OrbitalHub

Credits: NASA

In the previous two posts in this series, we presented NASA’s Lunar Reconnaissance Orbiter (LRO) and the Chandrayaan-1 mission, which was designed and developed by ISRO. These two missions are typical lunar scouting missions: the spacecraft with onboard remote-sensing instruments will orbit the Moon, collect scientific data, and relay it back to Earth.

NASA will launch another lunar scouting spacecraft on the same Atlas V rocket with LRO: the Lunar Crater Observation and Sensing Satellite (LCROSS). This mission is not a typical scouting mission and we will see why in this post.

In 1999, a precursor of LRO and LCROSS called the Lunar Prospector detected traces of concentrated hydrogen at the lunar poles. As a result, the LCROSS mission’s main goal is to confirm the presence or absence of water in a permanently shadowed crater near a lunar polar region. At the present time, landing a probe on the lunar surface and performing excavations or drilling would be very expensive. A less expensive solution for the LCROSS mission is to use a kinetic impactor to excavate a crater on the surface of the Moon.

Credits: NASA

After the launch, LRO will separate from LCROSS, and continue on a solo journey to the Moon. LCROSS will remain attached to the Centaur upper stage of the Atlas V launch system.

While LRO will follow a trajectory that will place it in a polar lunar orbit, LCROSS will execute a flyby of the Moon, and use an elongated Earth orbit to position itself on an impact trajectory. During this time, the LCROSS mission team will perform instrument calibration and corrections for the impact trajectory. The target of the impact will be the lunar south pole.

Seven minutes before the impact, LCROSS will separate from Centaur. The Centaur will be used as a kinetic impactor. Having a mass of approximately 2,200 kg, on impact, it will excavate a crater 20 meters wide and 3 meters deep. According to NASA scientists, more than 250 tons of lunar material will be propelled into space.

Credits: NASA

LCROSS will then fly through the debris of the previous impact. The instruments onboard LCROSS will collect scientific data and the spacecraft will relay it back to Earth. LCROSS will end its mission four minutes after the Centaur impact by creating its own impact crater on the lunar surface. The last S in LCROSS should stand for Smasher instead of Satellite considering the final act of the mission!

The scientific instruments onboard LCROSS cover a wide spectrum: two near-infrared spectrometers, a visible light spectrometer, two mid-infrared cameras, two near-infrared cameras, a visible camera, and a visible radiometer. The instruments can detect traces of organics, hydrocarbons, hydrated minerals, water ice, and water vapor. More details about the LCROSS scientific payload can be found on LCROSS mission page.

I wonder to what extent the debris caused by the impact of Centaur and LCROSS will interfere with the scientific instruments onboard LRO and Chandrayaan-1. Both LRO and Chandrayaan-1 will be orbiting the Moon on polar orbits at that time.

We presented in a previous post the Lunar Reconnaissance Orbiter (LRO) mission. The goals of the LRO mission are to map the lunar resources and to create a detailed 3D map of the lunar surface in preparation for future NASA missions to the Moon. However, NASA is not the only space agency that has high hopes regarding the exploration of the Moon. The Indian Space Research Organization (ISRO) is another agency heavily involved in space activities.

Credits: ISRO

Interest in undertaking a lunar scientific mission was sparked at a meeting of the Indian Academy of Sciences in 1999. One year later, the Astronautical Society of India made a recommendation supporting the idea.

The ISRO formed a National Lunar Mission Task Force that involved leading Indian scientists. The Task Force provided an assessment on the feasibility of such a mission. The mission, called Chandrayaan-1, was approved in November 2003 for an estimated cost of $83 million USD.

The Chandrayaan-1 spacecraft is a 1.5 meter cube with a weight mass of approximately 523 kg. The spacecraft bus is based on an already developed meteorological satellite. Chandrayaan-1 will carry a 30 kg probe that will be released to penetrate the lunar surface. The power for the onboard systems is generated by a solar panel. The 750 watts generated by the solar panel will be stored by the rechargeable batteries onboard the spacecraft. Maneuvering in the lunar orbit is done using a bipropellant propulsion system.

Credits: ISRO

The scientific payload contains a diverse collection of instruments. The instruments were designed and developed by ISRO, ESA, NASA, and the Bulgarian Space Agency.

There are two instruments that will map the surface of the Moon: the Terrain Mapping Camera (TMC) will produce a 5 meter resolution map of the surface, and the Lunar Laser Ranging Instrument (LLRI) will scan the lunar surface and determine the surface topography.

The X-ray spectrometer onboard the spacecraft has three components: the Imaging X-ray Spectrometer (CIXS), the High Energy X-ray/gamma ray spectrometer (HEX), and the Solar X-ray Monitor (SXM). The X-ray spectrometer will measure the concentration of certain elements on the lunar surface as well as monitor the solar flux in order to normalize the results of the measurements taken.

The mineralogical configuration of the surface will be mapped by four instruments: the Hyper Spectral Imager (HySI), the Sub-keV Atom Reflecting Analyzer (SARA), the Moon Mineralogy Mapper (M3), and the Near-Infrared Spectrometer (SIR-2).

The Radiation Dose Monitor (RADOM-7) will record the radiation levels in the lunar orbit.

Credits: ISRO

ISRO has two operational launch vehicles: the Polar Satellite Launch Vehicle (PSLV) and the Geosynchronous Satellite Launch Vehicle (GSLV). For Chandrayaan-1, ISRO has chosen to use PSLV as a launch vehicle. The PSLV developmental flights were completed in 1996 and the rocket has had 12 successful missions since then. PSLV is 44.43 meters tall and has a weight of 294 tonnes at launch. It can inject a payload of 1,000 kg – 1,200 kg into a polar orbit.

The launch of the Chandrayaan-1 mission is scheduled for the end of October 2008. The PSLV rocket will take off from the Satish Dhawan Space Center in Sriharikota on the southeast coast of India. The transfer to the lunar orbit will take approximately five days and after additional maneuvers the spacecraft will reach its final polar orbit, 100 km above the surface. The spacecraft will be operational for two years.

The Chandrayaan-1 mission opens the door to future lunar missions. ISRO has already committed to a second Chandrayaan mission that will land a rover on the surface of the Moon. The rover will perform a number of experiments on the lunar surface and the results will be relayed to Earth by the Chandrayaan-2 orbiter.

We will come back with more details about the Chandrayaan-1 mission as the events unfold. Please stay tuned on the OrbitalHub frequency.

Some of the most important questions asked in modern science are: how did the Universe begin, how did it evolve to its present state, and how will it continue to evolve in the future? To ask these questions, the remnant radiation that filled the Universe immediately after the Big Bang must be analyzed. This remnant radiation is known as the Cosmic Microwave Background (CMB).

Credits: ESA

ESA plans to answer these questions with Planck: the first European mission to study the birth of the Universe. The Planck Mission will collect CMB radiation measurements using highly sensitive sensors that are operating at very low temperatures. The measurements will be used to map the smallest variations of the CMB detected to date.

The Planck spacecraft will weigh around 1,900 kg at launch. It is 4.2 m high and has a maximum diameter of 4.2 m. There are two modules that comprise the spacecraft: a service module and the payload module.

The service module contains the systems for power generation, attitude control, data handling and communication, and the warm components of the scientific payload. The payload module contains the telescope, the optical bench, the detectors, and the cooling system (which is of critical importance, as we shall see).

The telescope is an important onboard component. The Planck telescope is a Gregorian telescope with an off-axis parabolic primary mirror 1.75 x 1.5 meters in size. A secondary mirror focuses the incoming microwave radiation on two sets of highly sensitive detectors: the Low Frequency Instrument (LFI) and the High Frequency Instrument (HFI). The Gregorian design offers two key advantages: it is compact and it does not block the optical path.

Credits: ESA/Thales

The LFI will be operating at –253 degrees Celsius. The array of twenty-two tuned radio receivers that comprise LFI will produce high-sensitivity, multi-frequency measurements of the microwave sky in the frequency range of 27 GHz to 77 GHz.

The HFI has to be cooled to –272.9 degrees Celsius in order to operate (one tenth of one degree above the absolute zero!). HFI’s fifty-two bolometric detectors will produce high-sensitivity, multi-frequency measurements of the diffuse sky radiation in the frequency range of 84 GHz to 1 THz.

A baffle surrounds the telescope and instruments. The baffle prevents light from the Sun and the Moon from altering the measurements. A complex system of refrigerators is used onboard the spacecraft in order to achieve the temperatures needed for nominal operation. The detectors have to work at temperatures close to the absolute zero, otherwise their own emissions can alter the measurements.

The two instruments will be used to measure the small variations of the CMB across the sky. By combining the measurements, a full sky map of unprecedented precision will be produced. The map will help astronomers decide which theories on the birth and the evolution of the Universe are correct. Questions like ‘what is the age of the Universe?’ or ‘what is the nature of the dark-matter?’ will be answered.

The mission was initially designed as COBRAS/SAMBA (Cosmic Background Radiation Anisotropy Satellite and Satellite for Measurement of Background Anisotropies) because it grew out of two mission proposals that had similar objectives. When the mission was approved in 1996, it was also renamed as Planck in honor of the German scientist Max Planck (1858 – 1947). Max Planck was awarded the Nobel Prize for Physics in 1918.

Credits: ESA

The mission is a collaborative effort. The Planck spacecraft was designed and built by a consortium led by Alcatel Alenia Space (Cannes, France). The telescope mirrors are manufactured by EADS Astrium (Friedrichshafen, Germany). The Low Frequency Instrument (LFI) was designed and built by a consortium led by the Instituto di Astrofisica Spaziale e Fisica Cosmica (IASF) in Bologna, Italy. The High Frequency Instrument (HFI) was designed and built by a consortium led by the Institut d’Astrophysique Spatiale (CNRS) in Orsay, France.

The Planck Mission has two predecessors: the Cosmic Background Explorer (COBE) and the Wilkinson Microwave Anisotropy Probe (WMAP).

Credits: ESA

The Planck spacecraft will be launched in early 2009 from Kourou, French Guiana. An Ariane 5 booster will place the spacecraft in a trajectory towards the L2 point. The L2 point stands for Second Lagrangian Point and it is located around 1.5 million kilometers away from Earth in a direction diametrically opposite the Sun. It will be a dual launch configuration, as the Herschel spacecraft will be launched together with Planck.

Between four to six months after the launch, Planck will reach its final position. It will take six more months before Planck will be declared operational.

Planck will perform scientific measurements for fifteen months, allowing two complete sky surveys. The spacecraft will be operational as along as there are resources for the cooling systems onboard.

For more details on the ESA’s Planck Mission you can visit the mission’s home page on the ESA website.

NASA’s return to the Moon requires careful preparation. Finding safe landing sites, locating potential resources, and taking measurements of the radiation environment are some of the tasks the Lunar Reconnaissance Orbiter (LRO) spacecraft will perform while in lunar orbit. LRO is an unmanned mission that will create a comprehensive atlas of the moon’s surface and resources.

The data gathered by LRO will be crucial in designing and building a permanent lunar outpost. The data will also be used to reduce the risk and increase the productivity of the future manned missions to the Moon.

The launch of LRO is scheduled for February 2009. An Atlas V rocket launched from the Kennedy Space Center will place the LRO on a transfer trajectory. After 4 days, the spacecraft will reach the Moon and after performing additional orbital maneuvers, it will move into its final orbit. The LRO’s final orbit will be a circular polar orbit 50 kilometers above the lunar surface.

Credits: NASA

The mission is designed to last for one year, with a possible extension. The total mass of the spacecraft is around 1,000 kilograms, of which 500 to 700 kilograms will be the fuel. The power is supplied by articulated solar arrays, and for the peak and eclipse periods a Li-Ion battery is used. The bandwidth of the communication link will be approximately 100-300 Mbps.

The LRO payload is comprised of six scientific instruments and one technology demonstration.

The Cosmic Ray Telescope for the Effects of Radiation (CRaTER) was built and developed by Boston University and the Massachusetts Institute of Technology in Boston. CRaTER will help explore the lunar radiation environment. The data gathered by measurements will help in the development of protective technologies that will keep future lunar crews safe.

The Diviner Lunar Radiometer Experiment (DLRE) was built and developed by the University of California, Los Angeles and the Jet Propulsion Laboratory in Pasadena, California. DLRE is capable of measuring surface and subsurface temperatures from orbit.

The Lyman-Alpha Mapping Project (LAMP) was built and developed at the Southwest Research Institute in San Antonio. LAMP will be used to map the entire lunar surface in the far ultraviolet spectrum.

Credits: NASA

The Lunar Exploration Neutron Detector (LEND) was developed at the Institute for Space Research in Moscow. This detector will create high-resolution maps of the hydrogen distribution and gather data about the neutron component of the lunar radiation.

The Lunar Orbiter Laser Altimeter (LOLA) was conceived and built at NASA’s Goddard Space Flight Center. LOLA will generate high-resolution three-dimensional maps of the moon’s surface.

The Lunar Reconnaissance Orbiter Camera (LROC), developed at Arizona State University at Tempe, will image the lunar surface in color and ultraviolet. LROC will be able to capture 1 m resolution images of the lunar poles.

The technology demonstration is called Mini-RF Technology Demonstration. The primary goal of this demonstration is to locate subsurface water ice deposits. The advanced single aperture radar (SAR) that will be used is capable of taking high-resolution imagery of the permanently shadowed regions on the lunar surface.

The data gathered by LRO will help us develop a better understanding of the lunar environment. This understanding is essential for a safe human return to the Moon and for the future exploration of our solar system.

Yes, they do. They really do! One of NASA’s deep space mission probes, New Horizons, is undergoing a check. The mission operators wake the spacecraft out of hibernation once a year. A number of checks are performed: the antennas must be pointed toward Earth, the trajectory must be corrected if needed, and instruments must be calibrated. These checks last more than a usual visit to a doctor… about 50 days. The operators verify the health of the spacecraft, perform maintenance on subsystems and instruments, and gather navigation data.

Credits: NASA

The highlight of the current check was the upload of a new version of the software that runs the spacecraft’s Command and Data Handling system. The brain transplant, as it was called, was a success. The mission team at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, sent the updates through NASA’s Deep Space Network (DSN) to the spacecraft. Two more updates are to be sent for both the Autonomy and Guidance and Control systems.

All commands that are sent to the spacecraft must pass a rigorous development and review process. After the command sequences are tested on the ground, the mission operations team will send them from the New Horizons Mission Operations Center at APL using the DSN, which is operated and managed by NASA’s Jet Propulsion Laboratory.

Credits: NASA

The New Horizons spacecraft was launched on January 19th, 2006 on top of an Atlas V rocket from Cape Canaveral Air Force Station, Florida.

The trajectory chosen for the probe is not complicated, as the probe is flying to Pluto using just one gravity boost from Jupiter. The journey consists of 5 segments: the early cruise, the Jupiter encounter, the interplanetary cruise, the Pluto-Charon encounter, and the Kuiper Belt.

During the early cruise segment of the voyage, spacecraft and instrument checkouts, instrument calibrations, and trajectory corrections were performed. Rehearsals for the Jupiter encounter were also conducted.

During the second segment of the voyage, the closest approach to Jupiter occurred on February 28th, 2007.

Credits: JHUAPL / SwRI

The third segment of the voyage consists mainly of spacecraft and instrument checkouts, trajectory corrections, instrument calibrations, and Pluto encounter rehearsals. This part of the voyage lasts for 8 years and is the current segment of the mission.

The Pluto-Charon encounter is planned for July 14th, 2015.

In the Kuiper Belt, plans are for one or two encounters with Kuiper Belt Objects (KBOs). These objects would be in the 40 to 90 kilometer size range and New Horizons would acquire the same data it collected during the Pluto-Charon encounter and send it back to Earth for analysis.

Credits: JHUAPL / SwRI

New Horizons is a small spacecraft. It weighs 478 kilograms in total, of which 77 kilograms is the hydrazine fuel, and 30 kilograms the scientific instruments. It measures 0.7×2.1×2.7 meters.

For communication with Earth, the spacecraft is using a 2.1 meter high-gain antenna. The data transfer rate is 38 kilobits per second at Jupiter, and 0.6 to 1.2 kilobits per second at Pluto. The data gathered during the encounter with Pluto will take 9 months to transmit back to Earth.

The scientific payload of the spacecraft draws less than 28 Watts of power. The mission uses a radioisotope thermoelectric generator (RTG) for power generation. The RTG contains 11 kilograms of plutonium dioxide. At the start of the mission, the RTG provided 240 Watts of energy at 30 Volts. Due to the decay of the plutonium, the power output decreases during the mission, and by the time of the Pluto encounter the RTG will only produce about 200 Watts.

The scientific instruments that were selected meet the mission’s goals. NASA set out a list of things it wanted to know about Pluto: the composition and behavior of the atmosphere, the appearance of the surface, the geological structures on the surface of Pluto, etc. The scientific payload contains seven instruments.

Credits: NASA

Ralph is a visible and infrared imager/spectrometer. It will obtain high-resolution color maps and surface composition maps of the surfaces of Pluto and Charon.

Alice is an ultraviolet imaging spectrometer. It will be used to analyze the composition and the structure of Pluto’s atmosphere and to look for atmospheres around Charon and Kuiper Belt Objects (KBOs).

REX is the Radio Science Experiment. It is a passive radiometer that measures atmospheric composition and temperature by using what is called an occultation technique: after passing Pluto, the spacecraft will point its antenna back to Earth and record the transmissions sent by the NASA’s DSN. The alterations of the transmissions caused by Pluto’s atmosphere will be recorded and sent back to Earth for analysis. REX will also be used to measure weak radio emissions from Pluto itself.

LORRI stands for Long Range Reconnaissance Imager. It is a telescopic camera and it will be used to obtain encounter data at long distances, to map Pluto’s far side and to provide high-resolution geologic data. LORRI will take images having 100-meter resolution.

SWAP, the solar wind and plasma spectrometer, stands for Solar Wind Around Pluto. It will measure the atmospheric escape rate and it will observe Pluto’s interaction with solar wind, determining whether Pluto has a magnetosphere or not.

Credits: NASA / JHUAPL

PEPSSI, Pluto Energetic Particle Spectrometer Science Investigation, is an energetic particle spectrometer used to measure the composition and density of plasma (ions) escaping from Pluto’s atmosphere.

SDC is the Student Dust Counter. It is the first scientific instrument built by students mounted on a space probe. It measures the space dust impacting the spacecraft during the voyage across the solar system, recording the count and the size of dust particles. It was built primarily by students from the University of Colorado in Boulder, with supervision from scientists.

If you want to know the present location of the spacecraft, there is a dedicated page on APL that you can visit.

For more information on the New Horizons Mission you can read the New Horizons Missions Guides document on the APL website.

The New Horizons Mission also has a page on Twitter.

Credits: ESA MPS for OSIRIS Team MPS/UPM/
LAM/IAA/RSSD/INTA/UPM/DASP/IDA

On September 6th, 2008, the ESA’s space probe Rosetta performed the first highlight on its 11 year mission: a close flyby the asteroid 2867 Steins. There are two more important events to occur during the mission, which are another flyby the asteroid 21 Lutetia in 2010 and the actual rendezvous with the comet 67/P Churyumov-Gerasimenko in 2014.

The Rosetta mission is special in many ways. It is the first mission to deploy a lander to the surface of a comet. It will also be the first to orbit the nucleus of a comet and to fly alongside a comet as it heads towards the inner Solar System.

Credits: ESA

Rosetta’s mission began on March 2nd, 2004, when the spacecraft lifted off from Kourou, French Guiana. In order to optimize the use of fuel, the probe has a very complicated trajectory to reach its final target, the comet 67/P Churyumov-Gerasimenko. The long trajectory includes three Earth-gravity assists (2004, 2007, and 2009) and one at Mars (2007). The probe uses the gravity wells of Earth and Mars to accelerate to the speed needed for the rendezvous with the comet. Most of the time, the probe is hibernating with the majority of its systems shut down in order to optimize the power consumption. At the time of the rendezvous, the remaining fuel will be used to slow down the probe to match the speed of the comet.

Credits: ESA/AOES Medialab

After reaching the comet, Rosetta will deploy a lander, called Philae, to the surface. While the probe will study the comet’s nucleus from a close orbit, the lander will take measurements from the comet’s surface. Because the gravity of the comet is very weak, the lander will use a harpoon to anchor itself to the surface.

Rosetta will stay with the comet more than one year, and during this time it will study one of the most primitive materials in the solar system. Scientists hope to discover the secrets of the physical and chemical processes that marked the beginning of the solar system some 5 billion years ago.

Credits: ESA/AOES Medialab

Traditionally, probes sent beyond the main asteroid belt employ radioisotope thermal generators (RTGs) as power generators. RTGs convert the heat from a radioactive source into electricity using an array of thermocouples. Instead, Rosetta is using solar cells for power generation. The probe deploys two impressive solar panels (a total area of 64 square meters). Even when close to the comet, the panels will be able to generate around 400 Watts of power. The panels can be rotated through +/- 180 degrees to track the Sun in every attitude assumed by the probe.

The probe is cube-shaped and measures 2.8×2.1×2.0 meters. At launch, it weighs 3,000 kg, including 1,670 kg of fuel, 165 kg of scientific payload for the orbiter, and 100 kg for the lander. The scientific instruments are accommodated on the lower side of the probe, which will be directed towards the comet during the last phase of the mission. Meanwhile, the probe will orbit the nucleus of the comet. A communication antenna 2.2 meters in diameter will be mounted on one side of the probe and on the opposite side the lander is attached. The other two lateral sides are used for anchoring the solar panels.

Credits: ESA/AOES Medialab

I was able to dig up more information about the probe and the lander in the mission launch kit on the EADS Astrium website.

The prime contractor for the spacecraft is Astrium Germany. The main sub-contractors are Astrium UK, Astrium France, and Alenia Spazio.

For propulsion and attitude control, the probe is using 24x10N bipropellant jets. The propulsion system is at the centre of the probe, where the tanks of propellant are located in the centre of a vertical tube.

I could not find an explanation as to why this design was chosen. Since the ability of the spacecraft to maneuver by using the onboard propulsion system is critical, I am assuming that the fuel tanks have to be protected from possible hits by micro meteorites.

Credits: ESA/AOES Medialab

The scientific instruments onboard Rosetta are: OSIRIS (Optical Spectroscopic and Infrared Remote Imaging System), ALICE (Ultraviolet Imaging Spectrometer), VIRTIS (Visible and Infrared Thermal Imaging System), MIRO (Microwave Instrument for Rosetta Orbiter), ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis), COSIMA (Cometary Secondary Ion Mass Analyser), MIDAS (Micro-Imaging Dust Analysis System), CONSERT (Comet Nucleus Sounding Experiment by Radiowave Transmission), GIADA (Grain Impact Analyser and Dust Accumulator), RPC (Rosetta Plasma Consortium), and RSI (Radio Science Investigation).

The lander is provided by a European consortium lead by the DLR (German Aeronautic Research Institute). Members of this consortium include ESA and the Austrian, Finnish, French, Hungarian, Irish, Italian, and British institutes.

Credits: ESA/AOES Medialab

The lander has a polygonal carbon fibre sandwich structure which is covered in solar cells. The antenna transmits data from the lander via the probe orbiting the comet.

There is an impressive collection of scientific instruments mounted on the lander as well: COSAC (Cometary Sampling and Composition experiment), MODULUS PTOMELY (Gas analyser), MUPUS (Multi-Purpose Sensors for Surface and Subsurface Science), ROMAP (Rosetta Lander Magnetometer and Plasma Monitor), SESAME (Surface Electrical Seismic and Acoustic Monitoring Experiments), APXS (Alpha X-ray Spectrometer), CONSERT (Comet Nucleus Sounding Experiment by Microwave Transmission), CIVA (Imager system using panoramic cameras), ROLIS (Rosetta Lander Imaging System used during the descend phase), and SD2 (Sample and Distribution Device, a sample acquisition system).

Credits: ESA

The scientific data collected by the instruments is transmitted to the Rosetta Mission Operations Centre (MOC) through a 8bps link. Due to the narrow bandwidth, the data cannot be sent back to Earth in real-time and has to be stored on the probe before being relayed.

The MOC at the European Space Operations Centre (ESOC) in Darmstadt has been controlling this long term mission since launch using ESA’s DSA 1 deep-space ground station at New Norcia.

It may seem like a long journey, but as in The Days of the Comet, the Rosetta mission could open up a whole new world of possibilities.