OrbitalHub

Credits: NASA/JPL

The Dawn spacecraft is currently performing the Mars flyby phase of its mission. The purpose of the Mars flyby is to alter the trajectory of the spacecraft in order to rendezvous with its first scientific target in the main asteroid belt.

The spacecraft will come within 549 km of the surface of Mars on February 17, 2009, at 4:28 PST.

The flyby is a gravity assist maneuver used in orbital mechanics to alter the trajectory of a spacecraft. The gravity assist is also known as a gravitational slingshot. The first ever gravity assist maneuver was performed by Mariner 10 in February 1974, and most of the interplanetary missions have made use of it since then.

The scientific objective of the Dawn mission is to answer important questions about the origin and the evolution of our solar system. The currently accepted theory about the formation of our solar system states that Jupiter’s gravity interfered with the accretion process, thereby preventing a planet from forming in the region between Jupiter and Mars. This led to the formation of the asteroid belt.

The asteroids chosen as scientific targets for the Dawn mission are Vesta and Ceres. Due to their size, they have survived the collisional phase, and it is believed that they have preserved the physical and chemical conditions of the early solar system. The asteroids have followed different evolutionary paths and have dissimilar characteristics, which makes them perfect research subjects.

Credits: NASA/JPL

The design of the Dawn spacecraft is based on Orbital’s STAR-2 series, and uses flight-proven components from other Orbital and JPL spacecraft: the propulsion system is based on the design used on Deep Space 1, the attitude control system used on Orbview, a hydrazine-based reaction control system used on the Indostar spacecraft, and command and data handling, as well as flight software, from the Orbview program.

The core structure of the spacecraft is a graphite composite cylinder, while the panels are aluminum core with aluminum/composite face sheets.

The central cylinder hosts the hydrazine and xenon tanks. The hydrazine tank can store 45 kg of fuel, while the xenon tank has a capacity of 450 kg.

The attitude control system (ACS) uses star trackers to estimate attitudes in cruise mode. A coarse Sun sensor (CSS) allows ACS to keep the solar panels normal to the Sun-spacecraft line. ACS also uses the hydrazine-based reaction control system for the control of attitude and for desaturation of the reaction wheels.

Credits: NASA/George Shelton

The solar panels are capable of producing more than 10 kW at 1 AU and 1 kW at 3 AU (on Ceres’ orbit).

The command and data handling system (CDHS) is based on a RAD6000 board running VxWorks. The software is written in C. There are 8GB available on the board as storage for engineering and scientific data.

The scientific payload consists of the Framing Camera (FC), the Gamma Ray and Neutron Detector (GRaND), and the visible and infrared (VIR) mapping spectrometer.

The FC will be used for determining the bulk density, the gravity field, for obtaining images of the surface, and for compiling topographic maps of Vesta and Ceres. In addition, the FC will capture images for optical navigation in the proximity of the asteroids. For reliability purposes, the payload includes two identical cameras that can run independently.

GRaND will serve for the determination of the elemental composition of the asteroids. GRaND is the result of the expertise accumulated during the Lunar Prospector and Mars Odyssey programs.

Credits: NASA/Jack Pfaller

VIR will help map the surface mineralogy of the asteroids. The instrument is a modified version of the visible and infrared spectrometer flying on the Rosetta mission.

The Dawn spacecraft uses ion propulsion to make its journey to Vesta and Ceres. Ion propulsion will also be used by Dawn during the low altitude flights over the asteroids.

While the fact that Dawn’s engines have a thrust of only 90 mN can hardly impress a reader, the important detail to mention when discussing propulsion systems is the specific impulse. Dawn’s engines have a specific impulse of 3100 s. For a chemical rocket, the specific impulse ranges from 250 s for solid rockets to 450 s for bipropellant liquid rockets. The only drawback (if this can be regarded as a drawback) is that the ion engines must be fired for much longer in order to achieve an equivalent trajectory.

With such high specific impulse engines, Dawn makes use of the fuel onboard in a very efficient way. The fuel used is xenon, a heavy noble gas placed in group 8A of the periodic table. The power produced by the large solar panels is used to ionize the fuel and then accelerate it with an electric field between two grids. In order to maintain a neutral plasma, electrons are injected into the beam after acceleration.

Credits: NASA/Amanda Diller

Dawn was launched from Cape Canaveral Air Force Station and injected on an interplanetary trajectory by a Delta II launch vehicle.

The main contributors to the Dawn mission are the University of California in Los Angeles (science lead, science operations, data products, archiving, and analysis), the Jet Propulsion Laboratory (project management, systems engineering, mission assurance, payload, navigation, mission operations, level zero data), and the Orbital Sciences Corporation (spacecraft design and fabrication, quality assurance, and payload integration).

The scientific payload was provided by the Los Alamos National Laboratory, the German Aerospace Center, the Max Planck Institute, and the Italian Aerospace Center. The Deep Space Network is responsible for data return from the spacecraft.

For more information about Dawn, you can visit the Dawn Mission Home Page on the JPL web site.

Credits: NASA

On January 3, 2004, the MER-A rover a.k.a. Spirit landed on Mars at the Gusev Crater. The second rover, MER-B a.k.a. Opportunity, followed twenty-one days later and landed at the Meridiani Planum.

They were both designed to operate for three months on the surface of Mars. Five years later, they are still operational and NASA has planned new missions for them.

Considering the harsh conditions on Mars, NASA’s twin rovers have accomplished remarkable things: they have returned a quarter-million images, driven more than thirteen miles, climbed a mountain, descended into impact craters, and survived dust storms. Using the Mars Odyssey orbiter as a communication relay, the rovers have sent more than 36 GB of scientific data back to Earth.

“These rovers are incredibly resilient considering the extreme environment the hardware experiences every day,” said John Callas, JPL project manager for Spirit and Opportunity. “We realize that a major rover component on either vehicle could fail at any time and end a mission with no advance notice, but on the other hand, we could accomplish the equivalent duration of four more prime missions on each rover in the year ahead.”

Credits: NASA

Digging into the MER mission archive, one detail caught my eye. The rovers carry plaques commemorating the crews of Columbia and Challenger, and some of the landmarks surrounding the landing sites of the rovers are dedicated to the astronauts of Apollo 1, Columbia, and Challenger.

Spirit is carrying a plaque commemorating the STS-107 Space Shuttle Columbia crew, which has been mounted on the high-gain antenna of the rover.

The names of the STS-107 crew are inscribed on the plaque: Rick D. Husband, William C. McCool, Michael P. Anderson, Kalpana Chawla, David M. Brown, Laurel B. Clark, and Ilan Ramon. Their names are now looking over the Martian landscapes.

To further honor their memory, the landing site of the MER Spirit is called the Columbia Memorial Station.

Credits: NASA

Three of the hills surrounding the Columbia Memorial Station are dedicated to the Apollo 1 crew: Gus Grissom, Ed White, and Roger Chafee. Grissom Hill is located 7.5 km to the southwest of Columbia Memorial Station, White Hill is 11.2 km northwest of the landing site, and Chafee Hill is located 14.3 km south-southwest of the landing site.

The area where Opportunity landed in the Meridiani Planum is called Challenger Memorial Station, in memory of the last crew of the Space Shuttle Challenger: Francis R. Scobee, Michael J. Smith, Judith A. Resnik, Ellison S. Onizuka, Ronald E. McNair, Gregory B. Jarvis, and Sharon Christa McAuliffe. I remember that Sharon Christa McAuliffe was NASA’s first teacher in space.

“The journeys have been motivated by science, but have led to something else important,” said Steve Squyres of Cornell University, in Ithaca, N.Y. Squyres is principal investigator for the rover science instruments. “This has turned into humanity’s first overland expedition on another planet. When people look back on this period of Mars exploration decades from now, Spirit and Opportunity may be considered most significant not for the science they accomplished, but for the first time we truly went exploring across the surface of Mars.”

Credits: NASA/JPL

The Mars Reconnaissance Orbiter (MRO) has completed the first phase of its science mission. During this phase, the orbiter returned seventy-three terabits of science data to Earth, which is more than all earlier Mars missions combined. The next phase of the MRO mission will take two years.

The list of scientific discoveries and observations made by MRO is stunning. We know now that Mars has a long history of climate change and that water was present in liquid form on its surface for hundreds of millions of years.

Signatures of a variety of watery environments have been observed, so future missions will be aware of locations that might reveal evidence of past life on Mars, if it ever existed.

MRO has imaged nearly forty percent of the Martian surface at such a high resolution that house-sized objects can be seen in detail. MRO has also conducted a mineral survey of the planet, covering sixty percent of its surface. Global weather maps were assembled using the data returned by MRO, and profiles of the subsurface and the polar caps have been put together using the radar mounted on MRO.

Credits: NASA/KSC

“These observations are now at the level of detail necessary to test hypotheses about when and where water has changed Mars and where future missions will be most productive as they search for habitable regions on Mars,” said Richard Zurek, Mars Reconnaissance Orbiter project scientist.

The images returned by MRO have been used by the Phoenix team to change the spacecraft’s landing site, and will help the NASA scientists select landing sites for future missions, like the Mars Science Laboratory (MSL).

Another role played by MRO was to relay commands to and to return data from the Phoenix lander during the five months the lander was operational on the Martian surface. MRO shared this task with the Mars Odyssey Orbiter.

MRO lifted off on August 12, 2005, from launch Complex 41 at Cape Canaveral Air Force Station. The cruise phase of the mission lasted seven months, the spacecraft reaching Mars orbit on March 10, 2006, after traveling on an outbound arc intercept trajectory.

MRO entered the final low orbit suited for science-data collection on November 2006, after slowing down in the Martian atmosphere by using aerobraking for five months. The first phase of the mission consisted in gathering information about Mars, and the remaining time left of its operational life will be dedicated mainly to using the spacecraft as a communication relay.

Credits: NASA/KSC

The declared goals of the MRO mission are: to determine whether life ever arose on Mars, to characterize the climate of Mars, to characterize the geology of Mars, and to prepare for human exploration.

The launcher of choice for the MRO mission was the Atlas V-401 launch vehicle, the smallest of the Atlas V family. This was the first launch of an Atlas V on an interplanetary mission.

The Atlas V-401 is a two-stage launch vehicle that does not use solid rocket boosters. The Atlas V-401 is fifty-seven meters tall and has a total mass at liftoff of 333,000 kg. Out of this, about 305,000 kg is fuel. In order to reach Mars orbit, MRO was accelerated to 11 km per second.

The first stage of the Atlas V, the Common Core Booster, is powered by liquid oxygen and RP-1. For the MRO mission, the first stage used a RD-180 engine. The RD-180 engine has an interesting story. It is a Russian-developed rocket engine, derived from the RD-170 used for the Zenit rockets.

Credits: NASA/JPL/KSC/Lockheed Martin Space Systems

Rights to use the RD-180 engine were acquired by General Dynamics Space Systems Division (later purchased by Lockheed Martin) in the early 1990s. The engine is co-produced by Pratt & Whitney and all production to date has been in Russia. According to Pratt & Whitney, RD-180 delivers a ten percent performance increase over current operational U.S. booster engines.

The stage weighs approximately 305,000 kg at launch and it provides about four million Newton of thrust for four minutes.

The upper stage of the Atlas V is the Centaur Upper Stage Booster. The Centaur is powered by liquid oxygen and liquid hydrogen. In the case of the MRO mission, it provided the remaining energy necessary to send the spacecraft to Mars.

The payload fairing used for the MRO mission was four meters in diameter. The role of the payload fairing was to protect the spacecraft from the weather on the ground as well as from the dynamic pressure during the atmospheric phase of the launch.

Lockheed Martin Commercial Launch Services developed the Atlas V as part of the US Air Force Evolved Expendable Launch Vehicle (EELV) program.

There are six science instruments, three engineering instruments, and two science-facility experiments carried by the MRO. The low orbit on which MRO is operating allowed the observation of the surface, atmosphere, and subsurface of Mars in unprecedented detail.

The science instruments are the HiRISE camera (High Resolution Imaging Science Experiment), the CTX camera (Context Camera), the MARCI camera (Mars Color Imager), the CRISM spectrometer (Compact Reconnaissance Imaging Spectrometer for Mars), the MCS radiometer (Mars Climate Sounder), and the SHARAD radar (SHAllow RADar).

Credits: HiRISE/MRO/LPL/NASA

The HiRISE camera provided the highest-resolution images from orbit to date, while the SHARAD can probe the subsurface using radar waves in the 15-25 MHz frequency band (these waves can penetrate the Martian crust up to one kilometer).

The engineering instruments assist the spacecraft navigation and communication. The Electra UHF Communications and Navigation Package is used as a communication relay between the Earth and landed crafts on Mars. The Optical Navigation Camera serves as a high-precision camera to guide incoming spacecrafts as they approach Mars. The Ka-band Telecommunications Experiment Package demonstrated the use of the Ka-band for power effective communications.

The science facility experiments are the Gravity Field Investigation Package, used for mapping the gravity field of Mars, and the Atmospheric Structure Investigation Accelerometers, which helped scientists understand the structure of the Martian atmosphere.

For more details on the MRO scientific payload, you can check out the dedicated page on the MRO mission web site.

The MRO was built by Lockheed Martin for NASA’s Jet Propulsion Laboratory in California. Fully loaded, the spacecraft had a mass of almost two tons. The spacecraft carried 1,149 kg of propellant for trajectory correction maneuvers and for the burns needed for the Mars capture.

Credits: NASA/JPL

The main bus of the spacecraft presents two massive solar arrays that can generate 2,000 W of power. On top, the high-gain antenna is the main means of communication with both Earth and other spacecrafts. The SHARAD antenna is the long pole behind the bus.

Other visible features are the HiRISE camera, the Electra telecommunications package, and the Context Imager (CTX).

You can visit the home page of the MRO mission on the NASA web site.

Credits: NASA

In 2002, an instrument on the Mars Odyssey spacecraft detected hydrogen under the Martian surface. This was regarded as clear evidence that there is subsurface water ice on Mars.

In 2003, NASA decided to revive a mission that was cancelled in 2001 due to the fact that a previous mission, the Mars Polar Lander, was lost in 1999. The revived mission was named Phoenix.

A Lander that could reach out and touch the ice was needed. The half-built spacecraft for the previously cancelled mission already had in place a 7.7-foot robotic arm that could do the trick.

A JPL team reviewed the data from the failed mission in 1999 and corrected the mistakes made. Every system used in the previous design was taken apart, tested, and examined. The suspected culprits were the retrorockets used during landing. More than a dozen issues that could have caused a failure of the new planned mission were found and fixed.

Credits: NASA / JPL

The Phoenix mission inherited a capable spacecraft partially built for the Mars Surveyor Program 2001. As we mentioned, the lessons learned from the Mars Polar Lander helped improve the existing systems. As for any other space mission, the conditions in which the spacecraft operates dictate the design.

In the case of the Phoenix mission, the following phases were considered: the launch, the cruise, the atmospheric entry, the touchdown, and the surface operations phase. The launch induces tremendous load forces and vibrations. The 10-month cruise to Mars exposes the spacecraft to the vacuum of space, solar radiation, and possible impacts with micrometeorites. During the atmospheric entry, the spacecraft is heated to thousands of degrees due to aero braking, and has to withstand tremendous deceleration during the parachute deployment. The extremely cold temperatures of the Martian arctic and the dust storms must be considered during the surface operations phase.

Credits: NASA / JPL

Several instruments are mounted on the Lander: the robotic arm (RA), the robotic arm camera (RAC), the thermal and evolved gas analyzer (TEGA), the Mars descent imager (MARDI), the meteorological station (MET), the surface stereo imager (SSI), and the microscopy, electrochemistry, and conductivity analyzer (MECA).

The RA was built by the Jet Propulsion Laboratory and was designed to perform the scouting operations on Mars, such as digging trenches and scooping the soil and water ice samples. RA delivered the samples to the TEGA and the MECA. RA is 2.35 meters long, it has an elbow joint in the middle, and it is capable of digging trenches 0.5 meters deep in the Martian soil.

The University of Arizona and the Max Planck Institute in Germany built the RAC. The camera is attached to the RA, just above the scoop placed at the end of the arm. RAC provided close-up, full-color images.

Credits: NASA / JPL

TEGA was developed by the University of Arizona and University of Texas, Dallas. TEGA used eight tiny ovens to analyze eight unique ice and soil samples. By employing a process called scanning calorimetry, and by using a mass spectrometer to analyze the gas obtained in the furnaces as the temperature raised to 1000 degrees Celsius, TEGA determined the ratio of various isotopes of hydrogen, oxygen, carbon, and nitrogen.

MARDI was built by Malin Space Science Systems. From what I could gather, the MARDI was not used by the Lander due to some integration issues.

The Canadian Space Agency (YAY Canada!) was responsible for the overall development of the meteorological station (MET). Two companies from Ontario, MD Robotics and Optech Inc., provided the instruments for the station.

The SSI served as the eyes of the Phoenix mission. SSI provided high-resolution, stereo, panoramic images of the Martian arctic. An extended mast holds the SSI, so the images were recorded from two meters above the ground.

Credits: NASA / JPL

MECA was built by the Jet Propulsion Laboratory. The instrument was used to characterize the soil by dissolving small amounts of soil in water. MECA determined the pH, the mineral composition, as well as the concentration of dissolved oxygen and carbon dioxide in the soil samples that were collected.

We would like to highlight some of the important moments during the mission:

August 4, 2007 – Delta II rocket launch from Cape Canaveral. The three-stage Delta II rocket with nine solid rocket boosters lifted off from Cape Canaveral, carrying the Phoenix spacecraft on the first leg of its journey to Mars.

Credits: NASA / JPL -Caltech / University of Arizona

May 25, 2008 – Phoenix Mars Lander touchdown. The Phoenix entered the Martian atmosphere at 13,000 mph. It took 7 minutes for the Lander to slow down with the aid of a parachute and to land using its retrorockets. The mission team did not have to wait long before discovering ice because the blasts from the retrorockets had blown away the topsoil during landing and revealed ice patches under the lander.

November 2, 2008 – Last signal received from the Lander. On this date, communication was established for the last time with Phoenix. Due to the latitude of the landing site, not enough sunlight is available and the solar arrays are unable to collect the power necessary to charge the batteries that operate the instruments mounted on the Lander. At the landing site, the weather conditions are worsening.

November 10, 2008 – Mission declared completed. NASA declares that the Mars Phoenix Lander has completed a successful mission on the Red Planet. Phoenix Mars Lander has ceased communications after being operational for more than five months (the designed operational life of the mission was 90 days).

November 13, 2008 – Mission Honored. NASA’s Phoenix Mars Lander was awarded Best of What’s New Grand Award in the aviation and space category by Popular Science magazine.

Credits: NASA / JPL

The Mars Phoenix Lander made significant contributions to the study of the Red Planet. Phoenix verified the presence of water ice under the Martian surface, and it returned thousands of pictures from Mars. Phoenix also found small concentrations of salts that could be nutrients for life, it discovered perchlorate salt, and calcium carbonate, which is a marker of effects of liquid water.

Phoenix provided a mission long weather record, with data on temperature, pressure, humidity, and wind, as well as observations on snow, haze, clouds, frost, and whirlwinds.

Principal Investigator Peter H. Smith of the University of Arizona led the Phoenix mission. The project management was done at NASA’s Jet Propulsion Laboratory and the development at Lockheed Martin Space Systems in Denver. Other contributors were the Canadian Space Agency, the University of Neuchatel (Switzerland), the University of Copenhagen (Denmark), the Max Planck Institute (Germany), and the Finnish Meteorological Institute.

For more information about the Phoenix mission, check out the NASA Phoenix Mars Lander Page.

Credits: ESA/AOES Medialab

In a previous post, we presented the Planck spacecraft. We would like to dedicate this post to Planck’s big brother, Herschel. Why b(r)other? Because Planck and Herschel will be launched into space by the same Ariane 5 launcher and they will share the fairing section during the launch phase of the mission. Why big? Well, because Herschel is a larger spacecraft than Planck… actually Herschel is the largest space telescope ever built.

Just to have an idea about the size of the infrared telescope onboard the Herschel spacecraft, the primary mirror has a diameter of 3.5 m and a mass of only 350 kg. In comparison, the mirror of the Hubble space telescope has a diameter of 2.4 m and a mass of 1.5 tons. Obviously, a great deal of effort has been put into minimizing the mass of the telescope, an advance made possible by present-day technology.

The infrared telescope will become operational four months after its launch and will have a nominal mission lifetime of three years. The objectives that ESA set for the Herschel Space Observatory are ambitious: the study of the galaxies in the early universe, the investigation of the creation of stars, the observation of the chemical composition of the atmosphere and surfaces of comets, planets and satellites, as well as examining the molecular chemistry of the universe.

Like Planck, Herschel will observe the sky from the second Lagrangean Point (L2) of the Sun-Earth system. The instruments onboard Herschel will collect long-wavelength infrared radiation. Herschel will be the only space observatory to cover the spectral range from the far infrared to sub-millimeter, which is the reason why the initial name of the space observatory was Far Infrared and Sub-millimeter Telescope (FIRST).

Credits: ESA

The Herschel spacecraft will have 3.3 tons at launch, with a length of 7.5 m and a cross section of 4×4 m. The spacecraft comprises of two modules: the service module and the payload module. While the service module contains the systems for power conditioning, attitude control, data handling and communications, and the warm parts of the scientific instruments, the payload module contains the telescope, the optical bench, the cold parts of the scientific instruments and the cooling system. A sunshield protects the telescope and the cryostat from solar radiation. The sunshield also carries solar cells for power generation.

In order to make accurate observations of the infrared spectrum, parts of the scientific instruments onboard have to be cooled to temperatures close to absolute zero. Two thousand liters of liquid helium will be used for primary cooling during the mission. In addition, each detector onboard is equipped with additional cooling systems.

Credits: ESA/Guarniero

Herschel will not be the first infrared telescope launched into space. There are three predecessors that we would like to mention here: IRAS, the US-Dutch-British satellite launched in 1983, ISO – launched by ESA in 1995, and the NASA’s Spitzer Space Telescope – launched in 2003. However, these three infrared space telescopes were operated on Earth orbits. As we mentioned, Herschel will operate in the L2 point, away from any interference that would affect the scientific instruments onboard. Operating in the L2 point will also help with regard to thermal stability because the spacecraft will not move in and out of eclipse regions.

The launch date is set for early 2009. The journey to the final operational position will take around four months. The European Space Operations Control Center (ESOC) in Darmstadt will coordinate the mission.

Credits: NASA GSFC

The solar wind generated by our Sun carves out a protective bubble around the solar system, called the heliosphere. The interstellar medium, consisting of the gas and the dust found between the galaxies, interacts with the solar wind and defines the actual boundary, which is called the termination shock.

NASA has designed a mission to map the boundary of the solar system. The mission is called IBEX (Interstellar Boundary Explorer) and it is ready to launch. The data collected by IBEX will allow scientists to understand the interaction between our Sun and the galaxy for the first time. Understanding this interaction will help us protect future astronauts from the danger of galactic cosmic rays.

In January 2005, the Orbital Science Corporation was selected to develop, build, and launch a small spacecraft for NASA’s IBEX mission. The IBEX spacecraft is based on an already existing bus: the MicroStar satellite. IBEX will be launched by a Pegasus XL rocket, which will be dropped from an aircraft flying over the Pacific Ocean.

Credits: NASA GSFC

Pegasus began its commercial career in April 1990, and since then it has launched more than 80 satellites into space.

Pegasus is a three-stage launching system used to deploy small satellites weighing up to 1,000 pounds into Low Earth Orbit (LEO). An aircraft carries Pegasus to an altitude of 40,000 feet.

The rocket is released and free-falls before igniting its engines. It takes roughly ten minutes for Pegasus to deliver a satellite into orbit.

Pegasus will place IBEX into a 130 mile altitude orbit. An extra solid-fueled rocket will boost the spacecraft from the LEO. IBEX’s final orbit will be a highly elliptical orbit with the perigee at an altitude of 7,000 km and the apogee at 236,000 km. IBEX has to operate in this orbit because any interference from the Earth’s magnetosphere would make it impossible to take accurate measurements with the scientific instruments onboard.

Credits: NASA GSFC

IBEX has a mass of only 83.33 lbs (roughly 38 kg) and is described by NASA as being the size of a bus tire. The instruments onboard IBEX will collect particles called energetic neutral atoms (ENAs). The ENAs are radiated from the termination shock region. The ENA hits recorded by the instruments onboard IBEX will be used to create a map of this region.

The mission is scheduled to launch tomorrow, October 19th, 2008. The spacecraft will be operational for 24 months. You can find out more about the IBEX spacecraft on NASA’s IBEX mission web page.