Hubble: using moonlight to study Venus transit

A reduced resolution sample of an image from the Hubble Space Telescope, trained upon bright 109 million year old Tycho , with its hemisphere-wide ray system visible to the naked eye from Earth. A rare time when Hubble and human sight overlap. When Venus transits across the disk of the Sun a month from now, a rare event which will not occur again until 2117, Hubble will be trained on the Moon, using very subtle variations in the reflected sunlight to analyze Venus and its atmosphere [NASA/ESA/D. Ehrenbach (IPAG)].

This mottled landscape showing the impact crater Tycho is among the most violent-looking places on our Moon. Astronomers didn't aim NASA's Hubble Space Telescope to study Tycho, however. The image was taken in preparation to observe the transit of Venus across the Sun's face on June 5-6.

Hubble cannot look at the Sun directly, so astronomers are planning to point the telescope at the Earth's moon, using it as a mirror to capture reflected sunlight and isolate the small fraction of the light that passes through Venus's atmosphere. Imprinted on that small amount of light are the fingerprints of the planet's atmospheric makeup.

These observations will mimic a technique that is already being used to sample the atmospheres of giant planets outside our solar system passing in front of their stars. In the case of the Venus transit observations, astronomers already know the chemical makeup of Venus's atmosphere, and that it does not show signs of life on the planet. But the Venus transit will be used to test whether this technique will have a chance of detecting the very faint fingerprints of an Earth-like planet, even one that might be habitable for life, outside our solar system that similarly transits its own star. Venus is an excellent proxy because it is similar in size and mass to our planet.

The astronomers will use an arsenal of Hubble instruments, the Advanced Camera for Surveys, Wide Field Camera 3, and Space Telescope Imaging Spectrograph, to view the transit in a range of wavelengths, from ultraviolet to near-infrared light. During the transit, Hubble will snap images and perform spectroscopy, dividing the sunlight into its constituent colors, which could yield information about the makeup of Venus's atmosphere.

Hubble will observe the Moon for seven hours, before, during, and after the transit so the astronomers can compare the data. Astronomers need the long observation because they are looking for extremely faint spectral signatures. Only 1/100,000th of the sunlight will filter through Venus's atmosphere and be reflected off the Moon.

This image, taken with Hubble's Advanced Camera for Surveys, reveals lunar features as small as roughly 560 feet (170 meters) across. The large "bulls-eye" near the top of the picture is the impact crater, caused by an asteroid strike about 100 million years ago. The bright trails radiating from the crater were formed by material ejected from the impact area during the asteroid collision. Tycho is about 50 miles (80 kilometers) wide and is circled by a rim of material rising almost 3 miles (5 kilometers) above the crater floor. The image measures 430 miles (700 kilometers) across, which is slightly larger than New Mexico.

Because the astronomers only have one shot at observing the transit, they had to carefully plan how the study would be carried out. Part of their planning included the test observations of the Moon, made on Jan. 11, 2012, as shown in the release image.

Hubble will need to be locked onto the same location on the Moon for more than seven hours, the transit's duration. For roughly 40 minutes of each 96-minute orbit of Hubble around the Earth, the Earth occults Hubble's view of the Moon. So, during the test observations, the astronomers wanted to make sure they could point Hubble to precisely the same target area.

This is the last time this century sky watchers can view Venus passing in front of the Sun. The next transit won't happen until 2117. Venus transits occur in pairs, separated by eight years. The last event was witnessed in 2004. [NASA/ESA/Ehrenreich,  IPAG/CNRS/Université Joseph Fourie].

'The Shuttle's most dangerous mission'

Jacqui Goddard - London Daily-Mail - "It’s a belt-and-suspenders kind of approach," says STS125 Cmdr Scott Altman. "But when your suspenders fail, you’re glad to have the belt. I don’t know if I’ll be breathing comfortably until our wheels stop back at KSC."

Among the greatest hazards facing Atlantis is the intense amount of space junk - such as broken satellites and dead rockets - that is cluttering the area where the shuttle will rendezvous with Hubble.

Shuttle flights usually only go to the International Space Station no more than 250 miles up - but at 350 miles, where Hubble flies, the hazards are far greater.

During five highly risky spacewalks, they will clamber aboard Hubble to repair and replace instruments contained inside, upgrading its capabilities and prolonging its life for another five years.

Without new cameras, gyroscopes and batteries, Hubble will otherwise burn out. But with the space shuttle fleet due to retire next year and its successor not due for completion until at least 2015, this is the last chance to fix its problems.

'The adrenalin is certainly pumping,' said Dr David Leckrone, Nasa’s senior Hubble scientist.

Astronaut John Grunsfeld likens the intricacy of the tasks he and his colleagues will perform to 'performing brain surgery in space.'

They will face major hurdles, such as unscrewing dozens of minute screws while wearing gloves five layers thick and removing razor-sharp circuit boards capable of piercing the $10 million spacesuits that keep them alive in the vacuum of space.

'I would consider this the climbing Mount Everest of spacewalking missions,' said Mr Grunsfeld, 51.

'The big unknowns are where we’re pushing the envelope further than its been done before in spaceflight…we’re trying some techniques that haven’t been done before.

'In training it’s been going very well…the only hesitation I have is that Hubble has a way of surprising us.'

You could say "Oh it’s going to be a piece of cake, we’ve done this five times" - except on this mission we are going to be repairing instruments that were never designed to be repaired in orbit,' explained Ed Weiler, Nasa’s associate administrator for science missions.

He added: 'This is really going to be tough, the toughest servicing mission we have ever attempted.'

Nasa promises that, if successful, Atlantis’s mission will allow Hubble to once more 'push the boundaries of how deep in space and how far back in time humanity can see.'

Cdr Altman, who said: 'It’s going to be a busy time, it is challenging - and it’s going to be amazing.'

Daily Mail article HERE.

Veteran space walker will celebrate fellow Chicago Allumnus Hubble's other legacy on repair mission

John Grunsfeld will take Edwin Hubble's
100 year-old basketball into orbit on STS-125

From Steve Koppes -
Chicago Chronicle News Office (Excerpt)

Grunsfeld had borrowed the basketball from the Department of Physical Education and Athletics, with Turner serving as intermediary, so that he could fly it into orbit. He plans to return the basketball personally to the University after the mission, when it will go on display at the Gerald Ratner Athletics Center.

Grunsfeld grew up near the University’s campus on Chicago’s South Side, where Nobel laureate Enrico Fermi oversaw construction of the first nuclear reactor during World War II.

“I was inspired as a young man by the exploits of Enrico Fermi as a scientist and as a mountaineer in the Dolomites, and he became a role model for me,” said Grunsfeld, who studied physics at Chicago.

Before joining NASA in 1992, he had amassed research experience in X-ray and gamma-ray astronomy, high-energy cosmic ray studies and the development of new detectors and instrumentation. Grunsfeld has since used the Hubble Telescope in his own research. As NASA’s chief scientist from 2003 to 2004, Grunsfeld helped develop the President’s Vision for Space Exploration.

Read the article HERE.

Hubble mission means the moon to astronomer-turned-astronaut

Florida Today - Two days after President George W. Bush directed NASA to return American astronauts to the moon, John Grunsfeld stood in support of a decision to kill a Hubble Space Telescope servicing mission deemed too dangerous after the Columbia accident.

Flying aboard shuttle Atlantis, Grunsfeld and his crewmates aim to install two new Hubble science instruments, resuscitate two others and outfit the observatory with new batteries and gyroscopes that will enable it to operate through at least 2013.

For an encore, Grunsfeld will use his telescope time to do research that has wide public appeal, a link to human spaceflight and significant scientific merit. "What I want to do with Hubble is shoot the moon," he said.

Grunsfeld will help equip Hubble with a new planetary camera and then use the instrument to examine ultraviolet light reflected from a huge crater on the face of the moon. The idea is to prospect for minerals, such as titanium oxides, that could be converted to breathing air or even rocket fuel at a moon base.

Read the rest of the story HERE.

Atlantis mission to Hubble delayed into fall

AFP - The space shuttle Atlantis and her pending final mission, and a final mission, by popular demand, to perform maintenance and repair on the Hubble Space Telescope previously set for August 28 has been pushed back four to five weeks, NASA said Thursday.

Continuing troubles with newly-designed External Tank deliveries finally caught up with flight planners, affecting the schedule of the eight remaining Shuttle flights until the three vehicle fleet is retired in 2010.

"Right now Hubble's mission is scheduled for August 28; we really cannot make that date with the external tank processing," shuttle program manager John Shannon explained at a press conference Thursday.

"The changes we have made adds about four to five weeks of processing time on those two tanks," he said.

The shuttle's mission to Hubble -- orbiting at 600 kilometers -- is unusual because post-Columbia safety protocols require a second shuttle on the pad and ready for launch nearby. Two external tanks have to be prepared, which makes production and delivery difficulties more problematic.

In case of a major problem with the Hubble mission the shuttle and its crew of seven cannot head to dock at the International Space Station (ISS). So a second shuttle needs to be at the ready, to be launched in case of emergency.

"I would expect that sometime this month we will come forward and not just have the Hubble mission date ... but really some pretty good numbers for the next six to ten flights," Shannon said.

Read more HERE.

Liquid Lunar Telescopes

Among the reasons NASA wasn't as enthusiastic as the general public and America's school-age kids, to perform a final Hubble Telescope servicing mission, now scheduled as perhaps the last scheduled mission of the Space Shuttle Altantis later this summer, is the James Webb Space Telescope, under construction and slated for flight and "first light" in 2013.

Naturally, following the decision to retire the three remaining Shuttles after the Columbia disaster in February 2003, both the risk and cost were considered too high. But NASA also knew, as magnificent as Hubble has been, even its astounding capabilities had long been overshadowed by those planned for follow-up missions such as the Webb.

The Hubble concept, after all, was born at the same time as that of the Shuttle itself, beginning in 1972. Originally both were supposed to be in service by 1976 and in time for the America's Bicentennial.

The Shuttle's cargo bay was planned around the dimensions of the Hubble, but the new technologies necessary for the eventual success of both projects, and endless budget cutbacks following the scrapping of Apollo, delayed both for many years. Columbia did not fly until 1981 and an additional decade, almost 15 years after its planned deployment, Hubble was finally carried into orbit, along with an embarrassing micro-flaw in the main mirror putting it in need of innovative corrective lenses installed in an "inherently dangerous" servicing mission, before it began to live up to its full potential.

Along with the easily ruptured spacesuits from wriggling pressurized fingers in places they weren't ever meant to poke, the Hubble flies more than 100 kilometers higher than the Shuttle's design, and closed to the Van Allen radiation belts, increasing the lifetime probability of "REID," or "Radiation Exposure Induced Death," which NASA protocols limit to 3 percent per astronaut, per career. While the Hubble flies closer to the Equator than the Space Station, even operations of the mission are limited during its passing though the fringe of the South Atlantic Anomaly, where the inner Van Allen Belt dips to its closest point to Low Earth Orbit.

Trips through the Van Allen Belt are hazardous, but not the killing field they are often made out to be by those who claim the Apollo lunar missions were frauds perpetrated on the world.

Yet another reason to eventually de-orbit the Hubble is the eventual erosion of the telescope due to prolonged exposure to Cosmic Rays of high energy and mass, particularly during Solar Minimums, when CR's are less attinuated by as much as 50 percent by a stronger solar influence during Solar Maximum. Space is wrongly considered not be an erosive environment, but more is constantly at work on humans and equipment than repeated exposure to stark heat and cold as the vehicle passes from dark shadow to full sunlight during most orbits.

This is another reason even the improved shielding built into the International Space Station cannot last forever. NASA now plans to decommission the Station, which is only 80 percent complete, in 2016.

Even so, Hubble's primary collecting mirror is "only" two and a half meters wide. The development of active, segmented and binocular earth bound telescopes have nearly overcome the very limitations of being down on Earth and under the shifting atmosphere that Hubble was designed to address, with the exception of baselines wider than any available on Earth or what can be constructed inside Earth's gravity well - the very limitations that once made the Hale Telescope on Mount Palomar in 1936 "the largest telescope possible."

By contrast, the James Webb Space Telescope will boast a mirror five meters in diameter, with seven times the light collecting ability. And beyond this, NASA is thinking even larger, with concepts using liquid metal mirrors stationed on the Moon.

"The (LMT) telescope would be anywhere from 66 feet to 328 feet wide," writes William Harris of "How Stuff Works."

"It would collect 1,736 times more light than Hubble and penetrate the depths of the (optical) universe," Harris explains, giving Webb the ability to resolve the very beginnings of the end of the "Cosmic Dark Age," and the first sudden proliferation of stars after the early Universe's beginning, and with unimaginable detail revealed of the "realm of the blue galaxies," today mere smudges on Hubble's famous and astounding Deep Field images.

Read more HERE.