¶ISS: R.I.P. 2031? The first component of the International Space Station, the Zarya Control Module, surpassed its 25th year in space last November—a major achievement for a project that was originally planned to last just 15 years. The current U.S. administration has extended operational support for the ISS through 2030, and the station’s European, Japanese, and Canadian partners have committed to the same timeline. Russia originally announced its intention to withdraw from the station after 2024, but in April 2023, the Russian government formally agreed to an extension through 2028. Under the present plan, the station's decommissioning would utilize natural orbital decay and/or propulsive retrograde maneuvers to lower the station’s altitude from ~420 km where it orbits today. These procedures could start as early as 2026, depending on solar cycle activity. Eventually, around June 2030, three Russian Progress vehicles would lower the station to the 270 km “point of no return” holding orbit as needed to establish proper ground tracks. The recently proposed United States Deorbit Vehicle (USDV), having hypothetically been attached a year prior, would then perform a final deorbit burn when the ISS perigee is ~150 km. While most of the $150B, 420-tonne ISS reentering Earth’s atmosphere at ~29,000 kph will disintegrate, heat-resistant components, such as truss sections, will splash down in the South Pacific Oceanic Uninhabited Area. The NASA USDV contract also includes contingencies for the vehicle to launch prior to 2030 or as late as 2035. Other considerations for ISS end-of-life scenarios included raising the station’s altitude to a graveyard orbit (energetically very hard, but then it would be preserved for future generations!), allowing natural orbital decay to lead to an uncontrolled reentry (this seems bad), or returning certain components to Earth (e.g., to the Smithsonian) after disassembly. Throwing away this much orbital mass seems crazy, and the idea to transition the US-led functions of the ISS to private operators was considered in 2016 and again in 2018, but instead, NASA has shifted its plan to support commercial space stations in order to obtain a more affordable and diverse presence in LEO. Axiom Space was awarded $140 million under the 2021 NextSTEP program. Its first module, Hab One, is on track to attach to the ISS in 2026. Hab One is planned to be joined by three more Axiom modules, forming the Axiom Orbital Segment, which will eventually detach and function as a free-flying commercial station. Also awarded in 2021 were three proposals for the NASA Commercial LEO Destinations (CLD) program. Despite some major changes in the companies involved, one project being abandoned, and reports that another proposal may not proceed as planned (c.f. Issue 239), two of these private stations, namely Starlab and Orbital Reef, officially remain under development for 2028 operations. Vast has also partnered with NASA via an unfunded Space Act Agreement and is aiming for its Haven-1 module to launch in 2025, followed by a Starship-class module in 2028. |
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 | ISS end-of-life deorbit planning assumptions for a 2031 timeline. Credits NASA. |
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¶Short Papers- Enceladus’s Tiger Stripe faults, which shoot out plumes of water, may open and close like elevator doors due to tidal forces during the moon’s 33-hour orbit around Saturn (paper).
- Three years of Hubble observations of exoplanet WASP 121 b showed clear evidence of variation with time, which modeling suggests are weather patterns in the hot, Jupiter-like planet’s atmosphere (paper).
- Two ancient streams of stars that may have formed the Milky Way some 12 billion years ago have been identified by ESA’s Gaia mission. Named Shakti and Shiva, the streams contain ~10 million compositionally similar stars that are all 12-13 billion years old (paper).
- The magnetism of iron particles in 3.7 billion-year-old rocks from Greenland show that Earth definitely had a magnetosphere at least that long ago (paper).
- Not only did DART’s impact on Dimorphos change its orbit, but also its shape, transforming it from an oblate spheroid to a triaxial ellipsoid (paper). ESA’s Hera, launching in October, should confirm this new analysis of the available data.
- And, based on measurements from DART, scientists at Lawrence Livermore National Laboratory simulated the energy deposition of a hypothetical nuclear device on an asteroid (paper)—which is hopefully the only way humans will ever use nuclear weapons again.
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 | Simulation results of setting off a nuke near the surface of a near-Earth object. |
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¶Redwire goes VLEO. Redwire recently announced the development of not one but two very low Earth orbit (VLEO) spacecraft platforms. Redwire’s SabreSat is a sleek, low-drag VLEO spacecraft that consumes the tenuous atmosphere at 90 to 350 km to provide fuel for its electric propulsion system so that it can stay in orbit. Meanwhile, Redwire’s Phantom, under development in Belgium with collaboration from Thales Alenia Space, is part of ESA’s VLEO Skimsat program. The two systems have different technological heritages and are targeting different markets. SabreSat is also larger, designed to carry 200 kg payloads while Phantom can carry 50 kg. Customers (especially government ones) are interested in VLEO because it allows sensors of the same size to produce better ground resolution and because it avoids issues with the growing debris population in LEO (in VLEO, debris, including defunct VLEO spacecraft, fall out of orbit quickly). Other companies working on VLEO include Albedo, EOI Space, Kreios Space, Phase Four (funded by DARPA), and various other governmental efforts in the US, China, and elsewhere. Challenges for these crosses between aircraft and spacecraft are managing significant drag and surviving exposure to large amounts of atomic oxygen. Spacecraft have flown in VLEO before, including ESA’s Gravity Field and Steady-State Ocean Circulation Explorer (2009-2013) which mapped Earth’s gravity from an altitude of about 255 km, JAXA’s Super Low Altitude Test Satellite (2017-2019), and MIT Lincoln Laboratory’s 16U Agile MicroSat (2022-2023; mission update ppt). |
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 | A likely somewhat fantastical impression of the missile-like SabreSat in VLEO. |
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| ¶News in brief. Perseverance has been on Mars for 1,000 sols (Martian days) ● Starliner’s launch has been further delayed due to a helium leak in the spacecraft’s propulsion system ● Lithuania is the 40th country to sign the Artemis Accords ● SatVu will build HotSat-2 and 3 to revive their thermal imaging constellation after HotSat-1 failed six months into its mission ● Weather intelligence firm Tomorrow.io received a $10.2M DoD contract to produce two satellites with microwave sounders for military weather forecasting ● Russia launched a classified payload aboard a Soyuz-2, possibly a continuation of a previous launch of a research spacecraft with test components for a potential nuclear-powered anti satellite weapon two years ago, or having some other anti satellite capabilities ● A 40 kg chunk of space debris (likely from a SpaceX rocket) landed on a farm in Saskatchewan ● China launched four optical remote sensing satellites ● The US Air Force is imposing financial penalties on ULA for launch delays with Vulcan; it needs a second launch for certification before full use in classified government missions ● For the 12th straight year, NASA continues to be the best place to work in the US government ● BepiColombo, the joint ESA/JAXA mission to Mercury, is experiencing issues with its electric thrusters that are currently unable to fire at full power ● A SpaceX Falcon 9 launched for the 21st time, setting a new reuse record ● NASA signed an agreement to provide americium radioisotope heater units (a first) and a US launch provider for ESA’s ExoMars Rosalind Franklin rover ● After nearly two years, Blue Origin’s New Shepard launched six tourists into suborbital space for just under 10 minutes before returning to Earth safely (despite an anomaly with one of the three parachutes on the crew capsule). |
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¶Etc.- A quick roundup of more solar storm content: The Sun emitted another massive flare, an X8.7, the largest of this solar cycle, but any CME didn’t hit Earth; solar activity results in a puffier atmosphere and more drag to orbiting spacecraft, including Hubble; here’s a graph of the power required by Sentinel2’s attitude and orbit control system due to solar perturbations; and, lots more aurorae photos!
- Book Review: ‘Challenger,’ by Adam Higginbotham, an important lesson of history to remember as we embark on the Artemis era and the inevitable political pressures of another race to the Moon.
- NPR: Private mission to save Hubble Space Telescope raises concerns, NASA emails show. The last Hubble servicing mission was 15 years ago this month.
- Check out this gorgeous video taken by the Extreme Ultraviolet Imager (EUI) instrument on ESA's Solar Orbiter in September 2023, showing the Sun’s lower atmosphere and corona. It includes features known as moss, spicules, eruptions, and rain.
- Here is a striking video of a meteor seen in Portugal, Spain, and France, thought to be of cometary origin (due to its velocity of 45 km/s). More videos and sightings.
- Lots of new EO data products: a soil moisture product from Spire (using GNSS Reflectometry), a flood product from Iceye (using SAR), Capella Space’s automated vessel identification product (SAR), Planet’s now-LiDAR-validated forest carbon product (optical), and Muon Space’s upcoming wildfire monitoring constellation in partnership with Earth Fire Alliance (multispectral). The UK also just funded the development of 12 additional climate-focused EO instruments.
- Methane emissions from gas flaring are being hidden from satellite monitors.
- Ars Technica took a stab at decoding SpaceX’s ever-changing plans for Starship in Florida.
- How many model rocket engines would it take to launch a real rocket into space? 🚀
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Europa, as seen by JunoCam during its closest flyby yet of the Jovian moon (coming within 355 km) on Sept. 29, 2022. Credit: Image data: NASA/JPL-Caltech/SwRI/MSSS; Image processing: Björn Jónsson (CC BY 3.0) |  |
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