The most complex servicing mission to date on the Hubble Space Telescope is underway
Tamara Traubman
If everything goes as planned, today, around two o'clock in the afternoon Israel time, astronauts will take off aboard the space shuttle Columbia on a journey to the Hubble Space Telescope orbiting the Earth. Their task is not simple and involves technical challenges, but if you succeed Hubble will be given a wider and sharper view of the universe.
"This is the most technically challenging service mission we have performed so far," said Dr. Ann Kinney, director of NASA's Astronomy and Physics Division, in an interview with CNN yesterday. During the mission, the astronauts will turn off the telescope, for the first time since it was placed in space, to install a new power control unit. They will also install a new camera, repair the existing camera that stopped working and replace the solar panels and the gyroscope responsible for aligning and stabilizing the telescope. The mission, which will last 12 days, includes five "spacewalks", all of which are complex and extremely important. These spacewalks will be performed by four astronauts, who have been trained for this mission for about two years.
The Hubble telescope was launched into space in April 1990 and has since become one of the most important tools in modern astronomy. NASA and the European Space Agency, which maintain the telescope, have so far launched three service missions to carry out repairs and upgrades to the telescope (the most famous of which was the first service mission in 1993, during which lenses were installed to correct an embarrassing defect that was discovered in the telescope's main mirror and caused blurry images to be received). The Hubble was originally designed to work for twenty years. The current service task is the penultimate task. The next mission was set for 2004
The new scientific instrument that will be installed in Hubble is called "Advanced Camera for Surveys" (ACS). "This camera increases Hubble's photography capability in terms of the width of the imaged area by approximately two times, and it is characterized by a sensitivity approximately five times greater than the current one," Prof. Mario Livio said this week in a telephone interview from his office at the Space Telescope Science Institute in Baltimore, USA. According to him, the improved degree of sensitivity and efficiency will allow Hubble to see objects and details that could not be distinguished before. NASA is trying to illustrate Hubble's new vision ability using the following example: if the camera was placed in Washington, it would be able to distinguish between two fireflies standing in Tokyo, two meters apart, instead of seeing them as one light source.
A few years ago, the space telescope took a photo called "The Deep Field of Hubble". It revealed a host of distant galaxies and other findings that led cosmologists to reconsider some of their theories about the evolution of galaxies. In order to photograph the "deep field", Prof. Livio says, observations were made for about ten days. The new camera, on the other hand, will make it possible to survey an area of the sky that is twice as large, in about three days. "After a year or two in space, this camera will detect more galaxies and pale stars than all of Hubble's previous instruments combined," said Prof. Holland Ford, Johns Hopkins University astronomer and head of the team that built the camera, in an official announcement published by the Space Telescope Science Institute.
According to Amiel Sternberg, professor of astrophysics at Tel Aviv University, the new camera will enable research in a very wide range of subjects, including the evolution of galaxies and quasars, which are enormous flares of light that receive their energy from enormous black holes. According to him, cosmologists also hope to gather new clues about two historical and critical centers for the evolution of the universe: dark matter and dark energy. Dark matter is invisible and it is still unclear what it is made of, but scientists believe that it makes up at least 80% of the matter in the universe. Even less is known about dark energy. Its existence has actually been proven only in recent years and it probably causes the acceleration of the rate of expansion of the universe.
The camera is also equipped with a channel sensitive only to ultraviolet radiation. "Among other things, it will be used to study the weather on the planets in our solar system," says Prof. Livio. Because ultraviolet radiation is mainly emitted from extremely hot objects, cosmologists will use this channel to study quasars as well.
Many cosmologists are competing among themselves for the right to make observations using the new camera, which cost about 75 million dollars to build. One of those who received permission to make an observation is Prof. Dan Maoz from Tel Aviv University, who will investigate black holes using the ultraviolet channel. A few years ago it became clear that at the center of most galaxies resides a black hole. But following these findings, a mystery arose: despite their enormous mass and the fact that there is a lot of material nearby that they can absorb, most of these black holes appear to be dormant. Using the ultraviolet radiation emitted from their surroundings, Prof. Maoz hopes to produce clues that will help in solving the mystery, and also in understanding their nature and role in the evolution of galaxies.
"The high resolution of the camera," says Prof. Sternberg, "will greatly contribute to the study of star formation and planetary systems in the Milky Way galaxy." Some astronomers even hope to observe, for the first time, the planets directly. Although astronomers have already discovered dozens of planets outside our solar system, they have never been able to observe them directly but have inferred their existence based on observations of suns outside our solar system. In the observations, the researchers noticed changes in the light emitted from the suns, and they believe that it is the gravitational force of the planets surrounding them that causes those changes.
When scientists and engineers designed the Hubble they knew it would become obsolete within a few years due to the rapid advancement of technology. That is why the telescope was designed so that even after it is placed in space, astronauts on service missions can add instruments to it and perfect it. The ACS camera will replace the last original device in Hubble today, the Faint Object Camera. The astronauts will also put another camera back into operation, Nikmos, which is already in the telescope.
The NIKMOS was an important addition that was launched in 1997. For its operation, an extremely low temperature is required - approximately 203 degrees Celsius below zero. In the first two years, the NICMOS operated as required, but over time the solid nitrogen that was used to cool it was consumed and in January 1999 it stopped working. The NICAMS is able to absorb infrared radiation and distinguish the most distant galaxies as they appeared when the age of the universe was about a fifth of its current age. The astronauts will replace the current Nikmos cooling system with a new and experimental cooling system.
The biggest technical challenge will be replacing the telescope's power supply unit. The unit transfers energy from the solar panels to the telescope's batteries and to devices that consume electricity. The ten-year-old unit is indeed operational, but NASA believes that it is already obsolete and wants to replace it with a new one, although it was not originally designed to be replaced. "This exchange will be very difficult," says Prof. Livio. "This unit has 36 connections, which the astronauts will have to disconnect and reconnect with the gloves and cumbersome suits they wear." Also, to replace the power supply unit the astronauts will have to turn the Hubble off and on again, for the first time since it was placed in space. According to Livio preliminary simulations show that this is possible, "but it is still a dangerous exercise".
The space telescope, the next generation
In the back of the Hubble Space Telescope, a new telescope has already begun to blow - "The Space Telescope, the next generation". Its launch is expected to take place around 2009 and should redefine the boundaries of astronomy.
The "next generation" telescope will be equipped with powerful detectors for the reception of infrared radiation, suitable for observations of very distant objects (the more distant an object, the more its light rays are deflected to the red). For the first time, scientists hope, a telescope will be able to observe the depths of the universe, to the ancient times when the first stars and galaxies were formed.
The cost of the ambitious project is currently estimated at about 1.3 billion dollars. The US Space Agency (NASA), the European Space Agency and the Canadian Space Agency are partners in the project. The Hubble Space Telescope hovers at a distance of about 579 kilometers from Earth, which allows astronauts to be sent to it on service missions to repair deficiencies and upgrade; The "next generation" telescope will be placed too far away to be able to do this. The long distance is necessary, among other things, to enable the operation of the infrared detectors that operate at the lowest temperature.
Scientists believe that after the universe was created, about 14 million years ago in the "Big Bang", there was a dark period they call the "Middle Ages of the Universe", when there were no stars and the universe was completely dark. As the universe continued to expand and cool, there came an age when the gas in the universe began to crystallize into stars and galaxies, such as those seen today in the night sky. The "next generation" telescope is supposed to make observations that will discover stars and galaxies from this period, when the first stars began to form.
Cosmologists believe that the "next generation" telescope will make it possible to find out the main questions in cosmology - for example, how the galaxies developed, what is the shape of the universe, and what is the mysterious "dark matter" that makes up most of the matter in the universe - in a way that has not been possible until now.
The space shuttle captured the "Hubble"
After two days of chasing in space, the "Columbia" team managed to catch the space telescope; In the coming days, repairs and renovations will be carried out; A malfunction in the shuttle threatened to stop the mission - but it was finally repaired from the ground
Sunday, 3 March 2002, 20:56
The space shuttle Columbia managed to "capture" the Hubble space telescope today in order to carry out a number of adjustments and repairs. After a chase of almost two days, the wayward telescope was captured about 580 kilometers above Mexico.
Tomorrow, two pairs of astronauts are scheduled to perform several spacewalks over the next five days, during which new parts will be installed in the telescope. The one who finally managed to capture the Hubble telescope, is the astronaut Nancy Currie, who with the help of the shuttle's robotic arm successfully performed the complex task. The Hubble weighs 12.5 tons and is about 13 meters long.
For one of the Columbia astronauts, meeting Hubble was like meeting an old friend. John Grunsfeld met the telescope in '99 the last time it underwent repairs. Yesterday they also feared that the shuttle would not be able to carry out its mission due to a technical problem and the control center in Florida considered returning it to Earth. During the night, the flight engineers on the ground managed to find a solution to the problem and the "green light" was given to continue the mission. The crew members in space woke up to the sounds of "Mission Impossible" broadcast to them from the ground to illustrate the rescue of the mission against all odds.
The Discovery landed; NASA expresses great satisfaction
The seven crew members of the shuttle Discovery landed yesterday in the early hours of the morning at the Kennedy Space Center, after successfully repairing the "Hubble" space telescope. "Welcome to Earth after a fantastic flight," Scott Altman from ground control told them.
Tamara Traubman
The astronauts left Earth last Monday (Israel time) and stayed in space for eight days, three of which were dedicated to repairing and refurbishing the telescope. According to the original plan, their mission was supposed to last ten days, but NASA was forced to shorten it due to several delays in the launch, caused by technical problems of the shuttle and severe weather conditions.
Yesterday, NASA expressed great satisfaction with the completion of the mission and defined it as "extremely successful". This is after a series of embarrassing failures that happened recently, including one Mars spacecraft that apparently crashed due to a navigation error, which resulted from confusion between metric and English measurement units, and a second Mars spacecraft, the fate of which is still unknown to this day.
{Appeared in Haaretz newspaper, 29/12/1999{
