Mirrors for the LDCM Operational Land Imager (OLI) Telescope.
NASA
Special Topics: LDCM and LDCM Components
The OLI telescope uses a four-mirror compact design. The optics are positioned inside a lightweight, yet highly stable, carbon composite optical bench (i.e., a substrate on which the optics are mounted) that has special features to control undesired stray light (stray light is any light entering the optics from someplace other than the observed Earth surface, or imaging “target”).
Because OLI is a push-broom instrument, as opposed to a scanner (or “whisk-broom”), it has a wide field-of-view to cover the entire ground swath width. Wide field-of-view telescopes are generally susceptible to stray light, so the OLI telescope is designed for improved stray light control. The number and shapes of the mirrors meet the required optical design parameters, like focal length, for example, within a size that also meets the volume and mass requirements for the instrument.
Note: The previous Landsat sensors have used scanner or “whisk-broom” technology. This means that a mirror scans from side-to-side across the satellite path directing light into the instrument detectors. The OLI uses push-broom technology meaning that an array of detectors is used to image the entire swath/width of the satellite path simultaneously.
Landsat Data Continuity Mission Becomes an Observatory
Landsat Data Continuity Mission Becomes an Observatory
TIRS being hoisted into place on the LDCM satellite in Gilbert, Ariz.
Orbital Science Corp
• Engineers at Orbital Sciences Corporation, Gilbert, Ariz., have installed the Thermal Infrared Sensor (TIRS) instrument back onto to the Landsat Data Continuity Mission (LDCM) spacecraft. With both the Operational Land Imager (OLI) and TIRS instruments now on the spacecraft, LDCM is a complete observatory.After the TIRS instrument was shipped to Orbital in February, engineers discovered that helium had leaked from the TIRS cryogenic cooler. The cooler keeps the detectors extremely cold, which is required for the instrument to detect thermal infrared radiation emitted from Earth. The leak was quickly repaired, the cooler was re-pressurized with helium, and TIRS was re-installed onto the instrument deck of the spacecraft. Once the TIRS instrument is electrically connected later this month, TIRS will be ready to begin environmental testing with the rest of the observatory.
The engineering team at NASA’s Goddard Space Flight Center in Greenbelt, Md., built TIRS on an accelerated schedule, going from a design on paper to a completed instrument in 43 months. An instrument of this type usually takes another year to complete.
Under contract to NASA, Orbital is responsible for providing the spacecraft bus, installing the science instruments and performing system-level integration and testing of the Observatory prior to launch. Ball Aerospace & Technologies Corp. built the OLI. The USGS developed the LDCM ground system.
An artist’s impression of gravitational waves generated by binary neutron stars.
Credits: R. Hurt/Caltech-JPL
by Kat Troche of the Astronomical Society of the Pacific
September 2025 marks ten years since the first direct detection of gravitational waves as predicted by Albert Einstein’s 1916 theory of General Relativity. These invisible ripples in space were first directly detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO). Traveling at the speed of light (~186,000 miles per second), these waves stretch and squeeze the fabric of space itself, changing the distance between objects as they pass.
Waves In Space
Gravitational waves are created when massive objects accelerate in space, especially in violent events. LIGO detected the first gravitational waves when two black holes, orbiting one another, finally merged, creating ripples in space-time. But these waves are not exclusive to black holes. If a star were to go supernova, it could produce the same effect. Neutron stars can also create these waves for various reasons. While these waves are invisible to the human eye, this animation from NASA’s Science Visualization Studio shows the merger of two black holes and the waves they create in the process.
Two black holes orbit each other, generating space-time ripples called gravitational waves in this animation. As the black holes get closer, the waves increase in until they merge completely.
NASA’s Goddard Space Flight Center Conceptual Image Lab
How It Works
A gravitational wave observatory, like LIGO, is built with two tunnels, each approximately 2.5 miles long, arranged in an “L” shape. At the end of each tunnel, a highly polished 40 kg mirror (about 16 inches across) is mounted; this will reflect the laser beam that is sent from the observatory. A laser beam is sent from the observatory room and split into two, with equal parts traveling down each tunnel, bouncing off the mirrors at the end. When the beams return, they are recombined. If the arm lengths are perfectly equal, the light waves cancel out in just the right way, producing darkness at the detector. But if a gravitational wave passes, it slightly stretches one arm while squeezing the other, so the returning beams no longer cancel perfectly, creating a flicker of light that reveals the wave’s presence.
When a gravitational wave passes by Earth, it squeezes and stretches space. LIGO can detect this squeezing and stretching. Each LIGO observatory has two “arms” that are each more than 2 miles (4 kilometers) long. A passing gravitational wave causes the length of the arms to change slightly. The observatory uses lasers, mirrors, and extremely sensitive instruments to detect these tiny changes.
NASA
The actual detection happens at the point of recombination, when even a minuscule stretching of one arm and squeezing of the other changes how long it takes the laser beams to return. This difference produces a measurable shift in the interference pattern. To be certain that the signal is real and not local noise, both LIGO observatories — one in Washington State (LIGO Hanford) and the other in Louisiana (LIGO Livingston) — must record the same pattern within milliseconds. When they do, it’s confirmation of a gravitational wave rippling through Earth. We don’t feel these waves as they pass through our planet, but we now have a method of detecting them!
While the average person may not have a laser interferometer lying around in the backyard, you can help with two projects geared toward detecting gravitational waves and the black holes that contribute to them:
Black Hole Hunters:Using data from the TESS satellite, you would study graphs of how the brightness of stars changes over time, looking for an effect called gravitational microlensing. This lensing effect can indicate that a massive object has passed in front of a star, such as a black hole.
Gravity Spy:You can help LIGO scientists with their gravitational wave research by looking for glitches that may mimic gravitational waves. By sorting out the mimics, we can train algorithms on how to detect the real thing.
You can also use gelatin, magnetic marbles, and a small mirror for a more hands-on demonstration on how gravitational waves move through space-time with JPL’s Dropping In With Gravitational Waves activity!
NASA, Blue Origin Invite Media to Attend Mars Mission Launch
A stylized illustration shows the twin ESCAPADE spacecraft entering Mars’ orbit.
Credits: James Rattray/Rocket Lab USA
NASA and Blue Origin are reopening media accreditation for the launch of the agency’s ESCAPADE (Escape and Plasma Acceleration and Dynamics Explorers) mission. The twin ESCAPADE spacecraft will study the solar wind’s interaction with Mars, providing insight into the planet’s real-time response to space weather and how solar activity drives atmospheric escape. This will be the second launch of Blue Origin’s New Glenn rocket.
Media interested in covering ESCAPADE launch activities must apply for media credentials. Media who previously applied for media credentials for the ESCAPADE launch do not need to reapply.
U.S. media and U.S. citizens representing international media must apply by 11:59 p.m. EDT on Monday, Oct. 13. Media accreditation requests should be submitted online to: https://media.ksc.nasa.gov.
Blue Origin is targeting later this fall for the launch of New Glenn’s second mission (NG-2) from Space Launch Complex 36 at Cape Canaveral Space Force Station in Florida. Accredited media will have the opportunity to participate in prelaunch media activities and cover the launch. Once a specific launch date is targeted, NASA and Blue Origin will communicate additional details regarding the media event schedule.
NASA will post updates on launch preparations for the twin Martian orbiters on the ESCAPADE blog.
The ESCAPADE mission is part of the NASA Small Innovative Missions for Planetary Exploration program and is funded by the agency’s Heliophysics Division. The mission is led by the University of California, Berkeley Space Sciences Laboratory, and Rocket Lab designed the spacecraft. The agency’s Launch Services Program, based at NASA’s Kennedy Space Center in Florida, secured launch services under the VADR (Venture-class Acquisition of Dedicated and Rideshare) contract.
Crew Works Advanced Science Hardware and Conducts Lab Inspections
NASA astronauts Zena Cardman and Mike Fincke, both Expedtion 73 Flight Engineers, pose for a portrait inside the International Space Station’s Kibo laboratory module during science hardware maintenance in Kibo’s airlock.
NASA
Space science hardware once again topped the schedule for the Expedition 73 crew aboard the International Space Station on Tuesday. Life support and electronics maintenance to keep the orbital outpost in tip-top shape filled the rest of the day for the space lab residents.
Spacecraft humidity removal gear and ultra-high temperature physics were the focus for Flight Engineers Jonny Kim of NASA and Kimiya Yui of JAXA (Japan Aerospace Exploration Agency). Kim installed and activated a new technology demonstration in the Harmony module testing the removal of moisture from a spacecraft’s environment for recycling. Results may advance regenerative life support systems on future missions to the Moon, Mars, and beyond such due to the inability to resupply crews living and working farther away from Earth. Yui worked in the Kibo laboratory module on the Electrostatic Levitation Furnace (ELF) processing samples inside the experimental device. ELF uses lasers to safely heat materials to ultra-high temperatures as sensors and cameras measure thermophysical properties difficult to obtain in Earth’s gravity.
NASA Flight Engineer Mike Fincke installed the new Heat Transfer Host 2 fluid physics research hardware inside the Columbus laboratory module. The advanced gear will look at two-phase heat transfer, or condensation when gas turns to liquid, potentially leading to the design of advanced thermal systems for spacecraft carrying humans on deep space missions.
NASA Flight Engineer Zena Cardman spent her day primarily on life support maintenance first transferring fluids inside the Destiny laboratory module. Afterward, she collected airflow measurements and inspected ventilation systems throughout the space station’s U.S. segment with assistance from Kim. Finally, Cardman inspected cables and insulation for signs of corrosion and degradation in the Unity and Harmony modules. At the beginning of her shift, Cardman spent a few minutes swapping samples cassettes inside the Advanced Sample Experiment Processor-4 for an experiment investigating how to manufacture pharmaceuticals off the Earth.
Station Commander Sergey Ryzhikov of Roscosmos spent most of his shift replacing power supply components inside the Zarya module. He wrapped up his day jogging on the Zvezda service module’s treadmill for a regularly scheduled space fitness test. Flight Engineer Alexey Zubritsky concentrated on maintenance throughout Tuesday servicing the Elektron oxygen generator in Zvezda and conducting the yearly inspection inside the Roscosmos segment’s modules for moisture, corrosion, or damage. Flight Engineer Oleg Platonov explored how blood circulates to the microcirculatory system, the smallest blood vessels, in a crew member’s limbs using specialized blood pressure cuffs and electrodes.
