Space Sunday: Exoplanets and updates

Newly discovered Earth-size planet TOI 700 e orbits within the habitable zone of its star in this illustration. Its Earth-size sibling, TOI 700 d, can be seen in the distance. Credit: NASA/JPL-Caltech/Robert Hurt

Since its launch in April 2018, TESS, the Transiting Exoplanet Survey Satellite, has located 5,969 candidate exoplanets within the immediate (cosmically speaking) neighbourhood of our solar system. Of these, 268 have been confirmed as actual planets – although 1,720 have been dismissed as false positives.

Three of the positives were located orbiting a red dwarf star called TOI 700, some 100 light-years away and within the constellation Dorado, one of which sits within the star’s habitable zone where liquid water might exist on the surface.

And now a fourth has been added to the tally, with the confirmed discovery of TOI 700-e, another planet within the star’s habitable zone. Like TOI 700-d, the other planet within the star’s habitable zone, it is roughly Earth-sized – around 95% the size of Earth, marking it as slightly smaller than TOI 700-d, which is 1.1 times the side of Earth.

This is one of only a few systems with multiple, small, habitable-zone planets that we know of. That makes the TOI 700 system an exciting prospect for additional follow-up. Planet e is about 10% smaller than planet d, so the system also shows how additional TESS observations help us find smaller and smaller worlds.

– Emily Gilbert, NASA’s Jet Propulsion Laboratory

TOI 700-d was actually the first Earth-sized planet TESS located within the habitable zone of s star, and wobbles in its orbit, and those of the other two planets TOI 700-b and TOI 700-c, led Gilbert and her team to task TESS with a re-visit to the system in the belief another planet might be hidden within it, hence the discovery of TOI 700-e.

All of the planets are likely tidally locked to their star – always keeping the same side facing it as they make their orbits. This makes the chances of them supporting life complicated, as one side is always exposed to the heat of the star, and the other to the freezing cold of space. Between them, along the terminator, they may have more temperate regions, but assuming the planets have an atmosphere, the temperate regions could be ravaged by storms where warm and cold fronts continuous meet.  All four planets have short orbital periods – 10 days for the innermost planet 700-b to just over 37 days for the newly-discovered 700-e. Planets b, d, and e are likely rocky, while planet c is likely more similar to Neptune.

The term habitable zone also deserves some expansion, as it actually covers two overlapping zones around a star, the optimistic habitable zone (OHZ) and the conservative habitable zone (CHZ). The former is a region around a star where water may have existed at some point in the planet’s history; the CHZ is a more tightly-constrained region where scientists hypothesize liquid surface water might have existed for most of a planet’s history and it may have developed a more Earth-like atmosphere. TOI 700-e is in the optimistic habitable zone for its star.

That said, determining the habitability of solid rocky planets within the OHZ / CHZ of a star is impossible at our stage of exoplanet science. Simply put, they are fat too small to be seen well enough to make firm conclusions. All scientists can say is that a planet might be potentially habitable and then explain their detailed findings. In the case of TOI 700-e, the science team notes:

With a radius of 0.953 Earth radii, TOI-700-e is likely a rocky planet with a probability of 87%, [and a] timescale for tidal locking of to be on order a few million years. Given the age of the system, it is likely that the planet is in a locked-in synchronous or pseudo-synchronous rotation.

– Emily Gilbert, NASA’s Jet Propulsion Laboratory

One interesting aspect of the TOI 700 system is that while the star in an M-type red dwarf, a spectral type known for violent, powerful flares which could play havoc with the atmosphere and environment of the planets orbiting it. However, TOI 700 is older and more quiescent than its siblings and so perhaps less violent towards its children. Given this, and the fact it is a multi-planet system with two Earth-sized planets sitting within it OHZ, it forms a counterpoint to TRAPPIST-1, a younger, more aggressive M-class star with seven Earth-sized planets orbiting them, four of them within its own OHZ. Studies of both systems offers the potential for extended comparative study, potentially helping scientists better understanding of exoplanet systems form and M-type stars (the most numerous type of star in the galaxy), and how the planets within them retain (or lose) their atmospheres.

The discovery of TOI 700-e is a further demonstration on how the search for exoplanets is progressing. Prior to the launch of the long-running Kepler Space Telescope, only a handful of exoplanets had been discovered, and the number is now over 5,000, with discoveries in recent years revealing more and more Earth-sized worlds and multi-planet systems.

While the number of confirmed planets is small, TESS is adding to that total, and out ability to understand such worlds is gaining a boost thanks the James Webb Space Telescope (JWST). The instruments on the telescope are designed to study exoplanet atmospheres and use spectroscopy to determine their compositions. In fact, this work has already started with the planet Bocaprins (WASP 39b), a “hot Jupiter” planet 700 light years way, with JWST confirming its atmosphere contains sodium, potassium, carbon dioxide, carbon monoxide, water vapour and most significantly, sulphur dioxide.

The James Webb Space Telescope could both assist in the discovery of exoplanets and in analysing their atmospheres. Credit: NASA

The last is important both because it is the first time scientists have found this molecule anywhere outside of our Solar System, confirming photochemical reactions can take place in the atmospheres of exoplanets, and confirms JWST can detect such photochemical reactions within planetary atmospheres over vast distances – .something which could be an important factor in determining what interactions might be taking place in the atmospheres of many exoplanets.

As such, exoplanet science is maturing rapidly.

Soyuz MS-22 Update

Russia has confirmed it will launch Soyuz MS-23 to the International Space Station in an uncrewed mode to replace the Soyuz MS-22 vehicle which suffered a major coolant leak in December 2022, following what is theorised a piece of dust striking the external radiator at a speed of 7 km/s.

Following the accident, a number of western experts suggested the Soyuz vehicle would be incapable of maintaining a safe temperature in the crew cabin during a return to Earth. After a month-long review of the situation, including examining options for a space-based repair, the Russian space agency Roscosmos has reached the same conclusion.

Video of the Soyuz MS-22 coolant leak, December 14th 2022. Credit: NASA

Soyuz MS-23 will therefore launch on or around February 20th in an automated configuration to provide the means for cosmonauts Sergey Prokopyev and Dmitri Petelin and NASA astronaut Franco Rubio to return to Earth at a later date – exactly when that will be is unclear; as a result of needing to use MS-23 as a replacement vehicle, crew rotations on the Russian side of things will be disrupted, and so Roscomos expects the MS-22 crew to extend their stay on the station by “several months”.

However, the February launch for MS-23 still means that should an emergency evacuation of the station be required in the next month, the crew of MS-22 would be without a ride home. To cover this, it has been suggested at least one MS-22 crew member (likely Rubio) could return on Crew Dragon 5 with the four astronauts it flew to the ISS in October 2022, and remaining MS-22use that vehicle -the thinking at Roscosmos being that with a smaller crew, the damaged cooling system on the Soyuz wouldn’t be so strained and could maintain “safe” temperatures within the vehicle.

Once MS-23 has docked at the station, MS-22 will be prepared for an automated return to Earth, where the investigation into the coolant loss will continue.

Repairs to the damaged vehicle were ruled out due to the difficulties involved in any spacewalk to do so – not the least of which was the risk of ammonia contaminating the spacesuits used and then being brought back into the ISS in high enough concentrations that it might pose a serious health risk if inhaled by any of the crew.

Virgin’s Space Woes

In my last Space Sunday update I previewed the (then) forthcoming maiden launch of Virgin Orbit’s LauncherOne rocket, carrying a payload of nine smallsats from UK soil (see: Space Sunday: a launch, a budget, a station and an astronaut).

That launch went ahead as scheduled Monday, 9th, 2023, with the 747 carrier aircraft Cosmic Girl taking off from spaceport Cornwall (aka Newquay Airport) shortly after 22:00 UTC. Then, just over an hour later and out over the Atlantic Ocean south of the Republic of Ireland, it released the rocket.

Virgin Orbit’s Cosmic Girl departs Spaceport Cornwall at the start of the Start Me Up mission. Credit: Ben Birchall via Associated Press

At first everything appeared to go as planned, the motors of the rocket’s first stage ignited, and despite some very odd telemetry displayed on the live webcast for the launch (including the suggestion the rocket had exceeded the speed of light!), everything appeared to proceed well.

So well, in fact, that seven minutes after motor ignition, Virgin Orbit tweeted that the mission was a success and the payload and rocket upper stage had reached orbit. Only they hadn’t. As a result, some 30 minutes later, the tweet was deleted to be replaced with the news that the launch had failed, and the rocket’s payload lost – apparently the result of a “anomaly” with the rocket’s upper stage which caused the stage’s motors to shutdown before orbital velocity had been released.

Telemetry relayed during the launch webcast suggested something was not quite right somewhere, at one point indicating the rocket had exceeded the speed of light, and then recording its altitude as a negative value. Whether this was related to the “anomaly” which cause the premature shut-down of motors on the LauncherOne upper stage is unclear. Credit: Virgin Orbit

As a result of the launch failure – the second in just six launches -, operations have been suspended pending a determination of the cause of the “anomaly”. This is not good news for the company, which has been experiencing financial issues: it recently reported having only US $71 million in cash, and a negative cash flow of US $52.5 million – forcing the Virgin Group to inject some US $45 million into the company in late 2022. Following the opening of the markets, Virgin Orbit shares lost a further 14% of their value.

Nor is this the only financial turbulence for the Virgin Group’s space ambitions. Virgin Galactic, the sub-orbital “space tourism” company, has seen its share price fall from US $55 to just $5, in part due to a legal action brought against the company by a number of its investors.

Filed at the end of December 2021, the action alleges Virgin Galactic misled investors on the flightworthiness of the USS Unity space plane and its carrier aircraft MSS Eve, and also issued false claims relating to the first (and thus fair only) passenger-carrying flight, made in July 2021. Hearing the case, New York District Judge Allyne Ross has demonstrated sympathy with the plaintiffs, agreeing that Virgin Galactic may have “materially misled” investors between mid-2019 and the end of 2021. She also agreed that company founder and CEO may have benefited from matters arising from the July 2021 passenger flight.

An impressive view of MSS Eve framed against the Moon. Credit: Virgin Galactic

At the time, Virgin Galactic proclaimed it a “100% success” – despite knowing VSS Unity departed its assigned FAA flight corridor during its ascent, and the pilots should have aborted the flight, but instead the decision was made to press on and play down the situation after the fact. Then, just ahead of news about the transgression being made public – hitting the company’s share price – Branson sold some 10 million of his shares in the company for more than US $300 million. Responding to this, Branson’s legal team stated the sale was coincidental and part of a series of share divestments made over some 18 months to raise funds for Branson’s Virgin Atlantic airline, which at the time was struggling to overcome losses resulting from the pandemic.

Immediately after the July 2021 flight, all operations with both VSS Unity and MSS Eve were suspended so that they could enter an “extended period of maintenance and overhaul” – a move which further angered the investors filing the action. Intended to last 18 months, that period is now closing and the company is ramping to resume flight operations. These are due to start at some point in 2023 with a research flight for the Italian air force, which will then be followed by monthly tourism flights, MSS Eve being used between these in certification flight test for VSS Imagine.

SpaceX Starship Update

Among assorted launches and launch preparations (Falcon 9 and Falcon Heavy – which was due to launch as this article was being written), SpaceX has once again carried out the stacking of one of its new Starship vehicles with its Super Heavy launcher on the launch platform at its Starbase facilities in Boca Chica, Texas.

Booster 7 and Ship 24 – slated to be the vehicles to be used in the first attempt to fly the system to orbit (and the first flight of the 70-metre tall Supper Heavy) – were stacked one atop the other for the third time since mid-2022, on Monday, January 9th. The move was immediately met with speculation that the launch is “imminent”, which is not actually the case,

An Airbus Pléiades Neo satellite captured this view of SpaceX’s stacked Starship prototype on its orbital launch mount in South Texas, on January 12, 2023. Credit: Airbus

Rather, the latest stacking is to resume tests which had been expected what the two vehicles were last stacked towards the end of 2022 – notably (but not limited to) a wet dress rehearsal and a full static fire test of all 33 engines on the Super Heavy booster.

The former will see both Booster 7 and Ship 24 go through a full launch count-down (including taking on a full propellant load) which terminates immediately prior to engine ignition. Interestingly, it is only in the week immediately prior to the re-stacking of the vehicles that SpaceX got around to carrying out load tests on the elevated launch table to ensure it actually could handle a mass of 3000+ tonnes of propellants.

The static fire test will be the first time 33 Raptor engines have fired-up together and could be interesting. In the Wisdom of Musk, SpaceX have forgone any flame diverter mechanism (which would divert the blast of the engines and excess sound away from the stacked rocket to reduce the risk of either being deflected back against the vehicle and doing it a mischief) and instead allow the engine exhausts to slam unimpeded into the concrete apron some 10 metres below the base of the rocket.

During two previous static fire tests using less than half the booster’s full set of engines, this resulted in lumps of concrete and debris being hurled out from under the rocket in every direction, and also exposed the launch table legs to damage. While SpaceX has twice altered the area directly below the rocket and has added further cladding and protection to the launch table, it will be interesting to see how things fare during this test.

A dramatic picture (and not a rendering) of Ship 24 stacked on Booster 7 at Starbase Boca Chica, January 9th, 2023. Credit: SpaceX

Assuming the tests are all passed with flying colours, it still does not mean the system is cleared for a launch. For that to happen, SpaceX still require a launch license from the FAA – and that is unlikely to happen unless and until the company is in full compliance with a list of updates the FAA want to see made to the launch site ahead of any launch attempt. Whilst issued in June 2022 as a part of the FAA’s Environmental Review of the facilities, SpaceX has yet to fully comply with all of the requirements.