Posts Tagged ‘space exploration’

Slice of History: Low Speed Wind Tunnel

Monday, July 11th, 2011

By Julie Cooper

Each month in “Slice of History” we feature a historical photo from the JPL Archives. See more historical photos and explore the JPL Archives at https://beacon.jpl.nasa.gov/.

Low Speed Wind Tunnel
Low Speed Wind Tunnel — Photograph Number 383-6109Bc

In December 1974, this photo was taken of the Low Speed Wind Tunnel. NASA’s Jet Propulsion Laboratory had 21-, 20-, and 12-inch wind tunnels that were very well documented, but an April 1967 report about JPL wind tunnels does not mention this facility and very little is known about it. It appears in 1961 drawings of building 80, which was next door to the main wind tunnel building but it may have been relocated years later. The March 1968 JPL telephone book indicates that there was a Low Density Wind Tunnel in building 183, room 601, belonging to the Fluid Physics Section. The section number prefix for this image indicates that it was photographed for the Research and Advanced Concepts Section, but the photo was taken at the request of Paul Massier of the Structures and Dynamics Section. Massier was seen in the June “Slice of History” blog taken in the anechoic chamber.

This post was written for “Historical Photo of the Month,” a blog by Julie Cooper of JPL’s Library and Archives Group.


Out of This World (Literally): Week One

Friday, June 24th, 2011

By Andrew Crawford

He’s already been a classical violinist and a professional snowboarder. Now mechanical/aerospace engineering student and Montana-native Andrew Crawford is learning what it’s like to be an intern at NASA’s Jet Propulsion Laboratory. This summer, he’ll share his experiences working in the Deep Space Network’s Antenna Mechanical group. Read his full blog on the JPL Education website.

Jason Carlton oversees transportation of the Mars Science Laboratory rover
My mentor Jason Carlton oversees the high-bay hoisting of the spreader bar used to lift and stack the Mars Science Laboratory rover Curiosity and the rover container. Does it get much cooler than bunny suits?!

Checking in … beep-beep … beep-beep.

It’s been an incredible and almost surreal week in the land of jet propulsion, and to try and summarize the emotions and sights into words is daunting, as the vocabulary escapes me.

It seems as though around every corner, you meet someone who is so friendly and inspiring that it’s hard not to just smile and try and listen in amazement. From sending beeps aimed at distant galaxies looking for anomalies in the return signal, to brilliant twenty-somethings building descent stage thrusters capable of hovering above the surface of Mars like a UFO, to the beautiful array of different languages and cultures you hear just on your way to the coffee grove, the people and mission here make it hard to contain a smile.

The department I’m writing from is the Deep Space Network (DSN), Antenna Mechanical Group, an incredibly diverse group of people who have welcomed me with open arms. Comprised of a complex network and interface of all different departments and jobs, the DSN is responsible for monitoring all spacecraft currently exploring the universe, searching the night sky for signals and pushing the envelope of what is possible for future communication and data acquisition.

I have an official government NASA office with a phone and voice mail to boot, and the speed and vigor at which things move around here is mind-blowing. It seems imperative to listen and write fast, even if what you’re hearing seems unreal or beyond belief, and before you know it, you’re neck deep in documents and learning curves that didn’t seem possible when you got out of bed this morning. The part I enjoy tremendously is walking outside my office and seeing my fellow DSN antenna mechanical office mates, who are mechanical, civil, structural, aerospace engineers, attacking a white dry erase board with looks of determination. They make cuts in beams, figure out angles and calculate distributed loads in order to find failure points for future antenna-component construction, all of which Effat Rady, my amazing engineering professor at Montana State University has taught me and stressed the importance of, time and time again. It seems as thought the days are lightning quick here, and the only thing I can seem to do after riding my bike home is run in the San Gabriel mountains as far as I can to try to process everything that happened in a day.

The Mars Science Laboratory rover, Curiosity, the largest and most intelligent rover to date, departed the Lab this morning after years of complete dedication and planning by thousands of people.

I was one of a handful of people who was lucky enough to witness the incredible entourage and police escort of the rover — sending it one step further on its quest to explore where Mankind has not yet set foot — as my mentor Jason Carlton was an integral part of the rover, descent stage, and heat shield container builds, assembly, and mating of all components with their transports. He is with the rover as I write this now, bound for the NASA’s Kennedy Space Center aboard an Air Force plane, probably forty-thousand feet above you.

As I write, I’m sitting in the Media Relations Office at JPL bouncing off the walls as my blog goes live, now getting to share this amazing experience and my enthusiasm for this wonderful launching pad of planetary exploration.

› Read Andrew’s full blog on the JPL Education website


Dawn Sets its Sights, and Lens, on Vesta

Friday, June 24th, 2011

By Marc Rayman

NASA’s Dawn spacecraft is less than one month away from getting into orbit around its first target, the giant asteroid Vesta. Each month, Marc Rayman, Dawn’s chief engineer, shares an update on the mission’s progress.

Image of the giant asteroid Vesta from Dawn's approach
NASA’s Dawn spacecraft obtained this image on its approach to the protoplanet Vesta, the second-most massive object in the main asteroid belt. Image Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/PSI. › See more images

Dear Dawnstinations,

Vesta beckons, and Dawn responds. Now more than halfway through its approach to Vesta, Dawn continues creeping up on the destination it has been pursuing since it began its interplanetary travels. The separation between them gradually shrinks as the probe’s ion thrusting brings its orbit around the sun into a closer and closer match with Vesta’s. At the same time, the giant protoplanet’s gravity tugs gently on the approaching ship, luring it into orbit.

Starting at the beginning of the approach phase on May 3, Dawn interrupted thrusting once a week to photograph Vesta against the background stars. These images help navigators determine exactly where the probe is relative to its target. This technique does not replace other means of navigation but rather supplements them. One of the principal methods of establishing the spacecraft’s trajectory relies on accurately timing how long it takes radio signals, traveling, as all readers know, at the universal limit of the speed of light, to make the round trip between Earth and Dawn. Another uses the Doppler shift of the radio waves, or the slight change in pitch caused by the craft’s motion. These sensitive measurements remain essential to navigating the faraway ship as it sails the interplanetary seas.

Despite the very slow approach, the distance is small enough now that observing Vesta weekly is no longer sufficient. To achieve the navigational accuracy required to reach the intended orbit in early August, last week the frequency of imaging was increased to twice per week. In each session, half of the pictures are taken with long exposures to ensure many stars are detectable, thus overexposing the much brighter disc of the nearby Vesta. The other half use short exposures to ensure that the rocky world shows up correctly so its precise location can be measured. The visible and infrared mapping spectrometer has been commanded to observe Vesta during three of these sessions, each time providing valuable information that will help scientists select instrument settings for when Dawn is close enough to begin its detailed scientific measurements.

In addition to the regular campaign of imaging for navigation, mission controllers have other plans in store for the approach phase that were laid out more than a year ago. Twice in the next few weeks, the spacecraft will watch Vesta throughout its complete 5.3-hour rotation on its axis, revealing exciting new perspectives on this uncharted body. The explorer also will search for moons of the alien world.

› Continue reading Marc Rayman’s June 23, 2011 Dawn Journal


A Heartfelt Goodbye to a Spirited Mars Rover

Wednesday, May 25th, 2011

By John Callas

Mars Exploration Rover Project Manager John Callas sent this letter to his team shortly after the final command was sent to the Mars rover Sprit, which operated on the surface of Mars for more than six years and made numerous scientific discoveries.

Artist's concept of NASA's Mars Exploration Rover
Artist’s concept of NASA’s Mars Exploration Rover. Image credit: NASA/JPL-Caltech

Dear Team,

Last night, just after midnight, the last recovery command was sent to Spirit. It would be an understatement to say that this was a significant moment. Since the last communication from Spirit on March 22, 2010 (Sol 2210), as she entered her fourth Martian winter, nothing has been heard from her. There is a continued silence from the Gusev site on Mars.

We must remember that we are at this point because we did what we said we would do, to wear the rovers out exploring. For Spirit, we have done that, and then some.

Spirit was designed as a 3-month mission with a kilometer of traverse capability. The rover lasted over 6 years and drove over 7.7 kilometers [4.8 miles] and returned over 124,000 images. Importantly, it is not how long the rover lasted, but how much exploration and discovery Spirit has done.

This is a rover that faced continuous challenges and had to fight for every discovery. Nothing came easy for Spirit. When she landed, she had the Sol 18 flash memory anomaly that threatened her survival. Scientifically, Mars threw a curveball. What was to be a site for lakebed sediments at Gusev, turned out to be a plain of volcanic material as far as the rover eye could see. So Spirit dashed across the plains in an attempt to reach the distant Columbia Hills, believed to be more ancient than the plains.

Exceeding her prime mission duration and odometry, Spirit scrambled up the Columbia Hills, performing Martian mountaineering, something she was never designed to do. There Spirit found her first evidence of water-altered rocks, and later, carbonates.

The environment for Spirit was always harsher than for Opportunity. The winters are deeper and darker. And Gusev is much dustier than Meridiani. Spirit had an ever-increasing accumulation of dust on her arrays. Each winter became harder than the last.

It was after her second Earth year on Mars when Spirit descended down the other side of the Columbia Hills that she experienced the first major failure of the mission, her right-front wheel failed. Spirit had to re-learn to drive with just five wheels, driving mostly backwards dragging her failed wheel. It is out of this failure that Spirit made one of the most significant discoveries of the mission. Out of lemons, Spirit made lemonade.

Each winter was hard for Spirit. But with ever-accumulating dust and the failed wheel that limited the maximum achievable slope, Spirit had no options for surviving the looming fourth winter. So we made a hard push toward some high-value science to the south. But the first path there, up onto Home Plate, was not passable. So we went for Plan B, around to the northeast of Home Plate. That too was not passable and the clock was ticking. We were left with our last choice, the longest and most risky, to head around Home Plate to the west.

It was along this path that Spirit, with her degraded 5-wheel driving, broke through an unseen hazard and became embedded in unconsolidated fine material that trapped the rover. Even this unfortunate event turned into another exciting scientific discovery. We conducted a very ambitious extrication effort, but the extrication on Mars ran out of time with the fourth winter and was further complicated by another wheel failure.

With no favorable tilt and more dust on the arrays, Spirit likely ran out of energy and succumbed to the cold temperatures during the fourth winter. There was a plausible expectation that the rover might survive the cold and wake up in the spring, but a lack of response from the rover after more than 1,200 recovery commands were sent to rouse her indicates that Spirit will sleep forever.

But let’s remember the adventure we have had. Spirit has climbed mountains, survived rover-killing dust storms, rode out three cold, dark winters and made some of the most spectacular discoveries on Mars. She has told us that Mars was once like Earth. There was water and hot springs, the conditions that could have supported life. She has given us a foundation to further explore the Red Planet and to understand ourselves and our place in the universe.

But in addition to all the scientific discoveries Spirit has given us in her long, productive rover life, she has also given us a great intangible. Mars is no longer a strange, distant and unknown place. Mars is now our neighborhood. And we all go to work on Mars every day. Thank you, Spirit. Well done, little rover.

And to all of you, well done, too.

Sincerely,
John

› Learn more


Slice of History: Low Temperature Propellant Tests

Monday, May 16th, 2011

By Julie Cooper

Each month in “Slice of History” we’ll be featuring a historical photo from the JPL Archives. See more historical photos and explore the JPL Archives at https://beacon.jpl.nasa.gov/.

liquid propellant jet
Low Temperature Propellant Tests — Photograph Number 6-8

It was 1943 and JPL was at the beginning stages of rocket motor research and development.  Over the next decades, JPL would design and test rocket motors with a variety of sizes and propellants.  This small (50 pound thrust) liquid propellant jet unit was immersed in a bath of ice and salt in order to test the ignition properties of the propellants at temperatures near 0°F. 

This post was written for “Historical Photo of the Month,” a blog by Julie Cooper of JPL’s Library and Archives Group.


Dawn Begins its Vesta Phase

Tuesday, May 3rd, 2011

By Marc Rayman

NASA’s Dawn spacecraft is less than three months away from getting into orbit around its first target, the giant asteroid Vesta. Each month, Marc Rayman, Dawn’s chief engineer, shares an update on the mission’s progress.

Artist's concept of the Dawn spacecraft
Artist’s concept of NASA’s Dawn spacecraft. The giant asteroid Vesta, Dawn’s next destination, is on the lower left. The largest body in the asteroid belt and Dawn’s second destination, dwarf planet Ceres, is on the upper right. Image credit: NASA/JPL-Caltech

Dear Dawntalizingly Close Readers,

Dawn is on the threshold of a new world. After more than three and a half years of interplanetary travel covering in excess of 2.6 billion kilometers (1.6 billion miles), we are closing in on our first destination. Dawn is starting its approach to Vesta.

The interplanetary cruise phase of the mission ends today and the 15-month Vesta phase begins. The first three months are the “approach phase,” during which the spacecraft maneuvers to its first science orbit. Many of the activities during approach were discussed in detail in March and April last year, and now we are about to see those plans put into action.

The beginning of the phase is marked by the first images of the alien world Dawn has been pursuing since it left Earth. Vesta will appear as little more than a smudge, a small fuzzy blob in the science camera’s first pictures. But navigators will analyze where it shows up against the background stars to help pin down the location of the spacecraft relative to its target. To imagine how this works, suppose that distant trees are visible through a window in your house. If someone gave you a photo that had been taken through that window, you could determine where the photographer (Dawn) had been standing by lining up the edge of the window (Vesta) with the pattern of the background trees (stars). Because navigators know the exact position of each star, they can calculate where Dawn and Vesta are relative to each other. This process will be repeated as the craft closes in on Vesta, which ultimately will provide a window to the dawn of the solar system.

Even though the mysterious orb is still too far away to reveal new features, it will be exciting to receive these first pictures. During the approach phase, images will be released in periodic batches, with priority viewing for residents of Earth. The flow will be more frequent thereafter. For most of the two centuries that Vesta has been studied, it has been little more than a pinpoint of light. Interrupting thrusting once a week this month to glimpse its protoplanetary destination, Dawn will watch it grow from about five pixels across to 12. By June, the images should be comparable to the tantalizing views obtained by the Hubble Space Telescope. As the approach phase continues and the distance diminishes, the focus will grow still sharper and new details will appear in each subsequent set of images.

› Continue reading Marc Rayman’s May Dawn Journal


Alien Vs. Editor: Life As We May (or May Not) Know It

Monday, April 18th, 2011

By Steve Edberg

Alien vs. Editor is a forum for questions and answers about extrasolar planets and NASA’s search for life beyond our solar system. Leave your questions for author Steve Edberg and read more on the PlanetQuest website.

Tubeworms
Tubeworms that grow near the boundary where hot vent fluid mixes with cold seawater on the ocean floor are an example of extremophiles that broaden our perspective on where to look for life. Image credit: Nicolle Rager Fuller, National Science Foundation

A reader’s question (paraphrased): Why do astronomers assume there have to be conditions similar to Earth in order for life to exist? Who are we to define what life looks like and how would we know what we’re looking at if we really don’t know what we are looking for?

This has been a recurring question over the years, and I don’t think anyone interested in finding extraterrestrial life would dispute those thoughts. The problem is that we aren’t as clever as Mother Nature, so we don’t know what else to look for. More practically, we don’t know what other conditions to look for beyond those we are familiar with.

Science fiction writers have used their imaginations to propose other forms of life. Sir Fred Hoyle (an astronomer) wrote a novel titled “The Black Cloud,” (SPOILER/GIVEAWAY ALERT!! SKIP THE REST OF THIS SENTENCE IF YOU THINK YOU WILL READ THE BOOK) about a self-propelling interstellar cloud that came to orbit the sun to acquire energy (it stopped for lunch!) before moving on.

On the TV shows “Star Trek” and “Star Trek: The Next Generation,” the screenwriters came up with at least two forms of life that were completely novel. Naturally enough, the shows involving them were about recognizing that they were life and how to deal with it. The one on “Star Trek” was about rock-beings that tunneled through an asteroid or planet. The other, on “Star Trek TNG,” was about “nanites,” microscopic silicon crystals that were hive-like beings communicating among themselves electrically and with electromagnetic waves with the crew of Enterprise D.

These are three examples of potential life forms far different from what we are familiar with. But knowing what to look for and where is a long step from the presentation of these ideas in science fiction media.

Before the Viking landings on Mars in the 1970s, Carl Sagan gave talks about the life-detecting instruments aboard the landers, which were designed to detect life as we know it. He also mentioned that there was a camera aboard so that we could see any “silicon-based giraffes that might walk by,” so even then scientists were thinking about possible, unfamiliar forms of life.

The strategy being followed is to look for evidence of extraterrestrial life, as we recognize life, now, rather than wait until we figure out all the possibilities. Scientists study and search for new examples of “extremophiles” that live in extreme conditions compared to what most of life on Earth lives in, in order to broaden our perspective on where to look for life.

There are also radio and optical searches for evidence of extraterrestrial intelligence living (by whatever chemical process) on planets orbiting other stars that might be announcing their presence. And I recently heard that there is a meeting planned to consider what else we might look for in this arena, considering that the era of our radio transmissions out to the galaxy (TV and radio) could be coming to an end as we use more cable and fiber communications here on Earth.


Dawn Spacecraft Getting Ready for Vesta

Friday, April 1st, 2011

By Marc Rayman

NASA’s Dawn spacecraft is less than four months away from getting into orbit around its first target, the giant asteroid Vesta. Each month, Marc Rayman, Dawn’s chief engineer, shares an update on the mission’s progress.

Artist's concept of the Dawn spacecraft
Artist’s concept of NASA’s Dawn spacecraft. Image credit: NASA/JPL-Caltech

Dear Conndawnsseurs,

Three and a half years after launch, Dawn continues its travels around the sun, maneuvering to take the same orbital path as Vesta. Following its usual pattern, the spacecraft has spent most of the past month gently thrusting with its ion propulsion system. Some of the thrusting this month, however, was not designed to propel Dawn to Vesta. In addition, mission controllers stopped the thrusting to conduct other planned activities.

Spacecraft that use conventional propulsion coast through space most of the time, just as the moon coasts around Earth, and the planets and asteroids coast around the sun. In contrast, Dawn is in powered flight most of the time, using its ion propulsion system to change its orbit. The flight plan requires pointing the ion thruster in just the right direction to deliver the adventurer to its destination. The spacecraft orientation needed to aim the thruster ends up pointing the main antenna in an arbitrary direction. We have seen before that the robotic craft interrupts thrusting for about eight hours each week to direct the antenna toward Earth for communications.

Ever since Dawn’s trajectory was first being designed, long before launch, it has included coast periods for activities that require orientations incompatible with routine thrusting. One such period was the week of March 14; the previous was in July 2010.

Engineers and scientists operate the science instruments about twice each year to ensure they remain in good condition. This time was the last scheduled use of the sensors prior to their observations of Vesta. All tests showed they are in excellent condition and ready to expose the mysteries of the world they are about to visit.

Controllers transmitted upgraded software to each of the two identical science cameras, containing a few improvements over the version installed in July. The procedure went as smoothly as it had for previous software updates, including the first time such an operation was performed. After each camera received its new software, it performed its standard routine of exercises, just as it did only three weeks after reaching space. The tests confirmed that each camera’s electronics, optics, detector, cover, and filter wheel are in perfect condition.

Sometimes the spacecraft is turned to aim the cameras at carefully selected astronomical targets for their tests; other times, they take pictures of whatever stars happen to be in their field of view. This month’s tests were of the latter type, in which the orientation of the spacecraft was set to keep the antenna pointed at Earth. That put stars from a region near the border between Pisces and Cetus in the grasp of the cameras, quite appropriate for a ship voyaging across the cosmic ocean on its way to a distant and unfamiliar land.

Continue reading this entry from Marc Rayman’s Dawn journal …


Red, Red Moon and Other Lunar Eclipse Phenomena

Monday, December 20th, 2010

By Dr. David Diner

Total Lunar EclipseTiny airborne particles, or aerosols, can affect the appearance of the moon during a total lunar eclipse, sometimes giving it a reddish hue. Copyright Ian Sharp

A lunar eclipse occurs when the Earth is positioned between the sun and the moon. Although the Moon passes through the Earth’s shadow, the lunar disk remains partially illuminated by sunlight that is refracted and scattered by the Earth’s atmosphere.

Refraction is the bending of light that occurs when the rays pass through media of different densities (our atmosphere is more dense near the surface and less dense higher up). Scattering of sunlight by molecules of air also deflects the light into different directions, and this occurs with much greater efficiency at shorter (bluer) wavelengths, which is why the daylight sky appears blue. As we view the sun near sunrise or sunset the light traverses a longer path through the atmosphere than at midday, and when the air is relatively clear, the absence of shorter wavelengths causes the solar disk to appear orange.

Tiny airborne particles, also known as aerosols, also scatter sunlight. The relative efficiency of the scattering at different wavelengths depends on the size and composition of the particles. Pollution and dust in the lower atmosphere tends to subdue the color of the rising or setting sun, whereas fine smoke particles or tiny aerosols lofted to high altitudes during a major volcanic eruption can deepen the color to an intense shade of red.

If you were standing on the Moon’s surface during a lunar eclipse, you would see the Sun setting and rising behind the Earth, and you’d observe the refracted and scattered solar rays as they pass through the atmosphere surrounding our planet. Viewed from the Earth, these rays “fill in” the Earth’s shadow cast upon the lunar surface, imparting the Moon’s disk with a faint orange or reddish glow. Just as we sometimes observe sunrises and sunsets with different shades of orange, pink or red due to the presence of different types of aerosols, the color of the eclipsed lunar disk is also affected by the types of particles that are present in the Earth’s atmosphere at the time the eclipse occurs.


Lunar Eclipse, the Moon’s Interior, and the Holy GRAIL

Wednesday, December 15th, 2010

By Sami Asmar

Earth's moon

In addition to the awesome views they offer, lunar eclipses have always provided scientific clues about the moon’s shape, location and even surface composition. Although there will continue to be opportunities for observers to examine and reflect on fundamental concepts about the moon, such as its origin and interior structure, more modern tools are aiding these observations.

When it comes to understanding what a moon or a planet is made of remotely — short of touching it or placing seismometers on its surface or probes below the surface — classical physics comes to the rescue. By measuring the magnetic and gravitational forces that are generated on the inside and manifested on the outside of a planet or moon, we can learn volumes about the structure of its interior.

A spacecraft in the proximity of the moon can detect these forces. In the case of gravity, the mass of the moon will pull on the spacecraft due to gravitational attraction. If the spacecraft is transmitting a stable radio signal at the time, its frequency will shift by an amount exactly proportional to the forces pulling on the spacecraft.

This is how we weigh the moon and go further by measuring the detailed distribution of the densities of mountains and valleys as well as features below the moon’s surface. This collection of information is called the gravity field.

In the past, this has lead to the discovery mascons on the moon, or hidden, sub-surface concentrations of mass not obvious in images or topography. If not accounted for, mascons can complicate the navigation of future landed missions. A mission, human or robotic, attempting to land on the moon would need to have a detailed knowledge of the gravity field in order to navigate the landing process safely. If a spacecraft sensed gravitational pull higher than planned, it could jeopardize the mission.

GRAIL spacecraft

The Gravity Recovery and Interior Laboratory (GRAIL) mission, scheduled to launch in September, is comprised of twin spacecraft flying in formation with radio links between them to measure the moon’s gravity field globally. This is because a single spacecraft with a link to Earth would be obstructed when the spacecraft goes behind the moon, leaving us with no measurement for nearly half of the moon, since the moon’s far side never faces the Earth. The GRAIL technique may also reveal if the Moon has a core with a fluid layer.

So as you go out to watch the lunar eclipse on the night of Dec. 20, think about how much we’ve learned about the moon so far and what more we can learn through missions like GRAIL. Even at a close distance from Earth, the moon remains a mystery waiting be uncovered.