Members Can Post Anonymously On This Site
Hubble's Advanced Camera for Surveys Resumes Exploring the Universe
-
Similar Topics
-
By NASA
This archival photo shows engineers working on NASA’s Voyager 2 spacecraft on March 23, 1977. NASA/JPL-Caltech NASA’s Voyager mission launched in the 1970s. Today, it’s making history as it conducts new science. But how are two spacecraft from the ’70s not just surviving, but thriving farther out in space than any other spacecraft has been before?
A Little Mission Background
Voyager is a NASA mission made up of two different spacecraft, Voyager 1 and 2, which launched to space on Sept. 5, 1977, and Aug. 20, 1977, respectively. In the decades following launch, the pair took a grand tour of our solar system, studying Jupiter, Saturn, Uranus, and Neptune — one of NASA’s earliest efforts to explore the secrets of the universe. These twin probes later became the first spacecraft to operate in interstellar space — space outside the heliosphere, the bubble of solar wind and magnetic fields emanating from the Sun. Voyager 1 was the first to enter interstellar space in 2012, followed by Voyager 2 in 2018.
Today, Voyager continues not just because it can, but because it still has work to do studying interstellar space, the heliosphere, and how the two interact. “We wouldn’t be doing Voyager if it wasn’t taking science data,” said Suzanne Dodd, the mission’s current project manager and the director for the Interplanetary Network at NASA’s Jet Propulsion Laboratory.
But across billions of miles and decades of groundbreaking scientific exploration, this trailblazing interstellar journey has not been without its trials. So, what’s the Voyager secret to success?
In short: preparation and creativity.
As NASA’s two Voyager spacecraft travel out into deep space, they carry a small American flag and a Golden Record packed with pictures and sounds — mementos of our home planet. This picture shows John Casani, Voyager project manager in 1977, holding a small Dacron flag that was folded and sewed into the thermal blankets of the Voyager spacecraft before they launched 36 years ago. Below him lie the Golden Record (left) and its cover (right). In the background stands Voyager 2 before it headed to the launch pad. The picture was taken at Cape Canaveral, Fla., on Aug. 4, 1977. NASA/JPL-Caltech We Designed Them Not to Fail
According to John Casani, Voyager project manager from 1975 to launch in 1977, “we didn’t design them to last 30 years or 40 years, we designed them not to fail.”
One key driver of the mission’s longevity is redundancy. Voyager’s components weren’t just engineered with care, they were also made in duplicate.
According to Dodd, Voyager “was designed with nearly everything redundant. Having two spacecraft — right there is a redundancy.”
“We didn’t design them to last 30 years or 40 years, we designed them not to fail.”
John Casani
Voyager Project Manager, 1975-1977
A Cutting-Edge Power Source
The twin Voyager spacecraft can also credit their longevity to their long-lasting power source.
Each spacecraft is equipped with three radioisotope thermoelectric generators. These nuclear “batteries” were developed originally by the U.S. Department of Energy as part of the Atoms for Peace program enacted by President Eisenhower in 1955. Compared to other power options at the time — like solar power, which doesn’t have the reach to work beyond Jupiter — these generators have allowed Voyager to go much farther into space.
Each of NASA’s Voyager probes are equipped with three radioisotope thermoelectric generators (RTGs), including the one shown here at NASA’s Kennedy Space Center in Florida. The RTGs provide power for the spacecraft by converting the heat generated by the decay of plutonium-238 into electricity. Launched in 1977, the Voyager mission is managed for NASA by the agency’s Jet Propulsion Laboratory, a division of Caltech in Pasadena, California.
NASA/JPL-Caltech Voyager’s generators continue to take the mission farther than any before, but they also continue to generate less power each year, with instruments needing to be shut off over time to conserve power.
Creative Solutions
As a mission that has operated at the farthest edges of the heliosphere and beyond, Voyager has endured its fair share of challenges. With the spacecraft now in interstellar space running on software and hardware from the 1970s, Voyager’s problems require creative solutions.
Retired mission personnel who worked on Voyager in its earliest days have even come back out of retirement to collaborate with new mission personnel to not just fix big problems but to pass on important mission know-how to the next generation of scientists and engineers.
“From where I sit as a project manager, it’s really very exciting to see young engineers be excited to work on Voyager. To take on the challenges of an old mission and to work side by side with some of the masters, the people that built the spacecraft,” Dodd said. “They want to learn from each other.”
After receiving data about the health and status of Voyager 1 for the first time in five months, members of the Voyager flight team celebrate in a conference room at NASA’s Jet Propulsion Laboratory on April 20. Credit: NASA/JPL-Caltech NASA/JPL-Caltech Within just the last couple of years, Voyager has tested the mission team’s creativity with a number of complex issues. Most recently, the thrusters on Voyager 1’s thrusters, which control the spacecraft’s orientation and direction, became clogged. The thrusters allow the spacecraft to point their antennae and are critical to maintaining communications with Earth. Through careful coordination, the mission team was able to remotely switch the spacecraft to a different set of thrusters.
These kinds of repairs are extra challenging as a radio signal takes about 22 ½ hours to reach Voyager 1 from Earth and another 22 ½ hours to return. Signals to and from Voyager 2 take about 19 hours each way.
Voyager’s Interstellar Future
This brief peek behind the curtain highlights some of Voyager’s history and its secrets to success.
The Voyager probes may continue to operate into the late 2020s. As time goes on, continued operations will become more challenging as the mission’s power diminishes by 4 watts every year, and the two spacecraft will cool down as this power decreases. Additionally, unexpected anomalies could impact the mission’s functionality and longevity as they grow older.
As the mission presses on, the Voyager team grows this legacy of creative problem solving and collaboration while these twin interstellar travelers continue to expand our understanding of the vast and mysterious cosmos we inhabit.
Read More
The Story Behind Voyager 1’s Pale Blue Dot The Story Behind Voyager 1’s Family Portrait Pale Blue Dot Poster Voyager 1 Mission Page Voyager 2 Mission Page Share
Details
Last Updated Nov 04, 2024 Related Terms
Missions Voyager 1 Voyager 2 Voyager Program View the full article
-
By European Space Agency
When disaster strikes, maintaining communication is critical. Yet, terrestrial (ground) networks are often compromised, leaving civilians stranded and first responders without access to vital information. Limited bandwidth can severely delay crisis management efforts, potentially costing lives. Recent events around the world, including devastating floods and wildfires, underscore the increasing relevance and urgency for advanced disaster response technology.
View the full article
-
By NASA
The study of X-ray emission from astronomical objects reveals secrets about the Universe at the largest and smallest spatial scales. Celestial X-rays are produced by black holes consuming nearby stars, emitted by the million-degree gas that traces the structure between galaxies, and can be used to predict whether stars may be able to host planets hospitable to life. X-ray observations have shown that most of the visible matter in the universe exists as hot gas between galaxies and have conclusively demonstrated that the presence of “dark matter” is needed to explain galaxy cluster dynamics, that dark matter dominates the mass of galaxy clusters, and that it governs the expansion of the cosmos.
X-ray observations also enable us to probe mysteries of the Universe on the smallest scales. X-ray observations of compact objects such as white dwarfs, neutron stars, and black holes allow us to use the Universe as a physics laboratory to study conditions that are orders of magnitude more extreme in terms of density, pressure, temperature, and magnetic field strength than anything that can be produced on Earth. In this astrophysical laboratory, researchers expect to reveal new physics at the subatomic scale by conducting investigations such as probing the neutron star equation of state and testing quantum electrodynamics with observations of neutron star atmospheres. At NASA’s Marshall Space Flight Center, a team of scientists and engineers is building, testing, and flying innovative optics that bring the Universe’s X-ray mysteries into sharper focus.
A composite X-ray/Optical/Infrared image of the Crab Pulsar. The X-ray image from the Chandra X-ray Observatory (blue and white), reveals exquisite details in the central ring structures and gas flowing out of the polar jets. Optical light from the Hubble Space Telescope (purple) shows foreground and background stars as pinpoints of light. Infrared light from the Spitzer Space Telescope (pink) traces cooler gas in the nebula. Finally, magnetic field direction derived from X-ray polarization observed by the Imaging X-ray Polarimetry Explorer is shown as orange lines. Magnetic field lines: NASA/Bucciantini et al; X-ray: NASA/CXC/SAO; Optical: NASA/STScI; Infrared: NASA-JPL-Caltech Unlike optical telescopes that create images by reflecting or refracting light at near-90-degree angles (normal incidence), focusing X-ray optics must be designed to reflect light at very small angles (grazing incidence). At normal incidence, X-rays are either absorbed by the surface of a mirror or penetrate it entirely. However, at grazing angles of incidence, X-rays reflect very efficiently due to an effect called total external reflection. In grazing incidence, X-rays reflect off the surface of a mirror like rocks skipping on the surface of a pond.
A classic design for astronomical grazing incidence optics is the Wolter-I prescription, which consists of two reflecting surfaces, a parabola and hyperbola (see figure below). This optical prescription is revolved around the optical axis to produce a full-shell mirror (i.e., the mirror spans the full circumference) that resembles a gently tapered cone. To increase the light collecting area, multiple mirror shells with incrementally larger diameters and a common focus are fabricated and nested concentrically to comprise a mirror module assembly (MMA).
Focusing optics are critical to studying the X-ray universe because, in contrast to other optical systems like collimators or coded masks, they produce high signal-to-noise images with low background noise. Two key metrics that characterize the performance of X-ray optics are angular resolution, which is the ability of an optical system to discriminate between closely spaced objects, and effective area, which is the light collecting area of the telescope, typically quoted in units of cm2. Angular resolution is typically measured as the half-power diameter (HPD) of a focused spot in units of arcseconds. The HPD encircles half of the incident photons in a focused spot and measures the sharpness of the final image; a smaller number is better.
Schematic of a full-shell Wolter-I X-ray optic mirror module assembly with five concentrically nested mirror shells. Parallel rays of light enter from the left, reflect twice off the reflective inside surface of the shell (first off the parabolic segment and then off the hyperbolic segment), and converge at the focal plane. NASA MSFC NASA Marshall Space Flight Center (MSFC) has been building and flying lightweight, full-shell, focusing X-ray optics for over three decades, always meeting or exceeding angular resolution and effective area requirements. MSFC utilizes an electroformed nickel replication (ENR) technique to make these thin full-shell X-ray optics from nickel alloy.
X-ray optics development at MSFC began in the early 1990s with the fabrication of optics to support NASA’s Advanced X-ray Astrophysics Facility (AXAF-S) and then continued via the Constellation-X technology development programs. In 2001, MSFC launched a balloon payload that included two modules each with three mirrors, which produced the first focused hard X-ray (>10 keV) images of an astrophysical source by imaging Cygnus X-1, GRS 1915, and the Crab Nebula. This initial effort resulted in several follow-up missions over the next 12 years, and became known as the High Energy Replicated Optics (HERO) balloon program.
In 2012, the first of four sounding rocket flights of the Focusing Optics X-ray Solar Imager (FOXSI) flew with MSFC optics onboard, producing the first focused images of the Sun at energies greater than 5 keV. In 2019 the Astronomical Roentgen Telescope X-ray Concentrator (ART-XC) instrument on the Spectr-Roentgen-Gamma Mission launched with seven MSFC-fabricated X-ray MMAs, each containing 28 mirror shells. ART-XC is currently mapping the sky in the 4-30 keV hard X-ray energy range, studying exotic objects like neutron stars in our own galaxy as well as active galactic nuclei, which are spread across the visible universe. In 2021, the Imaging X-ray Polarimetry Explorer (IXPE), flew and is now performing extraordinary science with an MSFC-led team using three, 24-shell MMAs that were fabricated and calibrated in-house.
Most recently, in 2024, the fourth FOXSI sounding rocket campaign launched with a high-resolution MSFC MMA. The optics achieved 9.5 arcsecond HPD angular resolution during pre-flight test with an expected 7 arcsecond HPD in gravity-free flight, making this the highest angular resolution flight observation made with a nickel-replicated X-ray optic. Currently MSFC is fabricating an MMA for the Rocket Experiment Demonstration of a Soft X-ray (REDSoX) polarimeter, a sounding rocket mission that will fly a novel soft X-ray polarimeter instrument to observe active galactic nuclei. The REDSoX MMA optic will be 444 mm in diameter, which will make it the largest MMA ever produced by MSFC and the second largest replicated nickel X-ray optic in the world.
Scientists Wayne Baumgartner (left, crouched) and Nick Thomas (left, standing) calibrate an IXPE MMA in the MSFC 100 m Beamline. Scientist Stephen Bongiorno (right) applies epoxy to an IXPE shell during MMA assembly. NASA MSFC The ultimate performance of an X-ray optic is determined by errors in the shape, position, and roughness of the optical surface. To push the performance of X-ray optics toward even higher angular resolution and achieve more ambitious science goals, MSFC is currently engaged in a fundamental research and development effort to improve all aspects of full-shell optics fabrication.
Given that these optics are made with the Electroformed Nickel Replication technique, the fabrication process begins with creation of a replication master, called the mandrel, which is a negative of the desired optical surface. First, the mandrel is figured and polished to specification, then a thin layer of nickel alloy is electroformed onto the mandrel surface. Next, the nickel alloy layer is removed to produce a replicated optical shell, and finally the thin shell is attached to a stiff holding structure for use.
Each step in this process imparts some degree of error into the final replicated shell. Research and development efforts at MSFC are currently concentrating on reducing distortion induced during the electroforming metal deposition and release steps. Electroforming-induced distortion is caused by material stress built into the electroformed material as it deposits onto the mandrel. Decreasing release-induced distortion is a matter of reducing adhesion strength between the shell and mandrel, increasing strength of the shell material to prevent yielding, and reducing point defects in the release layer.
Additionally, verifying the performance of these advanced optics requires world-class test facilities. The basic premise of testing an optic designed for X-ray astrophysics is to place a small, bright X-ray source far away from the optic. If the angular size of the source, as viewed from the optic, is smaller than the angular resolution of the optic, the source is effectively simulating X-ray starlight. Due to the absorption of X-rays by air, the entire test facility light path must be placed inside a vacuum chamber.
At MSFC, a group of scientists and engineers operate the Marshall 100-meter X-ray beamline, a world-class end-to-end test facility for flight and laboratory X-ray optics, instruments, and telescopes. As per the name, it consists of a 100-meter-long vacuum tube with an 8-meter-long, 3-meter-diameter instrument chamber and a variety of X-ray sources ranging from 0.25 – 114 keV. Across the street sits the X-Ray and Cryogenic Facility (XRCF), a 527-meter-long beamline with an 18-meter-long, 6-meter-diameter instrument chamber. These facilities are available for the scientific community to use and highlight the comprehensive optics development and test capability that Marshall is known for.
Within the X-ray astrophysics community there exist a variety of angular resolution and effective area needs for focusing optics. Given its storied history in X-ray optics, MSFC is uniquely poised to fulfill requirements for large or small, medium- or high-angular-resolution X-ray optics. To help guide technology development, the astrophysics community convenes once per decade to produce a decadal survey. The need for high-angular-resolution and high-throughput X-ray optics is strongly endorsed by the National Academies of Sciences, Engineering, and Medicine report, Pathways to Discovery in Astronomy and Astrophysics for the 2020s.In pursuit of this goal, MSFC is continuing to advance the state of the art in full-shell optics. This work will enable the extraordinary mysteries of the X-ray universe to be revealed.
Project Leads
Dr. Jessica Gaskin and Dr. Stephen Bongiorno, NASA Marshall Space Flight Center (MSFC)
Sponsoring Organizations
The NASA Astrophysics Division supports this work primarily through the Internal Scientist Funding Model Direct Work Package and competed solicitations. This work is also supported by the Heliophysics Division through competed solicitations, as well as by directed work from other government entities.
Share
Details
Last Updated Oct 15, 2024 Related Terms
Astrophysics Astrophysics Division Marshall Astrophysics Marshall Space Flight Center Science-enabling Technology Technology Highlights Explore More
2 min read Hubble Spots a Grand Spiral of Starbursts
Article
4 days ago
6 min read NASA’s Hubble, New Horizons Team Up for a Simultaneous Look at Uranus
Article
6 days ago
4 min read NASA’s Hubble Watches Jupiter’s Great Red Spot Behave Like a Stress Ball
Article
6 days ago
View the full article
-
-
-
-
Check out these Videos
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.