RetiredRocketDocBlog Week of February 28, 2021

Interesting Space News


Space News (3/3, Subscription Publication) reports that the Space-X Starship prototype was launched from the company’s Boca Chica, Texas, “test site at about 6:15 p.m. Eastern. A launch attempt three hours earlier was aborted at engine ignition because of a ‘slightly conservative high thrust limit,’” SpaceX CEO Elon Musk tweeted. The vehicle “flew to a planned peak altitude of 10 kilometers, shutting down its three Raptor engines in sequence during the ascent. The vehicle then performed a ‘belly flop’ maneuver to a horizontal orientation to descend back to its landing pad.” On the “two previous Starship test flights, SpaceX had problems reigniting two Raptor engines needed for a powered landing after flipping back to a vertical orientation.” SpaceX “changed the procedure on this landing attempt, igniting all three and then shutting down two as needed for the landing.” The vehicle “touched down on the pad softly, rather than crash and explode, about six minutes and 20 seconds after liftoff.” The vehicle then exploded, approximately “eight minutes after landing.”

The Hill (3/3) reports that the “cause of the explosion this time around remains unknown.” SpaceX principal integration engineer John Insprucker said, “The Texas team has several more suborbital test vehicles in build, with number 11 ready to roll out to the pad in the very near future.” Musk “said the company is still ‘highly confident’ the crafts will be safe enough to carry passengers by 2023, although development and testing only began in 2019.”


I watched the broadcast and the article above fails to mention a bright stubborn fire at the base of the vehicle for a minute or so after landing. Unfortunately, I turned off the broadcast prior to the explosion. The intact landing was a major accomplishment. The fire and the resulting explosion were an O-Shit probably caused by a minor structural failure or a valve failure at landing. Unfortunately, there wasn’t much left to analyze so I hope telemetry gives them some clue as to what failed. I expect the explosion will delay the next launch, but if they can find the problem there shouldn’t be that much of a delay. I give Space-X full marks for solving the very difficult controls problem. The “belly flop” reentry attitude greatly simplifies their Thermal Protection System requirements and will reduce design and operating costs.


NetJets Obtains Purchase Right For 20 Of Aerion’s AS2 Supersonic Business Jets

Reuters (3/3) reports that Aerion “said on Wednesday Berkshire Hathaway’s private aircraft firm, NetJets, has obtained purchase rights for 20 of its AS2 business jets.” The AS2 “will be powered by engineered synthetic fuel and can reach supersonic speeds of up to Mach 1.4, or about 1,000 miles (1,610 km) per hour, which is 150% faster than conventional business jets, Aerion said.” Aerion, which is backed by The Boeing Company, now has a “global order backlog for the AS2...valued at more than $10 billion.”


I hate to admit it, but I was part of the SST team at Boeing back in the early 1970s. We ended up with a design that cruised at Mach 2.7, but it was not going to be allowed to fly supersonic over land because of the sonic boom problem. The aircraft pushes a sonic shock ahead of its nose because the air can’t get out of the way fast enough. When this “shock wave” propagates outward and when it reaches the ground, it is like the boom after lightning only it is strong enough to break window glass. The legal liability for thousands of broken windows essentially prevented the SST from overland supersonic flights. The inability to fly fast over land gutted the economics of the SST and was the main reason the program got cancelled. Now the Aerion AS2 is a different design and if it cruises high enough so that the shock wave at Mach 1.4 dissipates before it reaches the ground, they can avoid the sonic boom problem and their economics stand a chance. I assume they have done their homework, and all is well.


Space News (3/4, Subscription Publication) reports that NASA “has sharply increased the prices it charges commercial users of the International Space Station for cargo and other resources, a move that has left some companies confused and frustrated.” NASA said on its website that it was updating prices “to reflect full reimbursement for the value of NASA resources.” With the updated prices, “the cost to transport one kilogram of cargo up to the station, known as ‘upmass,’ went from $3,000 to $20,000. The cost to bring that one kilogram back down from the station, ‘downmass,’ went from $6,000 to $40,000. One hour of crew member time, previously $17,500, is now $130,000.


Why would NASA increase prices this much at this time? As far as I can tell it will not significantly change NASA’s ISS space budgets, so it must be to discourage future commercial space ventures. I have dealt with NASA space politics for over forty years, and this is just another of a never-ending string of NASA decisions to handicap or kill nascent commercial space entrepreneurs. Usually, it takes the form of offering a service for free that a commercial space company is planning offer as a business. A good example was a dedicated zero-gee commercial testing satellite to fly in the early 1990s. As soon as the prospective went out, NASA decided to offer the same service for free on the Shuttle and then on the ISS. I have never got a straight answer on why NASA does this, but it definitely happens.


Space News (3/4, Subscription Publication) reports that the Space Development Agency will issue a request for proposals (RFP) for the procurement of up to 150 satellites that will be launched in late 2024, Director Derek Tournear said Thursday. The RFP will be issued in August, and multiple contracts could be awarded by the end of the year, Tournear said. The agency “is building a fleet of satellites in low Earth orbit that includes a Transport Layer of data-relay satellites and a Tracking Layer of sensor satellites to detect and track missiles.” Tournear said that the Space Development Agency will meet with military leaders’ March 31 “to essentially decide what the minimum viable product is for Tranche 1.”


This makes sense but Low Earth Orbit (LEO) is getting crowded and one of these days two of the thousands of satellites in LEO are going to collide and generate a whole bunch of debris that is going to be hard to live with. My recommendation is to combine several features on each satellite and reduce the total fleet to a few thousand satellites instead of tens of thousands.

This would reduce the mean time to collision from a few years to tens of years and save a lot of future trouble.


Reuters (3/4) reports that scientists “have spotted a planet orbiting a star relatively near our solar system that may offer a prime opportunity to study the atmosphere of a rocky Earth-like alien world – the type of research that could aid the hunt for extraterrestrial life.” The researchers “said on Thursday the planet, called Gliese 486 b and classified as a ‘super-Earth,’ is not itself a promising candidate as a refuge for life.” However, the planet’s “proximity to Earth and its physical traits make it well suited for a study of its atmosphere with the next generation of space-borne and ground-based telescopes, starting with the James Webb Space Telescope that NASA has slated for an October launch.” An investigation of Gliese 486 b “could give scientists data to be able to decipher the atmospheres of other exoplanets, ... including ones that may host life.”


Gliese 486 is an M-dwarf star located 26.3 light-years away in the constellation of Virgo. Gliese 486 b is a hot Neptune with a measured temperature of about 820 deg F. It is close enough so that some atmospheric characteristics can be measured, but I’m having trouble as to how anything we can measure is applicable to Earth? Maybe the new James Webb Space Telescope can prove me wrong.


That’s my summary of the interesting Space News for this week.


Thanks for Reading


Dana Andrews

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