / pixel , acquiring spectral information in both the visible and infrared (IR), and obtaining detailed compositional measurements of the gas and dust. The CONTOUR Remote Imager and Spectrograph (CRISP) instrument, under development at The Johns Hopkins University Applied Physics Laboratory, achieves the primary imaging and spectral mapping objectives. CRISP includes a visible imager and 10-position filter wheel to survey the visible spectrum from 400 to 800 nm and provide high-resolution images of the nucleus. An imaging spectrograph, utilizing a 256×256 HgCdTe array and yielding a spectral resolution of 7 nm , analyzes the infrared IR spectrum from 800 to 2500 nm . A Stirling cycle refrigerator cools the IR array to cryogenic operating temperatures. The imager and spectrograph share a common optical path that includes a scan mirror to actively track the comet nucleus during approach and fly-by. An overview of the CRISP instrument is presented.

Deep Impact is a new NASA Discovery mission to launch in early 2004. This paper discusses the mission design strategies for this unique mission, which will target a 500-kg impactor into a comet nucleus at a speed of 10 km / s , in order to reveal the subsurface materials and structure. Trajectory designs are shown for reaching comet P/Tempel 1 near perihelion at its 2005 apparition and for the approach and flyby trajectories of the flyby spacecraft, which carries the impactor up to 24 h before impact. The mission and encounter timelines are discussed for the events of the cruise, approach, and encounter phases of the mission, including the strategies for observing the impact and returning the data to Earth.

The Comet Nucleus Sample and Return (CNSR) mission has been of great interest for many years. The mission objective is very clear and it provides the clues to the solar system and the origin of life. The paper presents the feasible CNSR scenario taking the advantage of Solar Electric Propulsion to the comet Wilson-Harrington (WH). The plan is found feasible, and the launch window is in 2005 and the spacecraft can return the sample back to the Earth in only 8 years. Another window that is open in 2009–2010 is also provided. They are making use of the ion engine propulsion accumulating the orbital energy at Earth distance, followed by the Earth gravity assist. This is the unique point enabling even the smaller spacecraft to accomplish this high energy mission. This strategy accelerates the spacecraft orbital energy up to 36– 40 km 2 / s 2 in C3 that is adequate for the flight to the comet WH. The idea shown here also includes: (1) the rendezvous point to be at Earth distance so that the electric propulsion is utilized at maximum and (2) the target comet to be extinct so that the sampling and in situ measurement scenario robust. The trajectory synthesis developed here and tactical target selection make this impressive mission to be envisioned even by smaller missions. This is not an endorsed mission but ISAS may consider collaborating with the foreign space organization on the mission.

The concept of using Earth-return trajectories in connection with missions to comets was originally proposed in 1972. Papers published in the 1970's and 1980's showed that by using multiple Earth-to-Earth transfers, it was possible to construct a trajectory that would encounter several comets. This technique was used for the first time by ESA's Giotto spacecraft. Following its encounter with Halley's comet in March 1986, Giotto used a single Earth gravity-assist maneuver to intercept comet Grigg-Skjellerup in July 1992. Japan's Sakigake spacecraft tried to use Earth gravity-assist maneuvers to reach comet Honda-Mrkos-Pajdusakova in 1996, but was not successful. Earth-return trajectories are essential elements of two Discovery-class missions to comets; Stardust, and the Comet Nucleus Tour (CONTOUR). The Stardust mission will be launched in February 1999, and will return dust samples collected from comet Wild-2 to the Earth in 2006. CONTOUR is scheduled for a launch in June 2002, and will use six Earth gravity-assist maneuvers to carry out three comet encounters: Encke in 2003; Schwassmann-Wachmann-3 in 2006; and d'Arrest in 2008. An extended-mission scenario would allow CONTOUR to accomplish two additional encounters: Tempel-2 in 2015, and Encke for a second time in 2023.

Summary CONTOUR, a Discovery-class flyby mission of three comets (Encke, d’Arrest, Tempel 1) provides the next step in comet exploration and is a useful precursor to more complex endeavors. The small, focused payload of three instruments (imager, dust analyzer/counter, mass spectrometer) will provide unique data on the composition of near-nucleus gas and dust, as well as on the global characteristics of the nuclei of three diverse comets. Most importantly, CONTOUR will provide the 10 m resolution (or better) imaging still needed to elucidate fundamental nucleus surface processes. A unique aspect of CONTOUR is the possibility of returning to Encke during an extended mission, for a second look after an interval of 10 years!

The nuclei of comets and the small icy moons of the outer planets are thought to be the most primitive objects in the solar system. Because of their pristine nature, in-situ measurements of composition, temperature, and mechanical properties will be a powerful tool in realization of one of NASA's major objectives: determination of the Solar System's origins and evolution. Cryo penetrators are a new class of penetrator vehicle investigated intensively since 1985 for NASA's Comet Rendezvous/Asteroid Flyby (CRAF) mission. They are specifically optimized for penetration and operation in icy bodies at temperatures below 150 degrees K. The CRAF studies were directed at investigation of comet nuclei, but the same design should be applicable to the icy moons of the outer planets and, with appropriate delivery systems, (similar to those envisioned for NASA's MESUR mission) to the Martian polar caps. This paper describes the design of a cryopenetrator based on the CRAF Configuration and designed for in-situ measurements of a comet nucleus as part of the Comet Nucleus Penetrator (CNP) Discovery mission. The ROSETTA nucleus rendezvous mission recently selected by ESA is another potential cryo penetrator application.

There is suggested an algorithm of the autonomous tracking of a minor celestial body (comet, asteroid or satellite) by the photo-TV-camera of the spacecraft during its flyby in the vicinity of the celestial body, investigated by the data of images obtained by this camera. This algorithm allows prediction of the celestial body angular position in order to point the onboard camera to the body. The field of applicability for the suggested algorithm taking into account various errors is being investigated. The problems of the optimization of the program of the autonomous tracking in order to decrease the prediction errors or to increase the prediction time interval are considered. The results obtained are illustrated by the example of the autonomous tracking of Halley's comet nucleus.

Among the major objectives of NASA's program of space exploration is a better understanding of the origin and evolution of the solar system. Crucial to this objective is the study of comets, which are thought to be the most primitive, pristine bodies remaining in the solar system. The importance of the study of comets has led NASA to plan a mission to rendezvous with comet Tempel 2 in 1997. Critical to the understanding of comets will be measurements of the nucleus material to determine its elemental and isotopic composition, its mechanical properties, and its thermal state and properties. This paper describes a proposal for a Comet Nucleus Penetrator to accomplish these measurement goals. The Comet Nucleus Penetrator will implant instruments into the comet's nucleus beneath a probable volatile-depleted surface mantle into material more representative of the bulk composition of the nucleus.