Tag: Spaceflight

China is readying for the next phases of its space ambitions.

In July, the country is due to launch its first mission to Mars. Officially referred to as the Mars Global Remote Sensing Orbiter and Small Rover mission, it comprises an orbiter, a lander vehicle and a small rover, with the orbiter and rover between them carrying the majority of the mission’s 18 scientific instruments.

The priorities for the mission include finding evidence of current or previous microbial life, and evaluating the planet’s surface and environment. In addition, solo and joint explorations of Mars, the orbiter and rover will produce maps of the Martian surface topography, and obtain data on soil characteristics, material composition, water ice, atmospheric composition, ionosphere field intensity, and other scientific data.

On April 24th, the Chinese announced the lander vehicle is to be called Tianwen, or “Quest for Heavenly Truth.” It will use a landing system comprising a parachute, retrorockets, and an airbag to achieve a soft landing. The rover will be solar powered, as with China’s Yutu family of lunar rovers.

The name represents the Chinese people’s relentless pursuit of truth, the country’s cultural inheritance of its understanding of nature and universe, as well as the unending explorations in science and technology.

– China’s National Space Administration (CNSA) statement

The Chinese tend to be fairly close-lipped about their space missions (among many other things), but from what has been announced, the mission is being built along similar lines to both NASA surface missions like InSight and MSL, and Europe’s ExoMars orbiter / lander missions. Following its arrival in Mars orbit in February 2021, the combined orbiter / lander will remain there for an unspecified period while the intended landing site is confirmed.

Once on the surface, the 200 gram 6-wheeled rover is expected to operate for at least 3 months, with a selection of its science systems comprising Ground-Penetrating Radar (GPR), to image about 100 m below the Martian surface, a magnetic field detector, a Mars meteorological instrument and multiple camera instruments. The rover is expected to be given its own name in due course.

At the same time, China rolled out a Long March 5B launcher in preparation for a mission to prove space station launch capabilities and to test a new spacecraft for deep space human space flight. It is expected to lift-off on, or around, May 5th 2020, carrying the first of China’s new generation of crew-capable vehicles designed to supersede the Soyuz-derived Shenzhou craft.

The new craft resembles an Apollo command and service module (CSM) combination, comprising a conical capsule vehicle protected by an atmospheric entry heat shield, and a cylindrical service module that provides the primary source of power and propulsion when operating in space. For the first flight, it will carry around 10 tonnes of fuel, intended to allow the vehicle to offer a similar mass to the core stage of the upcoming Chinese space station. The fuel will also allow the vehicle to reach a high orbit and and achieve a fast re-entry velocity.

This latter is important as the the new vehicle is intended for deep space crewed missions, including acting as the carrier for crews engaged in future missions to the Moon. Such missions will – like America’s Orion coming back from the Moon – return to Earth as a higher velocity than an orbital craft. As such, the first flight of this new Chinese vehicle will be somewhat similar in nature to the Orion’s first uncrewed flight in 2018.

To achieve its full envelope of uses, the new crew vehicle comes in two variants: a capsule and small service module which together weigh 14 tonnes, to be used in local orbital flights, and a version with a larger service module, giving a mass of 20 tonnes for the combined craft. This will likely be used for missions into deeper space. Either craft be able to carry up to six astronauts, or three astronauts and 500 kg of cargo to low Earth orbit.

Overall, the May launch of the vehicle has a lot hinging on it. A successful flight will clear the way for the two-month-long launch campaign required for the Mars Global Remote Sensing Orbiter and Small Rover mission mentioned above, using a Long March 5. In will also be see as opening the way for the Long March 5B vehicle to undergo a series of launches ahead of placing the 20-tonne Tianhe module, intended to be the core element of China’s new space station, due in early 2021. Weighing 20 tonnes, the module’s launch will mark the first in about a dozen that will be needed to complete the station between 2021 and 2022 /23.

When is an Exoplanet Not and Exoplanet?

As I’ve frequently remarked in these pages, we’ve so far confirmed the presence of over 4,000 exoplanets orbiting other stars. The number is such that it’s easy to think that detecting these worlds is just a matter of observing and waiting for that regular tell-tale dipping of brightness in a starts luminosity as seen from our orbiting telescopes, and which has been the more common means of detecting the worlds around other stars.

However, finding and confirming the presence of exoplanets is a complicated process, one that can be ripe with false positives. An example of this is Fomalhaut b, which has been puzzling astronomers since it was first observed in 2004. Orbiting the A-type main-sequence star Fomalhaut, some 25 light-years from Earth in the constellation of Piscis Austrinus, the planet was first observed by the Hubble Space Telescope, marking as the first to be detected in visible wavelengths (that is. the Direct Imaging Method).

Continue reading “Space Sunday: China’s missions and a disappearing “planet”” →

It is hard to believe fifty years after the fact, that with only two missions to surface of the Moon, America was ready to end its love affair with NASA by the time Apollo 13 lifted-off from Kennedy Space Centre’s Pad 39A at 19:13 UTC (14:13 EST) on Saturday, April 11th, 1970.

Already by that date, the Saturn V construction programme had been cancelled, leaving NASA with enough vehicles for seven more flights, and one of those (formerly Apollo 20) had been re-assigned to fly what would become the Skylab orbital laboratory (Apollo mission 18 and 19 would be later be cancelled completely their launch vehicles relegated to museum pieces).

Even Apollo 13 itself had something of a rocky path to the launch pad. Under the prevailing NASA crew rotation protocols, the prime crew for the mission was to have been Gordon Cooper, Edgar Mitchell, and Donn F.Eisele, but NASA’s Director of Flight Crew Operations Donald “Deke” Slayton vetoed any participation in a prime crew by Cooper, who had a lax attitude towards training, and by Eisle as a result of incidents that occurred in the Apollo 7 flight and for bringing the agency’s public image into disrepute as a result of an extramarital affair.

Instead, Slayton placed the crew due to fly Apollo 14 forward to take the prime slots for Apollo 13, with US Navy captain and veteran of three previous space flights, James Arthur “Jim” Lovell Jr., as commander and fellow test pilots Fred Haise (USAF) Thomas Kenneth “Ken” Mattingly II (USN) as the lunar module pilot (LMP) and command module pilot (CMP) respectively.  Their back-up crew were John Young, Charles Duke and John Leonard “Jack” Swigert Jr, with whom they shared time in training and simulation work for the mission.

Seven days prior to launch, Charles Duke was diagnosed with rubella, and Mattingly was the only man in the two crews not immune through prior exposure. Because of this, flight surgeons insisted he be removed from the prime crew in case he developed symptoms during the mission, and two days before launch, he was replaced by Swigert from the back-up crew (Mattingly subsequently never developed symptoms, and would eventually fly to the Moon on Apollo 16).

Even during the launch, the mission suffered what at the time appeared to be a relatively minor issue. Shortly after the separation of the Saturn V’s first stage the centre-most of the S-II second stage’s five engines was abruptly shut down automatically just 4 minutes into a planned 6.4 minute burn. The remaining four engines performed flawlessly, and no more thought was given to the issue at the time. Two and half hours later, the S-IVB upper stage motor was re-lit and Apollo 13 started its journey to the Moon.

Except for the launch, the three major TV networks showed little interest in Apollo 13. Planned broadcasts by the crew were not transmitted live, and America and the world carried on as if Apollo 13 wasn’t there.

After six successful Apollo flights, including two lunar landings, people were getting bored.

– Apollo 13 commander Jim Lovell reflecting on the lack of public
interest in the Apollo13 flight

All that changed on the night of April 13th/14th 1970, when the flight was almost 56 hours old and Apollo 13 was 330,00 km from Earth and less than a day from the Moon. The crew had just completed yet another televised transmission that had been ignored by the networks (and which included Richard Strauss’ Also Sprach Zarathustra, used as the iconic theme for Stanley Kubrick’s 2001 A Space Odyssey –  the latter being the command module’s (CM) call-sign), when mission control requested the crew carry out a number of tasks minor tasks, including one for Swigert, as CMP, to “stir” both of service module’s (SM) oxygen tanks.

These two tanks supplied oxygen both to the CM’s cabin and to the three fuel cells alongside them that provided electrical power to the entire command and service module (CSM) combination. Due to solar heating the oxygen in the tanks would “stratify”, so each day fans in to the tanks would be turned on to normalise the temperature and pressure readings. However, an extra stir had been requested in the hope of eliminating an incorrect pressure reading.

Swigert duly turned on the fans in both tanks as requested, and 90 seconds later, Apollo 13 was rocked by a “pretty large bang” that caused the attitude control system (ACS) to automatically fire to stabilise the vehicle, and the CM’s instruments to register sudden power fluctuations within the Main Bus B, one of the two electrical power distribution systems delivering electrical power to the CM.

The bang and fluctuations prompted Swigert and Lovell to both report to Earth that the vehicle had had a problem – but as instrument readings returned to normal, astronauts and engineers were momentarily confused. Lovell actually thought Haise had opened the LM’s cabin repressurisation valve (which also caused a bang) in an attempt to startle his crew mates. But Haise’s expression as he came up through the docking tunnel from the LM indicated he was as equally confused by the noise. Then the electrical output from both the power distribution systems started falling.

“OK Houston, we’ve had a problem here…” Swigert and Lovell in turn report Apollo 13 could be in difficulties

Checking the status of the three SM fuel cells, Haise found two completely dead and the third dangerously low. Swigert, engaged in checking the slowly decreasing pressure in oxygen tank 1 flipped the displays to check tank 2, only to find it completely depleted. Moving to the CM’s windows, Lovell reported the SM appeared to be venting “a gas of some sort” and the vehicle as being surrounded by a cloud of fine debris – clearly, something was seriously wrong.

Worse, struggling to maintain power levels, the surviving cell  was drawing on oxygen from the CM’s surge tank. This was a reserve of oxygen intended to supply the crew with a breathable atmosphere at the end of a mission, between the CM detaching from the SM and splashing down on Earth. Were that supply to be depleted, the crew would face certain death.

Realising the significance of the surge tank situation, veteran flight controller and White Team leader Eugene Francis “Gene” Kranz, ordered the fuel cell immediately isolated from the surge tank’s oxygen supply. This left the crew with an estimated 2 hours of oxygen to in tank 1 to power the remaining fuel cell before it was also depleted, killing the command module – and the crew. With that realisation, Apollo 13 switched from being a lunar landing mission to a rescue mission.

My concern was increasing all the time. It went from, “I wonder what this is going to do to the landing?” To “I wonder if we can get back home again?”

– Apollo 13 commander Jim Lovell at a post-flight press conference,
May 1970.

Two options were available for bringing the crew home: a direct abort or a free return. The first involved turning the CSM / LM combination through 180° and then using the big service propulsion system (SPS) on the SM to reverse course and fly back to Earth, which would take about 2 days.

The free return option involved continuing on around the Moon and using its gravity, combined with an engine burn, to return to Earth in about 4 days. Both approaches would require the crew to power down the CM and use the LM as a lifeboat – something that NASA had actually planned for just after the first Apollo flight to the Moon (Apollo 8, which also had Jim Lovell as a member of the crew).

Gee, I think back in Apollo 9 we first started looking at the LEM [Lunar Excursion Module, NASA’s original official title for the lunar module] as more-or-less a lifeboat and fortunately, although the exact procedures do not tailor the exact case we’ve got, we looked at the utilisation of the LEM for an awfully long time. So we knew what the limitations were and we developed workaround procedures wherever it was possible. I think the LEM spacecraft is in excellent shape and it’s fully capable of getting the crew back.

– Lead Flight Director, Apollo 13, Gene Kranz during a press conference,
April 14th, 1970

Mercury, the closest planet in our solar system to the Sun, is hardly the kind of place where you’d expect to find water ice. With surface temperatures reaching 400º C (750º F) on its sunlit side, the planet is fairly constantly broiled by the Sun. And yet NASA’s MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission did actually confirm ice on Mercury in 2012.

As with ice on the Moon, this water ice is located in deep craters around Mercury’s poles where the Sun never shines. What’s more, it appears to be created through a similar process and the lunar water ice; however, and in what may seem to be a counter-intuitive fact, the greater heat Mercury endures means it has far more ice located in its polar craters than the Moon.

It goes like this, electrically charged particles from the Sun’s solar wind interact with the oxygen present in some dust grains on the surface to produce hydroxyl  (OH – a single hydrogen atom and a single oxygen atom). This hydroxyl bonds in groups within Mercury’s surface material, just as they do on the Moon.

On both the Moon and Mercury, heat from the Sun both frees these hydroxyl groups and energises them, causing collisions that that produce free hydrogen and water molecules. Some of these water molecules are broken down by sunlight and dissipate. But others descend into deep, dark polar craters that are shielded from the Sun. Here they freeze to become a part of the growing, permanent glacial ice housed in the shadows.

However, because Mercury is so much closer to the Sun, the greater exposure to the solar wind and  – more importantly – greater heat means that the production and release of hydroxyl means that the production of hydrogen and water molecules is much greater – and some is the volume of those molecules falling into polar craters. Thus, the production of water ice on Mercury is much more pronounced – so pronounced that it is estimated some 10,000,000,000,000 kg (11,023,110,000 tons) of ice is generated over the course of 3 million years, cumulatively enough to account for around 10% on the total ice found on and under the surface of Mercury – the rest having being delivered via asteroid bombardment in the planet’s early history.

The process of the ice falling into the craters is a little like the song Hotel California. The water molecules can check in to the shadows, but they can never leave.

– Thom Orlando, Georgia Tech, a co-author of a new study into water ice on Mercury

Starliner: 61 Changes Required

On Friday, December 20th, 2019, NASA and Boeing, together with launch partner United Launch Alliance (ULA), attempted to undertake the first flight of the Boeing CST-100 Starliner commercial crew transportation system to the International Space Station (ISS).

The mission – called Orbital Flight Test-1 (OFT-1) should have seen the uncrewed Starliner craft achieve orbit and then rendezvous with the ISS, where it would dock and spend several days there before making a return to Earth and a parachute landing in the Mojave desert.

While, as I reported in Starliner’s first orbital flight, the majority of the mission was a success – the vehicle achieved orbit and was able to carry out as series of orbital tests before returning safely to a soft landing, issues with the craft meant the capsule incorrectly initiated a series of firings of the vehicle’s attitude control system (ACS) when they were not required. By the time the errors were corrected, the vehicle had insufficient fuel reserves left in the ACS system tanks to achieve a safe docking with the station, thus causing the rendezvous to be abandoned.

Since then, NASA and Boeing have been investigating the root cause of the ACS timing misfiring. The results of these investigations identified both technical and organisational issues within Boeing’s management of the CST-100 programme. At the same time, a NASA internal review identified several areas where the agency could make improvements with regard to its participation in the production and testing of Orion capsules.

In all, some 61 corrective actions have been identified by NASA that Boeing need to make to both the processing of Orion vehicles and in their flight management organisation. These include gaps in processes that prevented ground-based mission controllers identifying what had gone wrong with OFT-1 in order to initiate corrective action that might have allowed the vehicle to go forward with its rendezvous with the ISS.

Boeing has accepted all 61 recommendations from NASA, and has started to implement them. At the same time, it has indicated it is to overhaul all of its testing, review, and approval processes for CST-100 hardware and software, and institute changes with its engineering board authority. NASA also plans to perform an Organisation Safety Assessment (OSA) of the workplace culture at Boeing prior to any future CST-100 flights.

While there was no crew aboard the test vehicle, NASA has nevertheless designated the flight a “high visibility close call” in accordance with their own procedural requirements. This means that while it is unlikely they would have threatened a crew had they been aboard (in fact, a crew would likely have been able to immediately respond to the ACS issue and correct it) the anomalies during the flight were simply too big to ignore, and could have led to serious consequences under different circumstances.

No date has yet been confirmed for the second orbital flight for a Starliner vehicle. This is due to deliver a crew of three NASA astronauts (Nicole Mann, Mike Fincke and Christopher Ferguson) to what might yet be an extended stay at the ISS in what is regarded as the final test flight for the CST-100.

The first “operational” flight for Orion will comprise NASA personnel: mission commander Sunita Williams and Josh Cassada, ESA astronaut Thomas Pesquet and cosmonaut Andrei Borisenko. This flight will see the vehicle used in OFT-1 re-used as part of NASA’s plans to fly each CST-100 a number of times. Commander Williams was on hand to witness the vehicle’s return to Earth at the end of OFT-1, and she named the vehicle Calypso.