Black holes

Black Holes: What Are They?

Black holes are the evolutionary endpoints of stars at least 10 to 15 times as massive as the Sun. If a star that massive or larger undergoes a supernova explosion, it may leave behind a fairly massive burned out stellar remnant. With no outward forces to oppose gravitational forces, the remnant will collapse in on itself. The star eventually collapses to the point of zero volume and infinite density, creating what is known as a “singularity ". Around the singularity is a region where the force of gravity is so strong that not even light can escape. Thus, no information can reach us from this region. It is therefore called a black hole, and its surface is called the “event horizon ".

But contrary to popular myth, a black hole is not a cosmic vacuum cleaner. If our Sun was suddenly replaced with a black hole of the same mass, the Earth's orbit around the Sun would be unchanged. (Of course the Earth's temperature would change, and there would be no solar wind or solar magnetic storms affecting us.) To be "sucked" into a black hole, one has to cross inside the Schwarzschild radius. At this radius, the escape speed is equal to the speed of light, and once light passes through, even it cannot escape.

The Schwarzschild radius can be calculated using the equation for escape speed:

vesc = (2GM/R)1/2

For photons, or objects with no mass, we can substitute c (the speed of light) for Vesc and find the Schwarzschild radius, R, to be

R = 2GM/c2

If the Sun was replaced with a black hole that had the same mass as the Sun, the Schwarzschild radius would be 3 km (compared to the Sun's radius of nearly 700,000 km). Hence the Earth would have to get very close to get sucked into a black hole at the center of our Solar System.

source :

imagine.gsfc.nasa.gov/docs/science/know_l2/black_holes.html

Space Shuttle Challenger

Space Shuttle Challenger (NASA Orbiter Vehicle Designation: OV-099) was NASA's second Space Shuttle orbiter to be put into service, Columbia being the first. Its maiden flight was on April 4, 1983, and it completed nine missions before breaking apart 73 seconds after the launch of its tenth mission, STS-51-L on January 28, 1986, resulting in the death of all seven crew members. The accident led to a two-and-a-half year grounding of the shuttle fleet, with missions resuming in 1988 with the launch of Space Shuttle Discovery on STS-26.Challenger itself was replaced by the Space Shuttle Endeavour, which first launched in 1992.Endeavour was constructed from spare parts originally meant for Challenger and the other shuttles in the fleet.

History

Challenger was named after two previous vessels—first, HMS Challenger, a British corvettethat, from 1872 to 1876, was the command ship for the "Challenger expedition," conducting pioneering global marine research.^[2]; and second, the Apollo 17 lunar module Challenger,which landed on the Moon in 1972.

Construction

Because of the low production of orbiters, the Space Shuttle program decided to build a vehicle as a Structural Test Article, STA-099, that could later be converted to a flight vehicle. In order to prevent damage during structural testing, qualification tests were performed to a factor of safety of 1.2 times the design limit loads. The qualification tests were used to validate computational models, and compliance with the required 1.4 factor of safety was shown by analysis.

NASA planned to refit the prototype orbiter Enterprise (OV-101), used for flight testing, as the second operational orbiter. However, design changes made during construction of the first orbiter, Columbia (OV-102), would have required extensive rework. Because STA-099's qualification testing prevented damage, NASA found that rebuilding STA-099 as OV-099 would be less expensive than refitting Enterprise.

Challenger (and the orbiters built after it) had fewer tiles in its Thermal Protection System than Columbia. Most of the tiles on the payload bay doors, upper wing surface, and rear fuselage surface were replaced with DuPont white nomex felt insulation. This modification allowed Challenger to carry 2,500 lb (1,100 kg) more payload than Columbia. Challenger was also the first orbiter to have a head-up display system for use in the descent phase of a mission

source:en.wikipedia.org/wiki/Space_Shuttle_Challenger

New Lunar Tool Invented at Glenn

Researchers at NASA's Glenn Research Center have recently developed a new device that tests lunar soil strength called a vacuum bevameter. The vacuum bevameter measures the characteristics of lunar regolith simulants, or lunar soil simulants, in a vacuum chamber at specific temperatures while accounting for lunar gravity. Here, Dr. Heather Oravec, a postdoctoral researcher in the Tribology and Mechanical Components branch at Glenn, performs a bevameter test on simulated lunar regolith. This system may be used to predict strength characteristics of lunar regolith in previously unexplored regions of the moon.

This research was supported by an appointment to the NASA Postdoctoral Program at the Glenn Research Center, administered by Oak Ridge Associated Universities through a contract with NASA.

Image Credit: NASA
Michelle M. Murphy, (Wyle Information Systems LLC)

source:www.nasa.gov/centers/glenn/multimedia/imagegallery/if_59_vacuum.html#googtrans/en/ar

Navigator Technology Takes GPS to a New High

GPS navigational devices are as ubiquitous as cell phones, freely used by commercial and government users alike to determine location, time, and velocity. These tools, however, are only as good as the signals they receive. Now, NASA engineers have found a way to improve the reception of those signals.

GPS, which stands for the Global Positioning System, is a satellite-based navigation system made up of a network of 24 satellites placed into orbit by the U.S. Department of Defense. GPS originally was intended for military uses, but in the 1980s, the government made the system available for civilian use. GPS systems now are available to users worldwide who need accurate positioning, navigation, and timing services.

Thanks to a team of engineers from the NASA Goddard Space Flight Center in Greenbelt, Md., spacecraft operating in weak-signal areas — such as geosynchronous orbits where communications and weather satellites typically operate — will be able to acquire and track the weak GPS signals to determine their locations, much like motorists who use GPS to determine where they are. For their work developing the Navigator GPS receiver, the Goddard team was nominated for the coveted NASA "Invention of the Year" award, a prize reserved for NASA employees who have secured patents for their inventions. An announcement is expected shortly.

Although millions of people rely on GPS receivers today for terrestrial applications, onboard GPS navigation for spaceflight operations has been much more challenging — particularly for spacecraft operating above the GPS constellation, which is about 20,200 kilometers (12,727 miles) above Earth in an area normally referred to as high-Earth orbit. That is because existing GPS receivers could not adequately pick up the GPS signal, which is transmitted toward Earth, not away from it. As a result, spacecraft above the constellation could not reliably use GPS for tracking and navigational purposes, forcing them to use more expensive ground-tracking assets.

Seeing an opportunity to help lower mission costs, the Navigator team, led by Goddard engineer Luke Winternitz, used Research and Development (R&D) funding to develop algorithms and hardware for a prototype spacecraft GPS receiver that would allow spacecraft to acquire and track weak GPS signals at an altitude of 100,000 km (62,137 miles) — well above the GPS constellation, roughly one quarter of the distance to the moon.

"The R&D investment allowed us to develop the weak-signal Navigator GPS receiver and bring it to fruition," Winternitz says. "Proof of the value of this investment lies in the explosion of flight opportunities and commercialization ventures that have followed."

Since its development, the technology has secured flight opportunities on several new missions. Navigator will serve as the primary navigation sensor on NASA’s Global Precipitation Measurement Mission (GPM), which will study global rain and snowfall when it launches in 2013.

It is considered the enabling navigation technology for another Goddard-managed project, the Magnetospheric MultiScale (MMS) mission. The mission is made up of four identically instrumented spacecraft that will fly in formation in a very high-altitude Earth orbit, while measuring the 3-D structure and dynamics of Earth’s protective magnetosphere. The mission will rely on the Navigator GPS receiver’s improved sensitivity to help the satellites maintain their precise orbital position.

The Air Force Research Laboratory (AFRL) at Kirtland Air Force Base, N.M. is planning to use a Navigator engineering test unit in its "Plug-and-Play" spacecraft, an experimental satellite that can be developed and launched within days because it uses components that hook together in a manner similar to how a computer adds drives or printers via a Universal Serial Bus interface.

The Navigator team also has delivered an engineering test unit to the next-generation weather satellite called GOES-R, which the National Oceanic and Atmospheric Administration plans to launch in 2015. The contractor developing the spacecraft may use Navigator's signal-processing design in the spacecraft’s GPS receiver.

Broad Reach Engineering, an aerospace engineering firm that operates offices in Colorado and Arizona, meanwhile, is pursuing a commercial license for the Navigator signal-processing technology. It plans to use the technology to build a GPS unit for a U.S. government program currently under development. The company also plans to use Navigator to develop other products that could be used in potential commercial satellite programs or scientific missions, says Dan Smith, a Broad Reach project manager.

And if those successes weren't enough, Navigator proved its mettle during a first-of-its-kind experiment carried out during STS-125, the Hubble Space Telescope Servicing Mission last year. While astronauts rendezvoused with and grappled the telescope, the experiment used radar measurements of GPS signals that were reflected off the Hubble to provide range estimates during docking and undocking, proving a key relative navigation sensing technology that could potentially be used in a robotic rendezvous with the Hubble in the future.

"No question. The Navigator team has experienced an incredible level of success," says John Carl Adams, an assistant chief of technology for Goddard’s Applied Engineering and Technology Directorate’s mission engineering and systems analysis division. "I attribute their accomplishment to technical know-how, but also to a healthy entrepreneurial spirit. These guys saw a need and developed a solution, which is now driving down mission costs for civilian and military space programs and extending the range of spacecraft GPS sensing to geosynchronous orbits and beyond."

More Advances Planned

The team is now looking to further improve the technology.

Winternitz and his team are developing the next-generation Navigator receiver — one that can acquire the GPS signal even if the spacecraft carrying the receiver is located at lunar distances. Such a capability would reduce mission operational costs because ground controllers could track spacecraft via GPS rather than with expensive ground stations.

"We expect that the evolution of Navigator’s capabilities will open up a host of new applications and funding sources, including exploration and high-altitude science missions," Winternitz says. "Navigator’s selling points will continue to be that it can offer better navigation performance in weak-signal and highly dynamic environments

."source :www.nasa.gov/topics/technology/features/navigator-gps.html#googtrans/en/ar

Students Bring Fresh Perspective and New Technology to Webb Telescope

Deep inside Building 5 at NASA's Goddard Space Flight Center in Greenbelt, Md., graduate students are on the front lines of technology development adjusting lasers and mirrors and spending long hours at a computer terminals. University partnerships are playing key roles in developing new and innovative technologies for NASA missions while creating a pathway for future NASA scientists and engineers.

"Investments in students today help us build what comes after the Webb telescope," said Lee Feinberg, Webb telescope Optical Telescope Element Manager at NASA Goddard. "University professors serve on our advisory boards. It allows us to tap the brightest minds in the country."

Past experience bears out Feinberg's observations.

Six years ago, Matthew Bolcar was a graduate student from the University of Rochester, N.Y. when he started working at NASA Goddard. He has been exploring interesting problems and developing risk-reduction techniques related to aligning segmented mirrors on the Webb telescope.

The Webb telescope primary mirror is composed of 18 segments that will unfold to create a single 6.5-meter (21-foot) mirror system once the observatory reaches orbit and begins operations. To work properly, the mirrors must be perfectly aligned. "If there were a problem, the telescope's operators could adjust the mirrors from the ground to correct for any possible misalignments," said Bruce Dean, group leader of the Wavefront Sensing and Control (WFSC) group at NASA Goddard.

Dean's group was charged with developing the software to compute the optimum position of each of the 18 mirrors, and then adjusting and aligning them, if necessary. The work was funded by the Webb telescope technology development program and was patented by Goddard in 2009. Goddard worked together with Ball Aerospace & Technologies Corp. in 2005, to develop this flight software for the Webb Space Telescope.

In 2006-2007, a team of engineers from both Goddard and Ball Aerospace & Technologies Corp., successfully tested the WFSC algorithms on a laboratory model of the Webb Telescope, proving they are ready to work in space.

Today, Bolcar is a full-time optical engineer for the Goddard WFSC group. Currently, he is working on the Thermal InfraRed Sensor (TIRS) instrument that will fly on the Landsat Data Continuity Mission (LDCM), the next in a series of satellites that have remotely sensed Earth’s continental surfaces for more than 30 years. He's also working on an experimental instrument, called the Visible Nulling Coronagraph (VNC) that would be used for exoplanet detection.

The graduate fellowship and co-op programs give NASA time to train students for optical engineering. "It takes four to five years to really train someone in wavefront-sensing technology," Dean added.

University partnerships are a great way to get young engineers and scientists interested in NASA, Bolcar agreed. "When you're a graduate student, wherever the funding is, you are going to develop partnerships and relationships," he added. "There is a potential to go beyond graduate school. It's good for the university and its good for attracting young talent to NASA."

Alex Maldonado, a University of Arizona graduate student in optical engineering, is following in Bolcar's footsteps. He spends half his time working at Goddard as a co-op student and the other half taking classes at the university in Tucson, Ariz. When at Goddard, he researches new techniques for polishing optical lenses to prevent light scattering.

Astronomers need bigger and smoother mirrors that will collect more light to allow scientists to see faint objects farther into the distant universe. A common and effective technique for shaping optical lenses is called diamond-turning, where a diamond tip cuts away the lens material. However, this technique also introduces flaws that can deflect light. Maldonado spends much of his time designing and executing testing procedures to see if new polishing techniques reduce this effect -- efforts that will be applied to the Near Infrared Camera (NIRCam), a Webb telescope imager.

The University of Arizona is providing the Near Infrared Camera (NIRCam) to the Webb Space Telescope, an imager with a large field of view and high angular resolution. Prof. Marcia Rieke at the University is the lead for that instrument.

The James Webb Space Telescope is the next-generation premier space observatory, exploring deep space phenomena from distant galaxies to nearby planets and stars. The Webb Telescope will give scientists clues about the formation of the universe and the evolution of our own solar system, from the first light after the Big Bang to the formation of star systems capable of supporting life on planets like Earth.

"In addition to the students, we work with the professors," according to Dean. Bolcar's graduate professor, James R. Fienup, is a world-renowned expert in optics. "We asked him to help us cover high-risk areas on the Webb telescope," said Dean.

"This is a win-win for the schools and NASA," said Feinberg. "We fund their graduate students, and in return, we get really bright, fresh minds working on NASA's most challenging missions.

Expected to launch in 2014, the telescope is a joint project of NASA, the European Space Agency and the Canadian Space Agency.

For more information about the James Webb Space Telescope, visit:

http://www.jwst.nasa.gov

source :www.nasa.gov/topics/technology/features/partnerships.html#googtrans/en/ar

NASA to Launch Human-Like Robot to Join Space Station Crew

NASA will launch the first human-like robot to space later this year to become a permanent resident of the International Space Station. Robonaut 2, or R2, was developed jointly by NASA and General Motors under a cooperative agreement to develop a robotic assistant that can work alongside humans, whether they are astronauts in space or workers at GM manufacturing plants on Earth.

The 300-pound R2 consists of a head and a torso with two arms and two hands. R2 will launch on space shuttle Discovery as part of the STS-133 mission planned for September. Once aboard the station, engineers will monitor how the robot operates in weightlessness.

R2 will be confined to operations in the station's Destiny laboratory. However, future enhancements and modifications may allow it to move more freely around the station's interior or outside the complex.

"This project exemplifies the promise that a future generation of robots can have both in space and on Earth, not as replacements for humans but as companions that can carry out key supporting roles," said John Olson, director of NASA's Exploration Systems Integration Office at NASA Headquarters in Washington. "The combined potential of humans and robots is a perfect example of the sum equaling more than the parts. It will allow us to go farther and achieve more than we can probably even imagine today."

The dexterous robot not only looks like a human but also is designed to work like one. With human-like hands and arms, R2 is able to use the same tools station crew members use. In the future, the greatest benefits of humanoid robots in space may be as assistants or stand-in for astronauts during spacewalks or for tasks too difficult or dangerous for humans. For now, R2 is still a prototype and does not have adequate protection needed to exist outside the space station in the extreme temperatures of space.

Testing the robot inside the station will provide an important intermediate environment. R2 will be tested in microgravity and subjected to the station's radiation and electromagnetic interference environments. The interior operations will provide performance data about how a robot may work side-by-side with astronauts. As development activities progress on the ground, station crews may be provided hardware and software to update R2 to enable it to do new tasks.

R2 is undergoing extensive testing in preparation for its flight. Vibration, vacuum and radiation testing along with other procedures being conducted on R2 also benefit the team at GM. The automaker plans to use technologies from R2 in future advanced vehicle safety systems and manufacturing plant applications.

"The extreme levels of testing R2 has undergone as it prepares to venture to the International Space Station are on par with the validation our vehicles and components go through on the path to production," said Alan Taub, vice president of GM's global research and development. "The work done by GM and NASA engineers also will help us validate manufacturing technologies that will improve the health and safety of our GM team members at our manufacturing plants throughout the world. Partnerships between organizations such as GM and NASA help ensure space exploration, road travel and manufacturing can become even safer in the future."

source:www.nasa.gov/topics/technology/features/robonaut.html#googtrans/en/ar

NASA Scientists Monitor Ocean Temperatures to Understand Weather

Earth's oceans and atmosphere are engaged in a complex dance, continually exchanging heat and moisture. Ocean conditions directly influence the conditions of the atmosphere. To predict our weather, forecasters need the best information they can get about the state of affairs in the sea. That's where the Short-term Prediction Research and Transition, or SPoRT, project at the Marshall Space Flight Center steps in. The SPoRT team uses NASA Earth observation satellite sensors to provide ocean temperature updates to the National Weather Service four times daily. The SPoRT scientists recently enhanced their ability to detect changes in sea surface temperatures -- a variable that greatly affects weather in coastal regions -- and the public will benefit.

The SPoRT project is expanding its reach too. The previous sea surface temperature product covered the Gulf of Mexico and the southern and eastern coastlines of the U.S. The new coverage region will include all of the ocean areas surrounding North America, from the Hawaiian Islands to the middle of the Atlantic, and from Hudson's Bay and the Gulf of Alaska to the equator, including the tropical oceans where hurricanes form.

"Our enhanced sea surface temperature product brings in more data, allowing more up-to-date and accurate inputs into weather forecasts," explains Dr. Gary Jedlovec, satellite meteorologist and SPoRT principal investigator. "We're also expanding the coverage area, benefiting more communities along the coastal regions."

"Much of the energy for weather systems comes from the ocean," adds Frank LaFontaine, a SPoRT meteorologist. "That's why the sea surface temperature is so critical to forecasters. Many storm systems like to form and/or intensify over warm water, where there's a lot of potential energy for them to tap."

LaFontaine says that the new product will help even help researchers detect thermal currents and eddies, which are important because clouds tend to form along those lines.

"For instance, tropical depressions often start forming out at sea and strengthen over the warm tropical waters," explains LaFontaine. "Variations in sea surface temperatures in coastal regions can further strengthen or weaken the storm as it makes landfall."

The SPoRT team says the data provided by their new product could help forecasters predict how intense hurricanes or tropical storms will be.

"A hurricane can ramp up offshore in intensity level so quickly, there's not enough time to warn the public," says LaFontaine. "Our product could help with predicting that intensity surge."

The enhanced product achieves its improved level of detail by adding microwave readings from the Advanced Microwave Scanning Radiometer, or AMSR, a sensor aboard NASA's Aqua satellite, to the data already in use by the previous version of the SPoRT product. That version incorporated only infrared data from the MODerate-resolution Infrared Spectrometer, also known as MODIS, aboard the Aqua and Terra satellites. The microwave data complements the infrared data in an important way.

"Microwaves can penetrate the clouds, allowing us to take data over both clear and cloudy areas," says Jedlovec. "The old version of our product left gaps where the clouds were."

The data allows the scientists to resolve small changes in the temperatures at the ocean's surface at 1-kilometer, or 0.62 mile, intervals. To put it simply, if the water temperature varies 0.2 degrees Celsius, or 0.36 Fahrenheit, between a 1 kilometer square area and the next, they can detect that difference. This level of detail improves the models used to predict weather.

Kim Newton, 256-544-0034
Marshall Space Flight Center, Huntsville, Ala.
Kimberly.D.Newton@nasa.gov

source:

www.nasa.gov/topics/earth/features/sport.html

Puerto Rico and Germany Sport Fastest Buggies in NASA's 17th Annual Great Moonbuggy Race04.12.10

Through flips and spills over a simulated moon surface, two veteran contenders finally found their time to shine in NASA’s 17th annual Great Moonbuggy Race. The team representing the International Space Education Institute of Leipzig, Germany, won the high school division; and racers from the University of Puerto Rico in Humacao took first place in the college division.

The teams bested more than 70 teams from 18 states, Puerto Rico, Canada, Germany, India and Romania. More than 600 drivers, engineers and mechanics -- all students -- gathered with their team advisors and cheering sections to take part in the matchup of wits and wheels at the U.S. Space & Rocket Center April 9-10 in Huntsville, Ala.

The race is organized by NASA's Marshall Space Flight Center in Huntsville. It challenges students to design, build and race lightweight, human-powered buggies that tackle many of the same engineering challenges dealt with by Apollo-era lunar rover developers at the Marshall Center in the late 1960s.

The International Space Education Institute, known among moonbuggy racers as "Team Germany," has been a prominent contender in the competition since they debuted in 2007 as the German Space Education Institute. Their team this year included two Russian students, reflecting the school's expanded international scope.

The University of Puerto Rico in Humacao -- the only school in the world to enter a moonbuggy in every race since the event was founded in 1994 -- won the second-place prize in 2009, and finally took home first place in this, their 17th appearance.

The winning teams posted the fastest vehicle assembly and race times in their divisions and received the fewest on-course penalties. The International Space Education Institute finished the roughly half-mile course -- twisting curves, treacherous gravel pits and other obstacles simulating lunar surface conditions -- in just 3 minutes 37 seconds. The University of Puerto Rico at Humacao posted a time of 4 minutes 18 seconds.

source: www.nasa.gov/topics/moonmars/moonbuggy2010/winning_teams_2010.html

No Peep from Phoenix in Third Odyssey Listening Stint

Mars Odyssey and Phoenix Status Report

PASADENA, Calif. -- NASA's Mars Odyssey orbiter heard no signal from the Phoenix Mars Lander when it listened from orbit while passing over Phoenix 60 times last week.

Odyssey had also listened for a signal from Phoenix during periods in January and February. During the third campaign, April 5 through April 9, the sun stayed above the horizon continuously at the arctic site where Phoenix completed its mission in 2008.

The solar-powered lander examined ice, soil and atmosphere at the site for two months longer than its planned three-month mission before succumbing to seasonal decline in sunlight. It was not designed to withstand winter conditions. However, in case it did, NASA has used Odyssey to listen for the signals that Phoenix would have transmitted if abundant spring sunshine revived the lander.

"In the unlikely event that Phoenix had survived the harsh Martian arctic winter and been able to achieve a power-positive state with the return of continuous sunshine, there is a very high likelihood that one or more of these 60 overflights would have overlapped with a transmission attempt by the lander," said Chad Edwards, chief telecommunications engineer for the Mars Exploration Program at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

"This was the last of our three planned Phoenix search campaigns. The Mars program will evaluate the results in hand to assess whether further action is warranted," Edwards said.

Media contact: Guy Webster 818-354-6278
Jet Propulsion Laboratory, Pasadena, Calif.
guy.webster@jpl.nasa.gov

2010-126

source :www.nasa.gov/mission_pages/phoenix/news/phx20100413.html

Space Shuttle Atlantis Moves to Launch Pad for Final Planned Flight

posted: 22 April 2010 05:15 pm ET

CAPE CANAVERAL, Fla. — Space shuttle Atlantis held the spotlight late on Wednesday night into early Thursday morning as it rolled out of Kennedy Space Center's Vehicle Assembly Building (VAB) in Florida, on its way to the launch pad for what is planned to be its last flight.

The black-and-white winged-orbiter, mounted to an orange external fuel tank and twin white solid rocket boosters, left the voluminous building— the largest one-story building in the world — just before midnight atop a mobile launcher platform and crawler transporter tracked vehicle.

Atlantis' trip to the launch pad came just a day after the successful landing of its sister ship Discovery on Tuesday to wrap up a 15-day flight to the International Space Station.

"One of my favorite shots, almost as fantastic as launch, is coming out here in the middle of the night, watching it clear the VAB doors. When it moves out into the xenon lights and they're shining on it, there's just something very special about that," former astronaut and Kennedy Space Center director Bob Cabana told collectSPACE.com. "The beginning of this journey into space, it all starts when the whole stack rolls out."

Atlantis' first moves at 11:31 p.m. EDT Wednesday were also slated to be among its last.

source:www.space.com/missionlaunches/shuttle-atlantis-final-launch-pad-trip-cs-100422.html#googtrans/en/ar

Why Are Space Telescopes Better Than Earth-Based Telescopes?

By Remy Melina Staff Writer posted: 24 April 2010 03:31 am ET

The Hubble Space Telescope has beamed hundreds of thousands of images back to Earth over the past two decades. One might call it the most skilled paparazzo, snapping countless images of the stars.

Thanks to these images, scientists have been able to determine the age of the universe and shed light on the existence of dark energy. These extraordinary advancements have been possible because the Hubble images surpass those taken by Earth-based telescopes.

While ground-based observatories are usually located in highly elevated areas with minimal light pollution, they must contend with atmospheric turbulence, which limits the sharpness of images taken from this vantage point. (The effects of atmospheric turbulence are clear to anyone looking at the stars – this is why they appear to twinkle.)

In space, however, telescopes are able to get a clearer shot of everything from exploding stars to other galaxies.

Another disadvantage for ground-based telescopes is that the Earth's atmosphere absorbs much of the infrared and ultraviolet light that passes through it. Space telescopes can detect these waves.

Newer ground-based telescopes are using technological advances such as adaptive optics to try to correct or limit atmospheric distortion, but there's no way to see the wavelengths that the atmosphere blocks from reaching Earth, according to the Space Telescope Science Institute (STScI), which manages the Hubble research program.

One downside to space telescopes like the Hubble is that they are extremely difficult tomaintain and upgrade. The Hubble is the first telescope specifically designed to be repaired in space by astronauts, while other space telescopes cannot be serviced at all.

NASA scientists estimate that the telescope will only be able to keep taking pictures for five more years.

source :www.space.com/scienceastronomy/why-space-telescopes-are-better-100424.html