Space Sunday: tourist flights, landers, moons and rovers

A dramatic shot from the tail boom camera on VSS Unity just after the tail boom has been triggered to its raised “feathered” position to commence the gentle drop back into the denser atmosphere following a flight to an altitude just shy of 90 km (56.25 mi). Credit: Virgin Galactic

On Friday, February 22nd, Virgin Galactic’s VSS Unity completed a further test flight, its second time in just over two months, and in doing so set itself a new altitude record.

The space plane was released from its WhiteKnightTwo carrier, the VSM Eve at 16:53 UT, some 45 minutes after taking off from the Mojave Air and Space Port in California. The vehicle’s hybrid rocket moor was fired for roughly one minute, pushing the Unity and its crew of three to an altitude 89.9 km (56 mi), reaching a maximum velocity of Mach 3 in the process. After a successful “feathering” manoeuvre of the vehicle’s tail boom, Unity dropped back into the denser atmosphere and glided back to a runway landing in Mojave at 17:08 UT.

The flight, delayed by two days due to high winds over the planned flight test route, marked the first time the vehicle had carried a “passenger”: Beth Moses, Virgin Galactic’s chief astronaut instructor. She made the flight with David Mackay and Mike “Sooch” Masucci, respectively the company’s chief test pilot and lead trainer pilot. All three were making their first trips into space, Moses being aboard to provide practical validation and  data on aspects of the customer cabin and spaceflight environment from the perspective of “people in the back”. Her presence on the flight was not announced until after Unity had landed.

Beth, Sooch and I just enjoyed a pretty amazing flight which was beyond anything any of us has ever experienced. It was thrilling yet smooth and nicely controlled throughout with a view at the top, of the Earth from space, which exceeded all our expectations.

– Virgin Galactic chief test pilot David Mackay

Moses also kept an eye on the flight’s special payload – four science and technology demonstration packages provided by NASA under the agency’s Flight Opportunities Programme. Three of the packages had been flown on the Unity’s previous flight in December 2018.

Virgin Galactic have refused to indicate how many more test flights will be made before SpaceShipTwo starts carrying fare-paying passengers, although the company’s founder, Sir Richard Branson has indicated he hopes to fly on the vehicle in July 2019, possibly to mark the 50th anniversary of the Apollo 11 Moon landing. Speaking ahead of the February 22nd test flight, Mike Moses, president of Virgin Galactic and husband of Beth Moses, indicated that the company is in the “heart” of their flight test regime, and the focus is on expanding the envelope of flights, including their frequency, prior to committing to commercial flights.

VSS Unity touching down at Mojave Air and Space Port. Credit: Virgin Galactic

The altitudes reached by Unity thus far (just over 80 km / 50 mi on the December 2018 flight and now 89.9 km) have caused some to call into question whether or not VSS Unity has really been in space – including Jeff Bezos, who is heading Blue Origin, Virgin Galactic’s clearest rival in the sub-orbital passenger market.

Speaking about his own company’s test programme with their New Shephard launch system, Bezos emphasised the operational difference between the reusable New Shephard rock and its crew / passenger carrying capsule and Virgin’s SpaceShipTwo. The New Shephard is specifically designed to reach altitudes of 100 km (50 mi), somewhat higher that Virgin Galactic have thus far achieved. 100 km is important, as it marks the position of the Kármán Line, broadly (but not exclusively) considered to be the point above which where aerodynamics cease having any real influence over an aircraft’s performance, making it reliant on astronautics. Thus, it is seen by some as the boundary of space.

One of the issues that Virgin Galactic will have to address, eventually, is that they are not flying above the Kármán Line, not yet … We’ve always had as our mission that we wanted to fly above the Kármán Line, because we didn’t want there to be any asterisks next to your name about whether you’re an astronaut or not. That’s something they’re going to have to address, in my opinion.

– Jeff Bezos, New Origins founder, commenting on Virgin Galactic, February 20th, 2019

New Shephard is also in the midst of a test programme that could see it flying passengers before the end of 2019. Pictures is a text flight launch on January 23rd, 2019, the 10th test flight for the system, as captured via video. Credits: Blue Origin via CBS News

However, things are actually not that clear-cut. There is no international law defining the edge of space; for example, the United States – from which both New Shepherd and Virgin Galactic will fly (at least initially in the latter’s case) considers the boundary to be 80 km (50 mi), which Virgin Galactic can clearly exceed.

Further, Theodore von Kármán, after whom the line is named, suggested the boundary could lie anywhere between 91 km and 100 km altitude. The ambiguity is exacerbated by a proposal to set the “edge” of space in international law as the lowest perigee attainable by an orbiting space vehicle – which would place it somewhere between 130 km (81 mi) and 150 km (93 mi), somewhat beyond the capabilities of either SpaceShipTwo and New Shephard, which tends to render arguments about altitude and boundaries a little moot, particularly given the fact that whether at 80-90 km above the earth or at 100 km, passengers on either vehicle will experience the same degree of weightlessness.

Hyabusha2 Grabs Asteroid Sample

A Japanese probe sent to study an asteroid 300 million km from Earth for clues about the origin of life and the solar system has successfully completed a further part of its mission.

In September 2018, I wrote about Hyabusha2’s  mission to the asteroid Ryugu. At that time, the satellite had just deployed the first of its family of little rovers onto the asteroid. On February 21st, 2019 (February 22nd, Japan time) the vehicle briefly touched the surface of Ryugu using a sampling “horn”. At the same time, a tiny projectile was fired, allowing ejecta thrown up by the impact to be captured by the “horn”.

An image of asteroid Ryugu’s surface, captured by the Minerva 2-1B rover on Friday, September 21st, 2018 and issued by Jaxa on September 22nd. Credit: Jaxa

The samples represent surface material that has been subjected to cosmic radiation, impacts from micrometeorites, and general contamination. They will be used as a baseline for establishing the surface composition of the asteroid. There will be two further sample gathering operations, with the final one being an ambitious attempt to recover samples of pristine subsurface material.

This will see Hyabusha2 release a free-flying “gun” and camera over a sample gathering spot before moving to the far side of the asteroid for protection. The gun will fire a 2.5 kg copper projectile into the asteroid, the impact forming a new 2 metre diameter crater. After the dust from the impact has settled, Hayabusa2 will return to the crater to collect its samples.

Graphic showing Hyabusha2’s touch-and-go landing on Ryugu. Credit: Japan Aerospace Exploration Agency (JAXA)

All of the samples will be individually stored on the vehicle, which will commence a year-long return trip home in December 2019. On reaching Earth, it will release the samples in a small capsule, allowing them to be delivered for study by scientists.

Did Neptune’s Smallest Moon Result From a Collision?

In 2013, scientists reviewing and archive of images of Neptune taken by the Hubble Space Telescope (HST), identified what was potentially a “new” moon orbiting the planet. Checking back through HST image records to 2004, confirmed the object was a small moon, and it was accorded the designation S/2004 N 1.

In 2018 the moon was officially re-designated Neptune XIV, the 14th of Neptune’s panoply of moons, and given the name Hippocamp (aka Hippocampus, the mythological water horse). At a diameter of 34.8 km (21.75 mi), it is the smallest of Neptune’s moons thus far discovered – although how it formed has been the subject of some debate. Was it a small Kuiper belt object captured by Neptune?  Could it be the remnant of a former moon, destroyed in some form of collision with another body?

An artist’s impression of Hippocamp orbiting Neptune (with the Sun in the background, lower left corner). Credit: ESA / Hubble

Part of the fascination with this tiny moon is that, when all is said and done – it shouldn’t actually exist. Its orbit is so close to that of Proteus (the two are separated by just 12,070 km / 7,500 mi), the second largest of Neptune’s moons (and its largest primordial Moon, Triton most likely being a captured Kuiper Belt Object), that in theory, Proteus should have swept it up or pushed it aside a long time ago.

Now a study suggests that Hippocamp might be a fairly “recent” (in cosmological terms) addition to Neptune retinue, and its origins might be directly linked to Proteus.

Proteus as seen by Voyager 2 in 1989. Note the large impact crater, top right, possibly the point of origin for Hippocamp. Credit: NASA/Voyager 2

Some 400 km (250 mi) across, Proteus is a dark, mucky rock that was only discovered in 1989 when Voyager 2 flew past Neptune, capturing a picture of the moon as it did so. Prominent in that picture is a large impact crater, and the new study proposes Hippocamp to be part of the debris that broke free of Proteus when the crater was made, most likely as a result of a cometary impact.

If this theory is correct, it also gives rise to the idea that Hippocamp is a third generation Neptunian moon.

This idea goes like this. When Neptune formed, it – like the other gas giants in the solar system – actually migrated outwards from the Sun. As it did so, it hauled along its original moons, created by the accretion of debris “left over” from the planet’s formation. Then, at some point, Neptune pulled massive Triton under its sway.

Such is the gravitational mass of Triton, its influence, couple with that of Neptune, likely resulted in some or all of Neptune’s original moons being ripped apart by gravitational tides. Proteus likely accreted out of the aftermath of this cataclysm, making it a second generation moon. Thus, with Hippocamp potentially being the remnants of a collision between Proteus and a comet, it becomes a third generation moon.

SpaceX launches Israel’s Moon Lander

February 21st, 2019 saw the launch of a Falcon 9 rocket carrying a US Air Force smallsat, an Indonesian communications satellite and Israel’s Beresheet lunar lander (see my February 4th Space Sunday report). Following the launch, the lander mission, designed by the non-profit SpaceIL organisation, was the first to separate from the Falcon’s upper stage, commencing a two month flight to the Moon, where it will hopefully become the first private mission to land on another body in the solar system, and allow Israel to join the handful of nations that have successfully reached the Moon.

Beresheet lunar lander. Credit: SpaceIL

It will take time to reach the Moon because the vehicle doesn’t carry the kind of propulsion system and fuel supplies to power its way away from Earth. Instead, over several weeks it will gradually raise its orbital altitude, slowly spiralling away from Earth until it is snagged by the lunar gravity.

As that point, Beresheet will commence a gentle spiral down towards the Moon, the last 6 days of which will place it into a circular orbit from which it can make a descent to its desired landing area, close to Mare Serenitatis (the Sea of Serenity), a region previously visited by Apollo 17 and Russia’s Luna 21.

Once on the Moon, the lander should operate for at least 2-3 days as the Sun rises over its landing site. While it may last longer, it is believed the fierce “midday” heat on the sunlight face of the Moon will likely to “cook” the lander’s electronics and imaging system. However, there is a chance they might survive to the end of the lunar “day”, in which case the plummeting temperatures of the lunar “night” will kill the vehicle with cold. Either way, I’ll hopefully have more on this mission come April.

Following launch, the first stage of the Falcon 9 made a successful return to Earth, landing on the autonomous drone ship Of Course I Still Love You, concluding its third successful flight.

Curiosity Suffers “Hiccup”

At a time when the world was saying “goodbye” to NASA’s Mars Exploration Rover Opportunity (see The Little Rover That Could), “Oppys”big cousin, the Mars Science Laboratory Curiosity, was having problems of its own.

On Friday, February 15th the rover was going through a boot sequence when it unexpectedly switched into a safe mode in what the mission team described as a “hiccup”. This brought a halt to rover operations (with the exception of communications with Earth) while the problem was investigated.

Engineers spent the weekend of the 16th / 17th February attempting to diagnose the problem, and after more that 30 successful reboots, the decision was made on Tuesday, February 19th to command Curiosity to exit safe mode to resume normal operations. However, given the recent ending of the Opportunity mission, the MSL team are understandably being cautious with Curiosity’s workload, as indicated in a statement issued on February 22nd.

We’re still not sure of [the fault’s] exact cause and are gathering the relevant data for analysis. The rover experienced a one-time computer reset but has operated normally ever since, which is a good sign. We’re currently working to take a snapshot of its memory to better understand what might have happened.

In the short-term, we are limiting commands to the vehicle to minimise changes to its memory. We don’t want to destroy any evidence of what might have caused the computer reset. As a result, we expect science operations will be suspended for a short period of time.

– Steven Lee, MSL Deputy Project Manager, February 22nd, 2019

The rover is currently exploring a region – dubbed “Glen Torridon” – where clay minerals can be seen from orbit. Clay minerals, which form in water, are especially interesting to the rover’s science team. While the engineers address the computer reset, the science team will continue studying images and other data that have been collected from “Glen Torridon”, including examining images of a potential sample gathering drill site some 200 m (656 ft) from where the rover is currently parked.