Progress continues at a private space station, Starship reignites its engines for testing, and bidding farewell to a seasoned workhorse. This Week in Space

Cosmic Fireworks in Real-Time 

Some stars conclude their lives in a blaze of glory, exploding as supernovas that rival the brightness of entire galaxies for days. The sequence of events leading to this stellar finale captivates scientists, however these phenomena are difficult to study - partially due to the fact that predicting these explosions remains a challenge. These are quite rare events, but luckily, the vastness of the universe allows for the occasional detection of an active supernova and the direction of telescopes at it, enabling researchers to capture some of the activity and study the aftermath and the remnants left behind by such cosmic fireworks.

Despite these successes, the initial stages of a supernova and the processes leading to it continue to elude scientific understanding, at least from an observational evidence standpoint.

Last year, the research group of Prof. Avishay Gal-Yam from the Weizmann Institute  struck astronomical gold when a red supergiant star exploded into a supernova precisely during their observation window with the Hubble Space Telescope. On May 19, 2023, other researchers identified the supernova, and this early identification allowed research students Erez Zimmerman and Ido Irani to quickly perform the calculations and measurements needed for NASA to direct the telescope towards it. Within just two days, Hubble was aimed at the supernova in the Pinwheel Galaxy (M101), located about 22 million light-years, and thus managed to document much of its evolution in what is virtually real-time for us. Naturally, the definition of "real-time" is only relative since the explosion itself occurred over 20 million years ago, but its light has reached Earth only now. 

In parallel with analyzing the observational data, the researchers managed to locate previous images of the star that exploded,  enabling them to observe various stages of the explosion and compare them to the star's state prior to the explosion. They report their findings in an article published last week in the journal Nature. "When we compare the mass of the star after the explosion, which we measured from the explosion itself, to the mass of the star at the beginning of its life, a significant residue remains," said Irani. "The gap makes it possible to determine, with a very high probability, that the supernova left behind a black hole - into which the rest of the missing mass was apparently swallowed." This aligns with previous research by Gal-Yam and Irani, which found evidence for the formation of a heavy object such as a black hole or a neutron star following another supernova event. "Because of the proximity of the star and the quality of the data collected, this research is a rare opportunity to better understand the mechanisms that lead to the end of a star's life and the formation of a completely new thing," added Zimmerman.

Although real-time tracking of supernovas currently relies heavily on chance, it's conceivable that such discoveries will become routine in the near future, thanks to the Israeli space telescope, ULTRASAT, slated for launch in approximately two years. This telescope aims to scan the sky for bursts of ultraviolet radiation, indicative of energetic phenomena such as supernovas, among other things. Through comprehensive scanning, ULTRASAT will enable the nearly real-time identification of such events, facilitating the deployment of additional space-based and ground-based telescopes to investigate the diverse range of radiation emitted and characterize the underlying processes.

A video by the Weizmann Institute about the study:

Station on the Way to Space

The United States Space Agency (NASA) has approved four components of the Orbital Reef space station being developed by Blue Origin and Sierra Space. Orbital Reef is anticipated to serve as a private space station,  set to become operational after the retirement of the International Space Station (ISS) in 2030, and will allow NASA to sustain regular astronaut activities in low Earth orbit. Furthermore, it plans to offer living and working spaces for rent to private enterprises seeking to conduct space experiments, as well as to tourists able to afford a unique stay above Earth's atmosphere. Three years prior, these companies secured a $172 million grant from NASA to spearhead the station's development,  in collaboration with Axiom, another entity tasked with gradually constructing a private station leveraging the International Space Station's existing infrastructure

Last week, NASA announced that, following thorough examination, it has approved four components related to safety and life support systems. Among these is a system designed to recycle urine, sweat, and breath vapor into drinking water, mirroring the technology that has been operational for over fifteen years on the International Space Station. A common jest among astronauts is that yesterday's coffee becomes today's and tomorrow's coffee due to this recycling process. Additionally, the approved systems include the station's water tank, a water purification system, and an air quality monitoring and filtration system capable of detecting and filtering contaminants even at very low concentrations.

“These milestones are critical to ensuring that a commercial destination can support human life so NASA astronauts can continue to have access to low Earth orbit to conduct important scientific research in the unique microgravity environment,” said Angela Hart, manager of NASA’s Commercial Low Earth Orbit Development Program. “Additionally, each milestone that is completed allows NASA to gain insight into our partner’s progress on station design and development.”

Another place to live and work in, even if the water is recycled urine. Simulation of Orbital Reef Space Station | Source: Blue Origin

Starship Heating Up Engines Again

SpaceX is gearing up to conduct another test of the Starship spacecraft, potentially as early as May, just two months after the third - and most successful to date - test of the system, which took place in mid-March. Last Monday, the company conducted a static fire test – activating the engines without launching – of the spacecraft slated for the upcoming experiment, this time excluding the launch vehicle itself, the Super Heavy. According to a SpaceX tweet, all six engines performed as anticipated throughout the test

During the third test, the company achieved significant milestones, including a successful entry into the planned orbit, a standard flight of about 50 minutes with uninterrupted communication, the opening of the spacecraft's cargo bay, and experimentation with fuel transfer between tanks. However, the spacecraft disintegrated upon re-entry into the atmosphere, and prior to that, the company encountered issues with re-igniting the engines in space. Additionally, the launch vehicle, Super Heavy, failed to complete its planned landing maneuver over the sea.

The company is currently analyzing data from the most recent experiment in hopes of rectifying the failures for the upcoming test. "We'll figure out what happened on both stages" during descent "and get back to flight, hopefully in about six weeks,"  said SpaceX President and Chief Operating Officer Gwynne Shotwell at the recent Satellite 2024 conference in Washington. In light of the mission concluding in crashes, the Federal Aviation Administration (FAA) is conducting an investigation into the test flight, as it has with previous flights. SpaceX must rectify any flaws identified during the investigation to secure authorization for Starship's forthcoming test flight.

 All engines operated as anticipated. The Starship spacecraft slated for the upcoming fourth test flight during last week's static fire test | Photo: SpaceX

Farewell to a Workhorse

The veteran launch vehicle, Delta IV Heavy, is concluding its journey after many years of steadfast service. The final launch of the rocket by the United Launch Alliance (ULA) was planned for last Thursday, slated to deploy a satellite for the American intelligence agency, NRO, into orbit. This mission signifies the 44th launch of a Delta IV rocket spanning over two decades, and the 16th launch of its Heavy configuration designed for substantial payloads. With the exception of a partial failure during its inaugural launch, all previous missions have ended successfully. However, on Friday ULA announced that the company will further delay the final mission of its Delta Heavy IV rocket as "more time is needed to instill confidence in the system" prior to launch.

Ranked fourth in the world in terms of thrust power, Delta Heavy IV follows behind NASA's SLS, SpaceX's Falcon Heavy, and SpaceX's Super Heavy, the latter having launched Starship spacecraft into orbit twice despite not yet being operational. It is ranked slightly above China's Long March 5. Unlike reusable rockets, Delta IVs are single-use, with no recovery or reuse of their first stage or boosters. These powerful rockets have launched, among other missions, the Orion spacecraft on its inaugural test flight in 2014, and the Parker Solar Probe towards its mission to study the Sun in 2018.

Delta Heavy IV's place, along with that of the Atlas V rocket which is anticipated to be phased out in the coming years, will be assumed by ULA's latest development, the Vulcan Centaur rocket. The new rocket's debut launch earlier this year was a great success, although the spacecraft it carried did not reach the moon due to a fuel leak.

A veteran workhorse with an impressive record of success in launching heavy payloads. Delta IV Heavy launching an NRO satellite in 2019 | Photo: Michael Peterson/USAF, Public domain

Translated with the assistance of ChatGTP. Revised, expanded and edited by the staff of the Davidson Institute of Science Education