Back on Thursday, I posted an article about
the House NASA Reauthorization bill
that was going through the process and the impacts coming, including putting
up more programs for the private sector to bid on and take the lead in
them.
When that bill passed,
lawmakers had added an additional change to it.
Another add-on to the authorization bill would require NASA to reassess
whether to guide the International Space Station (ISS) toward a destructive
atmospheric reentry after it is decommissioned in 2030. The space agency’s
current plan is to deorbit the space station in 2031 over the Pacific Ocean,
where debris that survives the scorching reentry will fall into a remote,
unpopulated part of the sea.
...
The amendment tacked onto this year’s bill would not change the timeline for
ending operations on the ISS, but it asks NASA to reconsider its decision
about what to do with the complex after retirement.
The amendment would direct NASA to “carry out an engineering analysis to
evaluate the technical, operational, and logistical viability of
transferring the ISS to a safe orbital harbor and storing the ISS in such
harbor after the end of the operational low-Earth orbit lifetime of the ISS
to preserve the ISS for potential reuse and satisfy the objectives of NASA.”
Rep. George Whitesides (D-Calif.) and cosponsor Rep. Nick Begich
(R-Alaska) submitted the amendment, much like the amendment mentioned in
Thursday's post had bipartisan sponsors. It probably "looks better" (sells
better) than an amendment put up by only one side. Whitesides was a NASA
chief of staff and had been an executive in the space industry before his
election to the House.
In essence this is the same concept that several people have asked about
retiring the ISS here on the blog and, honestly, gets asked everywhere. Instead of splashing the ISS
into a deep spot in the Pacific, why not put it into a higher
orbit?
“The International Space Station is one of the most complex engineering
achievements in human history,” Whitesides said. “It represents more than
three decades of international collaboration and investment by US taxpayers
estimated at well over $100 billion. Current plans call for the station to
be deorbited at the end of its service life in 2030. This amendment does not
seek to change that policy. Instead, it asks a straightforward question:
Before we permanently dispose of an asset of this magnitude, should we fully
understand whether it’s viable to preserve it in orbit for potential use by
future generations?”
Of course, this has been analyzed before in the sense of determining just how
much orbital velocity has to be changed to get the desired change. That was
required to create the contract telling the eventual winning bidder (SpaceX) how much
change in orbital velocity is required to start to deorbit the ISS. A good
approximation of everything in the Low Earth Orbit range of the station is
that its orbital velocity is 17,000 mph. The required change in velocity is
127 mph, which is a tiny percentage of its current velocity: 0.75%.
Changing its speed by just 127 mph will consume about 10 tons (9 metric
tons) of propellant, according to a
NASA analysis released in 2024.
Everyone now is thinking how much mass are we talking about? The station mass
is around 450 tons, equivalent to two freight train locomotives, and measures
about the size of a football field.
The analysis document shows that NASA considered alternatives to discarding
the space station through reentry. One option NASA studied involved moving
the station into a higher orbit. At its current altitude, roughly 260 miles
(420 kilometers) above the Earth, the ISS would take one to two years to
reenter the atmosphere due to aerodynamic drag if reboosts weren’t
performed. NASA does not want the space station to make an uncontrolled
reentry because of the risk of fatalities, injuries, and property damage
from debris reaching the ground.
The amount of fuel required is around twice that 10 tons necessary to de-orbit
the ISS.
At that altitude, without any additional boosts, NASA says the space station
would likely remain in orbit for 100 years before succumbing to atmospheric
drag and burning up. Going higher still, the space station could be placed
in a 1,200-mile-high (2,000-kilometer) orbit, stable for more than 10,000
years, with about 146 tons (133 metric tons) of propellant.
There are two problems with sending the ISS to higher altitudes. One is that
it would require the development of new propulsive and tanker vehicles that
do not currently exist, according to NASA.
Developing new tankers and a new "Deorbit Dragon" isn't the end to the
possible difficulties. Putting the station in a higher orbit, also exposes it
to a higher chance of impact from space junk. The engineers who did that 2024
analysis say the peak risk is at an orbital height of 500 miles. “This
means that the likelihood of an impact leaving station unable to maneuver or
react to future threats, or even a significant impact resulting in complete
fragmentation, is unacceptably high.”
An alternative they don't spend much time examining is "leave it where it
is." NASA said in 2024 that engineers have “high confidence” that the
primary structure of the station could support operations beyond 2030. It's undoubtedly higher risk the longer the station stays there, and maybe some
sections could be replaced or just left empty and unused.
The oldest segments of the station have been in orbit since 1998, undergoing
day-night thermal cycles every 45 minutes as they orbit the planet. The
structural stability of the Russian section of the outpost is also in
question. Russian engineers traced a
small but persistent air leak
to microscopic structural cracks in one Russian module, but cosmonauts were
able to seal the cracks, and air pressure in the area is “holding steady,” a
NASA spokesperson said last month.
All that said, there's absolutely nothing wrong with asking, "are we doing the
right thing or being stupid?" Paying for another round of analysis, perhaps
with some different assumptions, could be good thing.
Then there's the way NASA has been encouraging the development of private space stations like the Vast Haven-1. Let the private sector develop the stations, make income from them, and let them decide how to handle problems like this. They're not as far along as everyone was talking about, but when has a new technology not had moments like that?
I'll just conclude with a saying that I like. "When you're doing things no one
has ever done before, you learn things no one has ever known before." A decision
like this has several of those things no one has done before embedded in it.
Artist’s illustration of SpaceX’s deorbit vehicle, based on the design of the company’s Dragon spacecraft. The modified spacecraft will have 46 Draco thrusters—30 for the deorbit maneuvers and 16 for attitude control. Credit: SpaceX